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Overview
Comment:1.0.41.0
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | sourceforge
Files: files | file ages | folders
SHA1: 06c93533ad49cfbd3561a63a29c4abbe17dbbc2c
User & Date: rmsimpson 2007-04-22 23:23:43
Context
2007-04-23
07:59
1.0.41.0 check-in: acd17b1cf8 user: rmsimpson tags: sourceforge
2007-04-22
23:23
1.0.41.0 check-in: 06c93533ad user: rmsimpson tags: sourceforge
2007-01-30
15:20
3.3.12 check-in: daf72d2d8e user: rmsimpson tags: sourceforge
Changes
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Added SQLite.Interop/FTS1/FTS1.vcproj.

















































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































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<?xml version="1.0" encoding="Windows-1252"?>
<VisualStudioProject
	ProjectType="Visual C++"
	Version="8.00"
	Name="SQLite.Interop.FTS1"
	ProjectGUID="{BCD6CA74-771B-49EE-9025-606CB839DA0B}"
	RootNamespace="FTS1"
	Keyword="Win32Proj"
	>
	<Platforms>
		<Platform
			Name="Win32"
		/>
		<Platform
			Name="Pocket PC 2003 (ARMV4)"
		/>
		<Platform
			Name="Itanium"
		/>
		<Platform
			Name="x64"
		/>
	</Platforms>
	<ToolFiles>
	</ToolFiles>
	<Configurations>
		<Configuration
			Name="Debug|Win32"
			OutputDirectory="$(ConfigurationName)"
			IntermediateDirectory="$(ConfigurationName)"
			ConfigurationType="4"
			CharacterSet="1"
			>
			<Tool
				Name="VCPreBuildEventTool"
			/>
			<Tool
				Name="VCCustomBuildTool"
			/>
			<Tool
				Name="VCXMLDataGeneratorTool"
			/>
			<Tool
				Name="VCWebServiceProxyGeneratorTool"
			/>
			<Tool
				Name="VCMIDLTool"
			/>
			<Tool
				Name="VCCLCompilerTool"
				Optimization="0"
				PreprocessorDefinitions="WIN32;_DEBUG;_LIB;SQLITE_ENABLE_FTS1"
				RuntimeLibrary="3"
				RuntimeTypeInfo="false"
				UsePrecompiledHeader="0"
				DebugInformationFormat="3"
			/>
			<Tool
				Name="VCManagedResourceCompilerTool"
			/>
			<Tool
				Name="VCResourceCompilerTool"
			/>
			<Tool
				Name="VCPreLinkEventTool"
			/>
			<Tool
				Name="VCLibrarianTool"
			/>
			<Tool
				Name="VCALinkTool"
			/>
			<Tool
				Name="VCXDCMakeTool"
			/>
			<Tool
				Name="VCBscMakeTool"
			/>
			<Tool
				Name="VCFxCopTool"
			/>
			<Tool
				Name="VCPostBuildEventTool"
			/>
		</Configuration>
		<Configuration
			Name="Release|Win32"
			OutputDirectory="$(ConfigurationName)"
			IntermediateDirectory="$(ConfigurationName)"
			ConfigurationType="4"
			CharacterSet="1"
			WholeProgramOptimization="1"
			>
			<Tool
				Name="VCPreBuildEventTool"
			/>
			<Tool
				Name="VCCustomBuildTool"
			/>
			<Tool
				Name="VCXMLDataGeneratorTool"
			/>
			<Tool
				Name="VCWebServiceProxyGeneratorTool"
			/>
			<Tool
				Name="VCMIDLTool"
			/>
			<Tool
				Name="VCCLCompilerTool"
				FavorSizeOrSpeed="1"
				PreprocessorDefinitions="WIN32;NDEBUG;_LIB;SQLITE_ENABLE_FTS1"
				StringPooling="true"
				ExceptionHandling="0"
				BufferSecurityCheck="false"
				EnableFunctionLevelLinking="true"
				RuntimeTypeInfo="false"
				UsePrecompiledHeader="0"
			/>
			<Tool
				Name="VCManagedResourceCompilerTool"
			/>
			<Tool
				Name="VCResourceCompilerTool"
			/>
			<Tool
				Name="VCPreLinkEventTool"
			/>
			<Tool
				Name="VCLibrarianTool"
			/>
			<Tool
				Name="VCALinkTool"
			/>
			<Tool
				Name="VCXDCMakeTool"
			/>
			<Tool
				Name="VCBscMakeTool"
			/>
			<Tool
				Name="VCFxCopTool"
			/>
			<Tool
				Name="VCPostBuildEventTool"
			/>
		</Configuration>
		<Configuration
			Name="Debug|Pocket PC 2003 (ARMV4)"
			OutputDirectory="$(PlatformName)\$(ConfigurationName)"
			IntermediateDirectory="$(PlatformName)\$(ConfigurationName)"
			ConfigurationType="4"
			CharacterSet="1"
			>
			<Tool
				Name="VCPreBuildEventTool"
			/>
			<Tool
				Name="VCCustomBuildTool"
			/>
			<Tool
				Name="VCXMLDataGeneratorTool"
			/>
			<Tool
				Name="VCWebServiceProxyGeneratorTool"
			/>
			<Tool
				Name="VCMIDLTool"
				TargetEnvironment="1"
			/>
			<Tool
				Name="VCCLCompilerTool"
				ExecutionBucket="7"
				AdditionalOptions="/GS-"
				Optimization="0"
				PreprocessorDefinitions="WIN32;_DEBUG;_LIB;SQLITE_ENABLE_FTS1"
				RuntimeTypeInfo="false"
				UsePrecompiledHeader="0"
				DebugInformationFormat="3"
			/>
			<Tool
				Name="VCManagedResourceCompilerTool"
			/>
			<Tool
				Name="VCResourceCompilerTool"
			/>
			<Tool
				Name="VCPreLinkEventTool"
			/>
			<Tool
				Name="VCLibrarianTool"
			/>
			<Tool
				Name="VCALinkTool"
			/>
			<Tool
				Name="VCXDCMakeTool"
			/>
			<Tool
				Name="VCBscMakeTool"
			/>
			<Tool
				Name="VCCodeSignTool"
			/>
			<Tool
				Name="VCPostBuildEventTool"
			/>
			<DeploymentTool
				ForceDirty="-1"
				RemoteDirectory=""
				RegisterOutput="0"
				AdditionalFiles=""
			/>
			<DebuggerTool
			/>
		</Configuration>
		<Configuration
			Name="Release|Pocket PC 2003 (ARMV4)"
			OutputDirectory="$(PlatformName)\$(ConfigurationName)"
			IntermediateDirectory="$(PlatformName)\$(ConfigurationName)"
			ConfigurationType="4"
			CharacterSet="1"
			WholeProgramOptimization="1"
			>
			<Tool
				Name="VCPreBuildEventTool"
			/>
			<Tool
				Name="VCCustomBuildTool"
			/>
			<Tool
				Name="VCXMLDataGeneratorTool"
			/>
			<Tool
				Name="VCWebServiceProxyGeneratorTool"
			/>
			<Tool
				Name="VCMIDLTool"
				TargetEnvironment="1"
			/>
			<Tool
				Name="VCCLCompilerTool"
				ExecutionBucket="7"
				FavorSizeOrSpeed="1"
				PreprocessorDefinitions="WIN32;NDEBUG;_LIB;SQLITE_ENABLE_FTS1"
				StringPooling="true"
				ExceptionHandling="0"
				BufferSecurityCheck="false"
				EnableFunctionLevelLinking="true"
				RuntimeTypeInfo="false"
				UsePrecompiledHeader="0"
			/>
			<Tool
				Name="VCManagedResourceCompilerTool"
			/>
			<Tool
				Name="VCResourceCompilerTool"
			/>
			<Tool
				Name="VCPreLinkEventTool"
			/>
			<Tool
				Name="VCLibrarianTool"
			/>
			<Tool
				Name="VCALinkTool"
			/>
			<Tool
				Name="VCXDCMakeTool"
			/>
			<Tool
				Name="VCBscMakeTool"
			/>
			<Tool
				Name="VCCodeSignTool"
			/>
			<Tool
				Name="VCPostBuildEventTool"
			/>
			<DeploymentTool
				ForceDirty="-1"
				RemoteDirectory=""
				RegisterOutput="0"
				AdditionalFiles=""
			/>
			<DebuggerTool
			/>
		</Configuration>
		<Configuration
			Name="Debug|Itanium"
			OutputDirectory="$(PlatformName)\$(ConfigurationName)"
			IntermediateDirectory="$(PlatformName)\$(ConfigurationName)"
			ConfigurationType="4"
			CharacterSet="1"
			>
			<Tool
				Name="VCPreBuildEventTool"
			/>
			<Tool
				Name="VCCustomBuildTool"
			/>
			<Tool
				Name="VCXMLDataGeneratorTool"
			/>
			<Tool
				Name="VCWebServiceProxyGeneratorTool"
			/>
			<Tool
				Name="VCMIDLTool"
				TargetEnvironment="2"
			/>
			<Tool
				Name="VCCLCompilerTool"
				Optimization="0"
				PreprocessorDefinitions="WIN32;_DEBUG;_LIB;SQLITE_ENABLE_FTS1"
				RuntimeLibrary="3"
				RuntimeTypeInfo="false"
				UsePrecompiledHeader="0"
				DebugInformationFormat="3"
			/>
			<Tool
				Name="VCManagedResourceCompilerTool"
			/>
			<Tool
				Name="VCResourceCompilerTool"
			/>
			<Tool
				Name="VCPreLinkEventTool"
			/>
			<Tool
				Name="VCLibrarianTool"
			/>
			<Tool
				Name="VCALinkTool"
			/>
			<Tool
				Name="VCXDCMakeTool"
			/>
			<Tool
				Name="VCBscMakeTool"
			/>
			<Tool
				Name="VCFxCopTool"
			/>
			<Tool
				Name="VCPostBuildEventTool"
			/>
		</Configuration>
		<Configuration
			Name="Release|Itanium"
			OutputDirectory="$(PlatformName)\$(ConfigurationName)"
			IntermediateDirectory="$(PlatformName)\$(ConfigurationName)"
			ConfigurationType="4"
			CharacterSet="1"
			WholeProgramOptimization="1"
			>
			<Tool
				Name="VCPreBuildEventTool"
			/>
			<Tool
				Name="VCCustomBuildTool"
			/>
			<Tool
				Name="VCXMLDataGeneratorTool"
			/>
			<Tool
				Name="VCWebServiceProxyGeneratorTool"
			/>
			<Tool
				Name="VCMIDLTool"
				TargetEnvironment="2"
			/>
			<Tool
				Name="VCCLCompilerTool"
				FavorSizeOrSpeed="1"
				PreprocessorDefinitions="WIN32;NDEBUG;_LIB;SQLITE_ENABLE_FTS1"
				StringPooling="true"
				ExceptionHandling="0"
				BufferSecurityCheck="false"
				EnableFunctionLevelLinking="true"
				RuntimeTypeInfo="false"
				UsePrecompiledHeader="0"
			/>
			<Tool
				Name="VCManagedResourceCompilerTool"
			/>
			<Tool
				Name="VCResourceCompilerTool"
			/>
			<Tool
				Name="VCPreLinkEventTool"
			/>
			<Tool
				Name="VCLibrarianTool"
			/>
			<Tool
				Name="VCALinkTool"
			/>
			<Tool
				Name="VCXDCMakeTool"
			/>
			<Tool
				Name="VCBscMakeTool"
			/>
			<Tool
				Name="VCFxCopTool"
			/>
			<Tool
				Name="VCPostBuildEventTool"
			/>
		</Configuration>
		<Configuration
			Name="Debug|x64"
			OutputDirectory="$(PlatformName)\$(ConfigurationName)"
			IntermediateDirectory="$(PlatformName)\$(ConfigurationName)"
			ConfigurationType="4"
			CharacterSet="1"
			>
			<Tool
				Name="VCPreBuildEventTool"
			/>
			<Tool
				Name="VCCustomBuildTool"
			/>
			<Tool
				Name="VCXMLDataGeneratorTool"
			/>
			<Tool
				Name="VCWebServiceProxyGeneratorTool"
			/>
			<Tool
				Name="VCMIDLTool"
				TargetEnvironment="3"
			/>
			<Tool
				Name="VCCLCompilerTool"
				Optimization="0"
				PreprocessorDefinitions="WIN32;_DEBUG;_LIB;SQLITE_ENABLE_FTS1"
				RuntimeLibrary="3"
				RuntimeTypeInfo="false"
				UsePrecompiledHeader="0"
				DebugInformationFormat="3"
			/>
			<Tool
				Name="VCManagedResourceCompilerTool"
			/>
			<Tool
				Name="VCResourceCompilerTool"
			/>
			<Tool
				Name="VCPreLinkEventTool"
			/>
			<Tool
				Name="VCLibrarianTool"
			/>
			<Tool
				Name="VCALinkTool"
			/>
			<Tool
				Name="VCXDCMakeTool"
			/>
			<Tool
				Name="VCBscMakeTool"
			/>
			<Tool
				Name="VCFxCopTool"
			/>
			<Tool
				Name="VCPostBuildEventTool"
			/>
		</Configuration>
		<Configuration
			Name="Release|x64"
			OutputDirectory="$(PlatformName)\$(ConfigurationName)"
			IntermediateDirectory="$(PlatformName)\$(ConfigurationName)"
			ConfigurationType="4"
			CharacterSet="1"
			WholeProgramOptimization="1"
			>
			<Tool
				Name="VCPreBuildEventTool"
			/>
			<Tool
				Name="VCCustomBuildTool"
			/>
			<Tool
				Name="VCXMLDataGeneratorTool"
			/>
			<Tool
				Name="VCWebServiceProxyGeneratorTool"
			/>
			<Tool
				Name="VCMIDLTool"
				TargetEnvironment="3"
			/>
			<Tool
				Name="VCCLCompilerTool"
				FavorSizeOrSpeed="1"
				PreprocessorDefinitions="WIN32;NDEBUG;_LIB;SQLITE_ENABLE_FTS1"
				StringPooling="true"
				ExceptionHandling="0"
				BufferSecurityCheck="false"
				EnableFunctionLevelLinking="true"
				RuntimeTypeInfo="false"
				UsePrecompiledHeader="0"
			/>
			<Tool
				Name="VCManagedResourceCompilerTool"
			/>
			<Tool
				Name="VCResourceCompilerTool"
			/>
			<Tool
				Name="VCPreLinkEventTool"
			/>
			<Tool
				Name="VCLibrarianTool"
			/>
			<Tool
				Name="VCALinkTool"
			/>
			<Tool
				Name="VCXDCMakeTool"
			/>
			<Tool
				Name="VCBscMakeTool"
			/>
			<Tool
				Name="VCFxCopTool"
			/>
			<Tool
				Name="VCPostBuildEventTool"
			/>
		</Configuration>
	</Configurations>
	<References>
	</References>
	<Files>
		<Filter
			Name="Source Files"
			Filter="cpp;c;cc;cxx;def;odl;idl;hpj;bat;asm;asmx"
			UniqueIdentifier="{4FC737F1-C7A5-4376-A066-2A32D752A2FF}"
			>
			<File
				RelativePath=".\fts1.c"
				>
			</File>
			<File
				RelativePath=".\fts1_hash.c"
				>
			</File>
			<File
				RelativePath=".\fts1_porter.c"
				>
			</File>
			<File
				RelativePath=".\fts1_tokenizer1.c"
				>
			</File>
		</Filter>
		<Filter
			Name="Header Files"
			Filter="h;hpp;hxx;hm;inl;inc;xsd"
			UniqueIdentifier="{93995380-89BD-4b04-88EB-625FBE52EBFB}"
			>
			<File
				RelativePath=".\fts1.h"
				>
			</File>
			<File
				RelativePath=".\fts1_hash.h"
				>
			</File>
			<File
				RelativePath=".\fts1_tokenizer.h"
				>
			</File>
			<File
				RelativePath=".\sqlite3.h"
				>
			</File>
			<File
				RelativePath=".\sqlite3ext.h"
				>
			</File>
		</Filter>
		<Filter
			Name="Resource Files"
			Filter="rc;ico;cur;bmp;dlg;rc2;rct;bin;rgs;gif;jpg;jpeg;jpe;resx;tiff;tif;png;wav"
			UniqueIdentifier="{67DA6AB6-F800-4c08-8B7A-83BB121AAD01}"
			>
		</Filter>
		<File
			RelativePath=".\ReadMe.txt"
			>
		</File>
	</Files>
	<Globals>
	</Globals>
</VisualStudioProject>

Added SQLite.Interop/FTS1/fts1.c.












































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































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/* The author disclaims copyright to this source code.
 *
 * This is an SQLite module implementing full-text search.
 */

/*
** The code in this file is only compiled if:
**
**     * The FTS1 module is being built as an extension
**       (in which case SQLITE_CORE is not defined), or
**
**     * The FTS1 module is being built into the core of
**       SQLite (in which case SQLITE_ENABLE_FTS1 is defined).
*/
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS1)

#if defined(SQLITE_ENABLE_FTS1) && !defined(SQLITE_CORE)
# define SQLITE_CORE 1
#endif

#include <assert.h>
#if !defined(__APPLE__)
#include <malloc.h>
#else
#include <stdlib.h>
#endif
#include <stdio.h>
#include <string.h>
#include <ctype.h>

#include "fts1.h"
#include "fts1_hash.h"
#include "fts1_tokenizer.h"
#include "sqlite3.h"
#include "sqlite3ext.h"
SQLITE_EXTENSION_INIT1


#if 0
# define TRACE(A)  printf A; fflush(stdout)
#else
# define TRACE(A)
#endif

/* utility functions */

typedef struct StringBuffer {
  int len;      /* length, not including null terminator */
  int alloced;  /* Space allocated for s[] */ 
  char *s;      /* Content of the string */
} StringBuffer;

static void initStringBuffer(StringBuffer *sb){
  sb->len = 0;
  sb->alloced = 100;
  sb->s = malloc(100);
  sb->s[0] = '\0';
}

static void nappend(StringBuffer *sb, const char *zFrom, int nFrom){
  if( sb->len + nFrom >= sb->alloced ){
    sb->alloced = sb->len + nFrom + 100;
    sb->s = realloc(sb->s, sb->alloced+1);
    if( sb->s==0 ){
      initStringBuffer(sb);
      return;
    }
  }
  memcpy(sb->s + sb->len, zFrom, nFrom);
  sb->len += nFrom;
  sb->s[sb->len] = 0;
}
static void append(StringBuffer *sb, const char *zFrom){
  nappend(sb, zFrom, strlen(zFrom));
}

/* We encode variable-length integers in little-endian order using seven bits
 * per byte as follows:
**
** KEY:
**         A = 0xxxxxxx    7 bits of data and one flag bit
**         B = 1xxxxxxx    7 bits of data and one flag bit
**
**  7 bits - A
** 14 bits - BA
** 21 bits - BBA
** and so on.
*/

/* We may need up to VARINT_MAX bytes to store an encoded 64-bit integer. */
#define VARINT_MAX 10

/* Write a 64-bit variable-length integer to memory starting at p[0].
 * The length of data written will be between 1 and VARINT_MAX bytes.
 * The number of bytes written is returned. */
static int putVarint(char *p, sqlite_int64 v){
  unsigned char *q = (unsigned char *) p;
  sqlite_uint64 vu = v;
  do{
    *q++ = (unsigned char) ((vu & 0x7f) | 0x80);
    vu >>= 7;
  }while( vu!=0 );
  q[-1] &= 0x7f;  /* turn off high bit in final byte */
  assert( q - (unsigned char *)p <= VARINT_MAX );
  return (int) (q - (unsigned char *)p);
}

/* Read a 64-bit variable-length integer from memory starting at p[0].
 * Return the number of bytes read, or 0 on error.
 * The value is stored in *v. */
static int getVarint(const char *p, sqlite_int64 *v){
  const unsigned char *q = (const unsigned char *) p;
  sqlite_uint64 x = 0, y = 1;
  while( (*q & 0x80) == 0x80 ){
    x += y * (*q++ & 0x7f);
    y <<= 7;
    if( q - (unsigned char *)p >= VARINT_MAX ){  /* bad data */
      assert( 0 );
      return 0;
    }
  }
  x += y * (*q++);
  *v = (sqlite_int64) x;
  return (int) (q - (unsigned char *)p);
}

static int getVarint32(const char *p, int *pi){
 sqlite_int64 i;
 int ret = getVarint(p, &i);
 *pi = (int) i;
 assert( *pi==i );
 return ret;
}

/*** Document lists ***
 *
 * A document list holds a sorted list of varint-encoded document IDs.
 *
 * A doclist with type DL_POSITIONS_OFFSETS is stored like this:
 *
 * array {
 *   varint docid;
 *   array {
 *     varint position;     (delta from previous position plus POS_BASE)
 *     varint startOffset;  (delta from previous startOffset)
 *     varint endOffset;    (delta from startOffset)
 *   }
 * }
 *
 * Here, array { X } means zero or more occurrences of X, adjacent in memory.
 *
 * A position list may hold positions for text in multiple columns.  A position
 * POS_COLUMN is followed by a varint containing the index of the column for
 * following positions in the list.  Any positions appearing before any
 * occurrences of POS_COLUMN are for column 0.
 *
 * A doclist with type DL_POSITIONS is like the above, but holds only docids
 * and positions without offset information.
 *
 * A doclist with type DL_DOCIDS is like the above, but holds only docids
 * without positions or offset information.
 *
 * On disk, every document list has positions and offsets, so we don't bother
 * to serialize a doclist's type.
 * 
 * We don't yet delta-encode document IDs; doing so will probably be a
 * modest win.
 *
 * NOTE(shess) I've thought of a slightly (1%) better offset encoding.
 * After the first offset, estimate the next offset by using the
 * current token position and the previous token position and offset,
 * offset to handle some variance.  So the estimate would be
 * (iPosition*w->iStartOffset/w->iPosition-64), which is delta-encoded
 * as normal.  Offsets more than 64 chars from the estimate are
 * encoded as the delta to the previous start offset + 128.  An
 * additional tiny increment can be gained by using the end offset of
 * the previous token to make the estimate a tiny bit more precise.
*/

/* It is not safe to call isspace(), tolower(), or isalnum() on
** hi-bit-set characters.  This is the same solution used in the
** tokenizer.
*/
/* TODO(shess) The snippet-generation code should be using the
** tokenizer-generated tokens rather than doing its own local
** tokenization.
*/
/* TODO(shess) Is __isascii() a portable version of (c&0x80)==0? */
static int safe_isspace(char c){
  return (c&0x80)==0 ? isspace(c) : 0;
}
static int safe_tolower(char c){
  return (c&0x80)==0 ? tolower(c) : c;
}
static int safe_isalnum(char c){
  return (c&0x80)==0 ? isalnum(c) : 0;
}

typedef enum DocListType {
  DL_DOCIDS,              /* docids only */
  DL_POSITIONS,           /* docids + positions */
  DL_POSITIONS_OFFSETS    /* docids + positions + offsets */
} DocListType;

/*
** By default, only positions and not offsets are stored in the doclists.
** To change this so that offsets are stored too, compile with
**
**          -DDL_DEFAULT=DL_POSITIONS_OFFSETS
**
*/
#ifndef DL_DEFAULT
# define DL_DEFAULT DL_POSITIONS
#endif

typedef struct DocList {
  char *pData;
  int nData;
  DocListType iType;
  int iLastColumn;    /* the last column written */
  int iLastPos;       /* the last position written */
  int iLastOffset;    /* the last start offset written */
} DocList;

enum {
  POS_END = 0,        /* end of this position list */
  POS_COLUMN,         /* followed by new column number */
  POS_BASE
};

/* Initialize a new DocList to hold the given data. */
static void docListInit(DocList *d, DocListType iType,
                        const char *pData, int nData){
  d->nData = nData;
  if( nData>0 ){
    d->pData = malloc(nData);
    memcpy(d->pData, pData, nData);
  } else {
    d->pData = NULL;
  }
  d->iType = iType;
  d->iLastColumn = 0;
  d->iLastPos = d->iLastOffset = 0;
}

/* Create a new dynamically-allocated DocList. */
static DocList *docListNew(DocListType iType){
  DocList *d = (DocList *) malloc(sizeof(DocList));
  docListInit(d, iType, 0, 0);
  return d;
}

static void docListDestroy(DocList *d){
  free(d->pData);
#ifndef NDEBUG
  memset(d, 0x55, sizeof(*d));
#endif
}

static void docListDelete(DocList *d){
  docListDestroy(d);
  free(d);
}

static char *docListEnd(DocList *d){
  return d->pData + d->nData;
}

/* Append a varint to a DocList's data. */
static void appendVarint(DocList *d, sqlite_int64 i){
  char c[VARINT_MAX];
  int n = putVarint(c, i);
  d->pData = realloc(d->pData, d->nData + n);
  memcpy(d->pData + d->nData, c, n);
  d->nData += n;
}

static void docListAddDocid(DocList *d, sqlite_int64 iDocid){
  appendVarint(d, iDocid);
  if( d->iType>=DL_POSITIONS ){
    appendVarint(d, POS_END);  /* initially empty position list */
    d->iLastColumn = 0;
    d->iLastPos = d->iLastOffset = 0;
  }
}

/* helper function for docListAddPos and docListAddPosOffset */
static void addPos(DocList *d, int iColumn, int iPos){
  assert( d->nData>0 );
  --d->nData;  /* remove previous terminator */
  if( iColumn!=d->iLastColumn ){
    assert( iColumn>d->iLastColumn );
    appendVarint(d, POS_COLUMN);
    appendVarint(d, iColumn);
    d->iLastColumn = iColumn;
    d->iLastPos = d->iLastOffset = 0;
  }
  assert( iPos>=d->iLastPos );
  appendVarint(d, iPos-d->iLastPos+POS_BASE);
  d->iLastPos = iPos;
}

/* Add a position to the last position list in a doclist. */
static void docListAddPos(DocList *d, int iColumn, int iPos){
  assert( d->iType==DL_POSITIONS );
  addPos(d, iColumn, iPos);
  appendVarint(d, POS_END);  /* add new terminator */
}

/*
** Add a position and starting and ending offsets to a doclist.
**
** If the doclist is setup to handle only positions, then insert
** the position only and ignore the offsets.
*/
static void docListAddPosOffset(
  DocList *d,             /* Doclist under construction */
  int iColumn,            /* Column the inserted term is part of */
  int iPos,               /* Position of the inserted term */
  int iStartOffset,       /* Starting offset of inserted term */
  int iEndOffset          /* Ending offset of inserted term */
){
  assert( d->iType>=DL_POSITIONS );
  addPos(d, iColumn, iPos);
  if( d->iType==DL_POSITIONS_OFFSETS ){
    assert( iStartOffset>=d->iLastOffset );
    appendVarint(d, iStartOffset-d->iLastOffset);
    d->iLastOffset = iStartOffset;
    assert( iEndOffset>=iStartOffset );
    appendVarint(d, iEndOffset-iStartOffset);
  }
  appendVarint(d, POS_END);  /* add new terminator */
}

/*
** A DocListReader object is a cursor into a doclist.  Initialize
** the cursor to the beginning of the doclist by calling readerInit().
** Then use routines
**
**      peekDocid()
**      readDocid()
**      readPosition()
**      skipPositionList()
**      and so forth...
**
** to read information out of the doclist.  When we reach the end
** of the doclist, atEnd() returns TRUE.
*/
typedef struct DocListReader {
  DocList *pDoclist;  /* The document list we are stepping through */
  char *p;            /* Pointer to next unread byte in the doclist */
  int iLastColumn;
  int iLastPos;  /* the last position read, or -1 when not in a position list */
} DocListReader;

/*
** Initialize the DocListReader r to point to the beginning of pDoclist.
*/
static void readerInit(DocListReader *r, DocList *pDoclist){
  r->pDoclist = pDoclist;
  if( pDoclist!=NULL ){
    r->p = pDoclist->pData;
  }
  r->iLastColumn = -1;
  r->iLastPos = -1;
}

/*
** Return TRUE if we have reached then end of pReader and there is
** nothing else left to read.
*/
static int atEnd(DocListReader *pReader){
  return pReader->pDoclist==0 || (pReader->p >= docListEnd(pReader->pDoclist));
}

/* Peek at the next docid without advancing the read pointer. 
*/
static sqlite_int64 peekDocid(DocListReader *pReader){
  sqlite_int64 ret;
  assert( !atEnd(pReader) );
  assert( pReader->iLastPos==-1 );
  getVarint(pReader->p, &ret);
  return ret;
}

/* Read the next docid.   See also nextDocid().
*/
static sqlite_int64 readDocid(DocListReader *pReader){
  sqlite_int64 ret;
  assert( !atEnd(pReader) );
  assert( pReader->iLastPos==-1 );
  pReader->p += getVarint(pReader->p, &ret);
  if( pReader->pDoclist->iType>=DL_POSITIONS ){
    pReader->iLastColumn = 0;
    pReader->iLastPos = 0;
  }
  return ret;
}

/* Read the next position and column index from a position list.
 * Returns the position, or -1 at the end of the list. */
static int readPosition(DocListReader *pReader, int *iColumn){
  int i;
  int iType = pReader->pDoclist->iType;

  if( pReader->iLastPos==-1 ){
    return -1;
  }
  assert( !atEnd(pReader) );

  if( iType<DL_POSITIONS ){
    return -1;
  }
  pReader->p += getVarint32(pReader->p, &i);
  if( i==POS_END ){
    pReader->iLastColumn = pReader->iLastPos = -1;
    *iColumn = -1;
    return -1;
  }
  if( i==POS_COLUMN ){
    pReader->p += getVarint32(pReader->p, &pReader->iLastColumn);
    pReader->iLastPos = 0;
    pReader->p += getVarint32(pReader->p, &i);
    assert( i>=POS_BASE );
  }
  pReader->iLastPos += ((int) i)-POS_BASE;
  if( iType>=DL_POSITIONS_OFFSETS ){
    /* Skip over offsets, ignoring them for now. */
    int iStart, iEnd;
    pReader->p += getVarint32(pReader->p, &iStart);
    pReader->p += getVarint32(pReader->p, &iEnd);
  }
  *iColumn = pReader->iLastColumn;
  return pReader->iLastPos;
}

/* Skip past the end of a position list. */
static void skipPositionList(DocListReader *pReader){
  DocList *p = pReader->pDoclist;
  if( p && p->iType>=DL_POSITIONS ){
    int iColumn;
    while( readPosition(pReader, &iColumn)!=-1 ){}
  }
}

/* Skip over a docid, including its position list if the doclist has
 * positions. */
static void skipDocument(DocListReader *pReader){
  readDocid(pReader);
  skipPositionList(pReader);
}

/* Skip past all docids which are less than [iDocid].  Returns 1 if a docid
 * matching [iDocid] was found.  */
static int skipToDocid(DocListReader *pReader, sqlite_int64 iDocid){
  sqlite_int64 d = 0;
  while( !atEnd(pReader) && (d=peekDocid(pReader))<iDocid ){
    skipDocument(pReader);
  }
  return !atEnd(pReader) && d==iDocid;
}

/* Return the first document in a document list.
*/
static sqlite_int64 firstDocid(DocList *d){
  DocListReader r;
  readerInit(&r, d);
  return readDocid(&r);
}

#ifdef SQLITE_DEBUG
/*
** This routine is used for debugging purpose only.
**
** Write the content of a doclist to standard output.
*/
static void printDoclist(DocList *p){
  DocListReader r;
  const char *zSep = "";

  readerInit(&r, p);
  while( !atEnd(&r) ){
    sqlite_int64 docid = readDocid(&r);
    if( docid==0 ){
      skipPositionList(&r);
      continue;
    }
    printf("%s%lld", zSep, docid);
    zSep =  ",";
    if( p->iType>=DL_POSITIONS ){
      int iPos, iCol;
      const char *zDiv = "";
      printf("(");
      while( (iPos = readPosition(&r, &iCol))>=0 ){
        printf("%s%d:%d", zDiv, iCol, iPos);
        zDiv = ":";
      }
      printf(")");
    }
  }
  printf("\n");
  fflush(stdout);
}
#endif /* SQLITE_DEBUG */

/* Trim the given doclist to contain only positions in column
 * [iRestrictColumn]. */
static void docListRestrictColumn(DocList *in, int iRestrictColumn){
  DocListReader r;
  DocList out;

  assert( in->iType>=DL_POSITIONS );
  readerInit(&r, in);
  docListInit(&out, DL_POSITIONS, NULL, 0);

  while( !atEnd(&r) ){
    sqlite_int64 iDocid = readDocid(&r);
    int iPos, iColumn;

    docListAddDocid(&out, iDocid);
    while( (iPos = readPosition(&r, &iColumn)) != -1 ){
      if( iColumn==iRestrictColumn ){
        docListAddPos(&out, iColumn, iPos);
      }
    }
  }

  docListDestroy(in);
  *in = out;
}

/* Trim the given doclist by discarding any docids without any remaining
 * positions. */
static void docListDiscardEmpty(DocList *in) {
  DocListReader r;
  DocList out;

  /* TODO: It would be nice to implement this operation in place; that
   * could save a significant amount of memory in queries with long doclists. */
  assert( in->iType>=DL_POSITIONS );
  readerInit(&r, in);
  docListInit(&out, DL_POSITIONS, NULL, 0);

  while( !atEnd(&r) ){
    sqlite_int64 iDocid = readDocid(&r);
    int match = 0;
    int iPos, iColumn;
    while( (iPos = readPosition(&r, &iColumn)) != -1 ){
      if( !match ){
        docListAddDocid(&out, iDocid);
        match = 1;
      }
      docListAddPos(&out, iColumn, iPos);
    }
  }

  docListDestroy(in);
  *in = out;
}

/* Helper function for docListUpdate() and docListAccumulate().
** Splices a doclist element into the doclist represented by r,
** leaving r pointing after the newly spliced element.
*/
static void docListSpliceElement(DocListReader *r, sqlite_int64 iDocid,
                                 const char *pSource, int nSource){
  DocList *d = r->pDoclist;
  char *pTarget;
  int nTarget, found;

  found = skipToDocid(r, iDocid);

  /* Describe slice in d to place pSource/nSource. */
  pTarget = r->p;
  if( found ){
    skipDocument(r);
    nTarget = r->p-pTarget;
  }else{
    nTarget = 0;
  }

  /* The sense of the following is that there are three possibilities.
  ** If nTarget==nSource, we should not move any memory nor realloc.
  ** If nTarget>nSource, trim target and realloc.
  ** If nTarget<nSource, realloc then expand target.
  */
  if( nTarget>nSource ){
    memmove(pTarget+nSource, pTarget+nTarget, docListEnd(d)-(pTarget+nTarget));
  }
  if( nTarget!=nSource ){
    int iDoclist = pTarget-d->pData;
    d->pData = realloc(d->pData, d->nData+nSource-nTarget);
    pTarget = d->pData+iDoclist;
  }
  if( nTarget<nSource ){
    memmove(pTarget+nSource, pTarget+nTarget, docListEnd(d)-(pTarget+nTarget));
  }

  memcpy(pTarget, pSource, nSource);
  d->nData += nSource-nTarget;
  r->p = pTarget+nSource;
}

/* Insert/update pUpdate into the doclist. */
static void docListUpdate(DocList *d, DocList *pUpdate){
  DocListReader reader;

  assert( d!=NULL && pUpdate!=NULL );
  assert( d->iType==pUpdate->iType);

  readerInit(&reader, d);
  docListSpliceElement(&reader, firstDocid(pUpdate),
                       pUpdate->pData, pUpdate->nData);
}

/* Propagate elements from pUpdate to pAcc, overwriting elements with
** matching docids.
*/
static void docListAccumulate(DocList *pAcc, DocList *pUpdate){
  DocListReader accReader, updateReader;

  /* Handle edge cases where one doclist is empty. */
  assert( pAcc!=NULL );
  if( pUpdate==NULL || pUpdate->nData==0 ) return;
  if( pAcc->nData==0 ){
    pAcc->pData = malloc(pUpdate->nData);
    memcpy(pAcc->pData, pUpdate->pData, pUpdate->nData);
    pAcc->nData = pUpdate->nData;
    return;
  }

  readerInit(&accReader, pAcc);
  readerInit(&updateReader, pUpdate);

  while( !atEnd(&updateReader) ){
    char *pSource = updateReader.p;
    sqlite_int64 iDocid = readDocid(&updateReader);
    skipPositionList(&updateReader);
    docListSpliceElement(&accReader, iDocid, pSource, updateReader.p-pSource);
  }
}

/*
** Read the next docid off of pIn.  Return 0 if we reach the end.
*
* TODO: This assumes that docids are never 0, but they may actually be 0 since
* users can choose docids when inserting into a full-text table.  Fix this.
*/
static sqlite_int64 nextDocid(DocListReader *pIn){
  skipPositionList(pIn);
  return atEnd(pIn) ? 0 : readDocid(pIn);
}

/*
** pLeft and pRight are two DocListReaders that are pointing to
** positions lists of the same document: iDocid. 
**
** If there are no instances in pLeft or pRight where the position
** of pLeft is one less than the position of pRight, then this
** routine adds nothing to pOut.
**
** If there are one or more instances where positions from pLeft
** are exactly one less than positions from pRight, then add a new
** document record to pOut.  If pOut wants to hold positions, then
** include the positions from pRight that are one more than a
** position in pLeft.  In other words:  pRight.iPos==pLeft.iPos+1.
**
** pLeft and pRight are left pointing at the next document record.
*/
static void mergePosList(
  DocListReader *pLeft,    /* Left position list */
  DocListReader *pRight,   /* Right position list */
  sqlite_int64 iDocid,     /* The docid from pLeft and pRight */
  DocList *pOut            /* Write the merged document record here */
){
  int iLeftCol, iLeftPos = readPosition(pLeft, &iLeftCol);
  int iRightCol, iRightPos = readPosition(pRight, &iRightCol);
  int match = 0;

  /* Loop until we've reached the end of both position lists. */
  while( iLeftPos!=-1 && iRightPos!=-1 ){
    if( iLeftCol==iRightCol && iLeftPos+1==iRightPos ){
      if( !match ){
        docListAddDocid(pOut, iDocid);
        match = 1;
      }
      if( pOut->iType>=DL_POSITIONS ){
        docListAddPos(pOut, iRightCol, iRightPos);
      }
      iLeftPos = readPosition(pLeft, &iLeftCol);
      iRightPos = readPosition(pRight, &iRightCol);
    }else if( iRightCol<iLeftCol ||
              (iRightCol==iLeftCol && iRightPos<iLeftPos+1) ){
      iRightPos = readPosition(pRight, &iRightCol);
    }else{
      iLeftPos = readPosition(pLeft, &iLeftCol);
    }
  }
  if( iLeftPos>=0 ) skipPositionList(pLeft);
  if( iRightPos>=0 ) skipPositionList(pRight);
}

/* We have two doclists:  pLeft and pRight.
** Write the phrase intersection of these two doclists into pOut.
**
** A phrase intersection means that two documents only match
** if pLeft.iPos+1==pRight.iPos.
**
** The output pOut may or may not contain positions.  If pOut
** does contain positions, they are the positions of pRight.
*/
static void docListPhraseMerge(
  DocList *pLeft,    /* Doclist resulting from the words on the left */
  DocList *pRight,   /* Doclist for the next word to the right */
  DocList *pOut      /* Write the combined doclist here */
){
  DocListReader left, right;
  sqlite_int64 docidLeft, docidRight;

  readerInit(&left, pLeft);
  readerInit(&right, pRight);
  docidLeft = nextDocid(&left);
  docidRight = nextDocid(&right);

  while( docidLeft>0 && docidRight>0 ){
    if( docidLeft<docidRight ){
      docidLeft = nextDocid(&left);
    }else if( docidRight<docidLeft ){
      docidRight = nextDocid(&right);
    }else{
      mergePosList(&left, &right, docidLeft, pOut);
      docidLeft = nextDocid(&left);
      docidRight = nextDocid(&right);
    }
  }
}

/* We have two doclists:  pLeft and pRight.
** Write the intersection of these two doclists into pOut.
** Only docids are matched.  Position information is ignored.
**
** The output pOut never holds positions.
*/
static void docListAndMerge(
  DocList *pLeft,    /* Doclist resulting from the words on the left */
  DocList *pRight,   /* Doclist for the next word to the right */
  DocList *pOut      /* Write the combined doclist here */
){
  DocListReader left, right;
  sqlite_int64 docidLeft, docidRight;

  assert( pOut->iType<DL_POSITIONS );

  readerInit(&left, pLeft);
  readerInit(&right, pRight);
  docidLeft = nextDocid(&left);
  docidRight = nextDocid(&right);

  while( docidLeft>0 && docidRight>0 ){
    if( docidLeft<docidRight ){
      docidLeft = nextDocid(&left);
    }else if( docidRight<docidLeft ){
      docidRight = nextDocid(&right);
    }else{
      docListAddDocid(pOut, docidLeft);
      docidLeft = nextDocid(&left);
      docidRight = nextDocid(&right);
    }
  }
}

/* We have two doclists:  pLeft and pRight.
** Write the union of these two doclists into pOut.
** Only docids are matched.  Position information is ignored.
**
** The output pOut never holds positions.
*/
static void docListOrMerge(
  DocList *pLeft,    /* Doclist resulting from the words on the left */
  DocList *pRight,   /* Doclist for the next word to the right */
  DocList *pOut      /* Write the combined doclist here */
){
  DocListReader left, right;
  sqlite_int64 docidLeft, docidRight, priorLeft;

  readerInit(&left, pLeft);
  readerInit(&right, pRight);
  docidLeft = nextDocid(&left);
  docidRight = nextDocid(&right);

  while( docidLeft>0 && docidRight>0 ){
    if( docidLeft<=docidRight ){
      docListAddDocid(pOut, docidLeft);
    }else{
      docListAddDocid(pOut, docidRight);
    }
    priorLeft = docidLeft;
    if( docidLeft<=docidRight ){
      docidLeft = nextDocid(&left);
    }
    if( docidRight>0 && docidRight<=priorLeft ){
      docidRight = nextDocid(&right);
    }
  }
  while( docidLeft>0 ){
    docListAddDocid(pOut, docidLeft);
    docidLeft = nextDocid(&left);
  }
  while( docidRight>0 ){
    docListAddDocid(pOut, docidRight);
    docidRight = nextDocid(&right);
  }
}

/* We have two doclists:  pLeft and pRight.
** Write into pOut all documents that occur in pLeft but not
** in pRight.
**
** Only docids are matched.  Position information is ignored.
**
** The output pOut never holds positions.
*/
static void docListExceptMerge(
  DocList *pLeft,    /* Doclist resulting from the words on the left */
  DocList *pRight,   /* Doclist for the next word to the right */
  DocList *pOut      /* Write the combined doclist here */
){
  DocListReader left, right;
  sqlite_int64 docidLeft, docidRight, priorLeft;

  readerInit(&left, pLeft);
  readerInit(&right, pRight);
  docidLeft = nextDocid(&left);
  docidRight = nextDocid(&right);

  while( docidLeft>0 && docidRight>0 ){
    priorLeft = docidLeft;
    if( docidLeft<docidRight ){
      docListAddDocid(pOut, docidLeft);
    }
    if( docidLeft<=docidRight ){
      docidLeft = nextDocid(&left);
    }
    if( docidRight>0 && docidRight<=priorLeft ){
      docidRight = nextDocid(&right);
    }
  }
  while( docidLeft>0 ){
    docListAddDocid(pOut, docidLeft);
    docidLeft = nextDocid(&left);
  }
}

static char *string_dup_n(const char *s, int n){
  char *str = malloc(n + 1);
  memcpy(str, s, n);
  str[n] = '\0';
  return str;
}

/* Duplicate a string; the caller must free() the returned string.
 * (We don't use strdup() since it's not part of the standard C library and
 * may not be available everywhere.) */
static char *string_dup(const char *s){
  return string_dup_n(s, strlen(s));
}

/* Format a string, replacing each occurrence of the % character with
 * zDb.zName.  This may be more convenient than sqlite_mprintf()
 * when one string is used repeatedly in a format string.
 * The caller must free() the returned string. */
static char *string_format(const char *zFormat,
                           const char *zDb, const char *zName){
  const char *p;
  size_t len = 0;
  size_t nDb = strlen(zDb);
  size_t nName = strlen(zName);
  size_t nFullTableName = nDb+1+nName;
  char *result;
  char *r;

  /* first compute length needed */
  for(p = zFormat ; *p ; ++p){
    len += (*p=='%' ? nFullTableName : 1);
  }
  len += 1;  /* for null terminator */

  r = result = malloc(len);
  for(p = zFormat; *p; ++p){
    if( *p=='%' ){
      memcpy(r, zDb, nDb);
      r += nDb;
      *r++ = '.';
      memcpy(r, zName, nName);
      r += nName;
    } else {
      *r++ = *p;
    }
  }
  *r++ = '\0';
  assert( r == result + len );
  return result;
}

static int sql_exec(sqlite3 *db, const char *zDb, const char *zName,
                    const char *zFormat){
  char *zCommand = string_format(zFormat, zDb, zName);
  int rc;
  TRACE(("FTS1 sql: %s\n", zCommand));
  rc = sqlite3_exec(db, zCommand, NULL, 0, NULL);
  free(zCommand);
  return rc;
}

static int sql_prepare(sqlite3 *db, const char *zDb, const char *zName,
                       sqlite3_stmt **ppStmt, const char *zFormat){
  char *zCommand = string_format(zFormat, zDb, zName);
  int rc;
  TRACE(("FTS1 prepare: %s\n", zCommand));
  rc = sqlite3_prepare(db, zCommand, -1, ppStmt, NULL);
  free(zCommand);
  return rc;
}

/* end utility functions */

/* Forward reference */
typedef struct fulltext_vtab fulltext_vtab;

/* A single term in a query is represented by an instances of
** the following structure.
*/
typedef struct QueryTerm {
  short int nPhrase; /* How many following terms are part of the same phrase */
  short int iPhrase; /* This is the i-th term of a phrase. */
  short int iColumn; /* Column of the index that must match this term */
  signed char isOr;  /* this term is preceded by "OR" */
  signed char isNot; /* this term is preceded by "-" */
  char *pTerm;       /* text of the term.  '\000' terminated.  malloced */
  int nTerm;         /* Number of bytes in pTerm[] */
} QueryTerm;


/* A query string is parsed into a Query structure.
 *
 * We could, in theory, allow query strings to be complicated
 * nested expressions with precedence determined by parentheses.
 * But none of the major search engines do this.  (Perhaps the
 * feeling is that an parenthesized expression is two complex of
 * an idea for the average user to grasp.)  Taking our lead from
 * the major search engines, we will allow queries to be a list
 * of terms (with an implied AND operator) or phrases in double-quotes,
 * with a single optional "-" before each non-phrase term to designate
 * negation and an optional OR connector.
 *
 * OR binds more tightly than the implied AND, which is what the
 * major search engines seem to do.  So, for example:
 * 
 *    [one two OR three]     ==>    one AND (two OR three)
 *    [one OR two three]     ==>    (one OR two) AND three
 *
 * A "-" before a term matches all entries that lack that term.
 * The "-" must occur immediately before the term with in intervening
 * space.  This is how the search engines do it.
 *
 * A NOT term cannot be the right-hand operand of an OR.  If this
 * occurs in the query string, the NOT is ignored:
 *
 *    [one OR -two]          ==>    one OR two
 *
 */
typedef struct Query {
  fulltext_vtab *pFts;  /* The full text index */
  int nTerms;           /* Number of terms in the query */
  QueryTerm *pTerms;    /* Array of terms.  Space obtained from malloc() */
  int nextIsOr;         /* Set the isOr flag on the next inserted term */
  int nextColumn;       /* Next word parsed must be in this column */
  int dfltColumn;       /* The default column */
} Query;


/*
** An instance of the following structure keeps track of generated
** matching-word offset information and snippets.
*/
typedef struct Snippet {
  int nMatch;     /* Total number of matches */
  int nAlloc;     /* Space allocated for aMatch[] */
  struct snippetMatch { /* One entry for each matching term */
    char snStatus;       /* Status flag for use while constructing snippets */
    short int iCol;      /* The column that contains the match */
    short int iTerm;     /* The index in Query.pTerms[] of the matching term */
    short int nByte;     /* Number of bytes in the term */
    int iStart;          /* The offset to the first character of the term */
  } *aMatch;      /* Points to space obtained from malloc */
  char *zOffset;  /* Text rendering of aMatch[] */
  int nOffset;    /* strlen(zOffset) */
  char *zSnippet; /* Snippet text */
  int nSnippet;   /* strlen(zSnippet) */
} Snippet;


typedef enum QueryType {
  QUERY_GENERIC,   /* table scan */
  QUERY_ROWID,     /* lookup by rowid */
  QUERY_FULLTEXT   /* QUERY_FULLTEXT + [i] is a full-text search for column i*/
} QueryType;

/* TODO(shess) CHUNK_MAX controls how much data we allow in segment 0
** before we start aggregating into larger segments.  Lower CHUNK_MAX
** means that for a given input we have more individual segments per
** term, which means more rows in the table and a bigger index (due to
** both more rows and bigger rowids).  But it also reduces the average
** cost of adding new elements to the segment 0 doclist, and it seems
** to reduce the number of pages read and written during inserts.  256
** was chosen by measuring insertion times for a certain input (first
** 10k documents of Enron corpus), though including query performance
** in the decision may argue for a larger value.
*/
#define CHUNK_MAX 256

typedef enum fulltext_statement {
  CONTENT_INSERT_STMT,
  CONTENT_SELECT_STMT,
  CONTENT_UPDATE_STMT,
  CONTENT_DELETE_STMT,

  TERM_SELECT_STMT,
  TERM_SELECT_ALL_STMT,
  TERM_INSERT_STMT,
  TERM_UPDATE_STMT,
  TERM_DELETE_STMT,

  MAX_STMT                     /* Always at end! */
} fulltext_statement;

/* These must exactly match the enum above. */
/* TODO(adam): Is there some risk that a statement (in particular,
** pTermSelectStmt) will be used in two cursors at once, e.g.  if a
** query joins a virtual table to itself?  If so perhaps we should
** move some of these to the cursor object.
*/
static const char *const fulltext_zStatement[MAX_STMT] = {
  /* CONTENT_INSERT */ NULL,  /* generated in contentInsertStatement() */
  /* CONTENT_SELECT */ "select * from %_content where rowid = ?",
  /* CONTENT_UPDATE */ NULL,  /* generated in contentUpdateStatement() */
  /* CONTENT_DELETE */ "delete from %_content where rowid = ?",

  /* TERM_SELECT */
  "select rowid, doclist from %_term where term = ? and segment = ?",
  /* TERM_SELECT_ALL */
  "select doclist from %_term where term = ? order by segment",
  /* TERM_INSERT */
  "insert into %_term (rowid, term, segment, doclist) values (?, ?, ?, ?)",
  /* TERM_UPDATE */ "update %_term set doclist = ? where rowid = ?",
  /* TERM_DELETE */ "delete from %_term where rowid = ?",
};

/*
** A connection to a fulltext index is an instance of the following
** structure.  The xCreate and xConnect methods create an instance
** of this structure and xDestroy and xDisconnect free that instance.
** All other methods receive a pointer to the structure as one of their
** arguments.
*/
struct fulltext_vtab {
  sqlite3_vtab base;               /* Base class used by SQLite core */
  sqlite3 *db;                     /* The database connection */
  const char *zDb;                 /* logical database name */
  const char *zName;               /* virtual table name */
  int nColumn;                     /* number of columns in virtual table */
  char **azColumn;                 /* column names.  malloced */
  char **azContentColumn;          /* column names in content table; malloced */
  sqlite3_tokenizer *pTokenizer;   /* tokenizer for inserts and queries */

  /* Precompiled statements which we keep as long as the table is
  ** open.
  */
  sqlite3_stmt *pFulltextStatements[MAX_STMT];
};

/*
** When the core wants to do a query, it create a cursor using a
** call to xOpen.  This structure is an instance of a cursor.  It
** is destroyed by xClose.
*/
typedef struct fulltext_cursor {
  sqlite3_vtab_cursor base;        /* Base class used by SQLite core */
  QueryType iCursorType;           /* Copy of sqlite3_index_info.idxNum */
  sqlite3_stmt *pStmt;             /* Prepared statement in use by the cursor */
  int eof;                         /* True if at End Of Results */
  Query q;                         /* Parsed query string */
  Snippet snippet;                 /* Cached snippet for the current row */
  int iColumn;                     /* Column being searched */
  DocListReader result;  /* used when iCursorType == QUERY_FULLTEXT */ 
} fulltext_cursor;

static struct fulltext_vtab *cursor_vtab(fulltext_cursor *c){
  return (fulltext_vtab *) c->base.pVtab;
}

static const sqlite3_module fulltextModule;   /* forward declaration */

/* Append a list of strings separated by commas to a StringBuffer. */
static void appendList(StringBuffer *sb, int nString, char **azString){
  int i;
  for(i=0; i<nString; ++i){
    if( i>0 ) append(sb, ", ");
    append(sb, azString[i]);
  }
}

/* Return a dynamically generated statement of the form
 *   insert into %_content (rowid, ...) values (?, ...)
 */
static const char *contentInsertStatement(fulltext_vtab *v){
  StringBuffer sb;
  int i;

  initStringBuffer(&sb);
  append(&sb, "insert into %_content (rowid, ");
  appendList(&sb, v->nColumn, v->azContentColumn);
  append(&sb, ") values (?");
  for(i=0; i<v->nColumn; ++i)
    append(&sb, ", ?");
  append(&sb, ")");
  return sb.s;
}

/* Return a dynamically generated statement of the form
 *   update %_content set [col_0] = ?, [col_1] = ?, ...
 *                    where rowid = ?
 */
static const char *contentUpdateStatement(fulltext_vtab *v){
  StringBuffer sb;
  int i;

  initStringBuffer(&sb);
  append(&sb, "update %_content set ");
  for(i=0; i<v->nColumn; ++i) {
    if( i>0 ){
      append(&sb, ", ");
    }
    append(&sb, v->azContentColumn[i]);
    append(&sb, " = ?");
  }
  append(&sb, " where rowid = ?");
  return sb.s;
}

/* Puts a freshly-prepared statement determined by iStmt in *ppStmt.
** If the indicated statement has never been prepared, it is prepared
** and cached, otherwise the cached version is reset.
*/
static int sql_get_statement(fulltext_vtab *v, fulltext_statement iStmt,
                             sqlite3_stmt **ppStmt){
  assert( iStmt<MAX_STMT );
  if( v->pFulltextStatements[iStmt]==NULL ){
    const char *zStmt;
    int rc;
    switch( iStmt ){
      case CONTENT_INSERT_STMT:
        zStmt = contentInsertStatement(v); break;
      case CONTENT_UPDATE_STMT:
        zStmt = contentUpdateStatement(v); break;
      default:
        zStmt = fulltext_zStatement[iStmt];
    }
    rc = sql_prepare(v->db, v->zDb, v->zName, &v->pFulltextStatements[iStmt],
                         zStmt);
    if( zStmt != fulltext_zStatement[iStmt]) free((void *) zStmt);
    if( rc!=SQLITE_OK ) return rc;
  } else {
    int rc = sqlite3_reset(v->pFulltextStatements[iStmt]);
    if( rc!=SQLITE_OK ) return rc;
  }

  *ppStmt = v->pFulltextStatements[iStmt];
  return SQLITE_OK;
}

/* Step the indicated statement, handling errors SQLITE_BUSY (by
** retrying) and SQLITE_SCHEMA (by re-preparing and transferring
** bindings to the new statement).
** TODO(adam): We should extend this function so that it can work with
** statements declared locally, not only globally cached statements.
*/
static int sql_step_statement(fulltext_vtab *v, fulltext_statement iStmt,
                              sqlite3_stmt **ppStmt){
  int rc;
  sqlite3_stmt *s = *ppStmt;
  assert( iStmt<MAX_STMT );
  assert( s==v->pFulltextStatements[iStmt] );

  while( (rc=sqlite3_step(s))!=SQLITE_DONE && rc!=SQLITE_ROW ){
    sqlite3_stmt *pNewStmt;

    if( rc==SQLITE_BUSY ) continue;
    if( rc!=SQLITE_ERROR ) return rc;

    rc = sqlite3_reset(s);
    if( rc!=SQLITE_SCHEMA ) return SQLITE_ERROR;

    v->pFulltextStatements[iStmt] = NULL;   /* Still in s */
    rc = sql_get_statement(v, iStmt, &pNewStmt);
    if( rc!=SQLITE_OK ) goto err;
    *ppStmt = pNewStmt;

    rc = sqlite3_transfer_bindings(s, pNewStmt);
    if( rc!=SQLITE_OK ) goto err;

    rc = sqlite3_finalize(s);
    if( rc!=SQLITE_OK ) return rc;
    s = pNewStmt;
  }
  return rc;

 err:
  sqlite3_finalize(s);
  return rc;
}

/* Like sql_step_statement(), but convert SQLITE_DONE to SQLITE_OK.
** Useful for statements like UPDATE, where we expect no results.
*/
static int sql_single_step_statement(fulltext_vtab *v,
                                     fulltext_statement iStmt,
                                     sqlite3_stmt **ppStmt){
  int rc = sql_step_statement(v, iStmt, ppStmt);
  return (rc==SQLITE_DONE) ? SQLITE_OK : rc;
}

/* insert into %_content (rowid, ...) values ([rowid], [pValues]) */
static int content_insert(fulltext_vtab *v, sqlite3_value *rowid,
                          sqlite3_value **pValues){
  sqlite3_stmt *s;
  int i;
  int rc = sql_get_statement(v, CONTENT_INSERT_STMT, &s);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_value(s, 1, rowid);
  if( rc!=SQLITE_OK ) return rc;

  for(i=0; i<v->nColumn; ++i){
    rc = sqlite3_bind_value(s, 2+i, pValues[i]);
    if( rc!=SQLITE_OK ) return rc;
  }

  return sql_single_step_statement(v, CONTENT_INSERT_STMT, &s);
}

/* update %_content set col0 = pValues[0], col1 = pValues[1], ...
 *                  where rowid = [iRowid] */
static int content_update(fulltext_vtab *v, sqlite3_value **pValues,
                          sqlite_int64 iRowid){
  sqlite3_stmt *s;
  int i;
  int rc = sql_get_statement(v, CONTENT_UPDATE_STMT, &s);
  if( rc!=SQLITE_OK ) return rc;

  for(i=0; i<v->nColumn; ++i){
    rc = sqlite3_bind_value(s, 1+i, pValues[i]);
    if( rc!=SQLITE_OK ) return rc;
  }

  rc = sqlite3_bind_int64(s, 1+v->nColumn, iRowid);
  if( rc!=SQLITE_OK ) return rc;

  return sql_single_step_statement(v, CONTENT_UPDATE_STMT, &s);
}

static void freeStringArray(int nString, const char **pString){
  int i;

  for (i=0 ; i < nString ; ++i) {
    if( pString[i]!=NULL ) free((void *) pString[i]);
  }
  free((void *) pString);
}

/* select * from %_content where rowid = [iRow]
 * The caller must delete the returned array and all strings in it.
 * null fields will be NULL in the returned array.
 *
 * TODO: Perhaps we should return pointer/length strings here for consistency
 * with other code which uses pointer/length. */
static int content_select(fulltext_vtab *v, sqlite_int64 iRow,
                          const char ***pValues){
  sqlite3_stmt *s;
  const char **values;
  int i;
  int rc;

  *pValues = NULL;

  rc = sql_get_statement(v, CONTENT_SELECT_STMT, &s);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_int64(s, 1, iRow);
  if( rc!=SQLITE_OK ) return rc;

  rc = sql_step_statement(v, CONTENT_SELECT_STMT, &s);
  if( rc!=SQLITE_ROW ) return rc;

  values = (const char **) malloc(v->nColumn * sizeof(const char *));
  for(i=0; i<v->nColumn; ++i){
    if( sqlite3_column_type(s, i)==SQLITE_NULL ){
      values[i] = NULL;
    }else{
      values[i] = string_dup((char*)sqlite3_column_text(s, i));
    }
  }

  /* We expect only one row.  We must execute another sqlite3_step()
   * to complete the iteration; otherwise the table will remain locked. */
  rc = sqlite3_step(s);
  if( rc==SQLITE_DONE ){
    *pValues = values;
    return SQLITE_OK;
  }

  freeStringArray(v->nColumn, values);
  return rc;
}

/* delete from %_content where rowid = [iRow ] */
static int content_delete(fulltext_vtab *v, sqlite_int64 iRow){
  sqlite3_stmt *s;
  int rc = sql_get_statement(v, CONTENT_DELETE_STMT, &s);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_int64(s, 1, iRow);
  if( rc!=SQLITE_OK ) return rc;

  return sql_single_step_statement(v, CONTENT_DELETE_STMT, &s);
}

/* select rowid, doclist from %_term
 *  where term = [pTerm] and segment = [iSegment]
 * If found, returns SQLITE_ROW; the caller must free the
 * returned doclist.  If no rows found, returns SQLITE_DONE. */
static int term_select(fulltext_vtab *v, const char *pTerm, int nTerm,
                       int iSegment,
                       sqlite_int64 *rowid, DocList *out){
  sqlite3_stmt *s;
  int rc = sql_get_statement(v, TERM_SELECT_STMT, &s);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_text(s, 1, pTerm, nTerm, SQLITE_STATIC);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_int(s, 2, iSegment);
  if( rc!=SQLITE_OK ) return rc;

  rc = sql_step_statement(v, TERM_SELECT_STMT, &s);
  if( rc!=SQLITE_ROW ) return rc;

  *rowid = sqlite3_column_int64(s, 0);
  docListInit(out, DL_DEFAULT,
              sqlite3_column_blob(s, 1), sqlite3_column_bytes(s, 1));

  /* We expect only one row.  We must execute another sqlite3_step()
   * to complete the iteration; otherwise the table will remain locked. */
  rc = sqlite3_step(s);
  return rc==SQLITE_DONE ? SQLITE_ROW : rc;
}

/* Load the segment doclists for term pTerm and merge them in
** appropriate order into out.  Returns SQLITE_OK if successful.  If
** there are no segments for pTerm, successfully returns an empty
** doclist in out.
**
** Each document consists of 1 or more "columns".  The number of
** columns is v->nColumn.  If iColumn==v->nColumn, then return
** position information about all columns.  If iColumn<v->nColumn,
** then only return position information about the iColumn-th column
** (where the first column is 0).
*/
static int term_select_all(
  fulltext_vtab *v,     /* The fulltext index we are querying against */
  int iColumn,          /* If <nColumn, only look at the iColumn-th column */
  const char *pTerm,    /* The term whose posting lists we want */
  int nTerm,            /* Number of bytes in pTerm */
  DocList *out          /* Write the resulting doclist here */
){
  DocList doclist;
  sqlite3_stmt *s;
  int rc = sql_get_statement(v, TERM_SELECT_ALL_STMT, &s);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_text(s, 1, pTerm, nTerm, SQLITE_STATIC);
  if( rc!=SQLITE_OK ) return rc;

  docListInit(&doclist, DL_DEFAULT, 0, 0);

  /* TODO(shess) Handle schema and busy errors. */
  while( (rc=sql_step_statement(v, TERM_SELECT_ALL_STMT, &s))==SQLITE_ROW ){
    DocList old;

    /* TODO(shess) If we processed doclists from oldest to newest, we
    ** could skip the malloc() involved with the following call.  For
    ** now, I'd rather keep this logic similar to index_insert_term().
    ** We could additionally drop elements when we see deletes, but
    ** that would require a distinct version of docListAccumulate().
    */
    docListInit(&old, DL_DEFAULT,
                sqlite3_column_blob(s, 0), sqlite3_column_bytes(s, 0));

    if( iColumn<v->nColumn ){   /* querying a single column */
      docListRestrictColumn(&old, iColumn);
    }

    /* doclist contains the newer data, so write it over old.  Then
    ** steal accumulated result for doclist.
    */
    docListAccumulate(&old, &doclist);
    docListDestroy(&doclist);
    doclist = old;
  }
  if( rc!=SQLITE_DONE ){
    docListDestroy(&doclist);
    return rc;
  }

  docListDiscardEmpty(&doclist);
  *out = doclist;
  return SQLITE_OK;
}

/* insert into %_term (rowid, term, segment, doclist)
               values ([piRowid], [pTerm], [iSegment], [doclist])
** Lets sqlite select rowid if piRowid is NULL, else uses *piRowid.
**
** NOTE(shess) piRowid is IN, with values of "space of int64" plus
** null, it is not used to pass data back to the caller.
*/
static int term_insert(fulltext_vtab *v, sqlite_int64 *piRowid,
                       const char *pTerm, int nTerm,
                       int iSegment, DocList *doclist){
  sqlite3_stmt *s;
  int rc = sql_get_statement(v, TERM_INSERT_STMT, &s);
  if( rc!=SQLITE_OK ) return rc;

  if( piRowid==NULL ){
    rc = sqlite3_bind_null(s, 1);
  }else{
    rc = sqlite3_bind_int64(s, 1, *piRowid);
  }
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_text(s, 2, pTerm, nTerm, SQLITE_STATIC);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_int(s, 3, iSegment);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_blob(s, 4, doclist->pData, doclist->nData, SQLITE_STATIC);
  if( rc!=SQLITE_OK ) return rc;

  return sql_single_step_statement(v, TERM_INSERT_STMT, &s);
}

/* update %_term set doclist = [doclist] where rowid = [rowid] */
static int term_update(fulltext_vtab *v, sqlite_int64 rowid,
                       DocList *doclist){
  sqlite3_stmt *s;
  int rc = sql_get_statement(v, TERM_UPDATE_STMT, &s);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_blob(s, 1, doclist->pData, doclist->nData, SQLITE_STATIC);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_int64(s, 2, rowid);
  if( rc!=SQLITE_OK ) return rc;

  return sql_single_step_statement(v, TERM_UPDATE_STMT, &s);
}

static int term_delete(fulltext_vtab *v, sqlite_int64 rowid){
  sqlite3_stmt *s;
  int rc = sql_get_statement(v, TERM_DELETE_STMT, &s);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_int64(s, 1, rowid);
  if( rc!=SQLITE_OK ) return rc;

  return sql_single_step_statement(v, TERM_DELETE_STMT, &s);
}

/*
** Free the memory used to contain a fulltext_vtab structure.
*/
static void fulltext_vtab_destroy(fulltext_vtab *v){
  int iStmt, i;

  TRACE(("FTS1 Destroy %p\n", v));
  for( iStmt=0; iStmt<MAX_STMT; iStmt++ ){
    if( v->pFulltextStatements[iStmt]!=NULL ){
      sqlite3_finalize(v->pFulltextStatements[iStmt]);
      v->pFulltextStatements[iStmt] = NULL;
    }
  }

  if( v->pTokenizer!=NULL ){
    v->pTokenizer->pModule->xDestroy(v->pTokenizer);
    v->pTokenizer = NULL;
  }
  
  free(v->azColumn);
  for(i = 0; i < v->nColumn; ++i) {
    sqlite3_free(v->azContentColumn[i]);
  }
  free(v->azContentColumn);
  free(v);
}

/*
** Token types for parsing the arguments to xConnect or xCreate.
*/
#define TOKEN_EOF         0    /* End of file */
#define TOKEN_SPACE       1    /* Any kind of whitespace */
#define TOKEN_ID          2    /* An identifier */
#define TOKEN_STRING      3    /* A string literal */
#define TOKEN_PUNCT       4    /* A single punctuation character */

/*
** If X is a character that can be used in an identifier then
** IdChar(X) will be true.  Otherwise it is false.
**
** For ASCII, any character with the high-order bit set is
** allowed in an identifier.  For 7-bit characters, 
** sqlite3IsIdChar[X] must be 1.
**
** Ticket #1066.  the SQL standard does not allow '$' in the
** middle of identfiers.  But many SQL implementations do. 
** SQLite will allow '$' in identifiers for compatibility.
** But the feature is undocumented.
*/
static const char isIdChar[] = {
/* x0 x1 x2 x3 x4 x5 x6 x7 x8 x9 xA xB xC xD xE xF */
    0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  /* 2x */
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0,  /* 3x */
    0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  /* 4x */
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1,  /* 5x */
    0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  /* 6x */
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0,  /* 7x */
};
#define IdChar(C)  (((c=C)&0x80)!=0 || (c>0x1f && isIdChar[c-0x20]))


/*
** Return the length of the token that begins at z[0]. 
** Store the token type in *tokenType before returning.
*/
static int getToken(const char *z, int *tokenType){
  int i, c;
  switch( *z ){
    case 0: {
      *tokenType = TOKEN_EOF;
      return 0;
    }
    case ' ': case '\t': case '\n': case '\f': case '\r': {
      for(i=1; safe_isspace(z[i]); i++){}
      *tokenType = TOKEN_SPACE;
      return i;
    }
    case '\'':
    case '"': {
      int delim = z[0];
      for(i=1; (c=z[i])!=0; i++){
        if( c==delim ){
          if( z[i+1]==delim ){
            i++;
          }else{
            break;
          }
        }
      }
      *tokenType = TOKEN_STRING;
      return i + (c!=0);
    }
    case '[': {
      for(i=1, c=z[0]; c!=']' && (c=z[i])!=0; i++){}
      *tokenType = TOKEN_ID;
      return i;
    }
    default: {
      if( !IdChar(*z) ){
        break;
      }
      for(i=1; IdChar(z[i]); i++){}
      *tokenType = TOKEN_ID;
      return i;
    }
  }
  *tokenType = TOKEN_PUNCT;
  return 1;
}

/*
** A token extracted from a string is an instance of the following
** structure.
*/
typedef struct Token {
  const char *z;       /* Pointer to token text.  Not '\000' terminated */
  short int n;         /* Length of the token text in bytes. */
} Token;

/*
** Given a input string (which is really one of the argv[] parameters
** passed into xConnect or xCreate) split the string up into tokens.
** Return an array of pointers to '\000' terminated strings, one string
** for each non-whitespace token.
**
** The returned array is terminated by a single NULL pointer.
**
** Space to hold the returned array is obtained from a single
** malloc and should be freed by passing the return value to free().
** The individual strings within the token list are all a part of
** the single memory allocation and will all be freed at once.
*/
static char **tokenizeString(const char *z, int *pnToken){
  int nToken = 0;
  Token *aToken = malloc( strlen(z) * sizeof(aToken[0]) );
  int n = 1;
  int e, i;
  int totalSize = 0;
  char **azToken;
  char *zCopy;
  while( n>0 ){
    n = getToken(z, &e);
    if( e!=TOKEN_SPACE ){
      aToken[nToken].z = z;
      aToken[nToken].n = n;
      nToken++;
      totalSize += n+1;
    }
    z += n;
  }
  azToken = (char**)malloc( nToken*sizeof(char*) + totalSize );
  zCopy = (char*)&azToken[nToken];
  nToken--;
  for(i=0; i<nToken; i++){
    azToken[i] = zCopy;
    n = aToken[i].n;
    memcpy(zCopy, aToken[i].z, n);
    zCopy[n] = 0;
    zCopy += n+1;
  }
  azToken[nToken] = 0;
  free(aToken);
  *pnToken = nToken;
  return azToken;
}

/*
** Convert an SQL-style quoted string into a normal string by removing
** the quote characters.  The conversion is done in-place.  If the
** input does not begin with a quote character, then this routine
** is a no-op.
**
** Examples:
**
**     "abc"   becomes   abc
**     'xyz'   becomes   xyz
**     [pqr]   becomes   pqr
**     `mno`   becomes   mno
*/
static void dequoteString(char *z){
  int quote;
  int i, j;
  if( z==0 ) return;
  quote = z[0];
  switch( quote ){
    case '\'':  break;
    case '"':   break;
    case '`':   break;                /* For MySQL compatibility */
    case '[':   quote = ']';  break;  /* For MS SqlServer compatibility */
    default:    return;
  }
  for(i=1, j=0; z[i]; i++){
    if( z[i]==quote ){
      if( z[i+1]==quote ){
        z[j++] = quote;
        i++;
      }else{
        z[j++] = 0;
        break;
      }
    }else{
      z[j++] = z[i];
    }
  }
}

/*
** The input azIn is a NULL-terminated list of tokens.  Remove the first
** token and all punctuation tokens.  Remove the quotes from
** around string literal tokens.
**
** Example:
**
**     input:      tokenize chinese ( 'simplifed' , 'mixed' )
**     output:     chinese simplifed mixed
**
** Another example:
**
**     input:      delimiters ( '[' , ']' , '...' )
**     output:     [ ] ...
*/
static void tokenListToIdList(char **azIn){
  int i, j;
  if( azIn ){
    for(i=0, j=-1; azIn[i]; i++){
      if( safe_isalnum(azIn[i][0]) || azIn[i][1] ){
        dequoteString(azIn[i]);
        if( j>=0 ){
          azIn[j] = azIn[i];
        }
        j++;
      }
    }
    azIn[j] = 0;
  }
}


/*
** Find the first alphanumeric token in the string zIn.  Null-terminate
** this token.  Remove any quotation marks.  And return a pointer to
** the result.
*/
static char *firstToken(char *zIn, char **pzTail){
  int n, ttype;
  while(1){
    n = getToken(zIn, &ttype);
    if( ttype==TOKEN_SPACE ){
      zIn += n;
    }else if( ttype==TOKEN_EOF ){
      *pzTail = zIn;
      return 0;
    }else{
      zIn[n] = 0;
      *pzTail = &zIn[1];
      dequoteString(zIn);
      return zIn;
    }
  }
  /*NOTREACHED*/
}

/* Return true if...
**
**   *  s begins with the string t, ignoring case
**   *  s is longer than t
**   *  The first character of s beyond t is not a alphanumeric
** 
** Ignore leading space in *s.
**
** To put it another way, return true if the first token of
** s[] is t[].
*/
static int startsWith(const char *s, const char *t){
  while( safe_isspace(*s) ){ s++; }
  while( *t ){
    if( safe_tolower(*s++)!=safe_tolower(*t++) ) return 0;
  }
  return *s!='_' && !safe_isalnum(*s);
}

/*
** An instance of this structure defines the "spec" of a
** full text index.  This structure is populated by parseSpec
** and use by fulltextConnect and fulltextCreate.
*/
typedef struct TableSpec {
  const char *zDb;         /* Logical database name */
  const char *zName;       /* Name of the full-text index */
  int nColumn;             /* Number of columns to be indexed */
  char **azColumn;         /* Original names of columns to be indexed */
  char **azContentColumn;  /* Column names for %_content */
  char **azTokenizer;      /* Name of tokenizer and its arguments */
} TableSpec;

/*
** Reclaim all of the memory used by a TableSpec
*/
static void clearTableSpec(TableSpec *p) {
  free(p->azColumn);
  free(p->azContentColumn);
  free(p->azTokenizer);
}

/* Parse a CREATE VIRTUAL TABLE statement, which looks like this:
 *
 * CREATE VIRTUAL TABLE email
 *        USING fts1(subject, body, tokenize mytokenizer(myarg))
 *
 * We return parsed information in a TableSpec structure.
 * 
 */
static int parseSpec(TableSpec *pSpec, int argc, const char *const*argv,
                     char**pzErr){
  int i, n;
  char *z, *zDummy;
  char **azArg;
  const char *zTokenizer = 0;    /* argv[] entry describing the tokenizer */

  assert( argc>=3 );
  /* Current interface:
  ** argv[0] - module name
  ** argv[1] - database name
  ** argv[2] - table name
  ** argv[3..] - columns, optionally followed by tokenizer specification
  **             and snippet delimiters specification.
  */

  /* Make a copy of the complete argv[][] array in a single allocation.
  ** The argv[][] array is read-only and transient.  We can write to the
  ** copy in order to modify things and the copy is persistent.
  */
  memset(pSpec, 0, sizeof(*pSpec));
  for(i=n=0; i<argc; i++){
    n += strlen(argv[i]) + 1;
  }
  azArg = malloc( sizeof(char*)*argc + n );
  if( azArg==0 ){
    return SQLITE_NOMEM;
  }
  z = (char*)&azArg[argc];
  for(i=0; i<argc; i++){
    azArg[i] = z;
    strcpy(z, argv[i]);
    z += strlen(z)+1;
  }

  /* Identify the column names and the tokenizer and delimiter arguments
  ** in the argv[][] array.
  */
  pSpec->zDb = azArg[1];
  pSpec->zName = azArg[2];
  pSpec->nColumn = 0;
  pSpec->azColumn = azArg;
  zTokenizer = "tokenize simple";
  for(i=3; i<argc; ++i){
    if( startsWith(azArg[i],"tokenize") ){
      zTokenizer = azArg[i];
    }else{
      z = azArg[pSpec->nColumn] = firstToken(azArg[i], &zDummy);
      pSpec->nColumn++;
    }
  }
  if( pSpec->nColumn==0 ){
    azArg[0] = "content";
    pSpec->nColumn = 1;
  }

  /*
  ** Construct the list of content column names.
  **
  ** Each content column name will be of the form cNNAAAA
  ** where NN is the column number and AAAA is the sanitized
  ** column name.  "sanitized" means that special characters are
  ** converted to "_".  The cNN prefix guarantees that all column
  ** names are unique.
  **
  ** The AAAA suffix is not strictly necessary.  It is included
  ** for the convenience of people who might examine the generated
  ** %_content table and wonder what the columns are used for.
  */
  pSpec->azContentColumn = malloc( pSpec->nColumn * sizeof(char *) );
  if( pSpec->azContentColumn==0 ){
    clearTableSpec(pSpec);
    return SQLITE_NOMEM;
  }
  for(i=0; i<pSpec->nColumn; i++){
    char *p;
    pSpec->azContentColumn[i] = sqlite3_mprintf("c%d%s", i, azArg[i]);
    for (p = pSpec->azContentColumn[i]; *p ; ++p) {
      if( !safe_isalnum(*p) ) *p = '_';
    }
  }

  /*
  ** Parse the tokenizer specification string.
  */
  pSpec->azTokenizer = tokenizeString(zTokenizer, &n);
  tokenListToIdList(pSpec->azTokenizer);

  return SQLITE_OK;
}

/*
** Generate a CREATE TABLE statement that describes the schema of
** the virtual table.  Return a pointer to this schema string.
**
** Space is obtained from sqlite3_mprintf() and should be freed
** using sqlite3_free().
*/
static char *fulltextSchema(
  int nColumn,                  /* Number of columns */
  const char *const* azColumn,  /* List of columns */
  const char *zTableName        /* Name of the table */
){
  int i;
  char *zSchema, *zNext;
  const char *zSep = "(";
  zSchema = sqlite3_mprintf("CREATE TABLE x");
  for(i=0; i<nColumn; i++){
    zNext = sqlite3_mprintf("%s%s%Q", zSchema, zSep, azColumn[i]);
    sqlite3_free(zSchema);
    zSchema = zNext;
    zSep = ",";
  }
  zNext = sqlite3_mprintf("%s,%Q)", zSchema, zTableName);
  sqlite3_free(zSchema);
  return zNext;
}

/*
** Build a new sqlite3_vtab structure that will describe the
** fulltext index defined by spec.
*/
static int constructVtab(
  sqlite3 *db,              /* The SQLite database connection */
  TableSpec *spec,          /* Parsed spec information from parseSpec() */
  sqlite3_vtab **ppVTab,    /* Write the resulting vtab structure here */
  char **pzErr              /* Write any error message here */
){
  int rc;
  int n;
  fulltext_vtab *v = 0;
  const sqlite3_tokenizer_module *m = NULL;
  char *schema;

  v = (fulltext_vtab *) malloc(sizeof(fulltext_vtab));
  if( v==0 ) return SQLITE_NOMEM;
  memset(v, 0, sizeof(*v));
  /* sqlite will initialize v->base */
  v->db = db;
  v->zDb = spec->zDb;       /* Freed when azColumn is freed */
  v->zName = spec->zName;   /* Freed when azColumn is freed */
  v->nColumn = spec->nColumn;
  v->azContentColumn = spec->azContentColumn;
  spec->azContentColumn = 0;
  v->azColumn = spec->azColumn;
  spec->azColumn = 0;

  if( spec->azTokenizer==0 ){
    return SQLITE_NOMEM;
  }
  /* TODO(shess) For now, add new tokenizers as else if clauses. */
  if( spec->azTokenizer[0]==0 || startsWith(spec->azTokenizer[0], "simple") ){
    sqlite3Fts1SimpleTokenizerModule(&m);
  }else if( startsWith(spec->azTokenizer[0], "porter") ){
    sqlite3Fts1PorterTokenizerModule(&m);
  }else{
    *pzErr = sqlite3_mprintf("unknown tokenizer: %s", spec->azTokenizer[0]);
    rc = SQLITE_ERROR;
    goto err;
  }
  for(n=0; spec->azTokenizer[n]; n++){}
  if( n ){
    rc = m->xCreate(n-1, (const char*const*)&spec->azTokenizer[1],
                    &v->pTokenizer);
  }else{
    rc = m->xCreate(0, 0, &v->pTokenizer);
  }
  if( rc!=SQLITE_OK ) goto err;
  v->pTokenizer->pModule = m;

  /* TODO: verify the existence of backing tables foo_content, foo_term */

  schema = fulltextSchema(v->nColumn, (const char*const*)v->azColumn,
                          spec->zName);
  rc = sqlite3_declare_vtab(db, schema);
  sqlite3_free(schema);
  if( rc!=SQLITE_OK ) goto err;

  memset(v->pFulltextStatements, 0, sizeof(v->pFulltextStatements));

  *ppVTab = &v->base;
  TRACE(("FTS1 Connect %p\n", v));

  return rc;

err:
  fulltext_vtab_destroy(v);
  return rc;
}

static int fulltextConnect(
  sqlite3 *db,
  void *pAux,
  int argc, const char *const*argv,
  sqlite3_vtab **ppVTab,
  char **pzErr
){
  TableSpec spec;
  int rc = parseSpec(&spec, argc, argv, pzErr);
  if( rc!=SQLITE_OK ) return rc;

  rc = constructVtab(db, &spec, ppVTab, pzErr);
  clearTableSpec(&spec);
  return rc;
}

  /* The %_content table holds the text of each document, with
  ** the rowid used as the docid.
  **
  ** The %_term table maps each term to a document list blob
  ** containing elements sorted by ascending docid, each element
  ** encoded as:
  **
  **   docid varint-encoded
  **   token elements:
  **     position+1 varint-encoded as delta from previous position
  **     start offset varint-encoded as delta from previous start offset
  **     end offset varint-encoded as delta from start offset
  **
  ** The sentinel position of 0 indicates the end of the token list.
  **
  ** Additionally, doclist blobs are chunked into multiple segments,
  ** using segment to order the segments.  New elements are added to
  ** the segment at segment 0, until it exceeds CHUNK_MAX.  Then
  ** segment 0 is deleted, and the doclist is inserted at segment 1.
  ** If there is already a doclist at segment 1, the segment 0 doclist
  ** is merged with it, the segment 1 doclist is deleted, and the
  ** merged doclist is inserted at segment 2, repeating those
  ** operations until an insert succeeds.
  **
  ** Since this structure doesn't allow us to update elements in place
  ** in case of deletion or update, these are simply written to
  ** segment 0 (with an empty token list in case of deletion), with
  ** docListAccumulate() taking care to retain lower-segment
  ** information in preference to higher-segment information.
  */
  /* TODO(shess) Provide a VACUUM type operation which both removes
  ** deleted elements which are no longer necessary, and duplicated
  ** elements.  I suspect this will probably not be necessary in
  ** practice, though.
  */
static int fulltextCreate(sqlite3 *db, void *pAux,
                          int argc, const char * const *argv,
                          sqlite3_vtab **ppVTab, char **pzErr){
  int rc;
  TableSpec spec;
  StringBuffer schema;
  TRACE(("FTS1 Create\n"));

  rc = parseSpec(&spec, argc, argv, pzErr);
  if( rc!=SQLITE_OK ) return rc;

  initStringBuffer(&schema);
  append(&schema, "CREATE TABLE %_content(");
  appendList(&schema, spec.nColumn, spec.azContentColumn);
  append(&schema, ")");
  rc = sql_exec(db, spec.zDb, spec.zName, schema.s);
  free(schema.s);
  if( rc!=SQLITE_OK ) goto out;

  rc = sql_exec(db, spec.zDb, spec.zName,
    "create table %_term(term text, segment integer, doclist blob, "
                        "primary key(term, segment));");
  if( rc!=SQLITE_OK ) goto out;

  rc = constructVtab(db, &spec, ppVTab, pzErr);

out:
  clearTableSpec(&spec);
  return rc;
}

/* Decide how to handle an SQL query. */
static int fulltextBestIndex(sqlite3_vtab *pVTab, sqlite3_index_info *pInfo){
  int i;
  TRACE(("FTS1 BestIndex\n"));

  for(i=0; i<pInfo->nConstraint; ++i){
    const struct sqlite3_index_constraint *pConstraint;
    pConstraint = &pInfo->aConstraint[i];
    if( pConstraint->usable ) {
      if( pConstraint->iColumn==-1 &&
          pConstraint->op==SQLITE_INDEX_CONSTRAINT_EQ ){
        pInfo->idxNum = QUERY_ROWID;      /* lookup by rowid */
        TRACE(("FTS1 QUERY_ROWID\n"));
      } else if( pConstraint->iColumn>=0 &&
                 pConstraint->op==SQLITE_INDEX_CONSTRAINT_MATCH ){
        /* full-text search */
        pInfo->idxNum = QUERY_FULLTEXT + pConstraint->iColumn;
        TRACE(("FTS1 QUERY_FULLTEXT %d\n", pConstraint->iColumn));
      } else continue;

      pInfo->aConstraintUsage[i].argvIndex = 1;
      pInfo->aConstraintUsage[i].omit = 1;

      /* An arbitrary value for now.
       * TODO: Perhaps rowid matches should be considered cheaper than
       * full-text searches. */
      pInfo->estimatedCost = 1.0;   

      return SQLITE_OK;
    }
  }
  pInfo->idxNum = QUERY_GENERIC;
  return SQLITE_OK;
}

static int fulltextDisconnect(sqlite3_vtab *pVTab){
  TRACE(("FTS1 Disconnect %p\n", pVTab));
  fulltext_vtab_destroy((fulltext_vtab *)pVTab);
  return SQLITE_OK;
}

static int fulltextDestroy(sqlite3_vtab *pVTab){
  fulltext_vtab *v = (fulltext_vtab *)pVTab;
  int rc;

  TRACE(("FTS1 Destroy %p\n", pVTab));
  rc = sql_exec(v->db, v->zDb, v->zName,
                "drop table if exists %_content;"
                "drop table if exists %_term;"
                );
  if( rc!=SQLITE_OK ) return rc;

  fulltext_vtab_destroy((fulltext_vtab *)pVTab);
  return SQLITE_OK;
}

static int fulltextOpen(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor){
  fulltext_cursor *c;

  c = (fulltext_cursor *) calloc(sizeof(fulltext_cursor), 1);
  /* sqlite will initialize c->base */
  *ppCursor = &c->base;
  TRACE(("FTS1 Open %p: %p\n", pVTab, c));

  return SQLITE_OK;
}


/* Free all of the dynamically allocated memory held by *q
*/
static void queryClear(Query *q){
  int i;
  for(i = 0; i < q->nTerms; ++i){
    free(q->pTerms[i].pTerm);
  }
  free(q->pTerms);
  memset(q, 0, sizeof(*q));
}

/* Free all of the dynamically allocated memory held by the
** Snippet
*/
static void snippetClear(Snippet *p){
  free(p->aMatch);
  free(p->zOffset);
  free(p->zSnippet);
  memset(p, 0, sizeof(*p));
}
/*
** Append a single entry to the p->aMatch[] log.
*/
static void snippetAppendMatch(
  Snippet *p,               /* Append the entry to this snippet */
  int iCol, int iTerm,      /* The column and query term */
  int iStart, int nByte     /* Offset and size of the match */
){
  int i;
  struct snippetMatch *pMatch;
  if( p->nMatch+1>=p->nAlloc ){
    p->nAlloc = p->nAlloc*2 + 10;
    p->aMatch = realloc(p->aMatch, p->nAlloc*sizeof(p->aMatch[0]) );
    if( p->aMatch==0 ){
      p->nMatch = 0;
      p->nAlloc = 0;
      return;
    }
  }
  i = p->nMatch++;
  pMatch = &p->aMatch[i];
  pMatch->iCol = iCol;
  pMatch->iTerm = iTerm;
  pMatch->iStart = iStart;
  pMatch->nByte = nByte;
}

/*
** Sizing information for the circular buffer used in snippetOffsetsOfColumn()
*/
#define FTS1_ROTOR_SZ   (32)
#define FTS1_ROTOR_MASK (FTS1_ROTOR_SZ-1)

/*
** Add entries to pSnippet->aMatch[] for every match that occurs against
** document zDoc[0..nDoc-1] which is stored in column iColumn.
*/
static void snippetOffsetsOfColumn(
  Query *pQuery,
  Snippet *pSnippet,
  int iColumn,
  const char *zDoc,
  int nDoc
){
  const sqlite3_tokenizer_module *pTModule;  /* The tokenizer module */
  sqlite3_tokenizer *pTokenizer;             /* The specific tokenizer */
  sqlite3_tokenizer_cursor *pTCursor;        /* Tokenizer cursor */
  fulltext_vtab *pVtab;                /* The full text index */
  int nColumn;                         /* Number of columns in the index */
  const QueryTerm *aTerm;              /* Query string terms */
  int nTerm;                           /* Number of query string terms */  
  int i, j;                            /* Loop counters */
  int rc;                              /* Return code */
  unsigned int match, prevMatch;       /* Phrase search bitmasks */
  const char *zToken;                  /* Next token from the tokenizer */
  int nToken;                          /* Size of zToken */
  int iBegin, iEnd, iPos;              /* Offsets of beginning and end */

  /* The following variables keep a circular buffer of the last
  ** few tokens */
  unsigned int iRotor = 0;             /* Index of current token */
  int iRotorBegin[FTS1_ROTOR_SZ];      /* Beginning offset of token */
  int iRotorLen[FTS1_ROTOR_SZ];        /* Length of token */

  pVtab = pQuery->pFts;
  nColumn = pVtab->nColumn;
  pTokenizer = pVtab->pTokenizer;
  pTModule = pTokenizer->pModule;
  rc = pTModule->xOpen(pTokenizer, zDoc, nDoc, &pTCursor);
  if( rc ) return;
  pTCursor->pTokenizer = pTokenizer;
  aTerm = pQuery->pTerms;
  nTerm = pQuery->nTerms;
  if( nTerm>=FTS1_ROTOR_SZ ){
    nTerm = FTS1_ROTOR_SZ - 1;
  }
  prevMatch = 0;
  while(1){
    rc = pTModule->xNext(pTCursor, &zToken, &nToken, &iBegin, &iEnd, &iPos);
    if( rc ) break;
    iRotorBegin[iRotor&FTS1_ROTOR_MASK] = iBegin;
    iRotorLen[iRotor&FTS1_ROTOR_MASK] = iEnd-iBegin;
    match = 0;
    for(i=0; i<nTerm; i++){
      int iCol;
      iCol = aTerm[i].iColumn;
      if( iCol>=0 && iCol<nColumn && iCol!=iColumn ) continue;
      if( aTerm[i].nTerm!=nToken ) continue;
      if( memcmp(aTerm[i].pTerm, zToken, nToken) ) continue;
      if( aTerm[i].iPhrase>1 && (prevMatch & (1<<i))==0 ) continue;
      match |= 1<<i;
      if( i==nTerm-1 || aTerm[i+1].iPhrase==1 ){
        for(j=aTerm[i].iPhrase-1; j>=0; j--){
          int k = (iRotor-j) & FTS1_ROTOR_MASK;
          snippetAppendMatch(pSnippet, iColumn, i-j,
                iRotorBegin[k], iRotorLen[k]);
        }
      }
    }
    prevMatch = match<<1;
    iRotor++;
  }
  pTModule->xClose(pTCursor);  
}


/*
** Compute all offsets for the current row of the query.  
** If the offsets have already been computed, this routine is a no-op.
*/
static void snippetAllOffsets(fulltext_cursor *p){
  int nColumn;
  int iColumn, i;
  int iFirst, iLast;
  fulltext_vtab *pFts;

  if( p->snippet.nMatch ) return;
  if( p->q.nTerms==0 ) return;
  pFts = p->q.pFts;
  nColumn = pFts->nColumn;
  iColumn = p->iCursorType;
  if( iColumn<0 || iColumn>=nColumn ){
    iFirst = 0;
    iLast = nColumn-1;
  }else{
    iFirst = iColumn;
    iLast = iColumn;
  }
  for(i=iFirst; i<=iLast; i++){
    const char *zDoc;
    int nDoc;
    zDoc = (const char*)sqlite3_column_text(p->pStmt, i+1);
    nDoc = sqlite3_column_bytes(p->pStmt, i+1);
    snippetOffsetsOfColumn(&p->q, &p->snippet, i, zDoc, nDoc);
  }
}

/*
** Convert the information in the aMatch[] array of the snippet
** into the string zOffset[0..nOffset-1].
*/
static void snippetOffsetText(Snippet *p){
  int i;
  int cnt = 0;
  StringBuffer sb;
  char zBuf[200];
  if( p->zOffset ) return;
  initStringBuffer(&sb);
  for(i=0; i<p->nMatch; i++){
    struct snippetMatch *pMatch = &p->aMatch[i];
    zBuf[0] = ' ';
    sprintf(&zBuf[cnt>0], "%d %d %d %d", pMatch->iCol,
        pMatch->iTerm, pMatch->iStart, pMatch->nByte);
    append(&sb, zBuf);
    cnt++;
  }
  p->zOffset = sb.s;
  p->nOffset = sb.len;
}

/*
** zDoc[0..nDoc-1] is phrase of text.  aMatch[0..nMatch-1] are a set
** of matching words some of which might be in zDoc.  zDoc is column
** number iCol.
**
** iBreak is suggested spot in zDoc where we could begin or end an
** excerpt.  Return a value similar to iBreak but possibly adjusted
** to be a little left or right so that the break point is better.
*/
static int wordBoundary(
  int iBreak,                   /* The suggested break point */
  const char *zDoc,             /* Document text */
  int nDoc,                     /* Number of bytes in zDoc[] */
  struct snippetMatch *aMatch,  /* Matching words */
  int nMatch,                   /* Number of entries in aMatch[] */
  int iCol                      /* The column number for zDoc[] */
){
  int i;
  if( iBreak<=10 ){
    return 0;
  }
  if( iBreak>=nDoc-10 ){
    return nDoc;
  }
  for(i=0; i<nMatch && aMatch[i].iCol<iCol; i++){}
  while( i<nMatch && aMatch[i].iStart+aMatch[i].nByte<iBreak ){ i++; }
  if( i<nMatch ){
    if( aMatch[i].iStart<iBreak+10 ){
      return aMatch[i].iStart;
    }
    if( i>0 && aMatch[i-1].iStart+aMatch[i-1].nByte>=iBreak ){
      return aMatch[i-1].iStart;
    }
  }
  for(i=1; i<=10; i++){
    if( safe_isspace(zDoc[iBreak-i]) ){
      return iBreak - i + 1;
    }
    if( safe_isspace(zDoc[iBreak+i]) ){
      return iBreak + i + 1;
    }
  }
  return iBreak;
}

/*
** If the StringBuffer does not end in white space, add a single
** space character to the end.
*/
static void appendWhiteSpace(StringBuffer *p){
  if( p->len==0 ) return;
  if( safe_isspace(p->s[p->len-1]) ) return;
  append(p, " ");
}

/*
** Remove white space from teh end of the StringBuffer
*/
static void trimWhiteSpace(StringBuffer *p){
  while( p->len>0 && safe_isspace(p->s[p->len-1]) ){
    p->len--;
  }
}



/*
** Allowed values for Snippet.aMatch[].snStatus
*/
#define SNIPPET_IGNORE  0   /* It is ok to omit this match from the snippet */
#define SNIPPET_DESIRED 1   /* We want to include this match in the snippet */

/*
** Generate the text of a snippet.
*/
static void snippetText(
  fulltext_cursor *pCursor,   /* The cursor we need the snippet for */
  const char *zStartMark,     /* Markup to appear before each match */
  const char *zEndMark,       /* Markup to appear after each match */
  const char *zEllipsis       /* Ellipsis mark */
){
  int i, j;
  struct snippetMatch *aMatch;
  int nMatch;
  int nDesired;
  StringBuffer sb;
  int tailCol;
  int tailOffset;
  int iCol;
  int nDoc;
  const char *zDoc;
  int iStart, iEnd;
  int tailEllipsis = 0;
  int iMatch;
  

  free(pCursor->snippet.zSnippet);
  pCursor->snippet.zSnippet = 0;
  aMatch = pCursor->snippet.aMatch;
  nMatch = pCursor->snippet.nMatch;
  initStringBuffer(&sb);

  for(i=0; i<nMatch; i++){
    aMatch[i].snStatus = SNIPPET_IGNORE;
  }
  nDesired = 0;
  for(i=0; i<pCursor->q.nTerms; i++){
    for(j=0; j<nMatch; j++){
      if( aMatch[j].iTerm==i ){
        aMatch[j].snStatus = SNIPPET_DESIRED;
        nDesired++;
        break;
      }
    }
  }

  iMatch = 0;
  tailCol = -1;
  tailOffset = 0;
  for(i=0; i<nMatch && nDesired>0; i++){
    if( aMatch[i].snStatus!=SNIPPET_DESIRED ) continue;
    nDesired--;
    iCol = aMatch[i].iCol;
    zDoc = (const char*)sqlite3_column_text(pCursor->pStmt, iCol+1);
    nDoc = sqlite3_column_bytes(pCursor->pStmt, iCol+1);
    iStart = aMatch[i].iStart - 40;
    iStart = wordBoundary(iStart, zDoc, nDoc, aMatch, nMatch, iCol);
    if( iStart<=10 ){
      iStart = 0;
    }
    if( iCol==tailCol && iStart<=tailOffset+20 ){
      iStart = tailOffset;
    }
    if( (iCol!=tailCol && tailCol>=0) || iStart!=tailOffset ){
      trimWhiteSpace(&sb);
      appendWhiteSpace(&sb);
      append(&sb, zEllipsis);
      appendWhiteSpace(&sb);
    }
    iEnd = aMatch[i].iStart + aMatch[i].nByte + 40;
    iEnd = wordBoundary(iEnd, zDoc, nDoc, aMatch, nMatch, iCol);
    if( iEnd>=nDoc-10 ){
      iEnd = nDoc;
      tailEllipsis = 0;
    }else{
      tailEllipsis = 1;
    }
    while( iMatch<nMatch && aMatch[iMatch].iCol<iCol ){ iMatch++; }
    while( iStart<iEnd ){
      while( iMatch<nMatch && aMatch[iMatch].iStart<iStart
             && aMatch[iMatch].iCol<=iCol ){
        iMatch++;
      }
      if( iMatch<nMatch && aMatch[iMatch].iStart<iEnd
             && aMatch[iMatch].iCol==iCol ){
        nappend(&sb, &zDoc[iStart], aMatch[iMatch].iStart - iStart);
        iStart = aMatch[iMatch].iStart;
        append(&sb, zStartMark);
        nappend(&sb, &zDoc[iStart], aMatch[iMatch].nByte);
        append(&sb, zEndMark);
        iStart += aMatch[iMatch].nByte;
        for(j=iMatch+1; j<nMatch; j++){
          if( aMatch[j].iTerm==aMatch[iMatch].iTerm
              && aMatch[j].snStatus==SNIPPET_DESIRED ){
            nDesired--;
            aMatch[j].snStatus = SNIPPET_IGNORE;
          }
        }
      }else{
        nappend(&sb, &zDoc[iStart], iEnd - iStart);
        iStart = iEnd;
      }
    }
    tailCol = iCol;
    tailOffset = iEnd;
  }
  trimWhiteSpace(&sb);
  if( tailEllipsis ){
    appendWhiteSpace(&sb);
    append(&sb, zEllipsis);
  }
  pCursor->snippet.zSnippet = sb.s;
  pCursor->snippet.nSnippet = sb.len;  
}


/*
** Close the cursor.  For additional information see the documentation
** on the xClose method of the virtual table interface.
*/
static int fulltextClose(sqlite3_vtab_cursor *pCursor){
  fulltext_cursor *c = (fulltext_cursor *) pCursor;
  TRACE(("FTS1 Close %p\n", c));
  sqlite3_finalize(c->pStmt);
  queryClear(&c->q);
  snippetClear(&c->snippet);
  if( c->result.pDoclist!=NULL ){
    docListDelete(c->result.pDoclist);
  }
  free(c);
  return SQLITE_OK;
}

static int fulltextNext(sqlite3_vtab_cursor *pCursor){
  fulltext_cursor *c = (fulltext_cursor *) pCursor;
  sqlite_int64 iDocid;
  int rc;

  TRACE(("FTS1 Next %p\n", pCursor));
  snippetClear(&c->snippet);
  if( c->iCursorType < QUERY_FULLTEXT ){
    /* TODO(shess) Handle SQLITE_SCHEMA AND SQLITE_BUSY. */
    rc = sqlite3_step(c->pStmt);
    switch( rc ){
      case SQLITE_ROW:
        c->eof = 0;
        return SQLITE_OK;
      case SQLITE_DONE:
        c->eof = 1;
        return SQLITE_OK;
      default:
        c->eof = 1;
        return rc;
    }
  } else {  /* full-text query */
    rc = sqlite3_reset(c->pStmt);
    if( rc!=SQLITE_OK ) return rc;

    iDocid = nextDocid(&c->result);
    if( iDocid==0 ){
      c->eof = 1;
      return SQLITE_OK;
    }
    rc = sqlite3_bind_int64(c->pStmt, 1, iDocid);
    if( rc!=SQLITE_OK ) return rc;
    /* TODO(shess) Handle SQLITE_SCHEMA AND SQLITE_BUSY. */
    rc = sqlite3_step(c->pStmt);
    if( rc==SQLITE_ROW ){   /* the case we expect */
      c->eof = 0;
      return SQLITE_OK;
    }
    /* an error occurred; abort */
    return rc==SQLITE_DONE ? SQLITE_ERROR : rc;
  }
}


/* Return a DocList corresponding to the query term *pTerm.  If *pTerm
** is the first term of a phrase query, go ahead and evaluate the phrase
** query and return the doclist for the entire phrase query.
**
** The result is stored in pTerm->doclist.
*/
static int docListOfTerm(
  fulltext_vtab *v,     /* The full text index */
  int iColumn,          /* column to restrict to.  No restrition if >=nColumn */
  QueryTerm *pQTerm,    /* Term we are looking for, or 1st term of a phrase */
  DocList **ppResult    /* Write the result here */
){
  DocList *pLeft, *pRight, *pNew;
  int i, rc;

  pLeft = docListNew(DL_POSITIONS);
  rc = term_select_all(v, iColumn, pQTerm->pTerm, pQTerm->nTerm, pLeft);
  if( rc ) return rc;
  for(i=1; i<=pQTerm->nPhrase; i++){
    pRight = docListNew(DL_POSITIONS);
    rc = term_select_all(v, iColumn, pQTerm[i].pTerm, pQTerm[i].nTerm, pRight);
    if( rc ){
      docListDelete(pLeft);
      return rc;
    }
    pNew = docListNew(i<pQTerm->nPhrase ? DL_POSITIONS : DL_DOCIDS);
    docListPhraseMerge(pLeft, pRight, pNew);
    docListDelete(pLeft);
    docListDelete(pRight);
    pLeft = pNew;
  }
  *ppResult = pLeft;
  return SQLITE_OK;
}

/* Add a new term pTerm[0..nTerm-1] to the query *q.
*/
static void queryAdd(Query *q, const char *pTerm, int nTerm){
  QueryTerm *t;
  ++q->nTerms;
  q->pTerms = realloc(q->pTerms, q->nTerms * sizeof(q->pTerms[0]));
  if( q->pTerms==0 ){
    q->nTerms = 0;
    return;
  }
  t = &q->pTerms[q->nTerms - 1];
  memset(t, 0, sizeof(*t));
  t->pTerm = malloc(nTerm+1);
  memcpy(t->pTerm, pTerm, nTerm);
  t->pTerm[nTerm] = 0;
  t->nTerm = nTerm;
  t->isOr = q->nextIsOr;
  q->nextIsOr = 0;
  t->iColumn = q->nextColumn;
  q->nextColumn = q->dfltColumn;
}

/*
** Check to see if the string zToken[0...nToken-1] matches any
** column name in the virtual table.   If it does,
** return the zero-indexed column number.  If not, return -1.
*/
static int checkColumnSpecifier(
  fulltext_vtab *pVtab,    /* The virtual table */
  const char *zToken,      /* Text of the token */
  int nToken               /* Number of characters in the token */
){
  int i;
  for(i=0; i<pVtab->nColumn; i++){
    if( memcmp(pVtab->azColumn[i], zToken, nToken)==0
        && pVtab->azColumn[i][nToken]==0 ){
      return i;
    }
  }
  return -1;
}

/*
** Parse the text at pSegment[0..nSegment-1].  Add additional terms
** to the query being assemblied in pQuery.
**
** inPhrase is true if pSegment[0..nSegement-1] is contained within
** double-quotes.  If inPhrase is true, then the first term
** is marked with the number of terms in the phrase less one and
** OR and "-" syntax is ignored.  If inPhrase is false, then every
** term found is marked with nPhrase=0 and OR and "-" syntax is significant.
*/
static int tokenizeSegment(
  sqlite3_tokenizer *pTokenizer,          /* The tokenizer to use */
  const char *pSegment, int nSegment,     /* Query expression being parsed */
  int inPhrase,                           /* True if within "..." */
  Query *pQuery                           /* Append results here */
){
  const sqlite3_tokenizer_module *pModule = pTokenizer->pModule;
  sqlite3_tokenizer_cursor *pCursor;
  int firstIndex = pQuery->nTerms;
  int iCol;
  int nTerm = 1;
  
  int rc = pModule->xOpen(pTokenizer, pSegment, nSegment, &pCursor);
  if( rc!=SQLITE_OK ) return rc;
  pCursor->pTokenizer = pTokenizer;

  while( 1 ){
    const char *pToken;
    int nToken, iBegin, iEnd, iPos;

    rc = pModule->xNext(pCursor,
                        &pToken, &nToken,
                        &iBegin, &iEnd, &iPos);
    if( rc!=SQLITE_OK ) break;
    if( !inPhrase &&
        pSegment[iEnd]==':' &&
         (iCol = checkColumnSpecifier(pQuery->pFts, pToken, nToken))>=0 ){
      pQuery->nextColumn = iCol;
      continue;
    }
    if( !inPhrase && pQuery->nTerms>0 && nToken==2
         && pSegment[iBegin]=='O' && pSegment[iBegin+1]=='R' ){
      pQuery->nextIsOr = 1;
      continue;
    }
    queryAdd(pQuery, pToken, nToken);
    if( !inPhrase && iBegin>0 && pSegment[iBegin-1]=='-' ){
      pQuery->pTerms[pQuery->nTerms-1].isNot = 1;
    }
    pQuery->pTerms[pQuery->nTerms-1].iPhrase = nTerm;
    if( inPhrase ){
      nTerm++;
    }
  }

  if( inPhrase && pQuery->nTerms>firstIndex ){
    pQuery->pTerms[firstIndex].nPhrase = pQuery->nTerms - firstIndex - 1;
  }

  return pModule->xClose(pCursor);
}

/* Parse a query string, yielding a Query object pQuery.
**
** The calling function will need to queryClear() to clean up
** the dynamically allocated memory held by pQuery.
*/
static int parseQuery(
  fulltext_vtab *v,        /* The fulltext index */
  const char *zInput,      /* Input text of the query string */
  int nInput,              /* Size of the input text */
  int dfltColumn,          /* Default column of the index to match against */
  Query *pQuery            /* Write the parse results here. */
){
  int iInput, inPhrase = 0;

  if( zInput==0 ) nInput = 0;
  if( nInput<0 ) nInput = strlen(zInput);
  pQuery->nTerms = 0;
  pQuery->pTerms = NULL;
  pQuery->nextIsOr = 0;
  pQuery->nextColumn = dfltColumn;
  pQuery->dfltColumn = dfltColumn;
  pQuery->pFts = v;

  for(iInput=0; iInput<nInput; ++iInput){
    int i;
    for(i=iInput; i<nInput && zInput[i]!='"'; ++i){}
    if( i>iInput ){
      tokenizeSegment(v->pTokenizer, zInput+iInput, i-iInput, inPhrase,
                       pQuery);
    }
    iInput = i;
    if( i<nInput ){
      assert( zInput[i]=='"' );
      inPhrase = !inPhrase;
    }
  }

  if( inPhrase ){
    /* unmatched quote */
    queryClear(pQuery);
    return SQLITE_ERROR;
  }
  return SQLITE_OK;
}

/* Perform a full-text query using the search expression in
** zInput[0..nInput-1].  Return a list of matching documents
** in pResult.
**
** Queries must match column iColumn.  Or if iColumn>=nColumn
** they are allowed to match against any column.
*/
static int fulltextQuery(
  fulltext_vtab *v,      /* The full text index */
  int iColumn,           /* Match against this column by default */
  const char *zInput,    /* The query string */
  int nInput,            /* Number of bytes in zInput[] */
  DocList **pResult,     /* Write the result doclist here */
  Query *pQuery          /* Put parsed query string here */
){
  int i, iNext, rc;
  DocList *pLeft = NULL;
  DocList *pRight, *pNew, *pOr;
  int nNot = 0;
  QueryTerm *aTerm;

  rc = parseQuery(v, zInput, nInput, iColumn, pQuery);
  if( rc!=SQLITE_OK ) return rc;

  /* Merge AND terms. */
  aTerm = pQuery->pTerms;
  for(i = 0; i<pQuery->nTerms; i=iNext){
    if( aTerm[i].isNot ){
      /* Handle all NOT terms in a separate pass */
      nNot++;
      iNext = i + aTerm[i].nPhrase+1;
      continue;
    }
    iNext = i + aTerm[i].nPhrase + 1;
    rc = docListOfTerm(v, aTerm[i].iColumn, &aTerm[i], &pRight);
    if( rc ){
      queryClear(pQuery);
      return rc;
    }
    while( iNext<pQuery->nTerms && aTerm[iNext].isOr ){
      rc = docListOfTerm(v, aTerm[iNext].iColumn, &aTerm[iNext], &pOr);
      iNext += aTerm[iNext].nPhrase + 1;
      if( rc ){
        queryClear(pQuery);
        return rc;
      }
      pNew = docListNew(DL_DOCIDS);
      docListOrMerge(pRight, pOr, pNew);
      docListDelete(pRight);
      docListDelete(pOr);
      pRight = pNew;
    }
    if( pLeft==0 ){
      pLeft = pRight;
    }else{
      pNew = docListNew(DL_DOCIDS);
      docListAndMerge(pLeft, pRight, pNew);
      docListDelete(pRight);
      docListDelete(pLeft);
      pLeft = pNew;
    }
  }

  if( nNot && pLeft==0 ){
    /* We do not yet know how to handle a query of only NOT terms */
    return SQLITE_ERROR;
  }

  /* Do the EXCEPT terms */
  for(i=0; i<pQuery->nTerms;  i += aTerm[i].nPhrase + 1){
    if( !aTerm[i].isNot ) continue;
    rc = docListOfTerm(v, aTerm[i].iColumn, &aTerm[i], &pRight);
    if( rc ){
      queryClear(pQuery);
      docListDelete(pLeft);
      return rc;
    }
    pNew = docListNew(DL_DOCIDS);
    docListExceptMerge(pLeft, pRight, pNew);
    docListDelete(pRight);
    docListDelete(pLeft);
    pLeft = pNew;
  }

  *pResult = pLeft;
  return rc;
}

/*
** This is the xFilter interface for the virtual table.  See
** the virtual table xFilter method documentation for additional
** information.
**
** If idxNum==QUERY_GENERIC then do a full table scan against
** the %_content table.
**
** If idxNum==QUERY_ROWID then do a rowid lookup for a single entry
** in the %_content table.
**
** If idxNum>=QUERY_FULLTEXT then use the full text index.  The
** column on the left-hand side of the MATCH operator is column
** number idxNum-QUERY_FULLTEXT, 0 indexed.  argv[0] is the right-hand
** side of the MATCH operator.
*/
/* TODO(shess) Upgrade the cursor initialization and destruction to
** account for fulltextFilter() being called multiple times on the
** same cursor.  The current solution is very fragile.  Apply fix to
** fts2 as appropriate.
*/
static int fulltextFilter(
  sqlite3_vtab_cursor *pCursor,     /* The cursor used for this query */
  int idxNum, const char *idxStr,   /* Which indexing scheme to use */
  int argc, sqlite3_value **argv    /* Arguments for the indexing scheme */
){
  fulltext_cursor *c = (fulltext_cursor *) pCursor;
  fulltext_vtab *v = cursor_vtab(c);
  int rc;
  char *zSql;

  TRACE(("FTS1 Filter %p\n",pCursor));

  zSql = sqlite3_mprintf("select rowid, * from %%_content %s",
                          idxNum==QUERY_GENERIC ? "" : "where rowid=?");
  sqlite3_finalize(c->pStmt);
  rc = sql_prepare(v->db, v->zDb, v->zName, &c->pStmt, zSql);
  sqlite3_free(zSql);
  if( rc!=SQLITE_OK ) return rc;

  c->iCursorType = idxNum;
  switch( idxNum ){
    case QUERY_GENERIC:
      break;

    case QUERY_ROWID:
      rc = sqlite3_bind_int64(c->pStmt, 1, sqlite3_value_int64(argv[0]));
      if( rc!=SQLITE_OK ) return rc;
      break;

    default:   /* full-text search */
    {
      const char *zQuery = (const char *)sqlite3_value_text(argv[0]);
      DocList *pResult;
      assert( idxNum<=QUERY_FULLTEXT+v->nColumn);
      assert( argc==1 );
      queryClear(&c->q);
      rc = fulltextQuery(v, idxNum-QUERY_FULLTEXT, zQuery, -1, &pResult, &c->q);
      if( rc!=SQLITE_OK ) return rc;
      if( c->result.pDoclist!=NULL ) docListDelete(c->result.pDoclist);
      readerInit(&c->result, pResult);
      break;
    }
  }

  return fulltextNext(pCursor);
}

/* This is the xEof method of the virtual table.  The SQLite core
** calls this routine to find out if it has reached the end of
** a query's results set.
*/
static int fulltextEof(sqlite3_vtab_cursor *pCursor){
  fulltext_cursor *c = (fulltext_cursor *) pCursor;
  return c->eof;
}

/* This is the xColumn method of the virtual table.  The SQLite
** core calls this method during a query when it needs the value
** of a column from the virtual table.  This method needs to use
** one of the sqlite3_result_*() routines to store the requested
** value back in the pContext.
*/
static int fulltextColumn(sqlite3_vtab_cursor *pCursor,
                          sqlite3_context *pContext, int idxCol){
  fulltext_cursor *c = (fulltext_cursor *) pCursor;
  fulltext_vtab *v = cursor_vtab(c);

  if( idxCol<v->nColumn ){
    sqlite3_value *pVal = sqlite3_column_value(c->pStmt, idxCol+1);
    sqlite3_result_value(pContext, pVal);
  }else if( idxCol==v->nColumn ){
    /* The extra column whose name is the same as the table.
    ** Return a blob which is a pointer to the cursor
    */
    sqlite3_result_blob(pContext, &c, sizeof(c), SQLITE_TRANSIENT);
  }
  return SQLITE_OK;
}

/* This is the xRowid method.  The SQLite core calls this routine to
** retrive the rowid for the current row of the result set.  The
** rowid should be written to *pRowid.
*/
static int fulltextRowid(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
  fulltext_cursor *c = (fulltext_cursor *) pCursor;

  *pRowid = sqlite3_column_int64(c->pStmt, 0);
  return SQLITE_OK;
}

/* Add all terms in [zText] to the given hash table.  If [iColumn] > 0,
 * we also store positions and offsets in the hash table using the given
 * column number. */
static int buildTerms(fulltext_vtab *v, fts1Hash *terms, sqlite_int64 iDocid,
                      const char *zText, int iColumn){
  sqlite3_tokenizer *pTokenizer = v->pTokenizer;
  sqlite3_tokenizer_cursor *pCursor;
  const char *pToken;
  int nTokenBytes;
  int iStartOffset, iEndOffset, iPosition;
  int rc;

  rc = pTokenizer->pModule->xOpen(pTokenizer, zText, -1, &pCursor);
  if( rc!=SQLITE_OK ) return rc;

  pCursor->pTokenizer = pTokenizer;
  while( SQLITE_OK==pTokenizer->pModule->xNext(pCursor,
                                               &pToken, &nTokenBytes,
                                               &iStartOffset, &iEndOffset,
                                               &iPosition) ){
    DocList *p;

    /* Positions can't be negative; we use -1 as a terminator internally. */
    if( iPosition<0 ){
      pTokenizer->pModule->xClose(pCursor);
      return SQLITE_ERROR;
    }

    p = fts1HashFind(terms, pToken, nTokenBytes);
    if( p==NULL ){
      p = docListNew(DL_DEFAULT);
      docListAddDocid(p, iDocid);
      fts1HashInsert(terms, pToken, nTokenBytes, p);
    }
    if( iColumn>=0 ){
      docListAddPosOffset(p, iColumn, iPosition, iStartOffset, iEndOffset);
    }
  }

  /* TODO(shess) Check return?  Should this be able to cause errors at
  ** this point?  Actually, same question about sqlite3_finalize(),
  ** though one could argue that failure there means that the data is
  ** not durable.  *ponder*
  */
  pTokenizer->pModule->xClose(pCursor);
  return rc;
}

/* Update the %_terms table to map the term [pTerm] to the given rowid. */
static int index_insert_term(fulltext_vtab *v, const char *pTerm, int nTerm,
                             DocList *d){
  sqlite_int64 iIndexRow;
  DocList doclist;
  int iSegment = 0, rc;

  rc = term_select(v, pTerm, nTerm, iSegment, &iIndexRow, &doclist);
  if( rc==SQLITE_DONE ){
    docListInit(&doclist, DL_DEFAULT, 0, 0);
    docListUpdate(&doclist, d);
    /* TODO(shess) Consider length(doclist)>CHUNK_MAX? */
    rc = term_insert(v, NULL, pTerm, nTerm, iSegment, &doclist);
    goto err;
  }
  if( rc!=SQLITE_ROW ) return SQLITE_ERROR;

  docListUpdate(&doclist, d);
  if( doclist.nData<=CHUNK_MAX ){
    rc = term_update(v, iIndexRow, &doclist);
    goto err;
  }

  /* Doclist doesn't fit, delete what's there, and accumulate
  ** forward.
  */
  rc = term_delete(v, iIndexRow);
  if( rc!=SQLITE_OK ) goto err;

  /* Try to insert the doclist into a higher segment bucket.  On
  ** failure, accumulate existing doclist with the doclist from that
  ** bucket, and put results in the next bucket.
  */
  iSegment++;
  while( (rc=term_insert(v, &iIndexRow, pTerm, nTerm, iSegment,
                         &doclist))!=SQLITE_OK ){
    sqlite_int64 iSegmentRow;
    DocList old;
    int rc2;

    /* Retain old error in case the term_insert() error was really an
    ** error rather than a bounced insert.
    */
    rc2 = term_select(v, pTerm, nTerm, iSegment, &iSegmentRow, &old);
    if( rc2!=SQLITE_ROW ) goto err;

    rc = term_delete(v, iSegmentRow);
    if( rc!=SQLITE_OK ) goto err;

    /* Reusing lowest-number deleted row keeps the index smaller. */
    if( iSegmentRow<iIndexRow ) iIndexRow = iSegmentRow;

    /* doclist contains the newer data, so accumulate it over old.
    ** Then steal accumulated data for doclist.
    */
    docListAccumulate(&old, &doclist);
    docListDestroy(&doclist);
    doclist = old;

    iSegment++;
  }

 err:
  docListDestroy(&doclist);
  return rc;
}

/* Add doclists for all terms in [pValues] to the hash table [terms]. */
static int insertTerms(fulltext_vtab *v, fts1Hash *terms, sqlite_int64 iRowid,
                sqlite3_value **pValues){
  int i;
  for(i = 0; i < v->nColumn ; ++i){
    char *zText = (char*)sqlite3_value_text(pValues[i]);
    int rc = buildTerms(v, terms, iRowid, zText, i);
    if( rc!=SQLITE_OK ) return rc;
  }
  return SQLITE_OK;
}

/* Add empty doclists for all terms in the given row's content to the hash
 * table [pTerms]. */
static int deleteTerms(fulltext_vtab *v, fts1Hash *pTerms, sqlite_int64 iRowid){
  const char **pValues;
  int i;

  int rc = content_select(v, iRowid, &pValues);
  if( rc!=SQLITE_OK ) return rc;

  for(i = 0 ; i < v->nColumn; ++i) {
    rc = buildTerms(v, pTerms, iRowid, pValues[i], -1);
    if( rc!=SQLITE_OK ) break;
  }

  freeStringArray(v->nColumn, pValues);
  return SQLITE_OK;
}

/* Insert a row into the %_content table; set *piRowid to be the ID of the
 * new row.  Fill [pTerms] with new doclists for the %_term table. */
static int index_insert(fulltext_vtab *v, sqlite3_value *pRequestRowid,
                        sqlite3_value **pValues,
                        sqlite_int64 *piRowid, fts1Hash *pTerms){
  int rc;

  rc = content_insert(v, pRequestRowid, pValues);  /* execute an SQL INSERT */
  if( rc!=SQLITE_OK ) return rc;
  *piRowid = sqlite3_last_insert_rowid(v->db);
  return insertTerms(v, pTerms, *piRowid, pValues);
}

/* Delete a row from the %_content table; fill [pTerms] with empty doclists
 * to be written to the %_term table. */
static int index_delete(fulltext_vtab *v, sqlite_int64 iRow, fts1Hash *pTerms){
  int rc = deleteTerms(v, pTerms, iRow);
  if( rc!=SQLITE_OK ) return rc;
  return content_delete(v, iRow);  /* execute an SQL DELETE */
}

/* Update a row in the %_content table; fill [pTerms] with new doclists for the
 * %_term table. */
static int index_update(fulltext_vtab *v, sqlite_int64 iRow,
                        sqlite3_value **pValues, fts1Hash *pTerms){
  /* Generate an empty doclist for each term that previously appeared in this
   * row. */
  int rc = deleteTerms(v, pTerms, iRow);
  if( rc!=SQLITE_OK ) return rc;

  rc = content_update(v, pValues, iRow);  /* execute an SQL UPDATE */
  if( rc!=SQLITE_OK ) return rc;

  /* Now add positions for terms which appear in the updated row. */
  return insertTerms(v, pTerms, iRow, pValues);
}

/* This function implements the xUpdate callback; it's the top-level entry
 * point for inserting, deleting or updating a row in a full-text table. */
static int fulltextUpdate(sqlite3_vtab *pVtab, int nArg, sqlite3_value **ppArg,
                   sqlite_int64 *pRowid){
  fulltext_vtab *v = (fulltext_vtab *) pVtab;
  fts1Hash terms;   /* maps term string -> PosList */
  int rc;
  fts1HashElem *e;

  TRACE(("FTS1 Update %p\n", pVtab));
  
  fts1HashInit(&terms, FTS1_HASH_STRING, 1);

  if( nArg<2 ){
    rc = index_delete(v, sqlite3_value_int64(ppArg[0]), &terms);
  } else if( sqlite3_value_type(ppArg[0]) != SQLITE_NULL ){
    /* An update:
     * ppArg[0] = old rowid
     * ppArg[1] = new rowid
     * ppArg[2..2+v->nColumn-1] = values
     * ppArg[2+v->nColumn] = value for magic column (we ignore this)
     */
    sqlite_int64 rowid = sqlite3_value_int64(ppArg[0]);
    if( sqlite3_value_type(ppArg[1]) != SQLITE_INTEGER ||
      sqlite3_value_int64(ppArg[1]) != rowid ){
      rc = SQLITE_ERROR;  /* we don't allow changing the rowid */
    } else {
      assert( nArg==2+v->nColumn+1);
      rc = index_update(v, rowid, &ppArg[2], &terms);
    }
  } else {
    /* An insert:
     * ppArg[1] = requested rowid
     * ppArg[2..2+v->nColumn-1] = values
     * ppArg[2+v->nColumn] = value for magic column (we ignore this)
     */
    assert( nArg==2+v->nColumn+1);
    rc = index_insert(v, ppArg[1], &ppArg[2], pRowid, &terms);
  }

  if( rc==SQLITE_OK ){
    /* Write updated doclists to disk. */
    for(e=fts1HashFirst(&terms); e; e=fts1HashNext(e)){
      DocList *p = fts1HashData(e);
      rc = index_insert_term(v, fts1HashKey(e), fts1HashKeysize(e), p);
      if( rc!=SQLITE_OK ) break;
    }
  }

  /* clean up */
  for(e=fts1HashFirst(&terms); e; e=fts1HashNext(e)){
    DocList *p = fts1HashData(e);
    docListDelete(p);
  }
  fts1HashClear(&terms);

  return rc;
}

/*
** Implementation of the snippet() function for FTS1
*/
static void snippetFunc(
  sqlite3_context *pContext,
  int argc,
  sqlite3_value **argv
){
  fulltext_cursor *pCursor;
  if( argc<1 ) return;
  if( sqlite3_value_type(argv[0])!=SQLITE_BLOB ||
      sqlite3_value_bytes(argv[0])!=sizeof(pCursor) ){
    sqlite3_result_error(pContext, "illegal first argument to html_snippet",-1);
  }else{
    const char *zStart = "<b>";
    const char *zEnd = "</b>";
    const char *zEllipsis = "<b>...</b>";
    memcpy(&pCursor, sqlite3_value_blob(argv[0]), sizeof(pCursor));
    if( argc>=2 ){
      zStart = (const char*)sqlite3_value_text(argv[1]);
      if( argc>=3 ){
        zEnd = (const char*)sqlite3_value_text(argv[2]);
        if( argc>=4 ){
          zEllipsis = (const char*)sqlite3_value_text(argv[3]);
        }
      }
    }
    snippetAllOffsets(pCursor);
    snippetText(pCursor, zStart, zEnd, zEllipsis);
    sqlite3_result_text(pContext, pCursor->snippet.zSnippet,
                        pCursor->snippet.nSnippet, SQLITE_STATIC);
  }
}

/*
** Implementation of the offsets() function for FTS1
*/
static void snippetOffsetsFunc(
  sqlite3_context *pContext,
  int argc,
  sqlite3_value **argv
){
  fulltext_cursor *pCursor;
  if( argc<1 ) return;
  if( sqlite3_value_type(argv[0])!=SQLITE_BLOB ||
      sqlite3_value_bytes(argv[0])!=sizeof(pCursor) ){
    sqlite3_result_error(pContext, "illegal first argument to offsets",-1);
  }else{
    memcpy(&pCursor, sqlite3_value_blob(argv[0]), sizeof(pCursor));
    snippetAllOffsets(pCursor);
    snippetOffsetText(&pCursor->snippet);
    sqlite3_result_text(pContext,
                        pCursor->snippet.zOffset, pCursor->snippet.nOffset,
                        SQLITE_STATIC);
  }
}

/*
** This routine implements the xFindFunction method for the FTS1
** virtual table.
*/
static int fulltextFindFunction(
  sqlite3_vtab *pVtab,
  int nArg,
  const char *zName,
  void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
  void **ppArg
){
  if( strcmp(zName,"snippet")==0 ){
    *pxFunc = snippetFunc;
    return 1;
  }else if( strcmp(zName,"offsets")==0 ){
    *pxFunc = snippetOffsetsFunc;
    return 1;
  }
  return 0;
}

static const sqlite3_module fulltextModule = {
  /* iVersion      */ 0,
  /* xCreate       */ fulltextCreate,
  /* xConnect      */ fulltextConnect,
  /* xBestIndex    */ fulltextBestIndex,
  /* xDisconnect   */ fulltextDisconnect,
  /* xDestroy      */ fulltextDestroy,
  /* xOpen         */ fulltextOpen,
  /* xClose        */ fulltextClose,
  /* xFilter       */ fulltextFilter,
  /* xNext         */ fulltextNext,
  /* xEof          */ fulltextEof,
  /* xColumn       */ fulltextColumn,
  /* xRowid        */ fulltextRowid,
  /* xUpdate       */ fulltextUpdate,
  /* xBegin        */ 0, 
  /* xSync         */ 0,
  /* xCommit       */ 0,
  /* xRollback     */ 0,
  /* xFindFunction */ fulltextFindFunction,
};

int sqlite3Fts1Init(sqlite3 *db){
  sqlite3_overload_function(db, "snippet", -1);
  sqlite3_overload_function(db, "offsets", -1);
  return sqlite3_create_module(db, "fts1", &fulltextModule, 0);
}

#if !SQLITE_CORE
int sqlite3_extension_init(sqlite3 *db, char **pzErrMsg,
                           const sqlite3_api_routines *pApi){
  SQLITE_EXTENSION_INIT2(pApi)
  return sqlite3Fts1Init(db);
}
#endif

#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS1) */

Added SQLite.Interop/FTS1/fts1.h.























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#include "sqlite3.h"

#ifdef __cplusplus
extern "C" {
#endif  /* __cplusplus */

int sqlite3Fts1Init(sqlite3 *db);

#ifdef __cplusplus
}  /* extern "C" */
#endif  /* __cplusplus */

Added SQLite.Interop/FTS1/fts1_hash.c.



































































































































































































































































































































































































































































































































































































































































































































































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/*
** 2001 September 22
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This is the implementation of generic hash-tables used in SQLite.
** We've modified it slightly to serve as a standalone hash table
** implementation for the full-text indexing module.
*/
#include <assert.h>
#include <stdlib.h>
#include <string.h>

/*
** The code in this file is only compiled if:
**
**     * The FTS1 module is being built as an extension
**       (in which case SQLITE_CORE is not defined), or
**
**     * The FTS1 module is being built into the core of
**       SQLite (in which case SQLITE_ENABLE_FTS1 is defined).
*/
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS1)


#include "fts1_hash.h"

static void *malloc_and_zero(int n){
  void *p = malloc(n);
  if( p ){
    memset(p, 0, n);
  }
  return p;
}

/* Turn bulk memory into a hash table object by initializing the
** fields of the Hash structure.
**
** "pNew" is a pointer to the hash table that is to be initialized.
** keyClass is one of the constants 
** FTS1_HASH_BINARY or FTS1_HASH_STRING.  The value of keyClass 
** determines what kind of key the hash table will use.  "copyKey" is
** true if the hash table should make its own private copy of keys and
** false if it should just use the supplied pointer.
*/
void sqlite3Fts1HashInit(fts1Hash *pNew, int keyClass, int copyKey){
  assert( pNew!=0 );
  assert( keyClass>=FTS1_HASH_STRING && keyClass<=FTS1_HASH_BINARY );
  pNew->keyClass = keyClass;
  pNew->copyKey = copyKey;
  pNew->first = 0;
  pNew->count = 0;
  pNew->htsize = 0;
  pNew->ht = 0;
  pNew->xMalloc = malloc_and_zero;
  pNew->xFree = free;
}

/* Remove all entries from a hash table.  Reclaim all memory.
** Call this routine to delete a hash table or to reset a hash table
** to the empty state.
*/
void sqlite3Fts1HashClear(fts1Hash *pH){
  fts1HashElem *elem;         /* For looping over all elements of the table */

  assert( pH!=0 );
  elem = pH->first;
  pH->first = 0;
  if( pH->ht ) pH->xFree(pH->ht);
  pH->ht = 0;
  pH->htsize = 0;
  while( elem ){
    fts1HashElem *next_elem = elem->next;
    if( pH->copyKey && elem->pKey ){
      pH->xFree(elem->pKey);
    }
    pH->xFree(elem);
    elem = next_elem;
  }
  pH->count = 0;
}

/*
** Hash and comparison functions when the mode is FTS1_HASH_STRING
*/
static int strHash(const void *pKey, int nKey){
  const char *z = (const char *)pKey;
  int h = 0;
  if( nKey<=0 ) nKey = (int) strlen(z);
  while( nKey > 0  ){
    h = (h<<3) ^ h ^ *z++;
    nKey--;
  }
  return h & 0x7fffffff;
}
static int strCompare(const void *pKey1, int n1, const void *pKey2, int n2){
  if( n1!=n2 ) return 1;
  return strncmp((const char*)pKey1,(const char*)pKey2,n1);
}

/*
** Hash and comparison functions when the mode is FTS1_HASH_BINARY
*/
static int binHash(const void *pKey, int nKey){
  int h = 0;
  const char *z = (const char *)pKey;
  while( nKey-- > 0 ){
    h = (h<<3) ^ h ^ *(z++);
  }
  return h & 0x7fffffff;
}
static int binCompare(const void *pKey1, int n1, const void *pKey2, int n2){
  if( n1!=n2 ) return 1;
  return memcmp(pKey1,pKey2,n1);
}

/*
** Return a pointer to the appropriate hash function given the key class.
**
** The C syntax in this function definition may be unfamilar to some 
** programmers, so we provide the following additional explanation:
**
** The name of the function is "hashFunction".  The function takes a
** single parameter "keyClass".  The return value of hashFunction()
** is a pointer to another function.  Specifically, the return value
** of hashFunction() is a pointer to a function that takes two parameters
** with types "const void*" and "int" and returns an "int".
*/
static int (*hashFunction(int keyClass))(const void*,int){
  if( keyClass==FTS1_HASH_STRING ){
    return &strHash;
  }else{
    assert( keyClass==FTS1_HASH_BINARY );
    return &binHash;
  }
}

/*
** Return a pointer to the appropriate hash function given the key class.
**
** For help in interpreted the obscure C code in the function definition,
** see the header comment on the previous function.
*/
static int (*compareFunction(int keyClass))(const void*,int,const void*,int){
  if( keyClass==FTS1_HASH_STRING ){
    return &strCompare;
  }else{
    assert( keyClass==FTS1_HASH_BINARY );
    return &binCompare;
  }
}

/* Link an element into the hash table
*/
static void insertElement(
  fts1Hash *pH,            /* The complete hash table */
  struct _fts1ht *pEntry,  /* The entry into which pNew is inserted */
  fts1HashElem *pNew       /* The element to be inserted */
){
  fts1HashElem *pHead;     /* First element already in pEntry */
  pHead = pEntry->chain;
  if( pHead ){
    pNew->next = pHead;
    pNew->prev = pHead->prev;
    if( pHead->prev ){ pHead->prev->next = pNew; }
    else             { pH->first = pNew; }
    pHead->prev = pNew;
  }else{
    pNew->next = pH->first;
    if( pH->first ){ pH->first->prev = pNew; }
    pNew->prev = 0;
    pH->first = pNew;
  }
  pEntry->count++;
  pEntry->chain = pNew;
}


/* Resize the hash table so that it cantains "new_size" buckets.
** "new_size" must be a power of 2.  The hash table might fail 
** to resize if sqliteMalloc() fails.
*/
static void rehash(fts1Hash *pH, int new_size){
  struct _fts1ht *new_ht;          /* The new hash table */
  fts1HashElem *elem, *next_elem;  /* For looping over existing elements */
  int (*xHash)(const void*,int);   /* The hash function */

  assert( (new_size & (new_size-1))==0 );
  new_ht = (struct _fts1ht *)pH->xMalloc( new_size*sizeof(struct _fts1ht) );
  if( new_ht==0 ) return;
  if( pH->ht ) pH->xFree(pH->ht);
  pH->ht = new_ht;
  pH->htsize = new_size;
  xHash = hashFunction(pH->keyClass);
  for(elem=pH->first, pH->first=0; elem; elem = next_elem){
    int h = (*xHash)(elem->pKey, elem->nKey) & (new_size-1);
    next_elem = elem->next;
    insertElement(pH, &new_ht[h], elem);
  }
}

/* This function (for internal use only) locates an element in an
** hash table that matches the given key.  The hash for this key has
** already been computed and is passed as the 4th parameter.
*/
static fts1HashElem *findElementGivenHash(
  const fts1Hash *pH, /* The pH to be searched */
  const void *pKey,   /* The key we are searching for */
  int nKey,
  int h               /* The hash for this key. */
){
  fts1HashElem *elem;            /* Used to loop thru the element list */
  int count;                     /* Number of elements left to test */
  int (*xCompare)(const void*,int,const void*,int);  /* comparison function */

  if( pH->ht ){
    struct _fts1ht *pEntry = &pH->ht[h];
    elem = pEntry->chain;
    count = pEntry->count;
    xCompare = compareFunction(pH->keyClass);
    while( count-- && elem ){
      if( (*xCompare)(elem->pKey,elem->nKey,pKey,nKey)==0 ){ 
        return elem;
      }
      elem = elem->next;
    }
  }
  return 0;
}

/* Remove a single entry from the hash table given a pointer to that
** element and a hash on the element's key.
*/
static void removeElementGivenHash(
  fts1Hash *pH,         /* The pH containing "elem" */
  fts1HashElem* elem,   /* The element to be removed from the pH */
  int h                 /* Hash value for the element */
){
  struct _fts1ht *pEntry;
  if( elem->prev ){
    elem->prev->next = elem->next; 
  }else{
    pH->first = elem->next;
  }
  if( elem->next ){
    elem->next->prev = elem->prev;
  }
  pEntry = &pH->ht[h];
  if( pEntry->chain==elem ){
    pEntry->chain = elem->next;
  }
  pEntry->count--;
  if( pEntry->count<=0 ){
    pEntry->chain = 0;
  }
  if( pH->copyKey && elem->pKey ){
    pH->xFree(elem->pKey);
  }
  pH->xFree( elem );
  pH->count--;
  if( pH->count<=0 ){
    assert( pH->first==0 );
    assert( pH->count==0 );
    fts1HashClear(pH);
  }
}

/* Attempt to locate an element of the hash table pH with a key
** that matches pKey,nKey.  Return the data for this element if it is
** found, or NULL if there is no match.
*/
void *sqlite3Fts1HashFind(const fts1Hash *pH, const void *pKey, int nKey){
  int h;                 /* A hash on key */
  fts1HashElem *elem;    /* The element that matches key */
  int (*xHash)(const void*,int);  /* The hash function */

  if( pH==0 || pH->ht==0 ) return 0;
  xHash = hashFunction(pH->keyClass);
  assert( xHash!=0 );
  h = (*xHash)(pKey,nKey);
  assert( (pH->htsize & (pH->htsize-1))==0 );
  elem = findElementGivenHash(pH,pKey,nKey, h & (pH->htsize-1));
  return elem ? elem->data : 0;
}

/* Insert an element into the hash table pH.  The key is pKey,nKey
** and the data is "data".
**
** If no element exists with a matching key, then a new
** element is created.  A copy of the key is made if the copyKey
** flag is set.  NULL is returned.
**
** If another element already exists with the same key, then the
** new data replaces the old data and the old data is returned.
** The key is not copied in this instance.  If a malloc fails, then
** the new data is returned and the hash table is unchanged.
**
** If the "data" parameter to this function is NULL, then the
** element corresponding to "key" is removed from the hash table.
*/
void *sqlite3Fts1HashInsert(
  fts1Hash *pH,        /* The hash table to insert into */
  const void *pKey,    /* The key */
  int nKey,            /* Number of bytes in the key */
  void *data           /* The data */
){
  int hraw;                 /* Raw hash value of the key */
  int h;                    /* the hash of the key modulo hash table size */
  fts1HashElem *elem;       /* Used to loop thru the element list */
  fts1HashElem *new_elem;   /* New element added to the pH */
  int (*xHash)(const void*,int);  /* The hash function */

  assert( pH!=0 );
  xHash = hashFunction(pH->keyClass);
  assert( xHash!=0 );
  hraw = (*xHash)(pKey, nKey);
  assert( (pH->htsize & (pH->htsize-1))==0 );
  h = hraw & (pH->htsize-1);
  elem = findElementGivenHash(pH,pKey,nKey,h);
  if( elem ){
    void *old_data = elem->data;
    if( data==0 ){
      removeElementGivenHash(pH,elem,h);
    }else{
      elem->data = data;
    }
    return old_data;
  }
  if( data==0 ) return 0;
  new_elem = (fts1HashElem*)pH->xMalloc( sizeof(fts1HashElem) );
  if( new_elem==0 ) return data;
  if( pH->copyKey && pKey!=0 ){
    new_elem->pKey = pH->xMalloc( nKey );
    if( new_elem->pKey==0 ){
      pH->xFree(new_elem);
      return data;
    }
    memcpy((void*)new_elem->pKey, pKey, nKey);
  }else{
    new_elem->pKey = (void*)pKey;
  }
  new_elem->nKey = nKey;
  pH->count++;
  if( pH->htsize==0 ){
    rehash(pH,8);
    if( pH->htsize==0 ){
      pH->count = 0;
      pH->xFree(new_elem);
      return data;
    }
  }
  if( pH->count > pH->htsize ){
    rehash(pH,pH->htsize*2);
  }
  assert( pH->htsize>0 );
  assert( (pH->htsize & (pH->htsize-1))==0 );
  h = hraw & (pH->htsize-1);
  insertElement(pH, &pH->ht[h], new_elem);
  new_elem->data = data;
  return 0;
}

#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS1) */

Added SQLite.Interop/FTS1/fts1_hash.h.

































































































































































































































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/*
** 2001 September 22
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This is the header file for the generic hash-table implemenation
** used in SQLite.  We've modified it slightly to serve as a standalone
** hash table implementation for the full-text indexing module.
**
*/
#ifndef _FTS1_HASH_H_
#define _FTS1_HASH_H_

/* Forward declarations of structures. */
typedef struct fts1Hash fts1Hash;
typedef struct fts1HashElem fts1HashElem;

/* A complete hash table is an instance of the following structure.
** The internals of this structure are intended to be opaque -- client
** code should not attempt to access or modify the fields of this structure
** directly.  Change this structure only by using the routines below.
** However, many of the "procedures" and "functions" for modifying and
** accessing this structure are really macros, so we can't really make
** this structure opaque.
*/
struct fts1Hash {
  char keyClass;          /* HASH_INT, _POINTER, _STRING, _BINARY */
  char copyKey;           /* True if copy of key made on insert */
  int count;              /* Number of entries in this table */
  fts1HashElem *first;    /* The first element of the array */
  void *(*xMalloc)(int);  /* malloc() function to use */
  void (*xFree)(void *);  /* free() function to use */
  int htsize;             /* Number of buckets in the hash table */
  struct _fts1ht {        /* the hash table */
    int count;               /* Number of entries with this hash */
    fts1HashElem *chain;     /* Pointer to first entry with this hash */
  } *ht;
};

/* Each element in the hash table is an instance of the following 
** structure.  All elements are stored on a single doubly-linked list.
**
** Again, this structure is intended to be opaque, but it can't really
** be opaque because it is used by macros.
*/
struct fts1HashElem {
  fts1HashElem *next, *prev; /* Next and previous elements in the table */
  void *data;                /* Data associated with this element */
  void *pKey; int nKey;      /* Key associated with this element */
};

/*
** There are 2 different modes of operation for a hash table:
**
**   FTS1_HASH_STRING        pKey points to a string that is nKey bytes long
**                           (including the null-terminator, if any).  Case
**                           is respected in comparisons.
**
**   FTS1_HASH_BINARY        pKey points to binary data nKey bytes long. 
**                           memcmp() is used to compare keys.
**
** A copy of the key is made if the copyKey parameter to fts1HashInit is 1.  
*/
#define FTS1_HASH_STRING    1
#define FTS1_HASH_BINARY    2

/*
** Access routines.  To delete, insert a NULL pointer.
*/
void sqlite3Fts1HashInit(fts1Hash*, int keytype, int copyKey);
void *sqlite3Fts1HashInsert(fts1Hash*, const void *pKey, int nKey, void *pData);
void *sqlite3Fts1HashFind(const fts1Hash*, const void *pKey, int nKey);
void sqlite3Fts1HashClear(fts1Hash*);

/*
** Shorthand for the functions above
*/
#define fts1HashInit   sqlite3Fts1HashInit
#define fts1HashInsert sqlite3Fts1HashInsert
#define fts1HashFind   sqlite3Fts1HashFind
#define fts1HashClear  sqlite3Fts1HashClear

/*
** Macros for looping over all elements of a hash table.  The idiom is
** like this:
**
**   fts1Hash h;
**   fts1HashElem *p;
**   ...
**   for(p=fts1HashFirst(&h); p; p=fts1HashNext(p)){
**     SomeStructure *pData = fts1HashData(p);
**     // do something with pData
**   }
*/
#define fts1HashFirst(H)  ((H)->first)
#define fts1HashNext(E)   ((E)->next)
#define fts1HashData(E)   ((E)->data)
#define fts1HashKey(E)    ((E)->pKey)
#define fts1HashKeysize(E) ((E)->nKey)

/*
** Number of entries in a hash table
*/
#define fts1HashCount(H)  ((H)->count)

#endif /* _FTS1_HASH_H_ */

Added SQLite.Interop/FTS1/fts1_porter.c.















































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































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/*
** 2006 September 30
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Implementation of the full-text-search tokenizer that implements
** a Porter stemmer.
*/

/*
** The code in this file is only compiled if:
**
**     * The FTS1 module is being built as an extension
**       (in which case SQLITE_CORE is not defined), or
**
**     * The FTS1 module is being built into the core of
**       SQLite (in which case SQLITE_ENABLE_FTS1 is defined).
*/
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS1)


#include <assert.h>
#if !defined(__APPLE__)
#include <malloc.h>
#else
#include <stdlib.h>
#endif
#include <stdio.h>
#include <string.h>
#include <ctype.h>

#include "fts1_tokenizer.h"

/*
** Class derived from sqlite3_tokenizer
*/
typedef struct porter_tokenizer {
  sqlite3_tokenizer base;      /* Base class */
} porter_tokenizer;

/*
** Class derived from sqlit3_tokenizer_cursor
*/
typedef struct porter_tokenizer_cursor {
  sqlite3_tokenizer_cursor base;
  const char *zInput;          /* input we are tokenizing */
  int nInput;                  /* size of the input */
  int iOffset;                 /* current position in zInput */
  int iToken;                  /* index of next token to be returned */
  char *zToken;                /* storage for current token */
  int nAllocated;              /* space allocated to zToken buffer */
} porter_tokenizer_cursor;


/* Forward declaration */
static const sqlite3_tokenizer_module porterTokenizerModule;


/*
** Create a new tokenizer instance.
*/
static int porterCreate(
  int argc, const char * const *argv,
  sqlite3_tokenizer **ppTokenizer
){
  porter_tokenizer *t;
  t = (porter_tokenizer *) calloc(sizeof(*t), 1);
  if( t==NULL ) return SQLITE_NOMEM;

  *ppTokenizer = &t->base;
  return SQLITE_OK;
}

/*
** Destroy a tokenizer
*/
static int porterDestroy(sqlite3_tokenizer *pTokenizer){
  free(pTokenizer);
  return SQLITE_OK;
}

/*
** Prepare to begin tokenizing a particular string.  The input
** string to be tokenized is zInput[0..nInput-1].  A cursor
** used to incrementally tokenize this string is returned in 
** *ppCursor.
*/
static int porterOpen(
  sqlite3_tokenizer *pTokenizer,         /* The tokenizer */
  const char *zInput, int nInput,        /* String to be tokenized */
  sqlite3_tokenizer_cursor **ppCursor    /* OUT: Tokenization cursor */
){
  porter_tokenizer_cursor *c;

  c = (porter_tokenizer_cursor *) malloc(sizeof(*c));
  if( c==NULL ) return SQLITE_NOMEM;

  c->zInput = zInput;
  if( zInput==0 ){
    c->nInput = 0;
  }else if( nInput<0 ){
    c->nInput = (int)strlen(zInput);
  }else{
    c->nInput = nInput;
  }
  c->iOffset = 0;                 /* start tokenizing at the beginning */
  c->iToken = 0;
  c->zToken = NULL;               /* no space allocated, yet. */
  c->nAllocated = 0;

  *ppCursor = &c->base;
  return SQLITE_OK;
}

/*
** Close a tokenization cursor previously opened by a call to
** porterOpen() above.
*/
static int porterClose(sqlite3_tokenizer_cursor *pCursor){
  porter_tokenizer_cursor *c = (porter_tokenizer_cursor *) pCursor;
  free(c->zToken);
  free(c);
  return SQLITE_OK;
}
/*
** Vowel or consonant
*/
static const char cType[] = {
   0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0,
   1, 1, 1, 2, 1
};

/*
** isConsonant() and isVowel() determine if their first character in
** the string they point to is a consonant or a vowel, according
** to Porter ruls.  
**
** A consonate is any letter other than 'a', 'e', 'i', 'o', or 'u'.
** 'Y' is a consonant unless it follows another consonant,
** in which case it is a vowel.
**
** In these routine, the letters are in reverse order.  So the 'y' rule
** is that 'y' is a consonant unless it is followed by another
** consonent.
*/
static int isVowel(const char*);
static int isConsonant(const char *z){
  int j;
  char x = *z;
  if( x==0 ) return 0;
  assert( x>='a' && x<='z' );
  j = cType[x-'a'];
  if( j<2 ) return j;
  return z[1]==0 || isVowel(z + 1);
}
static int isVowel(const char *z){
  int j;
  char x = *z;
  if( x==0 ) return 0;
  assert( x>='a' && x<='z' );
  j = cType[x-'a'];
  if( j<2 ) return 1-j;
  return isConsonant(z + 1);
}

/*
** Let any sequence of one or more vowels be represented by V and let
** C be sequence of one or more consonants.  Then every word can be
** represented as:
**
**           [C] (VC){m} [V]
**
** In prose:  A word is an optional consonant followed by zero or
** vowel-consonant pairs followed by an optional vowel.  "m" is the
** number of vowel consonant pairs.  This routine computes the value
** of m for the first i bytes of a word.
**
** Return true if the m-value for z is 1 or more.  In other words,
** return true if z contains at least one vowel that is followed
** by a consonant.
**
** In this routine z[] is in reverse order.  So we are really looking
** for an instance of of a consonant followed by a vowel.
*/
static int m_gt_0(const char *z){
  while( isVowel(z) ){ z++; }
  if( *z==0 ) return 0;
  while( isConsonant(z) ){ z++; }
  return *z!=0;
}

/* Like mgt0 above except we are looking for a value of m which is
** exactly 1
*/
static int m_eq_1(const char *z){
  while( isVowel(z) ){ z++; }
  if( *z==0 ) return 0;
  while( isConsonant(z) ){ z++; }
  if( *z==0 ) return 0;
  while( isVowel(z) ){ z++; }
  if( *z==0 ) return 1;
  while( isConsonant(z) ){ z++; }
  return *z==0;
}

/* Like mgt0 above except we are looking for a value of m>1 instead
** or m>0
*/
static int m_gt_1(const char *z){
  while( isVowel(z) ){ z++; }
  if( *z==0 ) return 0;
  while( isConsonant(z) ){ z++; }
  if( *z==0 ) return 0;
  while( isVowel(z) ){ z++; }
  if( *z==0 ) return 0;
  while( isConsonant(z) ){ z++; }
  return *z!=0;
}

/*
** Return TRUE if there is a vowel anywhere within z[0..n-1]
*/
static int hasVowel(const char *z){
  while( isConsonant(z) ){ z++; }
  return *z!=0;
}

/*
** Return TRUE if the word ends in a double consonant.
**
** The text is reversed here. So we are really looking at
** the first two characters of z[].
*/
static int doubleConsonant(const char *z){
  return isConsonant(z) && z[0]==z[1] && isConsonant(z+1);
}

/*
** Return TRUE if the word ends with three letters which
** are consonant-vowel-consonent and where the final consonant
** is not 'w', 'x', or 'y'.
**
** The word is reversed here.  So we are really checking the
** first three letters and the first one cannot be in [wxy].
*/
static int star_oh(const char *z){
  return
    z[0]!=0 && isConsonant(z) &&
    z[0]!='w' && z[0]!='x' && z[0]!='y' &&
    z[1]!=0 && isVowel(z+1) &&
    z[2]!=0 && isConsonant(z+2);
}

/*
** If the word ends with zFrom and xCond() is true for the stem
** of the word that preceeds the zFrom ending, then change the 
** ending to zTo.
**
** The input word *pz and zFrom are both in reverse order.  zTo
** is in normal order. 
**
** Return TRUE if zFrom matches.  Return FALSE if zFrom does not
** match.  Not that TRUE is returned even if xCond() fails and
** no substitution occurs.
*/
static int stem(
  char **pz,             /* The word being stemmed (Reversed) */
  const char *zFrom,     /* If the ending matches this... (Reversed) */
  const char *zTo,       /* ... change the ending to this (not reversed) */
  int (*xCond)(const char*)   /* Condition that must be true */
){
  char *z = *pz;
  while( *zFrom && *zFrom==*z ){ z++; zFrom++; }
  if( *zFrom!=0 ) return 0;
  if( xCond && !xCond(z) ) return 1;
  while( *zTo ){
    *(--z) = *(zTo++);
  }
  *pz = z;
  return 1;
}

/*
** This is the fallback stemmer used when the porter stemmer is
** inappropriate.  The input word is copied into the output with
** US-ASCII case folding.  If the input word is too long (more
** than 20 bytes if it contains no digits or more than 6 bytes if
** it contains digits) then word is truncated to 20 or 6 bytes
** by taking 10 or 3 bytes from the beginning and end.
*/
static void copy_stemmer(const char *zIn, int nIn, char *zOut, int *pnOut){
  int i, mx, j;
  int hasDigit = 0;
  for(i=0; i<nIn; i++){
    int c = zIn[i];
    if( c>='A' && c<='Z' ){
      zOut[i] = c - 'A' + 'a';
    }else{
      if( c>='0' && c<='9' ) hasDigit = 1;
      zOut[i] = c;
    }
  }
  mx = hasDigit ? 3 : 10;
  if( nIn>mx*2 ){
    for(j=mx, i=nIn-mx; i<nIn; i++, j++){
      zOut[j] = zOut[i];
    }
    i = j;
  }
  zOut[i] = 0;
  *pnOut = i;
}


/*
** Stem the input word zIn[0..nIn-1].  Store the output in zOut.
** zOut is at least big enough to hold nIn bytes.  Write the actual
** size of the output word (exclusive of the '\0' terminator) into *pnOut.
**
** Any upper-case characters in the US-ASCII character set ([A-Z])
** are converted to lower case.  Upper-case UTF characters are
** unchanged.
**
** Words that are longer than about 20 bytes are stemmed by retaining
** a few bytes from the beginning and the end of the word.  If the
** word contains digits, 3 bytes are taken from the beginning and
** 3 bytes from the end.  For long words without digits, 10 bytes
** are taken from each end.  US-ASCII case folding still applies.
** 
** If the input word contains not digits but does characters not 
** in [a-zA-Z] then no stemming is attempted and this routine just 
** copies the input into the input into the output with US-ASCII
** case folding.
**
** Stemming never increases the length of the word.  So there is
** no chance of overflowing the zOut buffer.
*/
static void porter_stemmer(const char *zIn, int nIn, char *zOut, int *pnOut){
  int i, j, c;
  char zReverse[28];
  char *z, *z2;
  if( nIn<3 || nIn>=sizeof(zReverse)-7 ){
    /* The word is too big or too small for the porter stemmer.
    ** Fallback to the copy stemmer */
    copy_stemmer(zIn, nIn, zOut, pnOut);
    return;
  }
  for(i=0, j=sizeof(zReverse)-6; i<nIn; i++, j--){
    c = zIn[i];
    if( c>='A' && c<='Z' ){
      zReverse[j] = c + 'a' - 'A';
    }else if( c>='a' && c<='z' ){
      zReverse[j] = c;
    }else{
      /* The use of a character not in [a-zA-Z] means that we fallback
      ** to the copy stemmer */
      copy_stemmer(zIn, nIn, zOut, pnOut);
      return;
    }
  }
  memset(&zReverse[sizeof(zReverse)-5], 0, 5);
  z = &zReverse[j+1];


  /* Step 1a */
  if( z[0]=='s' ){
    if(
     !stem(&z, "sess", "ss", 0) &&
     !stem(&z, "sei", "i", 0)  &&
     !stem(&z, "ss", "ss", 0)
    ){
      z++;
    }
  }

  /* Step 1b */  
  z2 = z;
  if( stem(&z, "dee", "ee", m_gt_0) ){
    /* Do nothing.  The work was all in the test */
  }else if( 
     (stem(&z, "gni", "", hasVowel) || stem(&z, "de", "", hasVowel))
      && z!=z2
  ){
     if( stem(&z, "ta", "ate", 0) ||
         stem(&z, "lb", "ble", 0) ||
         stem(&z, "zi", "ize", 0) ){
       /* Do nothing.  The work was all in the test */
     }else if( doubleConsonant(z) && (*z!='l' && *z!='s' && *z!='z') ){
       z++;
     }else if( m_eq_1(z) && star_oh(z) ){
       *(--z) = 'e';
     }
  }

  /* Step 1c */
  if( z[0]=='y' && hasVowel(z+1) ){
    z[0] = 'i';
  }

  /* Step 2 */
  switch( z[1] ){
   case 'a':
     stem(&z, "lanoita", "ate", m_gt_0) ||
     stem(&z, "lanoit", "tion", m_gt_0);
     break;
   case 'c':
     stem(&z, "icne", "ence", m_gt_0) ||
     stem(&z, "icna", "ance", m_gt_0);
     break;
   case 'e':
     stem(&z, "rezi", "ize", m_gt_0);
     break;
   case 'g':
     stem(&z, "igol", "log", m_gt_0);
     break;
   case 'l':
     stem(&z, "ilb", "ble", m_gt_0) ||
     stem(&z, "illa", "al", m_gt_0) ||
     stem(&z, "iltne", "ent", m_gt_0) ||
     stem(&z, "ile", "e", m_gt_0) ||
     stem(&z, "ilsuo", "ous", m_gt_0);
     break;
   case 'o':
     stem(&z, "noitazi", "ize", m_gt_0) ||
     stem(&z, "noita", "ate", m_gt_0) ||
     stem(&z, "rota", "ate", m_gt_0);
     break;
   case 's':
     stem(&z, "msila", "al", m_gt_0) ||
     stem(&z, "ssenevi", "ive", m_gt_0) ||
     stem(&z, "ssenluf", "ful", m_gt_0) ||
     stem(&z, "ssensuo", "ous", m_gt_0);
     break;
   case 't':
     stem(&z, "itila", "al", m_gt_0) ||
     stem(&z, "itivi", "ive", m_gt_0) ||
     stem(&z, "itilib", "ble", m_gt_0);
     break;
  }

  /* Step 3 */
  switch( z[0] ){
   case 'e':
     stem(&z, "etaci", "ic", m_gt_0) ||
     stem(&z, "evita", "", m_gt_0)   ||
     stem(&z, "ezila", "al", m_gt_0);
     break;
   case 'i':
     stem(&z, "itici", "ic", m_gt_0);
     break;
   case 'l':
     stem(&z, "laci", "ic", m_gt_0) ||
     stem(&z, "luf", "", m_gt_0);
     break;
   case 's':
     stem(&z, "ssen", "", m_gt_0);
     break;
  }

  /* Step 4 */
  switch( z[1] ){
   case 'a':
     if( z[0]=='l' && m_gt_1(z+2) ){
       z += 2;
     }
     break;
   case 'c':
     if( z[0]=='e' && z[2]=='n' && (z[3]=='a' || z[3]=='e')  && m_gt_1(z+4)  ){
       z += 4;
     }
     break;
   case 'e':
     if( z[0]=='r' && m_gt_1(z+2) ){
       z += 2;
     }
     break;
   case 'i':
     if( z[0]=='c' && m_gt_1(z+2) ){
       z += 2;
     }
     break;
   case 'l':
     if( z[0]=='e' && z[2]=='b' && (z[3]=='a' || z[3]=='i') && m_gt_1(z+4) ){
       z += 4;
     }
     break;
   case 'n':
     if( z[0]=='t' ){
       if( z[2]=='a' ){
         if( m_gt_1(z+3) ){
           z += 3;
         }
       }else if( z[2]=='e' ){
         stem(&z, "tneme", "", m_gt_1) ||
         stem(&z, "tnem", "", m_gt_1) ||
         stem(&z, "tne", "", m_gt_1);
       }
     }
     break;
   case 'o':
     if( z[0]=='u' ){
       if( m_gt_1(z+2) ){
         z += 2;
       }
     }else if( z[3]=='s' || z[3]=='t' ){
       stem(&z, "noi", "", m_gt_1);
     }
     break;
   case 's':
     if( z[0]=='m' && z[2]=='i' && m_gt_1(z+3) ){
       z += 3;
     }
     break;
   case 't':
     stem(&z, "eta", "", m_gt_1) ||
     stem(&z, "iti", "", m_gt_1);
     break;
   case 'u':
     if( z[0]=='s' && z[2]=='o' && m_gt_1(z+3) ){
       z += 3;
     }
     break;
   case 'v':
   case 'z':
     if( z[0]=='e' && z[2]=='i' && m_gt_1(z+3) ){
       z += 3;
     }
     break;
  }

  /* Step 5a */
  if( z[0]=='e' ){
    if( m_gt_1(z+1) ){
      z++;
    }else if( m_eq_1(z+1) && !star_oh(z+1) ){
      z++;
    }
  }

  /* Step 5b */
  if( m_gt_1(z) && z[0]=='l' && z[1]=='l' ){
    z++;
  }

  /* z[] is now the stemmed word in reverse order.  Flip it back
  ** around into forward order and return.
  */
  *pnOut = i = strlen(z);
  zOut[i] = 0;
  while( *z ){
    zOut[--i] = *(z++);
  }
}

/*
** Characters that can be part of a token.  We assume any character
** whose value is greater than 0x80 (any UTF character) can be
** part of a token.  In other words, delimiters all must have
** values of 0x7f or lower.
*/
static const char isIdChar[] = {
/* x0 x1 x2 x3 x4 x5 x6 x7 x8 x9 xA xB xC xD xE xF */
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0,  /* 3x */
    0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  /* 4x */
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1,  /* 5x */
    0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  /* 6x */
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0,  /* 7x */
};
#define idChar(C)  (((ch=C)&0x80)!=0 || (ch>0x2f && isIdChar[ch-0x30]))
#define isDelim(C) (((ch=C)&0x80)==0 && (ch<0x30 || !isIdChar[ch-0x30]))

/*
** Extract the next token from a tokenization cursor.  The cursor must
** have been opened by a prior call to porterOpen().
*/
static int porterNext(
  sqlite3_tokenizer_cursor *pCursor,  /* Cursor returned by porterOpen */
  const char **pzToken,               /* OUT: *pzToken is the token text */
  int *pnBytes,                       /* OUT: Number of bytes in token */
  int *piStartOffset,                 /* OUT: Starting offset of token */
  int *piEndOffset,                   /* OUT: Ending offset of token */
  int *piPosition                     /* OUT: Position integer of token */
){
  porter_tokenizer_cursor *c = (porter_tokenizer_cursor *) pCursor;
  const char *z = c->zInput;

  while( c->iOffset<c->nInput ){
    int iStartOffset, ch;

    /* Scan past delimiter characters */
    while( c->iOffset<c->nInput && isDelim(z[c->iOffset]) ){
      c->iOffset++;
    }

    /* Count non-delimiter characters. */
    iStartOffset = c->iOffset;
    while( c->iOffset<c->nInput && !isDelim(z[c->iOffset]) ){
      c->iOffset++;
    }

    if( c->iOffset>iStartOffset ){
      int n = c->iOffset-iStartOffset;
      if( n>c->nAllocated ){
        c->nAllocated = n+20;
        c->zToken = realloc(c->zToken, c->nAllocated);
        if( c->zToken==NULL ) return SQLITE_NOMEM;
      }
      porter_stemmer(&z[iStartOffset], n, c->zToken, pnBytes);
      *pzToken = c->zToken;
      *piStartOffset = iStartOffset;
      *piEndOffset = c->iOffset;
      *piPosition = c->iToken++;
      return SQLITE_OK;
    }
  }
  return SQLITE_DONE;
}

/*
** The set of routines that implement the porter-stemmer tokenizer
*/
static const sqlite3_tokenizer_module porterTokenizerModule = {
  0,
  porterCreate,
  porterDestroy,
  porterOpen,
  porterClose,
  porterNext,
};

/*
** Allocate a new porter tokenizer.  Return a pointer to the new
** tokenizer in *ppModule
*/
void sqlite3Fts1PorterTokenizerModule(
  sqlite3_tokenizer_module const**ppModule
){
  *ppModule = &porterTokenizerModule;
}

#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS1) */

Added SQLite.Interop/FTS1/fts1_tokenizer.h.





















































































































































































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/*
** 2006 July 10
**
** The author disclaims copyright to this source code.
**
*************************************************************************
** Defines the interface to tokenizers used by fulltext-search.  There
** are three basic components:
**
** sqlite3_tokenizer_module is a singleton defining the tokenizer
** interface functions.  This is essentially the class structure for
** tokenizers.
**
** sqlite3_tokenizer is used to define a particular tokenizer, perhaps
** including customization information defined at creation time.
**
** sqlite3_tokenizer_cursor is generated by a tokenizer to generate
** tokens from a particular input.
*/
#ifndef _FTS1_TOKENIZER_H_
#define _FTS1_TOKENIZER_H_

/* TODO(shess) Only used for SQLITE_OK and SQLITE_DONE at this time.
** If tokenizers are to be allowed to call sqlite3_*() functions, then
** we will need a way to register the API consistently.
*/
#include "sqlite3.h"

/*
** Structures used by the tokenizer interface.
*/
typedef struct sqlite3_tokenizer sqlite3_tokenizer;
typedef struct sqlite3_tokenizer_cursor sqlite3_tokenizer_cursor;
typedef struct sqlite3_tokenizer_module sqlite3_tokenizer_module;

struct sqlite3_tokenizer_module {
  int iVersion;                  /* currently 0 */

  /*
  ** Create and destroy a tokenizer.  argc/argv are passed down from
  ** the fulltext virtual table creation to allow customization.
  */
  int (*xCreate)(int argc, const char *const*argv,
                 sqlite3_tokenizer **ppTokenizer);
  int (*xDestroy)(sqlite3_tokenizer *pTokenizer);

  /*
  ** Tokenize a particular input.  Call xOpen() to prepare to
  ** tokenize, xNext() repeatedly until it returns SQLITE_DONE, then
  ** xClose() to free any internal state.  The pInput passed to
  ** xOpen() must exist until the cursor is closed.  The ppToken
  ** result from xNext() is only valid until the next call to xNext()
  ** or until xClose() is called.
  */
  /* TODO(shess) current implementation requires pInput to be
  ** nul-terminated.  This should either be fixed, or pInput/nBytes
  ** should be converted to zInput.
  */
  int (*xOpen)(sqlite3_tokenizer *pTokenizer,
               const char *pInput, int nBytes,
               sqlite3_tokenizer_cursor **ppCursor);
  int (*xClose)(sqlite3_tokenizer_cursor *pCursor);
  int (*xNext)(sqlite3_tokenizer_cursor *pCursor,
               const char **ppToken, int *pnBytes,
               int *piStartOffset, int *piEndOffset, int *piPosition);
};

struct sqlite3_tokenizer {
  const sqlite3_tokenizer_module *pModule;  /* The module for this tokenizer */
  /* Tokenizer implementations will typically add additional fields */
};

struct sqlite3_tokenizer_cursor {
  sqlite3_tokenizer *pTokenizer;       /* Tokenizer for this cursor. */
  /* Tokenizer implementations will typically add additional fields */
};

/*
** Get the module for a tokenizer which generates tokens based on a
** set of non-token characters.  The default is to break tokens at any
** non-alnum character, though the set of delimiters can also be
** specified by the first argv argument to xCreate().
*/
/* TODO(shess) This doesn't belong here.  Need some sort of
** registration process.
*/
void sqlite3Fts1SimpleTokenizerModule(sqlite3_tokenizer_module const**ppModule);
void sqlite3Fts1PorterTokenizerModule(sqlite3_tokenizer_module const**ppModule);

#endif /* _FTS1_TOKENIZER_H_ */

Added SQLite.Interop/FTS1/fts1_tokenizer1.c.



































































































































































































































































































































































































































































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/*
** The author disclaims copyright to this source code.
**
*************************************************************************
** Implementation of the "simple" full-text-search tokenizer.
*/

/*
** The code in this file is only compiled if:
**
**     * The FTS1 module is being built as an extension
**       (in which case SQLITE_CORE is not defined), or
**
**     * The FTS1 module is being built into the core of
**       SQLite (in which case SQLITE_ENABLE_FTS1 is defined).
*/
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS1)


#include <assert.h>
#if !defined(__APPLE__)
#include <malloc.h>
#else
#include <stdlib.h>
#endif
#include <stdio.h>
#include <string.h>
#include <ctype.h>

#include "fts1_tokenizer.h"

typedef struct simple_tokenizer {
  sqlite3_tokenizer base;
  char delim[128];             /* flag ASCII delimiters */
} simple_tokenizer;

typedef struct simple_tokenizer_cursor {
  sqlite3_tokenizer_cursor base;
  const char *pInput;          /* input we are tokenizing */
  int nBytes;                  /* size of the input */
  int iOffset;                 /* current position in pInput */
  int iToken;                  /* index of next token to be returned */
  char *pToken;                /* storage for current token */
  int nTokenAllocated;         /* space allocated to zToken buffer */
} simple_tokenizer_cursor;


/* Forward declaration */
static const sqlite3_tokenizer_module simpleTokenizerModule;

static int isDelim(simple_tokenizer *t, unsigned char c){
  return c<0x80 && t->delim[c];
}

/*
** Create a new tokenizer instance.
*/
static int simpleCreate(
  int argc, const char * const *argv,
  sqlite3_tokenizer **ppTokenizer
){
  simple_tokenizer *t;

  t = (simple_tokenizer *) calloc(sizeof(*t), 1);
  if( t==NULL ) return SQLITE_NOMEM;

  /* TODO(shess) Delimiters need to remain the same from run to run,
  ** else we need to reindex.  One solution would be a meta-table to
  ** track such information in the database, then we'd only want this
  ** information on the initial create.
  */
  if( argc>1 ){
    int i, n = strlen(argv[1]);
    for(i=0; i<n; i++){
      unsigned char ch = argv[1][i];
      /* We explicitly don't support UTF-8 delimiters for now. */
      if( ch>=0x80 ){
        free(t);
        return SQLITE_ERROR;
      }
      t->delim[ch] = 1;
    }
  } else {
    /* Mark non-alphanumeric ASCII characters as delimiters */
    int i;
    for(i=1; i<0x80; i++){
      t->delim[i] = !isalnum(i);
    }
  }

  *ppTokenizer = &t->base;
  return SQLITE_OK;
}

/*
** Destroy a tokenizer
*/
static int simpleDestroy(sqlite3_tokenizer *pTokenizer){
  free(pTokenizer);
  return SQLITE_OK;
}

/*
** Prepare to begin tokenizing a particular string.  The input
** string to be tokenized is pInput[0..nBytes-1].  A cursor
** used to incrementally tokenize this string is returned in 
** *ppCursor.
*/
static int simpleOpen(
  sqlite3_tokenizer *pTokenizer,         /* The tokenizer */
  const char *pInput, int nBytes,        /* String to be tokenized */
  sqlite3_tokenizer_cursor **ppCursor    /* OUT: Tokenization cursor */
){
  simple_tokenizer_cursor *c;

  c = (simple_tokenizer_cursor *) malloc(sizeof(*c));
  if( c==NULL ) return SQLITE_NOMEM;

  c->pInput = pInput;
  if( pInput==0 ){
    c->nBytes = 0;
  }else if( nBytes<0 ){
    c->nBytes = (int)strlen(pInput);
  }else{
    c->nBytes = nBytes;
  }
  c->iOffset = 0;                 /* start tokenizing at the beginning */
  c->iToken = 0;
  c->pToken = NULL;               /* no space allocated, yet. */
  c->nTokenAllocated = 0;

  *ppCursor = &c->base;
  return SQLITE_OK;
}

/*
** Close a tokenization cursor previously opened by a call to
** simpleOpen() above.
*/
static int simpleClose(sqlite3_tokenizer_cursor *pCursor){
  simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor;
  free(c->pToken);
  free(c);
  return SQLITE_OK;
}

/*
** Extract the next token from a tokenization cursor.  The cursor must
** have been opened by a prior call to simpleOpen().
*/
static int simpleNext(
  sqlite3_tokenizer_cursor *pCursor,  /* Cursor returned by simpleOpen */
  const char **ppToken,               /* OUT: *ppToken is the token text */
  int *pnBytes,                       /* OUT: Number of bytes in token */
  int *piStartOffset,                 /* OUT: Starting offset of token */
  int *piEndOffset,                   /* OUT: Ending offset of token */
  int *piPosition                     /* OUT: Position integer of token */
){
  simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor;
  simple_tokenizer *t = (simple_tokenizer *) pCursor->pTokenizer;
  unsigned char *p = (unsigned char *)c->pInput;

  while( c->iOffset<c->nBytes ){
    int iStartOffset;

    /* Scan past delimiter characters */
    while( c->iOffset<c->nBytes && isDelim(t, p[c->iOffset]) ){
      c->iOffset++;
    }

    /* Count non-delimiter characters. */
    iStartOffset = c->iOffset;
    while( c->iOffset<c->nBytes && !isDelim(t, p[c->iOffset]) ){
      c->iOffset++;
    }

    if( c->iOffset>iStartOffset ){
      int i, n = c->iOffset-iStartOffset;
      if( n>c->nTokenAllocated ){
        c->nTokenAllocated = n+20;
        c->pToken = realloc(c->pToken, c->nTokenAllocated);
        if( c->pToken==NULL ) return SQLITE_NOMEM;
      }
      for(i=0; i<n; i++){
        /* TODO(shess) This needs expansion to handle UTF-8
        ** case-insensitivity.
        */
        unsigned char ch = p[iStartOffset+i];
        c->pToken[i] = ch<0x80 ? tolower(ch) : ch;
      }
      *ppToken = c->pToken;
      *pnBytes = n;
      *piStartOffset = iStartOffset;
      *piEndOffset = c->iOffset;
      *piPosition = c->iToken++;

      return SQLITE_OK;
    }
  }
  return SQLITE_DONE;
}

/*
** The set of routines that implement the simple tokenizer
*/
static const sqlite3_tokenizer_module simpleTokenizerModule = {
  0,
  simpleCreate,
  simpleDestroy,
  simpleOpen,
  simpleClose,
  simpleNext,
};

/*
** Allocate a new simple tokenizer.  Return a pointer to the new
** tokenizer in *ppModule
*/
void sqlite3Fts1SimpleTokenizerModule(
  sqlite3_tokenizer_module const**ppModule
){
  *ppModule = &simpleTokenizerModule;
}

#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS1) */

Added SQLite.Interop/FTS1/sqlite3.h.



























































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































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/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the SQLite library
** presents to client programs.
**
** @(#) $Id: sqlite3.h,v 1.1 2007/04/22 23:26:33 rmsimpson Exp $
*/
#ifndef _SQLITE3_H_
#define _SQLITE3_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** Make sure we can call this stuff from C++.
*/
#ifdef __cplusplus
extern "C" {
#endif

/*
** The version of the SQLite library.
*/
#ifdef SQLITE_VERSION
# undef SQLITE_VERSION
#endif
#define SQLITE_VERSION         "3.3.16"

/*
** The format of the version string is "X.Y.Z<trailing string>", where
** X is the major version number, Y is the minor version number and Z
** is the release number. The trailing string is often "alpha" or "beta".
** For example "3.1.1beta".
**
** The SQLITE_VERSION_NUMBER is an integer with the value 
** (X*100000 + Y*1000 + Z). For example, for version "3.1.1beta", 
** SQLITE_VERSION_NUMBER is set to 3001001. To detect if they are using 
** version 3.1.1 or greater at compile time, programs may use the test 
** (SQLITE_VERSION_NUMBER>=3001001).
*/
#ifdef SQLITE_VERSION_NUMBER
# undef SQLITE_VERSION_NUMBER
#endif
#define SQLITE_VERSION_NUMBER 3003016

/*
** The version string is also compiled into the library so that a program
** can check to make sure that the lib*.a file and the *.h file are from
** the same version.  The sqlite3_libversion() function returns a pointer
** to the sqlite3_version variable - useful in DLLs which cannot access
** global variables.
*/
extern const char sqlite3_version[];
const char *sqlite3_libversion(void);

/*
** Return the value of the SQLITE_VERSION_NUMBER macro when the
** library was compiled.
*/
int sqlite3_libversion_number(void);

/*
** Each open sqlite database is represented by an instance of the
** following opaque structure.
*/
typedef struct sqlite3 sqlite3;


/*
** Some compilers do not support the "long long" datatype.  So we have
** to do a typedef that for 64-bit integers that depends on what compiler
** is being used.
*/
#ifdef SQLITE_INT64_TYPE
  typedef SQLITE_INT64_TYPE sqlite_int64;
  typedef unsigned SQLITE_INT64_TYPE sqlite_uint64;
#elif defined(_MSC_VER) || defined(__BORLANDC__)
  typedef __int64 sqlite_int64;
  typedef unsigned __int64 sqlite_uint64;
#else
  typedef long long int sqlite_int64;
  typedef unsigned long long int sqlite_uint64;
#endif

/*
** If compiling for a processor that lacks floating point support,
** substitute integer for floating-point
*/
#ifdef SQLITE_OMIT_FLOATING_POINT
# define double sqlite_int64
#endif

/*
** A function to close the database.
**
** Call this function with a pointer to a structure that was previously
** returned from sqlite3_open() and the corresponding database will by closed.
**
** All SQL statements prepared using sqlite3_prepare() or
** sqlite3_prepare16() must be deallocated using sqlite3_finalize() before
** this routine is called. Otherwise, SQLITE_BUSY is returned and the
** database connection remains open.
*/
int sqlite3_close(sqlite3 *);

/*
** The type for a callback function.
*/
typedef int (*sqlite3_callback)(void*,int,char**, char**);

/*
** A function to executes one or more statements of SQL.
**
** If one or more of the SQL statements are queries, then
** the callback function specified by the 3rd parameter is
** invoked once for each row of the query result.  This callback
** should normally return 0.  If the callback returns a non-zero
** value then the query is aborted, all subsequent SQL statements
** are skipped and the sqlite3_exec() function returns the SQLITE_ABORT.
**
** The 1st parameter is an arbitrary pointer that is passed
** to the callback function as its first parameter.
**
** The 2nd parameter to the callback function is the number of
** columns in the query result.  The 3rd parameter to the callback
** is an array of strings holding the values for each column.
** The 4th parameter to the callback is an array of strings holding
** the names of each column.
**
** The callback function may be NULL, even for queries.  A NULL
** callback is not an error.  It just means that no callback
** will be invoked.
**
** If an error occurs while parsing or evaluating the SQL (but
** not while executing the callback) then an appropriate error
** message is written into memory obtained from malloc() and
** *errmsg is made to point to that message.  The calling function
** is responsible for freeing the memory that holds the error
** message.   Use sqlite3_free() for this.  If errmsg==NULL,
** then no error message is ever written.
**
** The return value is is SQLITE_OK if there are no errors and
** some other return code if there is an error.  The particular
** return value depends on the type of error. 
**
** If the query could not be executed because a database file is
** locked or busy, then this function returns SQLITE_BUSY.  (This
** behavior can be modified somewhat using the sqlite3_busy_handler()
** and sqlite3_busy_timeout() functions below.)
*/
int sqlite3_exec(
  sqlite3*,                     /* An open database */
  const char *sql,              /* SQL to be executed */
  sqlite3_callback,             /* Callback function */
  void *,                       /* 1st argument to callback function */
  char **errmsg                 /* Error msg written here */
);

/*
** Return values for sqlite3_exec() and sqlite3_step()
*/
#define SQLITE_OK           0   /* Successful result */
/* beginning-of-error-codes */
#define SQLITE_ERROR        1   /* SQL error or missing database */
#define SQLITE_INTERNAL     2   /* NOT USED. Internal logic error in SQLite */
#define SQLITE_PERM         3   /* Access permission denied */
#define SQLITE_ABORT        4   /* Callback routine requested an abort */
#define SQLITE_BUSY         5   /* The database file is locked */
#define SQLITE_LOCKED       6   /* A table in the database is locked */
#define SQLITE_NOMEM        7   /* A malloc() failed */
#define SQLITE_READONLY     8   /* Attempt to write a readonly database */
#define SQLITE_INTERRUPT    9   /* Operation terminated by sqlite3_interrupt()*/
#define SQLITE_IOERR       10   /* Some kind of disk I/O error occurred */
#define SQLITE_CORRUPT     11   /* The database disk image is malformed */
#define SQLITE_NOTFOUND    12   /* NOT USED. Table or record not found */
#define SQLITE_FULL        13   /* Insertion failed because database is full */
#define SQLITE_CANTOPEN    14   /* Unable to open the database file */
#define SQLITE_PROTOCOL    15   /* NOT USED. Database lock protocol error */
#define SQLITE_EMPTY       16   /* Database is empty */
#define SQLITE_SCHEMA      17   /* The database schema changed */
#define SQLITE_TOOBIG      18   /* NOT USED. Too much data for one row */
#define SQLITE_CONSTRAINT  19   /* Abort due to contraint violation */
#define SQLITE_MISMATCH    20   /* Data type mismatch */
#define SQLITE_MISUSE      21   /* Library used incorrectly */
#define SQLITE_NOLFS       22   /* Uses OS features not supported on host */
#define SQLITE_AUTH        23   /* Authorization denied */
#define SQLITE_FORMAT      24   /* Auxiliary database format error */
#define SQLITE_RANGE       25   /* 2nd parameter to sqlite3_bind out of range */
#define SQLITE_NOTADB      26   /* File opened that is not a database file */
#define SQLITE_ROW         100  /* sqlite3_step() has another row ready */
#define SQLITE_DONE        101  /* sqlite3_step() has finished executing */
/* end-of-error-codes */

/*
** Using the sqlite3_extended_result_codes() API, you can cause
** SQLite to return result codes with additional information in
** their upper bits.  The lower 8 bits will be the same as the
** primary result codes above.  But the upper bits might contain
** more specific error information.
**
** To extract the primary result code from an extended result code,
** simply mask off the lower 8 bits.
**
**        primary = extended & 0xff;
**
** New result error codes may be added from time to time.  Software
** that uses the extended result codes should plan accordingly and be
** sure to always handle new unknown codes gracefully.
**
** The SQLITE_OK result code will never be extended.  It will always
** be exactly zero.
**
** The extended result codes always have the primary result code
** as a prefix.  Primary result codes only contain a single "_"
** character.  Extended result codes contain two or more "_" characters.
*/
#define SQLITE_IOERR_READ          (SQLITE_IOERR | (1<<8))
#define SQLITE_IOERR_SHORT_READ    (SQLITE_IOERR | (2<<8))
#define SQLITE_IOERR_WRITE         (SQLITE_IOERR | (3<<8))
#define SQLITE_IOERR_FSYNC         (SQLITE_IOERR | (4<<8))
#define SQLITE_IOERR_DIR_FSYNC     (SQLITE_IOERR | (5<<8))
#define SQLITE_IOERR_TRUNCATE      (SQLITE_IOERR | (6<<8))
#define SQLITE_IOERR_FSTAT         (SQLITE_IOERR | (7<<8))
#define SQLITE_IOERR_UNLOCK        (SQLITE_IOERR | (8<<8))
#define SQLITE_IOERR_RDLOCK        (SQLITE_IOERR | (9<<8))
#define SQLITE_IOERR_DELETE        (SQLITE_IOERR | (10<<8))

/*
** Enable or disable the extended result codes.
*/
int sqlite3_extended_result_codes(sqlite3*, int onoff);

/*
** Each entry in an SQLite table has a unique integer key.  (The key is
** the value of the INTEGER PRIMARY KEY column if there is such a column,
** otherwise the key is generated automatically.  The unique key is always
** available as the ROWID, OID, or _ROWID_ column.)  The following routine
** returns the integer key of the most recent insert in the database.
*/
sqlite_int64 sqlite3_last_insert_rowid(sqlite3*);

/*
** This function returns the number of database rows that were changed
** (or inserted or deleted) by the most recent SQL statement.  Only
** changes that are directly specified by the INSERT, UPDATE, or
** DELETE statement are counted.  Auxiliary changes caused by
** triggers are not counted.   Within the body of a trigger, however,
** the sqlite3_changes() API can be called to find the number of
** changes in the most recently completed INSERT, UPDATE, or DELETE
** statement within the body of the trigger.
**
** All changes are counted, even if they were later undone by a
** ROLLBACK or ABORT.  Except, changes associated with creating and
** dropping tables are not counted.
**
** If a callback invokes sqlite3_exec() or sqlite3_step() recursively,
** then the changes in the inner, recursive call are counted together
** with the changes in the outer call.
**
** SQLite implements the command "DELETE FROM table" without a WHERE clause
** by dropping and recreating the table.  (This is much faster than going
** through and deleting individual elements form the table.)  Because of
** this optimization, the change count for "DELETE FROM table" will be
** zero regardless of the number of elements that were originally in the
** table. To get an accurate count of the number of rows deleted, use
** "DELETE FROM table WHERE 1" instead.
*/
int sqlite3_changes(sqlite3*);

/*
** This function returns the number of database rows that have been
** modified by INSERT, UPDATE or DELETE statements since the database handle
** was opened. This includes UPDATE, INSERT and DELETE statements executed
** as part of trigger programs. All changes are counted as soon as the
** statement that makes them is completed (when the statement handle is
** passed to sqlite3_reset() or sqlite_finalise()).
**
** SQLite implements the command "DELETE FROM table" without a WHERE clause
** by dropping and recreating the table.  (This is much faster than going
** through and deleting individual elements form the table.)  Because of
** this optimization, the change count for "DELETE FROM table" will be
** zero regardless of the number of elements that were originally in the
** table. To get an accurate count of the number of rows deleted, use
** "DELETE FROM table WHERE 1" instead.
*/
int sqlite3_total_changes(sqlite3*);

/* This function causes any pending database operation to abort and
** return at its earliest opportunity.  This routine is typically
** called in response to a user action such as pressing "Cancel"
** or Ctrl-C where the user wants a long query operation to halt
** immediately.
**
** It is safe to call this routine from a different thread that the
** thread that is currently running the database operation. 
*/
void sqlite3_interrupt(sqlite3*);


/* These functions return true if the given input string comprises
** one or more complete SQL statements. For the sqlite3_complete() call,
** the parameter must be a nul-terminated UTF-8 string. For
** sqlite3_complete16(), a nul-terminated machine byte order UTF-16 string
** is required.
**
** This routine is useful for command-line input to see of the user has
** entered a complete statement of SQL or if the current statement needs
** to be continued on the next line.  The algorithm is simple.  If the 
** last token other than spaces and comments is a semicolon, then return 
** true.  Actually, the algorithm is a little more complicated than that
** in order to deal with triggers, but the basic idea is the same:  the
** statement is not complete unless it ends in a semicolon.
*/
int sqlite3_complete(const char *sql);
int sqlite3_complete16(const void *sql);

/*
** This routine identifies a callback function that is invoked
** whenever an attempt is made to open a database table that is
** currently locked by another process or thread.  If the busy callback
** is NULL, then sqlite3_exec() returns SQLITE_BUSY immediately if
** it finds a locked table.  If the busy callback is not NULL, then
** sqlite3_exec() invokes the callback with two arguments.  The
** first argument to the handler is a copy of the void* pointer which
** is the third argument to this routine.  The second argument to
** the handler is the number of times that the busy handler has
** been invoked for this locking event.  If the
** busy callback returns 0, then sqlite3_exec() immediately returns
** SQLITE_BUSY.  If the callback returns non-zero, then sqlite3_exec()
** tries to open the table again and the cycle repeats.
**
** The presence of a busy handler does not guarantee that
** it will be invoked when there is lock contention.
** If SQLite determines that invoking the busy handler could result in
** a deadlock, it will return SQLITE_BUSY instead.
** Consider a scenario where one process is holding a read lock that
** it is trying to promote to a reserved lock and
** a second process is holding a reserved lock that it is trying
** to promote to an exclusive lock.  The first process cannot proceed
** because it is blocked by the second and the second process cannot
** proceed because it is blocked by the first.  If both processes
** invoke the busy handlers, neither will make any progress.  Therefore,
** SQLite returns SQLITE_BUSY for the first process, hoping that this
** will induce the first process to release its read lock and allow
** the second process to proceed.
**
** The default busy callback is NULL.
**
** Sqlite is re-entrant, so the busy handler may start a new query. 
** (It is not clear why anyone would every want to do this, but it
** is allowed, in theory.)  But the busy handler may not close the
** database.  Closing the database from a busy handler will delete 
** data structures out from under the executing query and will 
** probably result in a coredump.
*/
int sqlite3_busy_handler(sqlite3*, int(*)(void*,int), void*);

/*
** This routine sets a busy handler that sleeps for a while when a
** table is locked.  The handler will sleep multiple times until 
** at least "ms" milleseconds of sleeping have been done.  After
** "ms" milleseconds of sleeping, the handler returns 0 which
** causes sqlite3_exec() to return SQLITE_BUSY.
**
** Calling this routine with an argument less than or equal to zero
** turns off all busy handlers.
*/
int sqlite3_busy_timeout(sqlite3*, int ms);

/*
** This next routine is really just a wrapper around sqlite3_exec().
** Instead of invoking a user-supplied callback for each row of the
** result, this routine remembers each row of the result in memory
** obtained from malloc(), then returns all of the result after the
** query has finished. 
**
** As an example, suppose the query result where this table:
**
**        Name        | Age
**        -----------------------
**        Alice       | 43
**        Bob         | 28
**        Cindy       | 21
**
** If the 3rd argument were &azResult then after the function returns
** azResult will contain the following data:
**
**        azResult[0] = "Name";
**        azResult[1] = "Age";
**        azResult[2] = "Alice";
**        azResult[3] = "43";
**        azResult[4] = "Bob";
**        azResult[5] = "28";
**        azResult[6] = "Cindy";
**        azResult[7] = "21";
**
** Notice that there is an extra row of data containing the column
** headers.  But the *nrow return value is still 3.  *ncolumn is
** set to 2.  In general, the number of values inserted into azResult
** will be ((*nrow) + 1)*(*ncolumn).
**
** After the calling function has finished using the result, it should 
** pass the result data pointer to sqlite3_free_table() in order to 
** release the memory that was malloc-ed.  Because of the way the 
** malloc() happens, the calling function must not try to call 
** free() directly.  Only sqlite3_free_table() is able to release 
** the memory properly and safely.
**
** The return value of this routine is the same as from sqlite3_exec().
*/
int sqlite3_get_table(
  sqlite3*,               /* An open database */
  const char *sql,       /* SQL to be executed */
  char ***resultp,       /* Result written to a char *[]  that this points to */
  int *nrow,             /* Number of result rows written here */
  int *ncolumn,          /* Number of result columns written here */
  char **errmsg          /* Error msg written here */
);

/*
** Call this routine to free the memory that sqlite3_get_table() allocated.
*/
void sqlite3_free_table(char **result);

/*
** The following routines are variants of the "sprintf()" from the
** standard C library.  The resulting string is written into memory
** obtained from malloc() so that there is never a possiblity of buffer
** overflow.  These routines also implement some additional formatting
** options that are useful for constructing SQL statements.
**
** The strings returned by these routines should be freed by calling
** sqlite3_free().
**
** All of the usual printf formatting options apply.  In addition, there
** is a "%q" option.  %q works like %s in that it substitutes a null-terminated
** string from the argument list.  But %q also doubles every '\'' character.
** %q is designed for use inside a string literal.  By doubling each '\''
** character it escapes that character and allows it to be inserted into
** the string.
**
** For example, so some string variable contains text as follows:
**
**      char *zText = "It's a happy day!";
**
** We can use this text in an SQL statement as follows:
**
**      char *z = sqlite3_mprintf("INSERT INTO TABLES('%q')", zText);
**      sqlite3_exec(db, z, callback1, 0, 0);
**      sqlite3_free(z);
**
** Because the %q format string is used, the '\'' character in zText
** is escaped and the SQL generated is as follows:
**
**      INSERT INTO table1 VALUES('It''s a happy day!')
**
** This is correct.  Had we used %s instead of %q, the generated SQL
** would have looked like this:
**
**      INSERT INTO table1 VALUES('It's a happy day!');
**
** This second example is an SQL syntax error.  As a general rule you
** should always use %q instead of %s when inserting text into a string 
** literal.
*/
char *sqlite3_mprintf(const char*,...);
char *sqlite3_vmprintf(const char*, va_list);
char *sqlite3_snprintf(int,char*,const char*, ...);

/*
** SQLite uses its own memory allocator.  On many installations, this
** memory allocator is identical to the standard malloc()/realloc()/free()
** and can be used interchangable.  On others, the implementations are
** different.  For maximum portability, it is best not to mix calls
** to the standard malloc/realloc/free with the sqlite versions.
*/
void *sqlite3_malloc(int);
void *sqlite3_realloc(void*, int);
void sqlite3_free(void*);

#ifndef SQLITE_OMIT_AUTHORIZATION
/*
** This routine registers a callback with the SQLite library.  The
** callback is invoked (at compile-time, not at run-time) for each
** attempt to access a column of a table in the database.  The callback
** returns SQLITE_OK if access is allowed, SQLITE_DENY if the entire
** SQL statement should be aborted with an error and SQLITE_IGNORE
** if the column should be treated as a NULL value.
*/
int sqlite3_set_authorizer(
  sqlite3*,
  int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),
  void *pUserData
);
#endif

/*
** The second parameter to the access authorization function above will
** be one of the values below.  These values signify what kind of operation
** is to be authorized.  The 3rd and 4th parameters to the authorization
** function will be parameters or NULL depending on which of the following
** codes is used as the second parameter.  The 5th parameter is the name
** of the database ("main", "temp", etc.) if applicable.  The 6th parameter
** is the name of the inner-most trigger or view that is responsible for
** the access attempt or NULL if this access attempt is directly from 
** input SQL code.
**
**                                          Arg-3           Arg-4
*/
#define SQLITE_COPY                  0   /* Table Name      File Name       */
#define SQLITE_CREATE_INDEX          1   /* Index Name      Table Name      */
#define SQLITE_CREATE_TABLE          2   /* Table Name      NULL            */
#define SQLITE_CREATE_TEMP_INDEX     3   /* Index Name      Table Name      */
#define SQLITE_CREATE_TEMP_TABLE     4   /* Table Name      NULL            */
#define SQLITE_CREATE_TEMP_TRIGGER   5   /* Trigger Name    Table Name      */
#define SQLITE_CREATE_TEMP_VIEW      6   /* View Name       NULL            */
#define SQLITE_CREATE_TRIGGER        7   /* Trigger Name    Table Name      */
#define SQLITE_CREATE_VIEW           8   /* View Name       NULL            */
#define SQLITE_DELETE                9   /* Table Name      NULL            */
#define SQLITE_DROP_INDEX           10   /* Index Name      Table Name      */
#define SQLITE_DROP_TABLE           11   /* Table Name      NULL            */
#define SQLITE_DROP_TEMP_INDEX      12   /* Index Name      Table Name      */
#define SQLITE_DROP_TEMP_TABLE      13   /* Table Name      NULL            */
#define SQLITE_DROP_TEMP_TRIGGER    14   /* Trigger Name    Table Name      */
#define SQLITE_DROP_TEMP_VIEW       15   /* View Name       NULL            */
#define SQLITE_DROP_TRIGGER         16   /* Trigger Name    Table Name      */
#define SQLITE_DROP_VIEW            17   /* View Name       NULL            */
#define SQLITE_INSERT               18   /* Table Name      NULL            */
#define SQLITE_PRAGMA               19   /* Pragma Name     1st arg or NULL */
#define SQLITE_READ                 20   /* Table Name      Column Name     */
#define SQLITE_SELECT               21   /* NULL            NULL            */
#define SQLITE_TRANSACTION          22   /* NULL            NULL            */
#define SQLITE_UPDATE               23   /* Table Name      Column Name     */
#define SQLITE_ATTACH               24   /* Filename        NULL            */
#define SQLITE_DETACH               25   /* Database Name   NULL            */
#define SQLITE_ALTER_TABLE          26   /* Database Name   Table Name      */
#define SQLITE_REINDEX              27   /* Index Name      NULL            */
#define SQLITE_ANALYZE              28   /* Table Name      NULL            */
#define SQLITE_CREATE_VTABLE        29   /* Table Name      Module Name     */
#define SQLITE_DROP_VTABLE          30   /* Table Name      Module Name     */
#define SQLITE_FUNCTION             31   /* Function Name   NULL            */

/*
** The return value of the authorization function should be one of the
** following constants:
*/
/* #define SQLITE_OK  0   // Allow access (This is actually defined above) */
#define SQLITE_DENY   1   /* Abort the SQL statement with an error */
#define SQLITE_IGNORE 2   /* Don't allow access, but don't generate an error */

/*
** Register a function for tracing SQL command evaluation.  The function
** registered by sqlite3_trace() is invoked at the first sqlite3_step()
** for the evaluation of an SQL statement.  The function registered by
** sqlite3_profile() runs at the end of each SQL statement and includes
** information on how long that statement ran.
**
** The sqlite3_profile() API is currently considered experimental and
** is subject to change.
*/
void *sqlite3_trace(sqlite3*, void(*xTrace)(void*,const char*), void*);
void *sqlite3_profile(sqlite3*,
   void(*xProfile)(void*,const char*,sqlite_uint64), void*);

/*
** This routine configures a callback function - the progress callback - that
** is invoked periodically during long running calls to sqlite3_exec(),
** sqlite3_step() and sqlite3_get_table(). An example use for this API is to 
** keep a GUI updated during a large query.
**
** The progress callback is invoked once for every N virtual machine opcodes,
** where N is the second argument to this function. The progress callback
** itself is identified by the third argument to this function. The fourth
** argument to this function is a void pointer passed to the progress callback
** function each time it is invoked.
**
** If a call to sqlite3_exec(), sqlite3_step() or sqlite3_get_table() results 
** in less than N opcodes being executed, then the progress callback is not
** invoked.
** 
** To remove the progress callback altogether, pass NULL as the third
** argument to this function.
**
** If the progress callback returns a result other than 0, then the current 
** query is immediately terminated and any database changes rolled back. If the
** query was part of a larger transaction, then the transaction is not rolled
** back and remains active. The sqlite3_exec() call returns SQLITE_ABORT. 
**
******* THIS IS AN EXPERIMENTAL API AND IS SUBJECT TO CHANGE ******
*/
void sqlite3_progress_handler(sqlite3*, int, int(*)(void*), void*);

/*
** Register a callback function to be invoked whenever a new transaction
** is committed.  The pArg argument is passed through to the callback.
** callback.  If the callback function returns non-zero, then the commit
** is converted into a rollback.
**
** If another function was previously registered, its pArg value is returned.
** Otherwise NULL is returned.
**
** Registering a NULL function disables the callback.
**
******* THIS IS AN EXPERIMENTAL API AND IS SUBJECT TO CHANGE ******
*/
void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);

/*
** Open the sqlite database file "filename".  The "filename" is UTF-8
** encoded for sqlite3_open() and UTF-16 encoded in the native byte order
** for sqlite3_open16().  An sqlite3* handle is returned in *ppDb, even
** if an error occurs. If the database is opened (or created) successfully,
** then SQLITE_OK is returned. Otherwise an error code is returned. The
** sqlite3_errmsg() or sqlite3_errmsg16()  routines can be used to obtain
** an English language description of the error.
**
** If the database file does not exist, then a new database is created.
** The encoding for the database is UTF-8 if sqlite3_open() is called and
** UTF-16 if sqlite3_open16 is used.
**
** Whether or not an error occurs when it is opened, resources associated
** with the sqlite3* handle should be released by passing it to
** sqlite3_close() when it is no longer required.
*/
int sqlite3_open(
  const char *filename,   /* Database filename (UTF-8) */
  sqlite3 **ppDb          /* OUT: SQLite db handle */
);
int sqlite3_open16(
  const void *filename,   /* Database filename (UTF-16) */
  sqlite3 **ppDb          /* OUT: SQLite db handle */
);

/*
** Return the error code for the most recent sqlite3_* API call associated
** with sqlite3 handle 'db'. SQLITE_OK is returned if the most recent 
** API call was successful.
**
** Calls to many sqlite3_* functions set the error code and string returned
** by sqlite3_errcode(), sqlite3_errmsg() and sqlite3_errmsg16()
** (overwriting the previous values). Note that calls to sqlite3_errcode(),
** sqlite3_errmsg() and sqlite3_errmsg16() themselves do not affect the
** results of future invocations.
**
** Assuming no other intervening sqlite3_* API calls are made, the error
** code returned by this function is associated with the same error as
** the strings  returned by sqlite3_errmsg() and sqlite3_errmsg16().
*/
int sqlite3_errcode(sqlite3 *db);

/*
** Return a pointer to a UTF-8 encoded string describing in english the
** error condition for the most recent sqlite3_* API call. The returned
** string is always terminated by an 0x00 byte.
**
** The string "not an error" is returned when the most recent API call was
** successful.
*/
const char *sqlite3_errmsg(sqlite3*);

/*
** Return a pointer to a UTF-16 native byte order encoded string describing
** in english the error condition for the most recent sqlite3_* API call.
** The returned string is always terminated by a pair of 0x00 bytes.
**
** The string "not an error" is returned when the most recent API call was
** successful.
*/
const void *sqlite3_errmsg16(sqlite3*);

/*
** An instance of the following opaque structure is used to represent
** a compiled SQL statment.
*/
typedef struct sqlite3_stmt sqlite3_stmt;

/*
** To execute an SQL query, it must first be compiled into a byte-code
** program using one of the following routines. The only difference between
** them is that the second argument, specifying the SQL statement to
** compile, is assumed to be encoded in UTF-8 for the sqlite3_prepare()
** function and UTF-16 for sqlite3_prepare16().
**
** The first parameter "db" is an SQLite database handle. The second
** parameter "zSql" is the statement to be compiled, encoded as either
** UTF-8 or UTF-16 (see above). If the next parameter, "nBytes", is less
** than zero, then zSql is read up to the first nul terminator.  If
** "nBytes" is not less than zero, then it is the length of the string zSql
** in bytes (not characters).
**
** *pzTail is made to point to the first byte past the end of the first
** SQL statement in zSql.  This routine only compiles the first statement
** in zSql, so *pzTail is left pointing to what remains uncompiled.
**
** *ppStmt is left pointing to a compiled SQL statement that can be
** executed using sqlite3_step().  Or if there is an error, *ppStmt may be
** set to NULL.  If the input text contained no SQL (if the input is and
** empty string or a comment) then *ppStmt is set to NULL.
**
** On success, SQLITE_OK is returned.  Otherwise an error code is returned.
*/
int sqlite3_prepare(
  sqlite3 *db,            /* Database handle */
  const char *zSql,       /* SQL statement, UTF-8 encoded */
  int nBytes,             /* Length of zSql in bytes. */
  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  const char **pzTail     /* OUT: Pointer to unused portion of zSql */
);
int sqlite3_prepare16(
  sqlite3 *db,            /* Database handle */
  const void *zSql,       /* SQL statement, UTF-16 encoded */
  int nBytes,             /* Length of zSql in bytes. */
  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  const void **pzTail     /* OUT: Pointer to unused portion of zSql */
);

/*
** Newer versions of the prepare API work just like the legacy versions
** but with one exception:  The a copy of the SQL text is saved in the
** sqlite3_stmt structure that is returned.  If this copy exists, it
** modifieds the behavior of sqlite3_step() slightly.  First, sqlite3_step()
** will no longer return an SQLITE_SCHEMA error but will instead automatically
** rerun the compiler to rebuild the prepared statement.  Secondly, 
** sqlite3_step() now turns a full result code - the result code that
** use used to have to call sqlite3_reset() to get.
*/
int sqlite3_prepare_v2(
  sqlite3 *db,            /* Database handle */
  const char *zSql,       /* SQL statement, UTF-8 encoded */
  int nBytes,             /* Length of zSql in bytes. */
  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  const char **pzTail     /* OUT: Pointer to unused portion of zSql */
);
int sqlite3_prepare16_v2(
  sqlite3 *db,            /* Database handle */
  const void *zSql,       /* SQL statement, UTF-16 encoded */
  int nBytes,             /* Length of zSql in bytes. */
  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  const void **pzTail     /* OUT: Pointer to unused portion of zSql */
);

/*
** Pointers to the following two opaque structures are used to communicate
** with the implementations of user-defined functions.
*/
typedef struct sqlite3_context sqlite3_context;
typedef struct Mem sqlite3_value;

/*
** In the SQL strings input to sqlite3_prepare() and sqlite3_prepare16(),
** one or more literals can be replace by parameters "?" or "?NNN" or 
** ":AAA" or "@AAA" or "$VVV" where NNN is a integer, AAA is an identifer,
** and VVV is a variable name according  to the syntax rules of the
** TCL programming language.  The value of these parameters (also called
** "host parameter names") can be set using the routines listed below.
**
** In every case, the first argument is a pointer to the sqlite3_stmt
** structure returned from sqlite3_prepare().  The second argument is the
** index of the host parameter name.  The first host parameter as an index 
** of 1.  For named host parameters (":AAA" or "$VVV") you can use 
** sqlite3_bind_parameter_index() to get the correct index value given
** the parameter name.  If the same named parameter occurs more than
** once, it is assigned the same index each time.
**
** The fifth argument to sqlite3_bind_blob(), sqlite3_bind_text(), and
** sqlite3_bind_text16() is a destructor used to dispose of the BLOB or
** text after SQLite has finished with it.  If the fifth argument is the
** special value SQLITE_STATIC, then the library assumes that the information
** is in static, unmanaged space and does not need to be freed.  If the
** fifth argument has the value SQLITE_TRANSIENT, then SQLite makes its
** own private copy of the data before the sqlite3_bind_* routine returns.
**
** The sqlite3_bind_* routine must be called before sqlite3_step() and after
** an sqlite3_prepare() or sqlite3_reset().  Bindings persist across
** multiple calls to sqlite3_reset() and sqlite3_step().  Unbound parameters 
** are interpreted as NULL.
*/
int sqlite3_bind_blob(sqlite3_stmt*, int, const void*, int n, void(*)(void*));
int sqlite3_bind_double(sqlite3_stmt*, int, double);
int sqlite3_bind_int(sqlite3_stmt*, int, int);
int sqlite3_bind_int64(sqlite3_stmt*, int, sqlite_int64);
int sqlite3_bind_null(sqlite3_stmt*, int);
int sqlite3_bind_text(sqlite3_stmt*, int, const char*, int n, void(*)(void*));
int sqlite3_bind_text16(sqlite3_stmt*, int, const void*, int, void(*)(void*));
int sqlite3_bind_value(sqlite3_stmt*, int, const sqlite3_value*);

/*
** Return the number of host parameters in a compiled SQL statement.  This
** routine was added to support DBD::SQLite.
*/
int sqlite3_bind_parameter_count(sqlite3_stmt*);

/*
** Return the name of the i-th name parameter.  Ordinary parameters "?" are
** nameless and a NULL is returned.  For parameters of the form :AAA or
** $VVV the complete text of the parameter name is returned, including
** the initial ":" or "$".  NULL is returned if the index is out of range.
*/
const char *sqlite3_bind_parameter_name(sqlite3_stmt*, int);

/*
** Return the index of a parameter with the given name.  The name
** must match exactly.  If no parameter with the given name is found,
** return 0.
*/
int sqlite3_bind_parameter_index(sqlite3_stmt*, const char *zName);

/*
** Set all the parameters in the compiled SQL statement to NULL.
*/
int sqlite3_clear_bindings(sqlite3_stmt*);

/*
** Return the number of columns in the result set returned by the compiled
** SQL statement. This routine returns 0 if pStmt is an SQL statement
** that does not return data (for example an UPDATE).
*/
int sqlite3_column_count(sqlite3_stmt *pStmt);

/*
** The first parameter is a compiled SQL statement. This function returns
** the column heading for the Nth column of that statement, where N is the
** second function parameter.  The string returned is UTF-8 for
** sqlite3_column_name() and UTF-16 for sqlite3_column_name16().
*/
const char *sqlite3_column_name(sqlite3_stmt*,int);
const void *sqlite3_column_name16(sqlite3_stmt*,int);

/*
** The first argument to the following calls is a compiled SQL statement.
** These functions return information about the Nth column returned by 
** the statement, where N is the second function argument.
**
** If the Nth column returned by the statement is not a column value,
** then all of the functions return NULL. Otherwise, the return the 
** name of the attached database, table and column that the expression
** extracts a value from.
**
** As with all other SQLite APIs, those postfixed with "16" return UTF-16
** encoded strings, the other functions return UTF-8. The memory containing
** the returned strings is valid until the statement handle is finalized().
**
** These APIs are only available if the library was compiled with the 
** SQLITE_ENABLE_COLUMN_METADATA preprocessor symbol defined.
*/
const char *sqlite3_column_database_name(sqlite3_stmt*,int);
const void *sqlite3_column_database_name16(sqlite3_stmt*,int);
const char *sqlite3_column_table_name(sqlite3_stmt*,int);
const void *sqlite3_column_table_name16(sqlite3_stmt*,int);
const char *sqlite3_column_origin_name(sqlite3_stmt*,int);
const void *sqlite3_column_origin_name16(sqlite3_stmt*,int);

/*
** The first parameter is a compiled SQL statement. If this statement
** is a SELECT statement, the Nth column of the returned result set 
** of the SELECT is a table column then the declared type of the table
** column is returned. If the Nth column of the result set is not at table
** column, then a NULL pointer is returned. The returned string is always
** UTF-8 encoded. For example, in the database schema:
**
** CREATE TABLE t1(c1 VARIANT);
**
** And the following statement compiled:
**
** SELECT c1 + 1, c1 FROM t1;
**
** Then this routine would return the string "VARIANT" for the second
** result column (i==1), and a NULL pointer for the first result column
** (i==0).
*/
const char *sqlite3_column_decltype(sqlite3_stmt *, int i);

/*
** The first parameter is a compiled SQL statement. If this statement
** is a SELECT statement, the Nth column of the returned result set 
** of the SELECT is a table column then the declared type of the table
** column is returned. If the Nth column of the result set is not at table
** column, then a NULL pointer is returned. The returned string is always
** UTF-16 encoded. For example, in the database schema:
**
** CREATE TABLE t1(c1 INTEGER);
**
** And the following statement compiled:
**
** SELECT c1 + 1, c1 FROM t1;
**
** Then this routine would return the string "INTEGER" for the second
** result column (i==1), and a NULL pointer for the first result column
** (i==0).
*/
const void *sqlite3_column_decltype16(sqlite3_stmt*,int);

/* 
** After an SQL query has been compiled with a call to either
** sqlite3_prepare() or sqlite3_prepare16(), then this function must be
** called one or more times to execute the statement.
**
** The return value will be either SQLITE_BUSY, SQLITE_DONE, 
** SQLITE_ROW, SQLITE_ERROR, or SQLITE_MISUSE.
**
** SQLITE_BUSY means that the database engine attempted to open
** a locked database and there is no busy callback registered.
** Call sqlite3_step() again to retry the open.
**
** SQLITE_DONE means that the statement has finished executing
** successfully.  sqlite3_step() should not be called again on this virtual
** machine.
**
** If the SQL statement being executed returns any data, then 
** SQLITE_ROW is returned each time a new row of data is ready
** for processing by the caller. The values may be accessed using
** the sqlite3_column_*() functions described below. sqlite3_step()
** is called again to retrieve the next row of data.
** 
** SQLITE_ERROR means that a run-time error (such as a constraint
** violation) has occurred.  sqlite3_step() should not be called again on
** the VM. More information may be found by calling sqlite3_errmsg().
**
** SQLITE_MISUSE means that the this routine was called inappropriately.
** Perhaps it was called on a virtual machine that had already been
** finalized or on one that had previously returned SQLITE_ERROR or
** SQLITE_DONE.  Or it could be the case the the same database connection
** is being used simulataneously by two or more threads.
*/
int sqlite3_step(sqlite3_stmt*);

/*
** Return the number of values in the current row of the result set.
**
** After a call to sqlite3_step() that returns SQLITE_ROW, this routine
** will return the same value as the sqlite3_column_count() function.
** After sqlite3_step() has returned an SQLITE_DONE, SQLITE_BUSY or
** error code, or before sqlite3_step() has been called on a 
** compiled SQL statement, this routine returns zero.
*/
int sqlite3_data_count(sqlite3_stmt *pStmt);

/*
** Values are stored in the database in one of the following fundamental
** types.
*/
#define SQLITE_INTEGER  1
#define SQLITE_FLOAT    2
/* #define SQLITE_TEXT  3  // See below */
#define SQLITE_BLOB     4
#define SQLITE_NULL     5

/*
** SQLite version 2 defines SQLITE_TEXT differently.  To allow both
** version 2 and version 3 to be included, undefine them both if a
** conflict is seen.  Define SQLITE3_TEXT to be the version 3 value.
*/
#ifdef SQLITE_TEXT
# undef SQLITE_TEXT
#else
# define SQLITE_TEXT     3
#endif
#define SQLITE3_TEXT     3

/*
** The next group of routines returns information about the information
** in a single column of the current result row of a query.  In every
** case the first parameter is a pointer to the SQL statement that is being
** executed (the sqlite_stmt* that was returned from sqlite3_prepare()) and
** the second argument is the index of the column for which information 
** should be returned.  iCol is zero-indexed.  The left-most column as an
** index of 0.
**
** If the SQL statement is not currently point to a valid row, or if the
** the colulmn index is out of range, the result is undefined.
**
** These routines attempt to convert the value where appropriate.  For
** example, if the internal representation is FLOAT and a text result
** is requested, sprintf() is used internally to do the conversion
** automatically.  The following table details the conversions that
** are applied:
**
**    Internal Type    Requested Type     Conversion
**    -------------    --------------    --------------------------
**       NULL             INTEGER         Result is 0
**       NULL             FLOAT           Result is 0.0
**       NULL             TEXT            Result is an empty string
**       NULL             BLOB            Result is a zero-length BLOB
**       INTEGER          FLOAT           Convert from integer to float
**       INTEGER          TEXT            ASCII rendering of the integer
**       INTEGER          BLOB            Same as for INTEGER->TEXT
**       FLOAT            INTEGER         Convert from float to integer
**       FLOAT            TEXT            ASCII rendering of the float
**       FLOAT            BLOB            Same as FLOAT->TEXT
**       TEXT             INTEGER         Use atoi()
**       TEXT             FLOAT           Use atof()
**       TEXT             BLOB            No change
**       BLOB             INTEGER         Convert to TEXT then use atoi()
**       BLOB             FLOAT           Convert to TEXT then use atof()
**       BLOB             TEXT            Add a \000 terminator if needed
**
** The following access routines are provided:
**
** _type()     Return the datatype of the result.  This is one of
**             SQLITE_INTEGER, SQLITE_FLOAT, SQLITE_TEXT, SQLITE_BLOB,
**             or SQLITE_NULL.
** _blob()     Return the value of a BLOB.
** _bytes()    Return the number of bytes in a BLOB value or the number
**             of bytes in a TEXT value represented as UTF-8.  The \000
**             terminator is included in the byte count for TEXT values.
** _bytes16()  Return the number of bytes in a BLOB value or the number
**             of bytes in a TEXT value represented as UTF-16.  The \u0000
**             terminator is included in the byte count for TEXT values.
** _double()   Return a FLOAT value.
** _int()      Return an INTEGER value in the host computer's native
**             integer representation.  This might be either a 32- or 64-bit
**             integer depending on the host.
** _int64()    Return an INTEGER value as a 64-bit signed integer.
** _text()     Return the value as UTF-8 text.
** _text16()   Return the value as UTF-16 text.
*/
const void *sqlite3_column_blob(sqlite3_stmt*, int iCol);
int sqlite3_column_bytes(sqlite3_stmt*, int iCol);
int sqlite3_column_bytes16(sqlite3_stmt*, int iCol);
double sqlite3_column_double(sqlite3_stmt*, int iCol);
int sqlite3_column_int(sqlite3_stmt*, int iCol);
sqlite_int64 sqlite3_column_int64(sqlite3_stmt*, int iCol);
const unsigned char *sqlite3_column_text(sqlite3_stmt*, int iCol);
const void *sqlite3_column_text16(sqlite3_stmt*, int iCol);
int sqlite3_column_type(sqlite3_stmt*, int iCol);
int sqlite3_column_numeric_type(sqlite3_stmt*, int iCol);
sqlite3_value *sqlite3_column_value(sqlite3_stmt*, int iCol);

/*
** The sqlite3_finalize() function is called to delete a compiled
** SQL statement obtained by a previous call to sqlite3_prepare()
** or sqlite3_prepare16(). If the statement was executed successfully, or
** not executed at all, then SQLITE_OK is returned. If execution of the
** statement failed then an error code is returned. 
**
** This routine can be called at any point during the execution of the
** virtual machine.  If the virtual machine has not completed execution
** when this routine is called, that is like encountering an error or
** an interrupt.  (See sqlite3_interrupt().)  Incomplete updates may be
** rolled back and transactions cancelled,  depending on the circumstances,
** and the result code returned will be SQLITE_ABORT.
*/
int sqlite3_finalize(sqlite3_stmt *pStmt);

/*
** The sqlite3_reset() function is called to reset a compiled SQL
** statement obtained by a previous call to sqlite3_prepare() or
** sqlite3_prepare16() back to it's initial state, ready to be re-executed.
** Any SQL statement variables that had values bound to them using
** the sqlite3_bind_*() API retain their values.
*/
int sqlite3_reset(sqlite3_stmt *pStmt);

/*
** The following two functions are used to add user functions or aggregates
** implemented in C to the SQL langauge interpreted by SQLite. The
** difference only between the two is that the second parameter, the
** name of the (scalar) function or aggregate, is encoded in UTF-8 for
** sqlite3_create_function() and UTF-16 for sqlite3_create_function16().
**
** The first argument is the database handle that the new function or
** aggregate is to be added to. If a single program uses more than one
** database handle internally, then user functions or aggregates must 
** be added individually to each database handle with which they will be
** used.
**
** The third parameter is the number of arguments that the function or
** aggregate takes. If this parameter is negative, then the function or
** aggregate may take any number of arguments.
**
** The fourth parameter is one of SQLITE_UTF* values defined below,
** indicating the encoding that the function is most likely to handle
** values in.  This does not change the behaviour of the programming
** interface. However, if two versions of the same function are registered
** with different encoding values, SQLite invokes the version likely to
** minimize conversions between text encodings.
**
** The seventh, eighth and ninth parameters, xFunc, xStep and xFinal, are
** pointers to user implemented C functions that implement the user
** function or aggregate. A scalar function requires an implementation of
** the xFunc callback only, NULL pointers should be passed as the xStep
** and xFinal parameters. An aggregate function requires an implementation
** of xStep and xFinal, but NULL should be passed for xFunc. To delete an
** existing user function or aggregate, pass NULL for all three function
** callback. Specifying an inconstent set of callback values, such as an
** xFunc and an xFinal, or an xStep but no xFinal, SQLITE_ERROR is
** returned.
*/
int sqlite3_create_function(
  sqlite3 *,
  const char *zFunctionName,
  int nArg,
  int eTextRep,
  void*,
  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  void (*xFinal)(sqlite3_context*)
);
int sqlite3_create_function16(
  sqlite3*,
  const void *zFunctionName,
  int nArg,
  int eTextRep,
  void*,
  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  void (*xFinal)(sqlite3_context*)
);

/*
** This function is deprecated.  Do not use it.  It continues to exist
** so as not to break legacy code.  But new code should avoid using it.
*/
int sqlite3_aggregate_count(sqlite3_context*);

/*
** The next group of routines returns information about parameters to
** a user-defined function.  Function implementations use these routines
** to access their parameters.  These routines are the same as the
** sqlite3_column_* routines except that these routines take a single
** sqlite3_value* pointer instead of an sqlite3_stmt* and an integer
** column number.
*/
const void *sqlite3_value_blob(sqlite3_value*);
int sqlite3_value_bytes(sqlite3_value*);
int sqlite3_value_bytes16(sqlite3_value*);
double sqlite3_value_double(sqlite3_value*);
int sqlite3_value_int(sqlite3_value*);
sqlite_int64 sqlite3_value_int64(sqlite3_value*);
const unsigned char *sqlite3_value_text(sqlite3_value*);
const void *sqlite3_value_text16(sqlite3_value*);
const void *sqlite3_value_text16le(sqlite3_value*);
const void *sqlite3_value_text16be(sqlite3_value*);
int sqlite3_value_type(sqlite3_value*);
int sqlite3_value_numeric_type(sqlite3_value*);

/*
** Aggregate functions use the following routine to allocate
** a structure for storing their state.  The first time this routine
** is called for a particular aggregate, a new structure of size nBytes
** is allocated, zeroed, and returned.  On subsequent calls (for the
** same aggregate instance) the same buffer is returned.  The implementation
** of the aggregate can use the returned buffer to accumulate data.
**
** The buffer allocated is freed automatically by SQLite.
*/
void *sqlite3_aggregate_context(sqlite3_context*, int nBytes);

/*
** The pUserData parameter to the sqlite3_create_function()
** routine used to register user functions is available to
** the implementation of the function using this call.
*/
void *sqlite3_user_data(sqlite3_context*);

/*
** The following two functions may be used by scalar user functions to
** associate meta-data with argument values. If the same value is passed to
** multiple invocations of the user-function during query execution, under
** some circumstances the associated meta-data may be preserved. This may
** be used, for example, to add a regular-expression matching scalar
** function. The compiled version of the regular expression is stored as
** meta-data associated with the SQL value passed as the regular expression
** pattern.
**
** Calling sqlite3_get_auxdata() returns a pointer to the meta data
** associated with the Nth argument value to the current user function
** call, where N is the second parameter. If no meta-data has been set for
** that value, then a NULL pointer is returned.
**
** The sqlite3_set_auxdata() is used to associate meta data with a user
** function argument. The third parameter is a pointer to the meta data
** to be associated with the Nth user function argument value. The fourth
** parameter specifies a 'delete function' that will be called on the meta
** data pointer to release it when it is no longer required. If the delete
** function pointer is NULL, it is not invoked.
**
** In practice, meta-data is preserved between function calls for
** expressions that are constant at compile time. This includes literal
** values and SQL variables.
*/
void *sqlite3_get_auxdata(sqlite3_context*, int);
void sqlite3_set_auxdata(sqlite3_context*, int, void*, void (*)(void*));


/*
** These are special value for the destructor that is passed in as the
** final argument to routines like sqlite3_result_blob().  If the destructor
** argument is SQLITE_STATIC, it means that the content pointer is constant
** and will never change.  It does not need to be destroyed.  The 
** SQLITE_TRANSIENT value means that the content will likely change in
** the near future and that SQLite should make its own private copy of
** the content before returning.
**
** The typedef is necessary to work around problems in certain
** C++ compilers.  See ticket #2191.
*/
typedef void (*sqlite3_destructor_type)(void*);
#define SQLITE_STATIC      ((sqlite3_destructor_type)0)
#define SQLITE_TRANSIENT   ((sqlite3_destructor_type)-1)

/*
** User-defined functions invoke the following routines in order to
** set their return value.
*/
void sqlite3_result_blob(sqlite3_context*, const void*, int, void(*)(void*));
void sqlite3_result_double(sqlite3_context*, double);
void sqlite3_result_error(sqlite3_context*, const char*, int);
void sqlite3_result_error16(sqlite3_context*, const void*, int);
void sqlite3_result_int(sqlite3_context*, int);
void sqlite3_result_int64(sqlite3_context*, sqlite_int64);
void sqlite3_result_null(sqlite3_context*);
void sqlite3_result_text(sqlite3_context*, const char*, int, void(*)(void*));
void sqlite3_result_text16(sqlite3_context*, const void*, int, void(*)(void*));
void sqlite3_result_text16le(sqlite3_context*, const void*, int,void(*)(void*));
void sqlite3_result_text16be(sqlite3_context*, const void*, int,void(*)(void*));
void sqlite3_result_value(sqlite3_context*, sqlite3_value*);

/*
** These are the allowed values for the eTextRep argument to
** sqlite3_create_collation and sqlite3_create_function.
*/
#define SQLITE_UTF8           1
#define SQLITE_UTF16LE        2
#define SQLITE_UTF16BE        3
#define SQLITE_UTF16          4    /* Use native byte order */
#define SQLITE_ANY            5    /* sqlite3_create_function only */
#define SQLITE_UTF16_ALIGNED  8    /* sqlite3_create_collation only */

/*
** These two functions are used to add new collation sequences to the
** sqlite3 handle specified as the first argument. 
**
** The name of the new collation sequence is specified as a UTF-8 string
** for sqlite3_create_collation() and a UTF-16 string for
** sqlite3_create_collation16(). In both cases the name is passed as the
** second function argument.
**
** The third argument must be one of the constants SQLITE_UTF8,
** SQLITE_UTF16LE or SQLITE_UTF16BE, indicating that the user-supplied
** routine expects to be passed pointers to strings encoded using UTF-8,
** UTF-16 little-endian or UTF-16 big-endian respectively.
**
** A pointer to the user supplied routine must be passed as the fifth
** argument. If it is NULL, this is the same as deleting the collation
** sequence (so that SQLite cannot call it anymore). Each time the user
** supplied function is invoked, it is passed a copy of the void* passed as
** the fourth argument to sqlite3_create_collation() or
** sqlite3_create_collation16() as its first parameter.
**
** The remaining arguments to the user-supplied routine are two strings,
** each represented by a [length, data] pair and encoded in the encoding
** that was passed as the third argument when the collation sequence was
** registered. The user routine should return negative, zero or positive if
** the first string is less than, equal to, or greater than the second
** string. i.e. (STRING1 - STRING2).
*/
int sqlite3_create_collation(
  sqlite3*, 
  const char *zName, 
  int eTextRep, 
  void*,
  int(*xCompare)(void*,int,const void*,int,const void*)
);
int sqlite3_create_collation16(
  sqlite3*, 
  const char *zName, 
  int eTextRep, 
  void*,
  int(*xCompare)(void*,int,const void*,int,const void*)
);

/*
** To avoid having to register all collation sequences before a database
** can be used, a single callback function may be registered with the
** database handle to be called whenever an undefined collation sequence is
** required.
**
** If the function is registered using the sqlite3_collation_needed() API,
** then it is passed the names of undefined collation sequences as strings
** encoded in UTF-8. If sqlite3_collation_needed16() is used, the names
** are passed as UTF-16 in machine native byte order. A call to either
** function replaces any existing callback.
**
** When the user-function is invoked, the first argument passed is a copy
** of the second argument to sqlite3_collation_needed() or
** sqlite3_collation_needed16(). The second argument is the database
** handle. The third argument is one of SQLITE_UTF8, SQLITE_UTF16BE or
** SQLITE_UTF16LE, indicating the most desirable form of the collation
** sequence function required. The fourth parameter is the name of the
** required collation sequence.
**
** The collation sequence is returned to SQLite by a collation-needed
** callback using the sqlite3_create_collation() or
** sqlite3_create_collation16() APIs, described above.
*/
int sqlite3_collation_needed(
  sqlite3*, 
  void*, 
  void(*)(void*,sqlite3*,int eTextRep,const char*)
);
int sqlite3_collation_needed16(
  sqlite3*, 
  void*,
  void(*)(void*,sqlite3*,int eTextRep,const void*)
);

/*
** Specify the key for an encrypted database.  This routine should be
** called right after sqlite3_open().
**
** The code to implement this API is not available in the public release
** of SQLite.
*/
int sqlite3_key(
  sqlite3 *db,                   /* Database to be rekeyed */
  const void *pKey, int nKey     /* The key */
);

/*
** Change the key on an open database.  If the current database is not
** encrypted, this routine will encrypt it.  If pNew==0 or nNew==0, the
** database is decrypted.
**
** The code to implement this API is not available in the public release
** of SQLite.
*/
int sqlite3_rekey(
  sqlite3 *db,                   /* Database to be rekeyed */
  const void *pKey, int nKey     /* The new key */
);

/*
** Sleep for a little while. The second parameter is the number of
** miliseconds to sleep for. 
**
** If the operating system does not support sleep requests with 
** milisecond time resolution, then the time will be rounded up to 
** the nearest second. The number of miliseconds of sleep actually 
** requested from the operating system is returned.
*/
int sqlite3_sleep(int);

/*
** Return TRUE (non-zero) if the statement supplied as an argument needs
** to be recompiled.  A statement needs to be recompiled whenever the
** execution environment changes in a way that would alter the program
** that sqlite3_prepare() generates.  For example, if new functions or
** collating sequences are registered or if an authorizer function is
** added or changed.
**
*/
int sqlite3_expired(sqlite3_stmt*);

/*
** Move all bindings from the first prepared statement over to the second.
** This routine is useful, for example, if the first prepared statement
** fails with an SQLITE_SCHEMA error.  The same SQL can be prepared into
** the second prepared statement then all of the bindings transfered over
** to the second statement before the first statement is finalized.
*/
int sqlite3_transfer_bindings(sqlite3_stmt*, sqlite3_stmt*);

/*
** If the following global variable is made to point to a
** string which is the name of a directory, then all temporary files
** created by SQLite will be placed in that directory.  If this variable
** is NULL pointer, then SQLite does a search for an appropriate temporary
** file directory.
**
** Once sqlite3_open() has been called, changing this variable will invalidate
** the current temporary database, if any.
*/
extern char *sqlite3_temp_directory;

/*
** This function is called to recover from a malloc() failure that occured
** within the SQLite library. Normally, after a single malloc() fails the 
** library refuses to function (all major calls return SQLITE_NOMEM).
** This function restores the library state so that it can be used again.
**
** All existing statements (sqlite3_stmt pointers) must be finalized or
** reset before this call is made. Otherwise, SQLITE_BUSY is returned.
** If any in-memory databases are in use, either as a main or TEMP
** database, SQLITE_ERROR is returned. In either of these cases, the 
** library is not reset and remains unusable.
**
** This function is *not* threadsafe. Calling this from within a threaded
** application when threads other than the caller have used SQLite is
** dangerous and will almost certainly result in malfunctions.
**
** This functionality can be omitted from a build by defining the 
** SQLITE_OMIT_GLOBALRECOVER at compile time.
*/
int sqlite3_global_recover(void);

/*
** Test to see whether or not the database connection is in autocommit
** mode.  Return TRUE if it is and FALSE if not.  Autocommit mode is on
** by default.  Autocommit is disabled by a BEGIN statement and reenabled
** by the next COMMIT or ROLLBACK.
*/
int sqlite3_get_autocommit(sqlite3*);

/*
** Return the sqlite3* database handle to which the prepared statement given
** in the argument belongs.  This is the same database handle that was
** the first argument to the sqlite3_prepare() that was used to create
** the statement in the first place.
*/
sqlite3 *sqlite3_db_handle(sqlite3_stmt*);

/*
** Register a callback function with the database connection identified by the 
** first argument to be invoked whenever a row is updated, inserted or deleted.
** Any callback set by a previous call to this function for the same 
** database connection is overridden.
**
** The second argument is a pointer to the function to invoke when a 
** row is updated, inserted or deleted. The first argument to the callback is
** a copy of the third argument to sqlite3_update_hook. The second callback 
** argument is one of SQLITE_INSERT, SQLITE_DELETE or SQLITE_UPDATE, depending
** on the operation that caused the callback to be invoked. The third and 
** fourth arguments to the callback contain pointers to the database and 
** table name containing the affected row. The final callback parameter is 
** the rowid of the row. In the case of an update, this is the rowid after 
** the update takes place.
**
** The update hook is not invoked when internal system tables are
** modified (i.e. sqlite_master and sqlite_sequence).
**
** If another function was previously registered, its pArg value is returned.
** Otherwise NULL is returned.
*/
void *sqlite3_update_hook(
  sqlite3*, 
  void(*)(void *,int ,char const *,char const *,sqlite_int64),
  void*
);

/*
** Register a callback to be invoked whenever a transaction is rolled
** back. 
**
** The new callback function overrides any existing rollback-hook
** callback. If there was an existing callback, then it's pArg value 
** (the third argument to sqlite3_rollback_hook() when it was registered) 
** is returned. Otherwise, NULL is returned.
**
** For the purposes of this API, a transaction is said to have been 
** rolled back if an explicit "ROLLBACK" statement is executed, or
** an error or constraint causes an implicit rollback to occur. The 
** callback is not invoked if a transaction is automatically rolled
** back because the database connection is closed.
*/
void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);

/*
** This function is only available if the library is compiled without
** the SQLITE_OMIT_SHARED_CACHE macro defined. It is used to enable or
** disable (if the argument is true or false, respectively) the 
** "shared pager" feature.
*/
int sqlite3_enable_shared_cache(int);

/*
** Attempt to free N bytes of heap memory by deallocating non-essential
** memory allocations held by the database library (example: memory 
** used to cache database pages to improve performance).
**
** This function is not a part of standard builds.  It is only created
** if SQLite is compiled with the SQLITE_ENABLE_MEMORY_MANAGEMENT macro.
*/
int sqlite3_release_memory(int);

/*
** Place a "soft" limit on the amount of heap memory that may be allocated by
** SQLite within the current thread. If an internal allocation is requested 
** that would exceed the specified limit, sqlite3_release_memory() is invoked
** one or more times to free up some space before the allocation is made.
**
** The limit is called "soft", because if sqlite3_release_memory() cannot free
** sufficient memory to prevent the limit from being exceeded, the memory is
** allocated anyway and the current operation proceeds.
**
** This function is only available if the library was compiled with the 
** SQLITE_ENABLE_MEMORY_MANAGEMENT option set.
** memory-management has been enabled.
*/
void sqlite3_soft_heap_limit(int);

/*
** This routine makes sure that all thread-local storage has been
** deallocated for the current thread.
**
** This routine is not technically necessary.  All thread-local storage
** will be automatically deallocated once memory-management and
** shared-cache are disabled and the soft heap limit has been set
** to zero.  This routine is provided as a convenience for users who
** want to make absolutely sure they have not forgotten something
** prior to killing off a thread.
*/
void sqlite3_thread_cleanup(void);

/*
** Return meta information about a specific column of a specific database
** table accessible using the connection handle passed as the first function 
** argument.
**
** The column is identified by the second, third and fourth parameters to 
** this function. The second parameter is either the name of the database
** (i.e. "main", "temp" or an attached database) containing the specified
** table or NULL. If it is NULL, then all attached databases are searched
** for the table using the same algorithm as the database engine uses to 
** resolve unqualified table references.
**
** The third and fourth parameters to this function are the table and column 
** name of the desired column, respectively. Neither of these parameters 
** may be NULL.
**
** Meta information is returned by writing to the memory locations passed as
** the 5th and subsequent parameters to this function. Any of these 
** arguments may be NULL, in which case the corresponding element of meta 
** information is ommitted.
**
** Parameter     Output Type      Description
** -----------------------------------
**
**   5th         const char*      Data type
**   6th         const char*      Name of the default collation sequence 
**   7th         int              True if the column has a NOT NULL constraint
**   8th         int              True if the column is part of the PRIMARY KEY
**   9th         int              True if the column is AUTOINCREMENT
**
**
** The memory pointed to by the character pointers returned for the 
** declaration type and collation sequence is valid only until the next 
** call to any sqlite API function.
**
** If the specified table is actually a view, then an error is returned.
**
** If the specified column is "rowid", "oid" or "_rowid_" and an 
** INTEGER PRIMARY KEY column has been explicitly declared, then the output 
** parameters are set for the explicitly declared column. If there is no
** explicitly declared IPK column, then the output parameters are set as 
** follows:
**
**     data type: "INTEGER"
**     collation sequence: "BINARY"
**     not null: 0
**     primary key: 1
**     auto increment: 0
**
** This function may load one or more schemas from database files. If an
** error occurs during this process, or if the requested table or column
** cannot be found, an SQLITE error code is returned and an error message
** left in the database handle (to be retrieved using sqlite3_errmsg()).
**
** This API is only available if the library was compiled with the
** SQLITE_ENABLE_COLUMN_METADATA preprocessor symbol defined.
*/
int sqlite3_table_column_metadata(
  sqlite3 *db,                /* Connection handle */
  const char *zDbName,        /* Database name or NULL */
  const char *zTableName,     /* Table name */
  const char *zColumnName,    /* Column name */
  char const **pzDataType,    /* OUTPUT: Declared data type */
  char const **pzCollSeq,     /* OUTPUT: Collation sequence name */
  int *pNotNull,              /* OUTPUT: True if NOT NULL constraint exists */
  int *pPrimaryKey,           /* OUTPUT: True if column part of PK */
  int *pAutoinc               /* OUTPUT: True if colums is auto-increment */
);

/*
****** EXPERIMENTAL - subject to change without notice **************
**
** Attempt to load an SQLite extension library contained in the file
** zFile.  The entry point is zProc.  zProc may be 0 in which case the
** name of the entry point defaults to "sqlite3_extension_init".
**
** Return SQLITE_OK on success and SQLITE_ERROR if something goes wrong.
**
** If an error occurs and pzErrMsg is not 0, then fill *pzErrMsg with 
** error message text.  The calling function should free this memory
** by calling sqlite3_free().
**
** Extension loading must be enabled using sqlite3_enable_load_extension()
** prior to calling this API or an error will be returned.
**
****** EXPERIMENTAL - subject to change without notice **************
*/
int sqlite3_load_extension(
  sqlite3 *db,          /* Load the extension into this database connection */
  const char *zFile,    /* Name of the shared library containing extension */
  const char *zProc,    /* Entry point.  Derived from zFile if 0 */
  char **pzErrMsg       /* Put error message here if not 0 */
);

/*
** So as not to open security holes in older applications that are
** unprepared to deal with extension load, and as a means of disabling
** extension loading while executing user-entered SQL, the following
** API is provided to turn the extension loading mechanism on and
** off.  It is off by default.  See ticket #1863.
**
** Call this routine with onoff==1 to turn extension loading on
** and call it with onoff==0 to turn it back off again.
*/
int sqlite3_enable_load_extension(sqlite3 *db, int onoff);

/*
****** EXPERIMENTAL - subject to change without notice **************
**
** Register an extension entry point that is automatically invoked
** whenever a new database connection is opened.
**
** This API can be invoked at program startup in order to register
** one or more statically linked extensions that will be available
** to all new database connections.
**
** Duplicate extensions are detected so calling this routine multiple
** times with the same extension is harmless.
**
** This routine stores a pointer to the extension in an array
** that is obtained from malloc().  If you run a memory leak
** checker on your program and it reports a leak because of this
** array, then invoke sqlite3_automatic_extension_reset() prior
** to shutdown to free the memory.
**
** Automatic extensions apply across all threads.
*/
int sqlite3_auto_extension(void *xEntryPoint);


/*
****** EXPERIMENTAL - subject to change without notice **************
**
** Disable all previously registered automatic extensions.  This
** routine undoes the effect of all prior sqlite3_automatic_extension()
** calls.
**
** This call disabled automatic extensions in all threads.
*/
void sqlite3_reset_auto_extension(void);


/*
****** EXPERIMENTAL - subject to change without notice **************
**
** The interface to the virtual-table mechanism is currently considered
** to be experimental.  The interface might change in incompatible ways.
** If this is a problem for you, do not use the interface at this time.
**
** When the virtual-table mechanism stablizes, we will declare the
** interface fixed, support it indefinitely, and remove this comment.
*/

/*
** Structures used by the virtual table interface
*/
typedef struct sqlite3_vtab sqlite3_vtab;
typedef struct sqlite3_index_info sqlite3_index_info;
typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor;
typedef struct sqlite3_module sqlite3_module;

/*
** A module is a class of virtual tables.  Each module is defined
** by an instance of the following structure.  This structure consists
** mostly of methods for the module.
*/
struct sqlite3_module {
  int iVersion;
  int (*xCreate)(sqlite3*, void *pAux,
               int argc, const char *const*argv,
               sqlite3_vtab **ppVTab, char**);
  int (*xConnect)(sqlite3*, void *pAux,
               int argc, const char *const*argv,
               sqlite3_vtab **ppVTab, char**);
  int (*xBestIndex)(sqlite3_vtab *pVTab, sqlite3_index_info*);
  int (*xDisconnect)(sqlite3_vtab *pVTab);
  int (*xDestroy)(sqlite3_vtab *pVTab);
  int (*xOpen)(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor);
  int (*xClose)(sqlite3_vtab_cursor*);
  int (*xFilter)(sqlite3_vtab_cursor*, int idxNum, const char *idxStr,
                int argc, sqlite3_value **argv);
  int (*xNext)(sqlite3_vtab_cursor*);
  int (*xEof)(sqlite3_vtab_cursor*);
  int (*xColumn)(sqlite3_vtab_cursor*, sqlite3_context*, int);
  int (*xRowid)(sqlite3_vtab_cursor*, sqlite_int64 *pRowid);
  int (*xUpdate)(sqlite3_vtab *, int, sqlite3_value **, sqlite_int64 *);
  int (*xBegin)(sqlite3_vtab *pVTab);
  int (*xSync)(sqlite3_vtab *pVTab);
  int (*xCommit)(sqlite3_vtab *pVTab);
  int (*xRollback)(sqlite3_vtab *pVTab);
  int (*xFindFunction)(sqlite3_vtab *pVtab, int nArg, const char *zName,
                       void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
                       void **ppArg);
};

/*
** The sqlite3_index_info structure and its substructures is used to
** pass information into and receive the reply from the xBestIndex
** method of an sqlite3_module.  The fields under **Inputs** are the
** inputs to xBestIndex and are read-only.  xBestIndex inserts its
** results into the **Outputs** fields.
**
** The aConstraint[] array records WHERE clause constraints of the
** form:
**
**         column OP expr
**
** Where OP is =, <, <=, >, or >=.  The particular operator is stored
** in aConstraint[].op.  The index of the column is stored in 
** aConstraint[].iColumn.  aConstraint[].usable is TRUE if the
** expr on the right-hand side can be evaluated (and thus the constraint
** is usable) and false if it cannot.
**
** The optimizer automatically inverts terms of the form "expr OP column"
** and makes other simplificatinos to the WHERE clause in an attempt to
** get as many WHERE clause terms into the form shown above as possible.
** The aConstraint[] array only reports WHERE clause terms in the correct
** form that refer to the particular virtual table being queried.
**
** Information about the ORDER BY clause is stored in aOrderBy[].
** Each term of aOrderBy records a column of the ORDER BY clause.
**
** The xBestIndex method must fill aConstraintUsage[] with information
** about what parameters to pass to xFilter.  If argvIndex>0 then
** the right-hand side of the corresponding aConstraint[] is evaluated
** and becomes the argvIndex-th entry in argv.  If aConstraintUsage[].omit
** is true, then the constraint is assumed to be fully handled by the
** virtual table and is not checked again by SQLite.
**
** The idxNum and idxPtr values are recorded and passed into xFilter.
** sqlite3_free() is used to free idxPtr if needToFreeIdxPtr is true.
**
** The orderByConsumed means that output from xFilter will occur in
** the correct order to satisfy the ORDER BY clause so that no separate
** sorting step is required.
**
** The estimatedCost value is an estimate of the cost of doing the
** particular lookup.  A full scan of a table with N entries should have
** a cost of N.  A binary search of a table of N entries should have a
** cost of approximately log(N).
*/
struct sqlite3_index_info {
  /* Inputs */
  const int nConstraint;     /* Number of entries in aConstraint */
  const struct sqlite3_index_constraint {
     int iColumn;              /* Column on left-hand side of constraint */
     unsigned char op;         /* Constraint operator */
     unsigned char usable;     /* True if this constraint is usable */
     int iTermOffset;          /* Used internally - xBestIndex should ignore */
  } *const aConstraint;      /* Table of WHERE clause constraints */
  const int nOrderBy;        /* Number of terms in the ORDER BY clause */
  const struct sqlite3_index_orderby {
     int iColumn;              /* Column number */
     unsigned char desc;       /* True for DESC.  False for ASC. */
  } *const aOrderBy;         /* The ORDER BY clause */

  /* Outputs */
  struct sqlite3_index_constraint_usage {
    int argvIndex;           /* if >0, constraint is part of argv to xFilter */
    unsigned char omit;      /* Do not code a test for this constraint */
  } *const aConstraintUsage;
  int idxNum;                /* Number used to identify the index */
  char *idxStr;              /* String, possibly obtained from sqlite3_malloc */
  int needToFreeIdxStr;      /* Free idxStr using sqlite3_free() if true */
  int orderByConsumed;       /* True if output is already ordered */
  double estimatedCost;      /* Estimated cost of using this index */
};
#define SQLITE_INDEX_CONSTRAINT_EQ    2
#define SQLITE_INDEX_CONSTRAINT_GT    4
#define SQLITE_INDEX_CONSTRAINT_LE    8
#define SQLITE_INDEX_CONSTRAINT_LT    16
#define SQLITE_INDEX_CONSTRAINT_GE    32
#define SQLITE_INDEX_CONSTRAINT_MATCH 64

/*
** This routine is used to register a new module name with an SQLite
** connection.  Module names must be registered before creating new
** virtual tables on the module, or before using preexisting virtual
** tables of the module.
*/
int sqlite3_create_module(
  sqlite3 *db,               /* SQLite connection to register module with */
  const char *zName,         /* Name of the module */
  const sqlite3_module *,    /* Methods for the module */
  void *                     /* Client data for xCreate/xConnect */
);

/*
** Every module implementation uses a subclass of the following structure
** to describe a particular instance of the module.  Each subclass will
** be taylored to the specific needs of the module implementation.   The
** purpose of this superclass is to define certain fields that are common
** to all module implementations.
**
** Virtual tables methods can set an error message by assigning a
** string obtained from sqlite3_mprintf() to zErrMsg.  The method should
** take care that any prior string is freed by a call to sqlite3_free()
** prior to assigning a new string to zErrMsg.  After the error message
** is delivered up to the client application, the string will be automatically
** freed by sqlite3_free() and the zErrMsg field will be zeroed.  Note
** that sqlite3_mprintf() and sqlite3_free() are used on the zErrMsg field
** since virtual tables are commonly implemented in loadable extensions which
** do not have access to sqlite3MPrintf() or sqlite3Free().
*/
struct sqlite3_vtab {
  const sqlite3_module *pModule;  /* The module for this virtual table */
  int nRef;                       /* Used internally */
  char *zErrMsg;                  /* Error message from sqlite3_mprintf() */
  /* Virtual table implementations will typically add additional fields */
};

/* Every module implementation uses a subclass of the following structure
** to describe cursors that point into the virtual table and are used
** to loop through the virtual table.  Cursors are created using the
** xOpen method of the module.  Each module implementation will define
** the content of a cursor structure to suit its own needs.
**
** This superclass exists in order to define fields of the cursor that
** are common to all implementations.
*/
struct sqlite3_vtab_cursor {
  sqlite3_vtab *pVtab;      /* Virtual table of this cursor */
  /* Virtual table implementations will typically add additional fields */
};

/*
** The xCreate and xConnect methods of a module use the following API
** to declare the format (the names and datatypes of the columns) of
** the virtual tables they implement.
*/
int sqlite3_declare_vtab(sqlite3*, const char *zCreateTable);

/*
** Virtual tables can provide alternative implementations of functions
** using the xFindFunction method.  But global versions of those functions
** must exist in order to be overloaded.
**
** This API makes sure a global version of a function with a particular
** name and number of parameters exists.  If no such function exists
** before this API is called, a new function is created.  The implementation
** of the new function always causes an exception to be thrown.  So
** the new function is not good for anything by itself.  Its only
** purpose is to be a place-holder function that can be overloaded
** by virtual tables.
**
** This API should be considered part of the virtual table interface,
** which is experimental and subject to change.
*/
int sqlite3_overload_function(sqlite3*, const char *zFuncName, int nArg);

/*
** The interface to the virtual-table mechanism defined above (back up
** to a comment remarkably similar to this one) is currently considered
** to be experimental.  The interface might change in incompatible ways.
** If this is a problem for you, do not use the interface at this time.
**
** When the virtual-table mechanism stablizes, we will declare the
** interface fixed, support it indefinitely, and remove this comment.
**
****** EXPERIMENTAL - subject to change without notice **************
*/

/*
** Undo the hack that converts floating point types to integer for
** builds on processors without floating point support.
*/
#ifdef SQLITE_OMIT_FLOATING_POINT
# undef double
#endif

#ifdef __cplusplus
}  /* End of the 'extern "C"' block */
#endif
#endif

Added SQLite.Interop/FTS1/sqlite3ext.h.





































































































































































































































































































































































































































































































































































































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/*
** 2006 June 7
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the SQLite interface for use by
** shared libraries that want to be imported as extensions into
** an SQLite instance.  Shared libraries that intend to be loaded
** as extensions by SQLite should #include this file instead of 
** sqlite3.h.
**
** @(#) $Id: sqlite3ext.h,v 1.1 2007/04/22 23:26:33 rmsimpson Exp $
*/
#ifndef _SQLITE3EXT_H_
#define _SQLITE3EXT_H_
#include "sqlite3.h"

typedef struct sqlite3_api_routines sqlite3_api_routines;

/*
** The following structure hold pointers to all of the SQLite API
** routines.
*/
struct sqlite3_api_routines {
  void * (*aggregate_context)(sqlite3_context*,int nBytes);
  int  (*aggregate_count)(sqlite3_context*);
  int  (*bind_blob)(sqlite3_stmt*,int,const void*,int n,void(*)(void*));
  int  (*bind_double)(sqlite3_stmt*,int,double);
  int  (*bind_int)(sqlite3_stmt*,int,int);
  int  (*bind_int64)(sqlite3_stmt*,int,sqlite_int64);
  int  (*bind_null)(sqlite3_stmt*,int);
  int  (*bind_parameter_count)(sqlite3_stmt*);
  int  (*bind_parameter_index)(sqlite3_stmt*,const char*zName);
  const char * (*bind_parameter_name)(sqlite3_stmt*,int);
  int  (*bind_text)(sqlite3_stmt*,int,const char*,int n,void(*)(void*));
  int  (*bind_text16)(sqlite3_stmt*,int,const void*,int,void(*)(void*));
  int  (*bind_value)(sqlite3_stmt*,int,const sqlite3_value*);
  int  (*busy_handler)(sqlite3*,int(*)(void*,int),void*);
  int  (*busy_timeout)(sqlite3*,int ms);
  int  (*changes)(sqlite3*);
  int  (*close)(sqlite3*);
  int  (*collation_needed)(sqlite3*,void*,void(*)(void*,sqlite3*,int eTextRep,const char*));
  int  (*collation_needed16)(sqlite3*,void*,void(*)(void*,sqlite3*,int eTextRep,const void*));
  const void * (*column_blob)(sqlite3_stmt*,int iCol);
  int  (*column_bytes)(sqlite3_stmt*,int iCol);
  int  (*column_bytes16)(sqlite3_stmt*,int iCol);
  int  (*column_count)(sqlite3_stmt*pStmt);
  const char * (*column_database_name)(sqlite3_stmt*,int);
  const void * (*column_database_name16)(sqlite3_stmt*,int);
  const char * (*column_decltype)(sqlite3_stmt*,int i);
  const void * (*column_decltype16)(sqlite3_stmt*,int);
  double  (*column_double)(sqlite3_stmt*,int iCol);
  int  (*column_int)(sqlite3_stmt*,int iCol);
  sqlite_int64  (*column_int64)(sqlite3_stmt*,int iCol);
  const char * (*column_name)(sqlite3_stmt*,int);
  const void * (*column_name16)(sqlite3_stmt*,int);
  const char * (*column_origin_name)(sqlite3_stmt*,int);
  const void * (*column_origin_name16)(sqlite3_stmt*,int);
  const char * (*column_table_name)(sqlite3_stmt*,int);
  const void * (*column_table_name16)(sqlite3_stmt*,int);
  const unsigned char * (*column_text)(sqlite3_stmt*,int iCol);
  const void * (*column_text16)(sqlite3_stmt*,int iCol);
  int  (*column_type)(sqlite3_stmt*,int iCol);
  sqlite3_value* (*column_value)(sqlite3_stmt*,int iCol);
  void * (*commit_hook)(sqlite3*,int(*)(void*),void*);
  int  (*complete)(const char*sql);
  int  (*complete16)(const void*sql);
  int  (*create_collation)(sqlite3*,const char*,int,void*,int(*)(void*,int,const void*,int,const void*));
  int  (*create_collation16)(sqlite3*,const char*,int,void*,int(*)(void*,int,const void*,int,const void*));
  int  (*create_function)(sqlite3*,const char*,int,int,void*,void (*xFunc)(sqlite3_context*,int,sqlite3_value**),void (*xStep)(sqlite3_context*,int,sqlite3_value**),void (*xFinal)(sqlite3_context*));
  int  (*create_function16)(sqlite3*,const void*,int,int,void*,void (*xFunc)(sqlite3_context*,int,sqlite3_value**),void (*xStep)(sqlite3_context*,int,sqlite3_value**),void (*xFinal)(sqlite3_context*));
  int (*create_module)(sqlite3*,const char*,const sqlite3_module*,void*);
  int  (*data_count)(sqlite3_stmt*pStmt);
  sqlite3 * (*db_handle)(sqlite3_stmt*);
  int (*declare_vtab)(sqlite3*,const char*);
  int  (*enable_shared_cache)(int);
  int  (*errcode)(sqlite3*db);
  const char * (*errmsg)(sqlite3*);
  const void * (*errmsg16)(sqlite3*);
  int  (*exec)(sqlite3*,const char*,sqlite3_callback,void*,char**);
  int  (*expired)(sqlite3_stmt*);
  int  (*finalize)(sqlite3_stmt*pStmt);
  void  (*free)(void*);
  void  (*free_table)(char**result);
  int  (*get_autocommit)(sqlite3*);
  void * (*get_auxdata)(sqlite3_context*,int);
  int  (*get_table)(sqlite3*,const char*,char***,int*,int*,char**);
  int  (*global_recover)(void);
  void  (*interruptx)(sqlite3*);
  sqlite_int64  (*last_insert_rowid)(sqlite3*);
  const char * (*libversion)(void);
  int  (*libversion_number)(void);
  void *(*malloc)(int);
  char * (*mprintf)(const char*,...);
  int  (*open)(const char*,sqlite3**);
  int  (*open16)(const void*,sqlite3**);
  int  (*prepare)(sqlite3*,const char*,int,sqlite3_stmt**,const char**);
  int  (*prepare16)(sqlite3*,const void*,int,sqlite3_stmt**,const void**);
  void * (*profile)(sqlite3*,void(*)(void*,const char*,sqlite_uint64),void*);
  void  (*progress_handler)(sqlite3*,int,int(*)(void*),void*);
  void *(*realloc)(void*,int);
  int  (*reset)(sqlite3_stmt*pStmt);
  void  (*result_blob)(sqlite3_context*,const void*,int,void(*)(void*));
  void  (*result_double)(sqlite3_context*,double);
  void  (*result_error)(sqlite3_context*,const char*,int);
  void  (*result_error16)(sqlite3_context*,const void*,int);
  void  (*result_int)(sqlite3_context*,int);
  void  (*result_int64)(sqlite3_context*,sqlite_int64);
  void  (*result_null)(sqlite3_context*);
  void  (*result_text)(sqlite3_context*,const char*,int,void(*)(void*));
  void  (*result_text16)(sqlite3_context*,const void*,int,void(*)(void*));
  void  (*result_text16be)(sqlite3_context*,const void*,int,void(*)(void*));
  void  (*result_text16le)(sqlite3_context*,const void*,int,void(*)(void*));
  void  (*result_value)(sqlite3_context*,sqlite3_value*);
  void * (*rollback_hook)(sqlite3*,void(*)(void*),void*);
  int  (*set_authorizer)(sqlite3*,int(*)(void*,int,const char*,const char*,const char*,const char*),void*);
  void  (*set_auxdata)(sqlite3_context*,int,void*,void (*)(void*));
  char * (*snprintf)(int,char*,const char*,...);
  int  (*step)(sqlite3_stmt*);
  int  (*table_column_metadata)(sqlite3*,const char*,const char*,const char*,char const**,char const**,int*,int*,int*);
  void  (*thread_cleanup)(void);
  int  (*total_changes)(sqlite3*);
  void * (*trace)(sqlite3*,void(*xTrace)(void*,const char*),void*);
  int  (*transfer_bindings)(sqlite3_stmt*,sqlite3_stmt*);
  void * (*update_hook)(sqlite3*,void(*)(void*,int ,char const*,char const*,sqlite_int64),void*);
  void * (*user_data)(sqlite3_context*);
  const void * (*value_blob)(sqlite3_value*);
  int  (*value_bytes)(sqlite3_value*);
  int  (*value_bytes16)(sqlite3_value*);
  double  (*value_double)(sqlite3_value*);
  int  (*value_int)(sqlite3_value*);
  sqlite_int64  (*value_int64)(sqlite3_value*);
  int  (*value_numeric_type)(sqlite3_value*);
  const unsigned char * (*value_text)(sqlite3_value*);
  const void * (*value_text16)(sqlite3_value*);
  const void * (*value_text16be)(sqlite3_value*);
  const void * (*value_text16le)(sqlite3_value*);
  int  (*value_type)(sqlite3_value*);
  char *(*vmprintf)(const char*,va_list);
  int (*overload_function)(sqlite3*, const char *zFuncName, int nArg);
  int (*prepare_v2)(sqlite3*,const char*,int,sqlite3_stmt**,const char**);
  int (*prepare16_v2)(sqlite3*,const void*,int,sqlite3_stmt**,const void**);
  int (*clear_bindings)(sqlite3_stmt*);
};

/*
** The following macros redefine the API routines so that they are
** redirected throught the global sqlite3_api structure.
**
** This header file is also used by the loadext.c source file
** (part of the main SQLite library - not an extension) so that
** it can get access to the sqlite3_api_routines structure
** definition.  But the main library does not want to redefine
** the API.  So the redefinition macros are only valid if the
** SQLITE_CORE macros is undefined.
*/
#ifndef SQLITE_CORE
#define sqlite3_aggregate_context      sqlite3_api->aggregate_context
#define sqlite3_aggregate_count        sqlite3_api->aggregate_count
#define sqlite3_bind_blob              sqlite3_api->bind_blob
#define sqlite3_bind_double            sqlite3_api->bind_double
#define sqlite3_bind_int               sqlite3_api->bind_int
#define sqlite3_bind_int64             sqlite3_api->bind_int64
#define sqlite3_bind_null              sqlite3_api->bind_null
#define sqlite3_bind_parameter_count   sqlite3_api->bind_parameter_count
#define sqlite3_bind_parameter_index   sqlite3_api->bind_parameter_index
#define sqlite3_bind_parameter_name    sqlite3_api->bind_parameter_name
#define sqlite3_bind_text              sqlite3_api->bind_text
#define sqlite3_bind_text16            sqlite3_api->bind_text16
#define sqlite3_bind_value             sqlite3_api->bind_value
#define sqlite3_busy_handler           sqlite3_api->busy_handler
#define sqlite3_busy_timeout           sqlite3_api->busy_timeout
#define sqlite3_changes                sqlite3_api->changes
#define sqlite3_close                  sqlite3_api->close
#define sqlite3_collation_needed       sqlite3_api->collation_needed
#define sqlite3_collation_needed16     sqlite3_api->collation_needed16
#define sqlite3_column_blob            sqlite3_api->column_blob
#define sqlite3_column_bytes           sqlite3_api->column_bytes
#define sqlite3_column_bytes16         sqlite3_api->column_bytes16
#define sqlite3_column_count           sqlite3_api->column_count
#define sqlite3_column_database_name   sqlite3_api->column_database_name
#define sqlite3_column_database_name16 sqlite3_api->column_database_name16
#define sqlite3_column_decltype        sqlite3_api->column_decltype
#define sqlite3_column_decltype16      sqlite3_api->column_decltype16
#define sqlite3_column_double          sqlite3_api->column_double
#define sqlite3_column_int             sqlite3_api->column_int
#define sqlite3_column_int64           sqlite3_api->column_int64
#define sqlite3_column_name            sqlite3_api->column_name
#define sqlite3_column_name16          sqlite3_api->column_name16
#define sqlite3_column_origin_name     sqlite3_api->column_origin_name
#define sqlite3_column_origin_name16   sqlite3_api->column_origin_name16
#define sqlite3_column_table_name      sqlite3_api->column_table_name
#define sqlite3_column_table_name16    sqlite3_api->column_table_name16
#define sqlite3_column_text            sqlite3_api->column_text
#define sqlite3_column_text16          sqlite3_api->column_text16
#define sqlite3_column_type            sqlite3_api->column_type
#define sqlite3_column_value           sqlite3_api->column_value
#define sqlite3_commit_hook            sqlite3_api->commit_hook
#define sqlite3_complete               sqlite3_api->complete
#define sqlite3_complete16             sqlite3_api->complete16
#define sqlite3_create_collation       sqlite3_api->create_collation
#define sqlite3_create_collation16     sqlite3_api->create_collation16
#define sqlite3_create_function        sqlite3_api->create_function
#define sqlite3_create_function16      sqlite3_api->create_function16
#define sqlite3_create_module          sqlite3_api->create_module
#define sqlite3_data_count             sqlite3_api->data_count
#define sqlite3_db_handle              sqlite3_api->db_handle
#define sqlite3_declare_vtab           sqlite3_api->declare_vtab
#define sqlite3_enable_shared_cache    sqlite3_api->enable_shared_cache
#define sqlite3_errcode                sqlite3_api->errcode
#define sqlite3_errmsg                 sqlite3_api->errmsg
#define sqlite3_errmsg16               sqlite3_api->errmsg16
#define sqlite3_exec                   sqlite3_api->exec
#define sqlite3_expired                sqlite3_api->expired
#define sqlite3_finalize               sqlite3_api->finalize
#define sqlite3_free                   sqlite3_api->free
#define sqlite3_free_table             sqlite3_api->free_table
#define sqlite3_get_autocommit         sqlite3_api->get_autocommit
#define sqlite3_get_auxdata            sqlite3_api->get_auxdata
#define sqlite3_get_table              sqlite3_api->get_table
#define sqlite3_global_recover         sqlite3_api->global_recover
#define sqlite3_interrupt              sqlite3_api->interruptx
#define sqlite3_last_insert_rowid      sqlite3_api->last_insert_rowid
#define sqlite3_libversion             sqlite3_api->libversion
#define sqlite3_libversion_number      sqlite3_api->libversion_number
#define sqlite3_malloc                 sqlite3_api->malloc
#define sqlite3_mprintf                sqlite3_api->mprintf
#define sqlite3_open                   sqlite3_api->open
#define sqlite3_open16                 sqlite3_api->open16
#define sqlite3_prepare                sqlite3_api->prepare
#define sqlite3_prepare16              sqlite3_api->prepare16
#define sqlite3_prepare_v2             sqlite3_api->prepare_v2
#define sqlite3_prepare16_v2           sqlite3_api->prepare16_v2
#define sqlite3_profile                sqlite3_api->profile
#define sqlite3_progress_handler       sqlite3_api->progress_handler
#define sqlite3_realloc                sqlite3_api->realloc
#define sqlite3_reset                  sqlite3_api->reset
#define sqlite3_result_blob            sqlite3_api->result_blob
#define sqlite3_result_double          sqlite3_api->result_double
#define sqlite3_result_error           sqlite3_api->result_error
#define sqlite3_result_error16         sqlite3_api->result_error16
#define sqlite3_result_int             sqlite3_api->result_int
#define sqlite3_result_int64           sqlite3_api->result_int64
#define sqlite3_result_null            sqlite3_api->result_null
#define sqlite3_result_text            sqlite3_api->result_text
#define sqlite3_result_text16          sqlite3_api->result_text16
#define sqlite3_result_text16be        sqlite3_api->result_text16be
#define sqlite3_result_text16le        sqlite3_api->result_text16le
#define sqlite3_result_value           sqlite3_api->result_value
#define sqlite3_rollback_hook          sqlite3_api->rollback_hook
#define sqlite3_set_authorizer         sqlite3_api->set_authorizer
#define sqlite3_set_auxdata            sqlite3_api->set_auxdata
#define sqlite3_snprintf               sqlite3_api->snprintf
#define sqlite3_step                   sqlite3_api->step
#define sqlite3_table_column_metadata  sqlite3_api->table_column_metadata
#define sqlite3_thread_cleanup         sqlite3_api->thread_cleanup
#define sqlite3_total_changes          sqlite3_api->total_changes
#define sqlite3_trace                  sqlite3_api->trace
#define sqlite3_transfer_bindings      sqlite3_api->transfer_bindings
#define sqlite3_update_hook            sqlite3_api->update_hook
#define sqlite3_user_data              sqlite3_api->user_data
#define sqlite3_value_blob             sqlite3_api->value_blob
#define sqlite3_value_bytes            sqlite3_api->value_bytes
#define sqlite3_value_bytes16          sqlite3_api->value_bytes16
#define sqlite3_value_double           sqlite3_api->value_double
#define sqlite3_value_int              sqlite3_api->value_int
#define sqlite3_value_int64            sqlite3_api->value_int64
#define sqlite3_value_numeric_type     sqlite3_api->value_numeric_type
#define sqlite3_value_text             sqlite3_api->value_text
#define sqlite3_value_text16           sqlite3_api->value_text16
#define sqlite3_value_text16be         sqlite3_api->value_text16be
#define sqlite3_value_text16le         sqlite3_api->value_text16le
#define sqlite3_value_type             sqlite3_api->value_type
#define sqlite3_vmprintf               sqlite3_api->vmprintf
#define sqlite3_overload_function      sqlite3_api->overload_function
#define sqlite3_prepare_v2             sqlite3_api->prepare_v2
#define sqlite3_prepare16_v2           sqlite3_api->prepare16_v2
#define sqlite3_clear_bindings         sqlite3_api->clear_bindings
#endif /* SQLITE_CORE */

#define SQLITE_EXTENSION_INIT1     const sqlite3_api_routines *sqlite3_api;
#define SQLITE_EXTENSION_INIT2(v)  sqlite3_api = v;

#endif /* _SQLITE3EXT_H_ */

Changes to SQLite.Interop/SQLite.Interop.rc.

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/////////////////////////////////////////////////////////////////////////////
//
// Version
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VS_VERSION_INFO VERSIONINFO
 FILEVERSION 1,0,39,1
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            VALUE "LegalCopyright", "Released to the public domain"
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    BEGIN
        VALUE "Translation", 0x409, 1200







|







 







|


|







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/////////////////////////////////////////////////////////////////////////////
//
// Version
//

VS_VERSION_INFO VERSIONINFO
 FILEVERSION 1,0,41,0
 PRODUCTVERSION 1,0,0,0
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    BEGIN
        VALUE "Translation", 0x409, 1200

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Changes to SQLite.Interop/crypt.c.

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#include "src/pager.c"

#ifndef SQLITE_OMIT_DISKIO
#ifdef SQLITE_HAS_CODEC

#include <windows.h>
#include <wincrypt.h>

// Extra padding before and after the cryptographic buffer
................................................................................
    }
  }

  // Create a new encryption block and assign the codec to the new attached database
  if (hKey)
  {
    LPCRYPTBLOCK pBlock = CreateCryptBlock(hKey, sqlite3BtreePager(db->aDb[nDb].pBt), NULL);
    sqlite3pager_set_codec(sqlite3BtreePager(db->aDb[nDb].pBt), sqlite3Codec, pBlock);
    db->aDb[nDb].pAux = pBlock;
    db->aDb[nDb].xFreeAux = DestroyCryptBlock;

    rc = SQLITE_OK;
  }
  return rc;
}
................................................................................

  // To rekey a database, we change the writekey for the pager.  The readkey remains
  // the same
  if (!pBlock) // Encrypt an unencrypted database
  {
    pBlock = CreateCryptBlock(hKey, p, NULL);
    pBlock->hReadKey = 0; // Original database is not encrypted
    sqlite3pager_set_codec(sqlite3BtreePager(pbt), sqlite3Codec, pBlock);
    db->aDb[0].pAux = pBlock;
    db->aDb[0].xFreeAux = DestroyCryptBlock;
  }
  else // Change the writekey for an already-encrypted database
  {
    pBlock->hWriteKey = hKey;
  }
................................................................................

  // Start a transaction
  rc = sqlite3BtreeBeginTrans(pbt, 1);

  if (!rc)
  {
    // Rewrite all the pages in the database using the new encryption key
    Pgno nPage = sqlite3pager_pagecount(p);
    Pgno nSkip = PAGER_MJ_PGNO(p);
    void *pPage;
    Pgno n;

    for(n = 1; rc == SQLITE_OK && n <= nPage; n ++)
    {
      if (n == nSkip) continue;
      rc = sqlite3pager_get(p, n, &pPage);
      if(!rc)
      {
        rc = sqlite3pager_write(pPage);
        sqlite3pager_unref(pPage);
      }
    }
  }

  // If we succeeded, try and commit the transaction
  if (!rc)
  {
................................................................................
    pBlock->hWriteKey = pBlock->hReadKey;
  }

  // If the readkey and writekey are both empty, there's no need for a codec on this
  // pager anymore.  Destroy the crypt block and remove the codec from the pager.
  if (!pBlock->hReadKey && !pBlock->hWriteKey)
  {
    sqlite3pager_set_codec(p, NULL, NULL);
    db->aDb[0].pAux = NULL;
    db->aDb[0].xFreeAux = NULL;
    DestroyCryptBlock(pBlock);
  }

  return rc;
}
<
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#ifndef SQLITE_OMIT_DISKIO
#ifdef SQLITE_HAS_CODEC

#include <windows.h>
#include <wincrypt.h>

// Extra padding before and after the cryptographic buffer
................................................................................
    }
  }

  // Create a new encryption block and assign the codec to the new attached database
  if (hKey)
  {
    LPCRYPTBLOCK pBlock = CreateCryptBlock(hKey, sqlite3BtreePager(db->aDb[nDb].pBt), NULL);
    sqlite3PagerSetCodec(sqlite3BtreePager(db->aDb[nDb].pBt), sqlite3Codec, pBlock);
    db->aDb[nDb].pAux = pBlock;
    db->aDb[nDb].xFreeAux = DestroyCryptBlock;

    rc = SQLITE_OK;
  }
  return rc;
}
................................................................................

  // To rekey a database, we change the writekey for the pager.  The readkey remains
  // the same
  if (!pBlock) // Encrypt an unencrypted database
  {
    pBlock = CreateCryptBlock(hKey, p, NULL);
    pBlock->hReadKey = 0; // Original database is not encrypted
    sqlite3PagerSetCodec(sqlite3BtreePager(pbt), sqlite3Codec, pBlock);
    db->aDb[0].pAux = pBlock;
    db->aDb[0].xFreeAux = DestroyCryptBlock;
  }
  else // Change the writekey for an already-encrypted database
  {
    pBlock->hWriteKey = hKey;
  }
................................................................................

  // Start a transaction
  rc = sqlite3BtreeBeginTrans(pbt, 1);

  if (!rc)
  {
    // Rewrite all the pages in the database using the new encryption key
    Pgno nPage = sqlite3PagerPagecount(p);
    Pgno nSkip = PAGER_MJ_PGNO(p);
    DbPage *pPage;
    Pgno n;

    for(n = 1; rc == SQLITE_OK && n <= nPage; n ++)
    {
      if (n == nSkip) continue;
      rc = sqlite3PagerGet(p, n, &pPage);
      if(!rc)
      {
        rc = sqlite3PagerWrite(pPage);
        sqlite3PagerUnref(pPage);
      }
    }
  }

  // If we succeeded, try and commit the transaction
  if (!rc)
  {
................................................................................
    pBlock->hWriteKey = pBlock->hReadKey;
  }

  // If the readkey and writekey are both empty, there's no need for a codec on this
  // pager anymore.  Destroy the crypt block and remove the codec from the pager.
  if (!pBlock->hReadKey && !pBlock->hWriteKey)
  {
    sqlite3PagerSetCodec(p, NULL, NULL);
    db->aDb[0].pAux = NULL;
    db->aDb[0].xFreeAux = NULL;
    DestroyCryptBlock(pBlock);
  }

  return rc;
}

Changes to SQLite.Interop/interop.c.

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#include "src/btree.c"
#include "src/vdbeint.h"
#include <tchar.h>

#if NDEBUG

#if _WIN32_WCE
#include "merge.h"

................................................................................
#include "merge_full.h"
#endif // _WIN32_WCE
#endif // NDEBUG

#ifdef OS_WIN

#include <tchar.h>




typedef void (WINAPI *SQLITEUSERFUNC)(void *, int, void **);
typedef int  (WINAPI *SQLITECOLLATION)(int, const void *, int, const void*);

typedef void (WINAPI *SQLITEUPDATEHOOK)(int, const char *, int, const char *, int, sqlite_int64);
typedef int  (WINAPI *SQLITECOMMITHOOK)();
typedef void (WINAPI *SQLITEROLLBACKHOOK)();
................................................................................
  pf[2](pctx, 0, 0);
}

__declspec(dllexport) void WINAPI sqlite3_sleep_interop(int milliseconds)
{
  Sleep(milliseconds);
}













































int SetCompression(const wchar_t *pwszFilename, unsigned short ufLevel)
{
#ifdef FSCTL_SET_COMPRESSION
  HMODULE hMod = GetModuleHandle(_T("KERNEL32"));
  CREATEFILEW pfunc;
  HANDLE hFile;
................................................................................
__declspec(dllexport) int WINAPI sqlite3_libversion_number_interop(void)
{
  return sqlite3_libversion_number();
}

__declspec(dllexport) int WINAPI sqlite3_close_interop(sqlite3 *db)
{


  return sqlite3_close(db);










}

__declspec(dllexport) int WINAPI sqlite3_exec_interop(sqlite3 *db, const char *sql, sqlite3_callback cb, void *pv, char **errmsg, int *plen)
{



  int n = sqlite3_exec(db, sql, cb, pv, errmsg);
  *plen = (*errmsg != 0) ? strlen(*errmsg) : 0;


  return n;
}

__declspec(dllexport) sqlite_int64 WINAPI sqlite3_last_insert_rowid_interop(sqlite3 *db)
{
  return sqlite3_last_insert_rowid(db);
}
................................................................................
__declspec(dllexport) void WINAPI sqlite3_free_interop(char *z)
{
  sqlite3_free(z);
}

__declspec(dllexport) int WINAPI sqlite3_open_interop(const char*filename, sqlite3 **ppdb)
{
  return sqlite3_open(filename, ppdb);



}

__declspec(dllexport) int WINAPI sqlite3_open16_interop(const void *filename, sqlite3 **ppdb)
{
  return sqlite3_open16(filename, ppdb);



}

__declspec(dllexport) int WINAPI sqlite3_errcode_interop(sqlite3 *db)
{
  return sqlite3_errcode(db);
}

................................................................................
__declspec(dllexport) const char * WINAPI sqlite3_errmsg_interop(sqlite3 *db, int *plen)
{
  const char *pval = sqlite3_errmsg(db);
  *plen = (pval != 0) ? strlen(pval) : 0;
  return pval;
}

__declspec(dllexport) const void * WINAPI sqlite3_errmsg16_interop(sqlite3 *db, int *plen)
{
  const void *pval = sqlite3_errmsg16(db);
  *plen = (pval != 0) ? wcslen((wchar_t *)pval) * sizeof(wchar_t): 0;
  return pval;
}

__declspec(dllexport) int WINAPI sqlite3_prepare_interop(sqlite3 *db, const char *sql, int nbytes, sqlite3_stmt **ppstmt, const char **pztail, int *plen)
{



  int n = sqlite3_prepare(db, sql, nbytes, ppstmt, pztail);
  *plen = (*pztail != 0) ? strlen(*pztail) : 0;

  return n;
}

__declspec(dllexport) int WINAPI sqlite3_prepare16_interop(sqlite3 *db, const void *sql, int nchars, sqlite3_stmt **ppstmt, const void **pztail, int *plen)
{



  int n = sqlite3_prepare16(db, sql, nchars * sizeof(wchar_t), ppstmt, pztail);
  *plen = (*pztail != 0) ? wcslen((wchar_t *)*pztail) * sizeof(wchar_t) : 0;

  return n;
}

__declspec(dllexport) int WINAPI sqlite3_bind_blob_interop(sqlite3_stmt *stmt, int iCol, const void *pv, int n, void(*cb)(void*))
{
  return sqlite3_bind_blob(stmt, iCol, pv, n, cb);
}
................................................................................
  const void *pval = sqlite3_column_decltype16(stmt, iCol);
  *plen = (pval != 0) ? wcslen((wchar_t *)pval) * sizeof(wchar_t) : 0;
  return pval;
}

__declspec(dllexport) int WINAPI sqlite3_step_interop(sqlite3_stmt *stmt)
{



  return sqlite3_step(stmt);



}

__declspec(dllexport) int WINAPI sqlite3_data_count_interop(sqlite3_stmt *stmt)
{
  return sqlite3_data_count(stmt);
}

................................................................................
__declspec(dllexport) int WINAPI sqlite3_column_type_interop(sqlite3_stmt *stmt, int iCol)
{
  return sqlite3_column_type(stmt, iCol);
}

__declspec(dllexport) int WINAPI sqlite3_finalize_interop(sqlite3_stmt *stmt)
{






  return sqlite3_finalize(stmt);














}

__declspec(dllexport) int WINAPI sqlite3_reset_interop(sqlite3_stmt *stmt)
{



  return sqlite3_reset(stmt);


}

__declspec(dllexport) int WINAPI sqlite3_create_function_interop(sqlite3 *psql, const char *zFunctionName, int nArg, int eTextRep, SQLITEUSERFUNC func, SQLITEUSERFUNC funcstep, SQLITEUSERFUNC funcfinal, void **ppCookie)
{
  int n;
  SQLITEUSERFUNC *p = (SQLITEUSERFUNC *)malloc(sizeof(SQLITEUSERFUNC) * 3);

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#include "src/sqlite3.c"
#include "crypt.c"
#include <tchar.h>

#if NDEBUG

#if _WIN32_WCE
#include "merge.h"

................................................................................
#include "merge_full.h"
#endif // _WIN32_WCE
#endif // NDEBUG

#ifdef OS_WIN

#include <tchar.h>

// Additional flag for sqlite3.flags, we use it as a reference counter
#define SQLITE_WantClose 0x01000000

typedef void (WINAPI *SQLITEUSERFUNC)(void *, int, void **);
typedef int  (WINAPI *SQLITECOLLATION)(int, const void *, int, const void*);

typedef void (WINAPI *SQLITEUPDATEHOOK)(int, const char *, int, const char *, int, sqlite_int64);
typedef int  (WINAPI *SQLITECOMMITHOOK)();
typedef void (WINAPI *SQLITEROLLBACKHOOK)();
................................................................................
  pf[2](pctx, 0, 0);
}

__declspec(dllexport) void WINAPI sqlite3_sleep_interop(int milliseconds)
{
  Sleep(milliseconds);
}

void InitializeDbMutex(sqlite3 *pdb)
{
  pdb->pTraceArg = (CRITICAL_SECTION *)sqliteMalloc(sizeof(CRITICAL_SECTION));
  InitializeCriticalSection(pdb->pTraceArg);
}

void EnterDbMutex(sqlite3 *pdb)
{
  if (pdb->pTraceArg)
  {
    EnterCriticalSection(pdb->pTraceArg);
  }
}

void LeaveDbMutex(sqlite3 *pdb)
{
  if (pdb->pTraceArg)
  {
    LeaveCriticalSection(pdb->pTraceArg);
  }
}

int sqlite3_closeAndFreeMutex(sqlite3 *db)
{
  CRITICAL_SECTION *pcrit = db->pTraceArg;
  int ret;
  EnterDbMutex(db);

  ret = sqlite3_close(db);
  if (ret == SQLITE_OK)
  {
    if (pcrit)
    {
      LeaveCriticalSection(pcrit);
      DeleteCriticalSection(pcrit);
      free(pcrit);
    }
  }
  else
    LeaveDbMutex(db);

  return ret;
}

int SetCompression(const wchar_t *pwszFilename, unsigned short ufLevel)
{
#ifdef FSCTL_SET_COMPRESSION
  HMODULE hMod = GetModuleHandle(_T("KERNEL32"));
  CREATEFILEW pfunc;
  HANDLE hFile;
................................................................................
__declspec(dllexport) int WINAPI sqlite3_libversion_number_interop(void)
{
  return sqlite3_libversion_number();
}

__declspec(dllexport) int WINAPI sqlite3_close_interop(sqlite3 *db)
{
  // Try and close the database.  If there are unfinalized statements, mark the database to be closed as
  // soon as the last finalized statement is closed
  int ret = sqlite3_closeAndFreeMutex(db);
  if (ret == SQLITE_BUSY)
  {
    if (db->pVdbe)
    {
      db->flags |= SQLITE_WantClose;
      ret = 0;
    }
  }

  return ret;
}

__declspec(dllexport) int WINAPI sqlite3_exec_interop(sqlite3 *db, const char *sql, sqlite3_callback cb, void *pv, char **errmsg, int *plen)
{ 
  int n;

  EnterDbMutex(db);
  n = sqlite3_exec(db, sql, cb, pv, errmsg);
  *plen = (*errmsg != 0) ? strlen(*errmsg) : 0;
  LeaveDbMutex(db);

  return n;
}

__declspec(dllexport) sqlite_int64 WINAPI sqlite3_last_insert_rowid_interop(sqlite3 *db)
{
  return sqlite3_last_insert_rowid(db);
}
................................................................................
__declspec(dllexport) void WINAPI sqlite3_free_interop(char *z)
{
  sqlite3_free(z);
}

__declspec(dllexport) int WINAPI sqlite3_open_interop(const char*filename, sqlite3 **ppdb)
{
  int ret = sqlite3_open(filename, ppdb);
  if (ret == SQLITE_OK) InitializeDbMutex(*ppdb);

  return ret;
}

__declspec(dllexport) int WINAPI sqlite3_open16_interop(const void *filename, sqlite3 **ppdb)
{
  int ret = sqlite3_open16(filename, ppdb);
  if (ret == SQLITE_OK) InitializeDbMutex(*ppdb);

  return ret;
}

__declspec(dllexport) int WINAPI sqlite3_errcode_interop(sqlite3 *db)
{
  return sqlite3_errcode(db);
}

................................................................................
__declspec(dllexport) const char * WINAPI sqlite3_errmsg_interop(sqlite3 *db, int *plen)
{
  const char *pval = sqlite3_errmsg(db);
  *plen = (pval != 0) ? strlen(pval) : 0;
  return pval;
}

__declspec(dllexport) const char * WINAPI sqlite3_errmsg_stmt_interop(sqlite3_stmt *stmt, int *plen)
{
  Vdbe *p = (Vdbe *)stmt;

  return sqlite3_errmsg_interop(p->db, plen);
}

__declspec(dllexport) int WINAPI sqlite3_prepare_interop(sqlite3 *db, const char *sql, int nbytes, sqlite3_stmt **ppstmt, const char **pztail, int *plen)
{
  int n;

  EnterDbMutex(db);
  n = sqlite3_prepare(db, sql, nbytes, ppstmt, pztail);
  *plen = (*pztail != 0) ? strlen(*pztail) : 0;
  LeaveDbMutex(db);
  return n;
}

__declspec(dllexport) int WINAPI sqlite3_prepare16_interop(sqlite3 *db, const void *sql, int nchars, sqlite3_stmt **ppstmt, const void **pztail, int *plen)
{
  int n;

  EnterDbMutex(db);
  n = sqlite3_prepare16(db, sql, nchars * sizeof(wchar_t), ppstmt, pztail);
  *plen = (*pztail != 0) ? wcslen((wchar_t *)*pztail) * sizeof(wchar_t) : 0;
  LeaveDbMutex(db);
  return n;
}

__declspec(dllexport) int WINAPI sqlite3_bind_blob_interop(sqlite3_stmt *stmt, int iCol, const void *pv, int n, void(*cb)(void*))
{
  return sqlite3_bind_blob(stmt, iCol, pv, n, cb);
}
................................................................................
  const void *pval = sqlite3_column_decltype16(stmt, iCol);
  *plen = (pval != 0) ? wcslen((wchar_t *)pval) * sizeof(wchar_t) : 0;
  return pval;
}

__declspec(dllexport) int WINAPI sqlite3_step_interop(sqlite3_stmt *stmt)
{
  int ret;

  EnterDbMutex(((Vdbe *)stmt)->db);
  ret = sqlite3_step(stmt);
  LeaveDbMutex(((Vdbe *)stmt)->db);

  return ret;
}

__declspec(dllexport) int WINAPI sqlite3_data_count_interop(sqlite3_stmt *stmt)
{
  return sqlite3_data_count(stmt);
}

................................................................................
__declspec(dllexport) int WINAPI sqlite3_column_type_interop(sqlite3_stmt *stmt, int iCol)
{
  return sqlite3_column_type(stmt, iCol);
}

__declspec(dllexport) int WINAPI sqlite3_finalize_interop(sqlite3_stmt *stmt)
{
  // Try and finalize a statement, and close the database it belonged to if the database was marked for closing
  Vdbe *p = (Vdbe *)stmt;
  sqlite3 *db = (p == NULL) ? NULL : p->db;
  int ret;

  EnterDbMutex(db);
  ret = sqlite3_finalize(stmt);
  LeaveDbMutex(db);

  if (ret == SQLITE_OK)
  {
    if (db->flags & SQLITE_WantClose)
    {
      if (db->pVdbe == NULL)
      {
        sqlite3_closeAndFreeMutex(db);
      }
    }
  }

  return ret;
}

__declspec(dllexport) int WINAPI sqlite3_reset_interop(sqlite3_stmt *stmt)
{
  int ret;

  EnterDbMutex(((Vdbe *)stmt)->db);
  ret = sqlite3_reset(stmt);
  LeaveDbMutex(((Vdbe *)stmt)->db);
  return ret;
}

__declspec(dllexport) int WINAPI sqlite3_create_function_interop(sqlite3 *psql, const char *zFunctionName, int nArg, int eTextRep, SQLITEUSERFUNC func, SQLITEUSERFUNC funcstep, SQLITEUSERFUNC funcfinal, void **ppCookie)
{
  int n;
  SQLITEUSERFUNC *p = (SQLITEUSERFUNC *)malloc(sizeof(SQLITEUSERFUNC) * 3);

Changes to SQLite.Interop/merge.h.

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// This code was automatically generated from assembly
// C:\Src\SQLite.NET\System.Data.SQLite\bin\CompactFramework\System.Data.SQLite.dll

#include <windef.h>

#pragma data_seg(".clr")
#pragma comment(linker, "/SECTION:.clr,ER")
  char __ph[128492] = {0}; // The number of bytes to reserve
#pragma data_seg()

typedef BOOL (WINAPI *DLLMAIN)(HANDLE, DWORD, LPVOID);
typedef struct EXTRA_STUFF
{
  DWORD dwNativeEntryPoint;
} EXTRA_STUFF, *LPEXTRA_STUFF;







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// This code was automatically generated from assembly
// C:\Src\SQLite.NET\System.Data.SQLite\bin\CompactFramework\System.Data.SQLite.dll

#include <windef.h>

#pragma data_seg(".clr")
#pragma comment(linker, "/SECTION:.clr,ER")
  char __ph[130148] = {0}; // The number of bytes to reserve
#pragma data_seg()

typedef BOOL (WINAPI *DLLMAIN)(HANDLE, DWORD, LPVOID);
typedef struct EXTRA_STUFF
{
  DWORD dwNativeEntryPoint;
} EXTRA_STUFF, *LPEXTRA_STUFF;

Changes to SQLite.Interop/merge_full.h.

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// This code was automatically generated from assembly
// C:\Src\SQLite.NET\System.Data.SQLite\bin\System.Data.SQLite.dll

#include <windef.h>

#pragma data_seg(".clr")
#pragma comment(linker, "/SECTION:.clr,ER")
  char __ph[137688] = {0}; // The number of bytes to reserve
#pragma data_seg()

typedef BOOL (WINAPI *DLLMAIN)(HANDLE, DWORD, LPVOID);
typedef struct EXTRA_STUFF
{
  DWORD dwNativeEntryPoint;
} EXTRA_STUFF, *LPEXTRA_STUFF;







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// This code was automatically generated from assembly
// C:\Src\SQLite.NET\System.Data.SQLite\bin\System.Data.SQLite.dll

#include <windef.h>

#pragma data_seg(".clr")
#pragma comment(linker, "/SECTION:.clr,ER")
  char __ph[138916] = {0}; // The number of bytes to reserve
#pragma data_seg()

typedef BOOL (WINAPI *DLLMAIN)(HANDLE, DWORD, LPVOID);
typedef struct EXTRA_STUFF
{
  DWORD dwNativeEntryPoint;
} EXTRA_STUFF, *LPEXTRA_STUFF;

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/*
** 2005 February 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that used to generate VDBE code
** that implements the ALTER TABLE command.
**
** $Id: alter.c,v 1.26 2007/01/30 15:20:47 rmsimpson Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** The code in this file only exists if we are not omitting the
** ALTER TABLE logic from the build.
*/
#ifndef SQLITE_OMIT_ALTERTABLE


/*
** This function is used by SQL generated to implement the 
** ALTER TABLE command. The first argument is the text of a CREATE TABLE or
** CREATE INDEX command. The second is a table name. The table name in 
** the CREATE TABLE or CREATE INDEX statement is replaced with the third
** argument and the result returned. Examples:
**
** sqlite_rename_table('CREATE TABLE abc(a, b, c)', 'def')
**     -> 'CREATE TABLE def(a, b, c)'
**
** sqlite_rename_table('CREATE INDEX i ON abc(a)', 'def')
**     -> 'CREATE INDEX i ON def(a, b, c)'
*/
static void renameTableFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  unsigned char const *zSql = sqlite3_value_text(argv[0]);
  unsigned char const *zTableName = sqlite3_value_text(argv[1]);

  int token;
  Token tname;
  unsigned char const *zCsr = zSql;
  int len = 0;
  char *zRet;

  /* The principle used to locate the table name in the CREATE TABLE 
  ** statement is that the table name is the first token that is immediatedly
  ** followed by a left parenthesis - TK_LP.
  */
  if( zSql ){
    do {
      /* Store the token that zCsr points to in tname. */
      tname.z = zCsr;
      tname.n = len;

      /* Advance zCsr to the next token. Store that token type in 'token',
      ** and it's length in 'len' (to be used next iteration of this loop).
      */
      do {
        zCsr += len;
        len = sqlite3GetToken(zCsr, &token);
      } while( token==TK_SPACE );
      assert( len>0 );
    } while( token!=TK_LP );

    zRet = sqlite3MPrintf("%.*s%Q%s", tname.z - zSql, zSql, 
       zTableName, tname.z+tname.n);
    sqlite3_result_text(context, zRet, -1, sqlite3FreeX);
  }
}

#ifndef SQLITE_OMIT_TRIGGER
/* This function is used by SQL generated to implement the
** ALTER TABLE command. The first argument is the text of a CREATE TRIGGER 
** statement. The second is a table name. The table name in the CREATE 
** TRIGGER statement is replaced with the third argument and the result 
** returned. This is analagous to renameTableFunc() above, except for CREATE
** TRIGGER, not CREATE INDEX and CREATE TABLE.
*/
static void renameTriggerFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  unsigned char const *zSql = sqlite3_value_text(argv[0]);
  unsigned char const *zTableName = sqlite3_value_text(argv[1]);

  int token;
  Token tname;
  int dist = 3;
  unsigned char const *zCsr = zSql;
  int len = 0;
  char *zRet;

  /* The principle used to locate the table name in the CREATE TRIGGER 
  ** statement is that the table name is the first token that is immediatedly
  ** preceded by either TK_ON or TK_DOT and immediatedly followed by one
  ** of TK_WHEN, TK_BEGIN or TK_FOR.
  */
  if( zSql ){
    do {
      /* Store the token that zCsr points to in tname. */
      tname.z = zCsr;
      tname.n = len;

      /* Advance zCsr to the next token. Store that token type in 'token',
      ** and it's length in 'len' (to be used next iteration of this loop).
      */
      do {
        zCsr += len;
        len = sqlite3GetToken(zCsr, &token);
      }while( token==TK_SPACE );
      assert( len>0 );

      /* Variable 'dist' stores the number of tokens read since the most
      ** recent TK_DOT or TK_ON. This means that when a WHEN, FOR or BEGIN 
      ** token is read and 'dist' equals 2, the condition stated above
      ** to be met.
      **
      ** Note that ON cannot be a database, table or column name, so
      ** there is no need to worry about syntax like 
      ** "CREATE TRIGGER ... ON ON.ON BEGIN ..." etc.
      */
      dist++;
      if( token==TK_DOT || token==TK_ON ){
        dist = 0;
      }
    } while( dist!=2 || (token!=TK_WHEN && token!=TK_FOR && token!=TK_BEGIN) );

    /* Variable tname now contains the token that is the old table-name
    ** in the CREATE TRIGGER statement.
    */
    zRet = sqlite3MPrintf("%.*s%Q%s", tname.z - zSql, zSql, 
       zTableName, tname.z+tname.n);
    sqlite3_result_text(context, zRet, -1, sqlite3FreeX);
  }
}
#endif   /* !SQLITE_OMIT_TRIGGER */

/*
** Register built-in functions used to help implement ALTER TABLE
*/
void sqlite3AlterFunctions(sqlite3 *db){
  static const struct {
     char *zName;
     signed char nArg;
     void (*xFunc)(sqlite3_context*,int,sqlite3_value **);
  } aFuncs[] = {
    { "sqlite_rename_table",    2, renameTableFunc},
#ifndef SQLITE_OMIT_TRIGGER
    { "sqlite_rename_trigger",  2, renameTriggerFunc},
#endif
  };
  int i;

  for(i=0; i<sizeof(aFuncs)/sizeof(aFuncs[0]); i++){
    sqlite3CreateFunc(db, aFuncs[i].zName, aFuncs[i].nArg,
        SQLITE_UTF8, 0, aFuncs[i].xFunc, 0, 0);
  }
}

/*
** Generate the text of a WHERE expression which can be used to select all
** temporary triggers on table pTab from the sqlite_temp_master table. If
** table pTab has no temporary triggers, or is itself stored in the 
** temporary database, NULL is returned.
*/
static char *whereTempTriggers(Parse *pParse, Table *pTab){
  Trigger *pTrig;
  char *zWhere = 0;
  char *tmp = 0;
  const Schema *pTempSchema = pParse->db->aDb[1].pSchema; /* Temp db schema */

  /* If the table is not located in the temp-db (in which case NULL is 
  ** returned, loop through the tables list of triggers. For each trigger
  ** that is not part of the temp-db schema, add a clause to the WHERE 
  ** expression being built up in zWhere.
  */
  if( pTab->pSchema!=pTempSchema ){
    for( pTrig=pTab->pTrigger; pTrig; pTrig=pTrig->pNext ){
      if( pTrig->pSchema==pTempSchema ){
        if( !zWhere ){
          zWhere = sqlite3MPrintf("name=%Q", pTrig->name);
        }else{
          tmp = zWhere;
          zWhere = sqlite3MPrintf("%s OR name=%Q", zWhere, pTrig->name);
          sqliteFree(tmp);
        }
      }
    }
  }
  return zWhere;
}

/*
** Generate code to drop and reload the internal representation of table
** pTab from the database, including triggers and temporary triggers.
** Argument zName is the name of the table in the database schema at
** the time the generated code is executed. This can be different from
** pTab->zName if this function is being called to code part of an 
** "ALTER TABLE RENAME TO" statement.
*/
static void reloadTableSchema(Parse *pParse, Table *pTab, const char *zName){
  Vdbe *v;
  char *zWhere;
  int iDb;                   /* Index of database containing pTab */
#ifndef SQLITE_OMIT_TRIGGER
  Trigger *pTrig;
#endif

  v = sqlite3GetVdbe(pParse);
  if( !v ) return;
  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
  assert( iDb>=0 );

#ifndef SQLITE_OMIT_TRIGGER
  /* Drop any table triggers from the internal schema. */
  for(pTrig=pTab->pTrigger; pTrig; pTrig=pTrig->pNext){
    int iTrigDb = sqlite3SchemaToIndex(pParse->db, pTrig->pSchema);
    assert( iTrigDb==iDb || iTrigDb==1 );
    sqlite3VdbeOp3(v, OP_DropTrigger, iTrigDb, 0, pTrig->name, 0);
  }
#endif

  /* Drop the table and index from the internal schema */
  sqlite3VdbeOp3(v, OP_DropTable, iDb, 0, pTab->zName, 0);

  /* Reload the table, index and permanent trigger schemas. */
  zWhere = sqlite3MPrintf("tbl_name=%Q", zName);
  if( !zWhere ) return;
  sqlite3VdbeOp3(v, OP_ParseSchema, iDb, 0, zWhere, P3_DYNAMIC);

#ifndef SQLITE_OMIT_TRIGGER
  /* Now, if the table is not stored in the temp database, reload any temp 
  ** triggers. Don't use IN(...) in case SQLITE_OMIT_SUBQUERY is defined. 
  */
  if( (zWhere=whereTempTriggers(pParse, pTab))!=0 ){
    sqlite3VdbeOp3(v, OP_ParseSchema, 1, 0, zWhere, P3_DYNAMIC);
  }
#endif
}

/*
** Generate code to implement the "ALTER TABLE xxx RENAME TO yyy" 
** command. 
*/
void sqlite3AlterRenameTable(
  Parse *pParse,            /* Parser context. */
  SrcList *pSrc,            /* The table to rename. */
  Token *pName              /* The new table name. */
){
  int iDb;                  /* Database that contains the table */
  char *zDb;                /* Name of database iDb */
  Table *pTab;              /* Table being renamed */
  char *zName = 0;          /* NULL-terminated version of pName */ 
  sqlite3 *db = pParse->db; /* Database connection */
  Vdbe *v;
#ifndef SQLITE_OMIT_TRIGGER
  char *zWhere = 0;         /* Where clause to locate temp triggers */
#endif
  
  if( sqlite3MallocFailed() ) goto exit_rename_table;
  assert( pSrc->nSrc==1 );

  pTab = sqlite3LocateTable(pParse, pSrc->a[0].zName, pSrc->a[0].zDatabase);
  if( !pTab ) goto exit_rename_table;
#ifndef SQLITE_OMIT_VIRTUALTABLE
  if( IsVirtual(pTab) ){
    sqlite3ErrorMsg(pParse, "virtual tables may not be altered");
    goto exit_rename_table;
  }
#endif
  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
  zDb = db->aDb[iDb].zName;

  /* Get a NULL terminated version of the new table name. */
  zName = sqlite3NameFromToken(pName);
  if( !zName ) goto exit_rename_table;

  /* Check that a table or index named 'zName' does not already exist
  ** in database iDb. If so, this is an error.
  */
  if( sqlite3FindTable(db, zName, zDb) || sqlite3FindIndex(db, zName, zDb) ){
    sqlite3ErrorMsg(pParse, 
        "there is already another table or index with this name: %s", zName);
    goto exit_rename_table;
  }

  /* Make sure it is not a system table being altered, or a reserved name
  ** that the table is being renamed to.
  */
  if( strlen(pTab->zName)>6 && 0==sqlite3StrNICmp(pTab->zName, "sqlite_", 7) ){
    sqlite3ErrorMsg(pParse, "table %s may not be altered", pTab->zName);
    goto exit_rename_table;
  }
  if( SQLITE_OK!=sqlite3CheckObjectName(pParse, zName) ){
    goto exit_rename_table;
  }

#ifndef SQLITE_OMIT_AUTHORIZATION
  /* Invoke the authorization callback. */
  if( sqlite3AuthCheck(pParse, SQLITE_ALTER_TABLE, zDb, pTab->zName, 0) ){
    goto exit_rename_table;
  }
#endif

  /* Begin a transaction and code the VerifyCookie for database iDb. 
  ** Then modify the schema cookie (since the ALTER TABLE modifies the
  ** schema).
  */
  v = sqlite3GetVdbe(pParse);
  if( v==0 ){
    goto exit_rename_table;
  }
  sqlite3BeginWriteOperation(pParse, 0, iDb);
  sqlite3ChangeCookie(db, v, iDb);

  /* Modify the sqlite_master table to use the new table name. */
  sqlite3NestedParse(pParse,
      "UPDATE %Q.%s SET "
#ifdef SQLITE_OMIT_TRIGGER
          "sql = sqlite_rename_table(sql, %Q), "
#else
          "sql = CASE "
            "WHEN type = 'trigger' THEN sqlite_rename_trigger(sql, %Q)"
            "ELSE sqlite_rename_table(sql, %Q) END, "
#endif
          "tbl_name = %Q, "
          "name = CASE "
            "WHEN type='table' THEN %Q "
            "WHEN name LIKE 'sqlite_autoindex%%' AND type='index' THEN "
              "'sqlite_autoindex_' || %Q || substr(name, %d+18,10) "
            "ELSE name END "
      "WHERE tbl_name=%Q AND "
          "(type='table' OR type='index' OR type='trigger');", 
      zDb, SCHEMA_TABLE(iDb), zName, zName, zName, 
#ifndef SQLITE_OMIT_TRIGGER
      zName,
#endif
      zName, strlen(pTab->zName), pTab->zName
  );

#ifndef SQLITE_OMIT_AUTOINCREMENT
  /* If the sqlite_sequence table exists in this database, then update 
  ** it with the new table name.
  */
  if( sqlite3FindTable(db, "sqlite_sequence", zDb) ){
    sqlite3NestedParse(pParse,
        "UPDATE %Q.sqlite_sequence set name = %Q WHERE name = %Q",
        zDb, zName, pTab->zName);
  }
#endif

#ifndef SQLITE_OMIT_TRIGGER
  /* If there are TEMP triggers on this table, modify the sqlite_temp_master
  ** table. Don't do this if the table being ALTERed is itself located in
  ** the temp database.
  */
  if( (zWhere=whereTempTriggers(pParse, pTab))!=0 ){
    sqlite3NestedParse(pParse, 
        "UPDATE sqlite_temp_master SET "
            "sql = sqlite_rename_trigger(sql, %Q), "
            "tbl_name = %Q "
            "WHERE %s;", zName, zName, zWhere);
    sqliteFree(zWhere);
  }
#endif

  /* Drop and reload the internal table schema. */
  reloadTableSchema(pParse, pTab, zName);

exit_rename_table:
  sqlite3SrcListDelete(pSrc);
  sqliteFree(zName);
}


/*
** This function is called after an "ALTER TABLE ... ADD" statement
** has been parsed. Argument pColDef contains the text of the new
** column definition.
**
** The Table structure pParse->pNewTable was extended to include
** the new column during parsing.
*/
void sqlite3AlterFinishAddColumn(Parse *pParse, Token *pColDef){
  Table *pNew;              /* Copy of pParse->pNewTable */
  Table *pTab;              /* Table being altered */
  int iDb;                  /* Database number */
  const char *zDb;          /* Database name */
  const char *zTab;         /* Table name */
  char *zCol;               /* Null-terminated column definition */
  Column *pCol;             /* The new column */
  Expr *pDflt;              /* Default value for the new column */

  if( pParse->nErr ) return;
  pNew = pParse->pNewTable;
  assert( pNew );

  iDb = sqlite3SchemaToIndex(pParse->db, pNew->pSchema);
  zDb = pParse->db->aDb[iDb].zName;
  zTab = pNew->zName;
  pCol = &pNew->aCol[pNew->nCol-1];
  pDflt = pCol->pDflt;
  pTab = sqlite3FindTable(pParse->db, zTab, zDb);
  assert( pTab );

#ifndef SQLITE_OMIT_AUTHORIZATION
  /* Invoke the authorization callback. */
  if( sqlite3AuthCheck(pParse, SQLITE_ALTER_TABLE, zDb, pTab->zName, 0) ){
    return;
  }
#endif

  /* If the default value for the new column was specified with a 
  ** literal NULL, then set pDflt to 0. This simplifies checking
  ** for an SQL NULL default below.
  */
  if( pDflt && pDflt->op==TK_NULL ){
    pDflt = 0;
  }

  /* Check that the new column is not specified as PRIMARY KEY or UNIQUE.
  ** If there is a NOT NULL constraint, then the default value for the
  ** column must not be NULL.
  */
  if( pCol->isPrimKey ){
    sqlite3ErrorMsg(pParse, "Cannot add a PRIMARY KEY column");
    return;
  }
  if( pNew->pIndex ){
    sqlite3ErrorMsg(pParse, "Cannot add a UNIQUE column");
    return;
  }
  if( pCol->notNull && !pDflt ){
    sqlite3ErrorMsg(pParse, 
        "Cannot add a NOT NULL column with default value NULL");
    return;
  }

  /* Ensure the default expression is something that sqlite3ValueFromExpr()
  ** can handle (i.e. not CURRENT_TIME etc.)
  */
  if( pDflt ){
    sqlite3_value *pVal;
    if( sqlite3ValueFromExpr(pDflt, SQLITE_UTF8, SQLITE_AFF_NONE, &pVal) ){
      /* malloc() has failed */
      return;
    }
    if( !pVal ){
      sqlite3ErrorMsg(pParse, "Cannot add a column with non-constant default");
      return;
    }
    sqlite3ValueFree(pVal);
  }

  /* Modify the CREATE TABLE statement. */
  zCol = sqliteStrNDup((char*)pColDef->z, pColDef->n);
  if( zCol ){
    char *zEnd = &zCol[pColDef->n-1];
    while( (zEnd>zCol && *zEnd==';') || isspace(*(unsigned char *)zEnd) ){
      *zEnd-- = '\0';
    }
    sqlite3NestedParse(pParse, 
        "UPDATE %Q.%s SET "
          "sql = substr(sql,1,%d) || ', ' || %Q || substr(sql,%d,length(sql)) "
        "WHERE type = 'table' AND name = %Q", 
      zDb, SCHEMA_TABLE(iDb), pNew->addColOffset, zCol, pNew->addColOffset+1,
      zTab
    );
    sqliteFree(zCol);
  }

  /* If the default value of the new column is NULL, then set the file
  ** format to 2. If the default value of the new column is not NULL,
  ** the file format becomes 3.
  */
  sqlite3MinimumFileFormat(pParse, iDb, pDflt ? 3 : 2);

  /* Reload the schema of the modified table. */
  reloadTableSchema(pParse, pTab, pTab->zName);
}

/*
** This function is called by the parser after the table-name in
** an "ALTER TABLE <table-name> ADD" statement is parsed. Argument 
** pSrc is the full-name of the table being altered.
**
** This routine makes a (partial) copy of the Table structure
** for the table being altered and sets Parse.pNewTable to point
** to it. Routines called by the parser as the column definition
** is parsed (i.e. sqlite3AddColumn()) add the new Column data to 
** the copy. The copy of the Table structure is deleted by tokenize.c 
** after parsing is finished.
**
** Routine sqlite3AlterFinishAddColumn() will be called to complete
** coding the "ALTER TABLE ... ADD" statement.
*/
void sqlite3AlterBeginAddColumn(Parse *pParse, SrcList *pSrc){
  Table *pNew;
  Table *pTab;
  Vdbe *v;
  int iDb;
  int i;
  int nAlloc;

  /* Look up the table being altered. */
  assert( pParse->pNewTable==0 );
  if( sqlite3MallocFailed() ) goto exit_begin_add_column;
  pTab = sqlite3LocateTable(pParse, pSrc->a[0].zName, pSrc->a[0].zDatabase);
  if( !pTab ) goto exit_begin_add_column;

#ifndef SQLITE_OMIT_VIRTUALTABLE
  if( IsVirtual(pTab) ){
    sqlite3ErrorMsg(pParse, "virtual tables may not be altered");
    goto exit_begin_add_column;
  }
#endif

  /* Make sure this is not an attempt to ALTER a view. */
  if( pTab->pSelect ){
    sqlite3ErrorMsg(pParse, "Cannot add a column to a view");
    goto exit_begin_add_column;
  }

  assert( pTab->addColOffset>0 );
  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);

  /* Put a copy of the Table struct in Parse.pNewTable for the
  ** sqlite3AddColumn() function and friends to modify.
  */
  pNew = (Table *)sqliteMalloc(sizeof(Table));
  if( !pNew ) goto exit_begin_add_column;
  pParse->pNewTable = pNew;
  pNew->nRef = 1;
  pNew->nCol = pTab->nCol;
  assert( pNew->nCol>0 );
  nAlloc = (((pNew->nCol-1)/8)*8)+8;
  assert( nAlloc>=pNew->nCol && nAlloc%8==0 && nAlloc-pNew->nCol<8 );
  pNew->aCol = (Column *)sqliteMalloc(sizeof(Column)*nAlloc);
  pNew->zName = sqliteStrDup(pTab->zName);
  if( !pNew->aCol || !pNew->zName ){
    goto exit_begin_add_column;
  }
  memcpy(pNew->aCol, pTab->aCol, sizeof(Column)*pNew->nCol);
  for(i=0; i<pNew->nCol; i++){
    Column *pCol = &pNew->aCol[i];
    pCol->zName = sqliteStrDup(pCol->zName);
    pCol->zColl = 0;
    pCol->zType = 0;
    pCol->pDflt = 0;
  }
  pNew->pSchema = pParse->db->aDb[iDb].pSchema;
  pNew->addColOffset = pTab->addColOffset;
  pNew->nRef = 1;

  /* Begin a transaction and increment the schema cookie.  */
  sqlite3BeginWriteOperation(pParse, 0, iDb);
  v = sqlite3GetVdbe(pParse);
  if( !v ) goto exit_begin_add_column;
  sqlite3ChangeCookie(pParse->db, v, iDb);

exit_begin_add_column:
  sqlite3SrcListDelete(pSrc);
  return;
}
#endif  /* SQLITE_ALTER_TABLE */
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Deleted SQLite.Interop/src/analyze.c.

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/*
** 2005 July 8
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code associated with the ANALYZE command.
**
** @(#) $Id: analyze.c,v 1.19 2007/01/30 15:20:47 rmsimpson Exp $
*/
#ifndef SQLITE_OMIT_ANALYZE
#include "sqliteInt.h"

/*
** This routine generates code that opens the sqlite_stat1 table on cursor
** iStatCur.
**
** If the sqlite_stat1 tables does not previously exist, it is created.
** If it does previously exist, all entires associated with table zWhere
** are removed.  If zWhere==0 then all entries are removed.
*/
static void openStatTable(
  Parse *pParse,          /* Parsing context */
  int iDb,                /* The database we are looking in */
  int iStatCur,           /* Open the sqlite_stat1 table on this cursor */
  const char *zWhere      /* Delete entries associated with this table */
){
  sqlite3 *db = pParse->db;
  Db *pDb;
  int iRootPage;
  Table *pStat;
  Vdbe *v = sqlite3GetVdbe(pParse);

  pDb = &db->aDb[iDb];
  if( (pStat = sqlite3FindTable(db, "sqlite_stat1", pDb->zName))==0 ){
    /* The sqlite_stat1 tables does not exist.  Create it.  
    ** Note that a side-effect of the CREATE TABLE statement is to leave
    ** the rootpage of the new table on the top of the stack.  This is
    ** important because the OpenWrite opcode below will be needing it. */
    sqlite3NestedParse(pParse,
      "CREATE TABLE %Q.sqlite_stat1(tbl,idx,stat)",
      pDb->zName
    );
    iRootPage = 0;  /* Cause rootpage to be taken from top of stack */
  }else if( zWhere ){
    /* The sqlite_stat1 table exists.  Delete all entries associated with
    ** the table zWhere. */
    sqlite3NestedParse(pParse,
       "DELETE FROM %Q.sqlite_stat1 WHERE tbl=%Q",
       pDb->zName, zWhere
    );
    iRootPage = pStat->tnum;
  }else{
    /* The sqlite_stat1 table already exists.  Delete all rows. */
    iRootPage = pStat->tnum;
    sqlite3VdbeAddOp(v, OP_Clear, pStat->tnum, iDb);
  }

  /* Open the sqlite_stat1 table for writing. Unless it was created
  ** by this vdbe program, lock it for writing at the shared-cache level. 
  ** If this vdbe did create the sqlite_stat1 table, then it must have 
  ** already obtained a schema-lock, making the write-lock redundant.
  */
  if( iRootPage>0 ){
    sqlite3TableLock(pParse, iDb, iRootPage, 1, "sqlite_stat1");
  }
  sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
  sqlite3VdbeAddOp(v, OP_OpenWrite, iStatCur, iRootPage);
  sqlite3VdbeAddOp(v, OP_SetNumColumns, iStatCur, 3);
}

/*
** Generate code to do an analysis of all indices associated with
** a single table.
*/
static void analyzeOneTable(
  Parse *pParse,   /* Parser context */
  Table *pTab,     /* Table whose indices are to be analyzed */
  int iStatCur,    /* Cursor that writes to the sqlite_stat1 table */
  int iMem         /* Available memory locations begin here */
){
  Index *pIdx;     /* An index to being analyzed */
  int iIdxCur;     /* Cursor number for index being analyzed */
  int nCol;        /* Number of columns in the index */
  Vdbe *v;         /* The virtual machine being built up */
  int i;           /* Loop counter */
  int topOfLoop;   /* The top of the loop */
  int endOfLoop;   /* The end of the loop */
  int addr;        /* The address of an instruction */
  int iDb;         /* Index of database containing pTab */

  v = sqlite3GetVdbe(pParse);
  if( pTab==0 || pTab->pIndex==0 ){
    /* Do no analysis for tables that have no indices */
    return;
  }

  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
  assert( iDb>=0 );
#ifndef SQLITE_OMIT_AUTHORIZATION
  if( sqlite3AuthCheck(pParse, SQLITE_ANALYZE, pTab->zName, 0,
      pParse->db->aDb[iDb].zName ) ){
    return;
  }
#endif

  /* Establish a read-lock on the table at the shared-cache level. */
  sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);

  iIdxCur = pParse->nTab;
  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
    KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);

    /* Open a cursor to the index to be analyzed
    */
    assert( iDb==sqlite3SchemaToIndex(pParse->db, pIdx->pSchema) );
    sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
    VdbeComment((v, "# %s", pIdx->zName));
    sqlite3VdbeOp3(v, OP_OpenRead, iIdxCur, pIdx->tnum,
        (char *)pKey, P3_KEYINFO_HANDOFF);
    nCol = pIdx->nColumn;
    if( iMem+nCol*2>=pParse->nMem ){
      pParse->nMem = iMem+nCol*2+1;
    }
    sqlite3VdbeAddOp(v, OP_SetNumColumns, iIdxCur, nCol+1);

    /* Memory cells are used as follows:
    **
    **    mem[iMem]:             The total number of rows in the table.
    **    mem[iMem+1]:           Number of distinct values in column 1
    **    ...
    **    mem[iMem+nCol]:        Number of distinct values in column N
    **    mem[iMem+nCol+1]       Last observed value of column 1
    **    ...
    **    mem[iMem+nCol+nCol]:   Last observed value of column N
    **
    ** Cells iMem through iMem+nCol are initialized to 0.  The others
    ** are initialized to NULL.
    */
    for(i=0; i<=nCol; i++){
      sqlite3VdbeAddOp(v, OP_MemInt, 0, iMem+i);
    }
    for(i=0; i<nCol; i++){
      sqlite3VdbeAddOp(v, OP_MemNull, iMem+nCol+i+1, 0);
    }

    /* Do the analysis.
    */
    endOfLoop = sqlite3VdbeMakeLabel(v);
    sqlite3VdbeAddOp(v, OP_Rewind, iIdxCur, endOfLoop);
    topOfLoop = sqlite3VdbeCurrentAddr(v);
    sqlite3VdbeAddOp(v, OP_MemIncr, 1, iMem);
    for(i=0; i<nCol; i++){
      sqlite3VdbeAddOp(v, OP_Column, iIdxCur, i);
      sqlite3VdbeAddOp(v, OP_MemLoad, iMem+nCol+i+1, 0);
      sqlite3VdbeAddOp(v, OP_Ne, 0x100, 0);
    }
    sqlite3VdbeAddOp(v, OP_Goto, 0, endOfLoop);
    for(i=0; i<nCol; i++){
      addr = sqlite3VdbeAddOp(v, OP_MemIncr, 1, iMem+i+1);
      sqlite3VdbeChangeP2(v, topOfLoop + 3*i + 3, addr);
      sqlite3VdbeAddOp(v, OP_Column, iIdxCur, i);
      sqlite3VdbeAddOp(v, OP_MemStore, iMem+nCol+i+1, 1);
    }
    sqlite3VdbeResolveLabel(v, endOfLoop);
    sqlite3VdbeAddOp(v, OP_Next, iIdxCur, topOfLoop);
    sqlite3VdbeAddOp(v, OP_Close, iIdxCur, 0);

    /* Store the results.  
    **
    ** The result is a single row of the sqlite_stmt1 table.  The first
    ** two columns are the names of the table and index.  The third column
    ** is a string composed of a list of integer statistics about the
    ** index.  The first integer in the list is the total number of entires
    ** in the index.  There is one additional integer in the list for each
    ** column of the table.  This additional integer is a guess of how many
    ** rows of the table the index will select.  If D is the count of distinct
    ** values and K is the total number of rows, then the integer is computed
    ** as:
    **
    **        I = (K+D-1)/D
    **
    ** If K==0 then no entry is made into the sqlite_stat1 table.  
    ** If K>0 then it is always the case the D>0 so division by zero
    ** is never possible.
    */
    sqlite3VdbeAddOp(v, OP_MemLoad, iMem, 0);
    addr = sqlite3VdbeAddOp(v, OP_IfNot, 0, 0);
    sqlite3VdbeAddOp(v, OP_NewRowid, iStatCur, 0);
    sqlite3VdbeOp3(v, OP_String8, 0, 0, pTab->zName, 0);
    sqlite3VdbeOp3(v, OP_String8, 0, 0, pIdx->zName, 0);
    sqlite3VdbeAddOp(v, OP_MemLoad, iMem, 0);
    sqlite3VdbeOp3(v, OP_String8, 0, 0, " ", 0);
    for(i=0; i<nCol; i++){
      sqlite3VdbeAddOp(v, OP_MemLoad, iMem, 0);
      sqlite3VdbeAddOp(v, OP_MemLoad, iMem+i+1, 0);
      sqlite3VdbeAddOp(v, OP_Add, 0, 0);
      sqlite3VdbeAddOp(v, OP_AddImm, -1, 0);
      sqlite3VdbeAddOp(v, OP_MemLoad, iMem+i+1, 0);
      sqlite3VdbeAddOp(v, OP_Divide, 0, 0);
      sqlite3VdbeAddOp(v, OP_ToInt, 0, 0);
      if( i==nCol-1 ){
        sqlite3VdbeAddOp(v, OP_Concat, nCol*2-1, 0);
      }else{
        sqlite3VdbeAddOp(v, OP_Dup, 1, 0);
      }
    }
    sqlite3VdbeOp3(v, OP_MakeRecord, 3, 0, "aaa", 0);
    sqlite3VdbeAddOp(v, OP_Insert, iStatCur, 0);
    sqlite3VdbeJumpHere(v, addr);
  }
}

/*
** Generate code that will cause the most recent index analysis to
** be laoded into internal hash tables where is can be used.
*/
static void loadAnalysis(Parse *pParse, int iDb){
  Vdbe *v = sqlite3GetVdbe(pParse);
  sqlite3VdbeAddOp(v, OP_LoadAnalysis, iDb, 0);
}

/*
** Generate code that will do an analysis of an entire database
*/
static void analyzeDatabase(Parse *pParse, int iDb){
  sqlite3 *db = pParse->db;
  Schema *pSchema = db->aDb[iDb].pSchema;    /* Schema of database iDb */
  HashElem *k;
  int iStatCur;
  int iMem;

  sqlite3BeginWriteOperation(pParse, 0, iDb);
  iStatCur = pParse->nTab++;
  openStatTable(pParse, iDb, iStatCur, 0);
  iMem = pParse->nMem;
  for(k=sqliteHashFirst(&pSchema->tblHash); k; k=sqliteHashNext(k)){
    Table *pTab = (Table*)sqliteHashData(k);
    analyzeOneTable(pParse, pTab, iStatCur, iMem);
  }
  loadAnalysis(pParse, iDb);
}

/*
** Generate code that will do an analysis of a single table in
** a database.
*/
static void analyzeTable(Parse *pParse, Table *pTab){
  int iDb;
  int iStatCur;

  assert( pTab!=0 );
  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
  sqlite3BeginWriteOperation(pParse, 0, iDb);
  iStatCur = pParse->nTab++;
  openStatTable(pParse, iDb, iStatCur, pTab->zName);
  analyzeOneTable(pParse, pTab, iStatCur, pParse->nMem);
  loadAnalysis(pParse, iDb);
}

/*
** Generate code for the ANALYZE command.  The parser calls this routine
** when it recognizes an ANALYZE command.
**
**        ANALYZE                            -- 1
**        ANALYZE  <database>                -- 2
**        ANALYZE  ?<database>.?<tablename>  -- 3
**
** Form 1 causes all indices in all attached databases to be analyzed.
** Form 2 analyzes all indices the single database named.
** Form 3 analyzes all indices associated with the named table.
*/
void sqlite3Analyze(Parse *pParse, Token *pName1, Token *pName2){
  sqlite3 *db = pParse->db;
  int iDb;
  int i;
  char *z, *zDb;
  Table *pTab;
  Token *pTableName;

  /* Read the database schema. If an error occurs, leave an error message
  ** and code in pParse and return NULL. */
  if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
    return;
  }

  if( pName1==0 ){
    /* Form 1:  Analyze everything */
    for(i=0; i<db->nDb; i++){
      if( i==1 ) continue;  /* Do not analyze the TEMP database */
      analyzeDatabase(pParse, i);
    }
  }else if( pName2==0 || pName2->n==0 ){
    /* Form 2:  Analyze the database or table named */
    iDb = sqlite3FindDb(db, pName1);
    if( iDb>=0 ){
      analyzeDatabase(pParse, iDb);
    }else{
      z = sqlite3NameFromToken(pName1);
      pTab = sqlite3LocateTable(pParse, z, 0);
      sqliteFree(z);
      if( pTab ){
        analyzeTable(pParse, pTab);
      }
    }
  }else{
    /* Form 3: Analyze the fully qualified table name */
    iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pTableName);
    if( iDb>=0 ){
      zDb = db->aDb[iDb].zName;
      z = sqlite3NameFromToken(pTableName);
      pTab = sqlite3LocateTable(pParse, z, zDb);
      sqliteFree(z);
      if( pTab ){
        analyzeTable(pParse, pTab);
      }
    }   
  }
}

/*
** Used to pass information from the analyzer reader through to the
** callback routine.
*/
typedef struct analysisInfo analysisInfo;
struct analysisInfo {
  sqlite3 *db;
  const char *zDatabase;
};

/*
** This callback is invoked once for each index when reading the
** sqlite_stat1 table.  
**
**     argv[0] = name of the index
**     argv[1] = results of analysis - on integer for each column
*/
static int analysisLoader(void *pData, int argc, char **argv, char **azNotUsed){
  analysisInfo *pInfo = (analysisInfo*)pData;
  Index *pIndex;
  int i, c;
  unsigned int v;
  const char *z;

  assert( argc==2 );
  if( argv==0 || argv[0]==0 || argv[1]==0 ){
    return 0;
  }
  pIndex = sqlite3FindIndex(pInfo->db, argv[0], pInfo->zDatabase);
  if( pIndex==0 ){
    return 0;
  }
  z = argv[1];
  for(i=0; *z && i<=pIndex->nColumn; i++){
    v = 0;
    while( (c=z[0])>='0' && c<='9' ){
      v = v*10 + c - '0';
      z++;
    }
    pIndex->aiRowEst[i] = v;
    if( *z==' ' ) z++;
  }
  return 0;
}

/*
** Load the content of the sqlite_stat1 table into the index hash tables.
*/
void sqlite3AnalysisLoad(sqlite3 *db, int iDb){
  analysisInfo sInfo;
  HashElem *i;
  char *zSql;

  /* Clear any prior statistics */
  for(i=sqliteHashFirst(&db->aDb[iDb].pSchema->idxHash);i;i=sqliteHashNext(i)){
    Index *pIdx = sqliteHashData(i);
    sqlite3DefaultRowEst(pIdx);
  }

  /* Check to make sure the sqlite_stat1 table existss */
  sInfo.db = db;
  sInfo.zDatabase = db->aDb[iDb].zName;
  if( sqlite3FindTable(db, "sqlite_stat1", sInfo.zDatabase)==0 ){
     return;
  }


  /* Load new statistics out of the sqlite_stat1 table */
  zSql = sqlite3MPrintf("SELECT idx, stat FROM %Q.sqlite_stat1",
                        sInfo.zDatabase);
  sqlite3SafetyOff(db);
  sqlite3_exec(db, zSql, analysisLoader, &sInfo, 0);
  sqlite3SafetyOn(db);
  sqliteFree(zSql);
}


#endif /* SQLITE_OMIT_ANALYZE */
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Deleted SQLite.Interop/src/attach.c.

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/*
** 2003 April 6
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used to implement the ATTACH and DETACH commands.
**
** $Id: attach.c,v 1.25 2007/01/30 15:20:47 rmsimpson Exp $
*/
#include "sqliteInt.h"

/*
** Resolve an expression that was part of an ATTACH or DETACH statement. This
** is slightly different from resolving a normal SQL expression, because simple
** identifiers are treated as strings, not possible column names or aliases.
**
** i.e. if the parser sees:
**
**     ATTACH DATABASE abc AS def
**
** it treats the two expressions as literal strings 'abc' and 'def' instead of
** looking for columns of the same name.
**
** This only applies to the root node of pExpr, so the statement:
**
**     ATTACH DATABASE abc||def AS 'db2'
**
** will fail because neither abc or def can be resolved.
*/
static int resolveAttachExpr(NameContext *pName, Expr *pExpr)
{
  int rc = SQLITE_OK;
  if( pExpr ){
    if( pExpr->op!=TK_ID ){
      rc = sqlite3ExprResolveNames(pName, pExpr);
    }else{
      pExpr->op = TK_STRING;
    }
  }
  return rc;
}

/*
** An SQL user-function registered to do the work of an ATTACH statement. The
** three arguments to the function come directly from an attach statement:
**
**     ATTACH DATABASE x AS y KEY z
**
**     SELECT sqlite_attach(x, y, z)
**
** If the optional "KEY z" syntax is omitted, an SQL NULL is passed as the
** third argument.
*/
static void attachFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  int i;
  int rc = 0;
  sqlite3 *db = sqlite3_user_data(context);
  const char *zName;
  const char *zFile;
  Db *aNew;
  char zErr[128];
  char *zErrDyn = 0;

  zFile = (const char *)sqlite3_value_text(argv[0]);
  zName = (const char *)sqlite3_value_text(argv[1]);
  if( zFile==0 ) zFile = "";
  if( zName==0 ) zName = "";

  /* Check for the following errors:
  **
  **     * Too many attached databases,
  **     * Transaction currently open
  **     * Specified database name already being used.
  */
  if( db->nDb>=MAX_ATTACHED+2 ){
    sqlite3_snprintf(
      sizeof(zErr), zErr, "too many attached databases - max %d", MAX_ATTACHED
    );
    goto attach_error;
  }
  if( !db->autoCommit ){
    strcpy(zErr, "cannot ATTACH database within transaction");
    goto attach_error;
  }
  for(i=0; i<db->nDb; i++){
    char *z = db->aDb[i].zName;
    if( z && zName && sqlite3StrICmp(z, zName)==0 ){
      sqlite3_snprintf(sizeof(zErr), zErr, "database %s is already in use", zName);
      goto attach_error;
    }
  }

  /* Allocate the new entry in the db->aDb[] array and initialise the schema
  ** hash tables.
  */
  if( db->aDb==db->aDbStatic ){
    aNew = sqliteMalloc( sizeof(db->aDb[0])*3 );
    if( aNew==0 ){
      return;
    }
    memcpy(aNew, db->aDb, sizeof(db->aDb[0])*2);
  }else{
    aNew = sqliteRealloc(db->aDb, sizeof(db->aDb[0])*(db->nDb+1) );
    if( aNew==0 ){
      return;
    } 
  }
  db->aDb = aNew;
  aNew = &db->aDb[db->nDb++];
  memset(aNew, 0, sizeof(*aNew));

  /* Open the database file. If the btree is successfully opened, use
  ** it to obtain the database schema. At this point the schema may
  ** or may not be initialised.
  */
  rc = sqlite3BtreeFactory(db, zFile, 0, MAX_PAGES, &aNew->pBt);
  if( rc==SQLITE_OK ){
    aNew->pSchema = sqlite3SchemaGet(aNew->pBt);
    if( !aNew->pSchema ){
      rc = SQLITE_NOMEM;
    }else if( aNew->pSchema->file_format && aNew->pSchema->enc!=ENC(db) ){
      strcpy(zErr, 
        "attached databases must use the same text encoding as main database");
      goto attach_error;
    }
  }
  aNew->zName = sqliteStrDup(zName);
  aNew->safety_level = 3;

#if SQLITE_HAS_CODEC
  {
    extern int sqlite3CodecAttach(sqlite3*, int, void*, int);
    extern void sqlite3CodecGetKey(sqlite3*, int, void**, int*);
    int nKey;
    char *zKey;
    int t = sqlite3_value_type(argv[2]);
    switch( t ){
      case SQLITE_INTEGER:
      case SQLITE_FLOAT:
        zErrDyn = sqliteStrDup("Invalid key value");
        rc = SQLITE_ERROR;
        break;
        
      case SQLITE_TEXT:
      case SQLITE_BLOB:
        nKey = sqlite3_value_bytes(argv[2]);
        zKey = (char *)sqlite3_value_blob(argv[2]);
        sqlite3CodecAttach(db, db->nDb-1, zKey, nKey);
        break;

      case SQLITE_NULL:
        /* No key specified.  Use the key from the main database */
        sqlite3CodecGetKey(db, 0, (void**)&zKey, &nKey);
        sqlite3CodecAttach(db, db->nDb-1, zKey, nKey);
        break;
    }
  }
#endif

  /* If the file was opened successfully, read the schema for the new database.
  ** If this fails, or if opening the file failed, then close the file and 
  ** remove the entry from the db->aDb[] array. i.e. put everything back the way
  ** we found it.
  */
  if( rc==SQLITE_OK ){
    sqlite3SafetyOn(db);
    rc = sqlite3Init(db, &zErrDyn);
    sqlite3SafetyOff(db);
  }
  if( rc ){
    int iDb = db->nDb - 1;
    assert( iDb>=2 );
    if( db->aDb[iDb].pBt ){
      sqlite3BtreeClose(db->aDb[iDb].pBt);
      db->aDb[iDb].pBt = 0;
      db->aDb[iDb].pSchema = 0;
    }
    sqlite3ResetInternalSchema(db, 0);
    db->nDb = iDb;
    if( rc==SQLITE_NOMEM ){
      if( !sqlite3MallocFailed() ) sqlite3FailedMalloc();
      sqlite3_snprintf(sizeof(zErr),zErr, "out of memory");
    }else{
      sqlite3_snprintf(sizeof(zErr),zErr, "unable to open database: %s", zFile);
    }
    goto attach_error;
  }
  
  return;

attach_error:
  /* Return an error if we get here */
  if( zErrDyn ){
    sqlite3_result_error(context, zErrDyn, -1);
    sqliteFree(zErrDyn);
  }else{
    zErr[sizeof(zErr)-1] = 0;
    sqlite3_result_error(context, zErr, -1);
  }
}

/*
** An SQL user-function registered to do the work of an DETACH statement. The
** three arguments to the function come directly from a detach statement:
**
**     DETACH DATABASE x
**
**     SELECT sqlite_detach(x)
*/
static void detachFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  const char *zName = (const char *)sqlite3_value_text(argv[0]);
  sqlite3 *db = sqlite3_user_data(context);
  int i;
  Db *pDb = 0;
  char zErr[128];

  if( zName==0 ) zName = "";
  for(i=0; i<db->nDb; i++){
    pDb = &db->aDb[i];
    if( pDb->pBt==0 ) continue;
    if( sqlite3StrICmp(pDb->zName, zName)==0 ) break;
  }

  if( i>=db->nDb ){
    sqlite3_snprintf(sizeof(zErr),zErr, "no such database: %s", zName);
    goto detach_error;
  }
  if( i<2 ){
    sqlite3_snprintf(sizeof(zErr),zErr, "cannot detach database %s", zName);
    goto detach_error;
  }
  if( !db->autoCommit ){
    strcpy(zErr, "cannot DETACH database within transaction");
    goto detach_error;
  }
  if( sqlite3BtreeIsInReadTrans(pDb->pBt) ){
    sqlite3_snprintf(sizeof(zErr),zErr, "database %s is locked", zName);
    goto detach_error;
  }

  sqlite3BtreeClose(pDb->pBt);
  pDb->pBt = 0;
  pDb->pSchema = 0;
  sqlite3ResetInternalSchema(db, 0);
  return;

detach_error:
  sqlite3_result_error(context, zErr, -1);
}

/*
** This procedure generates VDBE code for a single invocation of either the
** sqlite_detach() or sqlite_attach() SQL user functions.
*/
static void codeAttach(
  Parse *pParse,       /* The parser context */
  int type,            /* Either SQLITE_ATTACH or SQLITE_DETACH */
  const char *zFunc,   /* Either "sqlite_attach" or "sqlite_detach */
  int nFunc,           /* Number of args to pass to zFunc */
  Expr *pAuthArg,      /* Expression to pass to authorization callback */
  Expr *pFilename,     /* Name of database file */
  Expr *pDbname,       /* Name of the database to use internally */
  Expr *pKey           /* Database key for encryption extension */
){
  int rc;
  NameContext sName;
  Vdbe *v;
  FuncDef *pFunc;
  sqlite3* db = pParse->db;

#ifndef SQLITE_OMIT_AUTHORIZATION
  assert( sqlite3MallocFailed() || pAuthArg );
  if( pAuthArg ){
    char *zAuthArg = sqlite3NameFromToken(&pAuthArg->span);
    if( !zAuthArg ){
      goto attach_end;
    }
    rc = sqlite3AuthCheck(pParse, type, zAuthArg, 0, 0);
    sqliteFree(zAuthArg);
    if(rc!=SQLITE_OK ){
      goto attach_end;
    }
  }
#endif /* SQLITE_OMIT_AUTHORIZATION */

  memset(&sName, 0, sizeof(NameContext));
  sName.pParse = pParse;

  if( 
      SQLITE_OK!=(rc = resolveAttachExpr(&sName, pFilename)) ||
      SQLITE_OK!=(rc = resolveAttachExpr(&sName, pDbname)) ||
      SQLITE_OK!=(rc = resolveAttachExpr(&sName, pKey))
  ){
    pParse->nErr++;
    goto attach_end;
  }

  v = sqlite3GetVdbe(pParse);
  sqlite3ExprCode(pParse, pFilename);
  sqlite3ExprCode(pParse, pDbname);
  sqlite3ExprCode(pParse, pKey);

  assert( v || sqlite3MallocFailed() );
  if( v ){
    sqlite3VdbeAddOp(v, OP_Function, 0, nFunc);
    pFunc = sqlite3FindFunction(db, zFunc, strlen(zFunc), nFunc, SQLITE_UTF8,0);
    sqlite3VdbeChangeP3(v, -1, (char *)pFunc, P3_FUNCDEF);

    /* Code an OP_Expire. For an ATTACH statement, set P1 to true (expire this
    ** statement only). For DETACH, set it to false (expire all existing
    ** statements).
    */
    sqlite3VdbeAddOp(v, OP_Expire, (type==SQLITE_ATTACH), 0);
  }
  
attach_end:
  sqlite3ExprDelete(pFilename);
  sqlite3ExprDelete(pDbname);
  sqlite3ExprDelete(pKey);
}

/*
** Called by the parser to compile a DETACH statement.
**
**     DETACH pDbname
*/
void sqlite3Detach(Parse *pParse, Expr *pDbname){
  codeAttach(pParse, SQLITE_DETACH, "sqlite_detach", 1, pDbname, 0, 0, pDbname);
}

/*
** Called by the parser to compile an ATTACH statement.
**
**     ATTACH p AS pDbname KEY pKey
*/
void sqlite3Attach(Parse *pParse, Expr *p, Expr *pDbname, Expr *pKey){
  codeAttach(pParse, SQLITE_ATTACH, "sqlite_attach", 3, p, p, pDbname, pKey);
}

/*
** Register the functions sqlite_attach and sqlite_detach.
*/
void sqlite3AttachFunctions(sqlite3 *db){
  static const int enc = SQLITE_UTF8;
  sqlite3CreateFunc(db, "sqlite_attach", 3, enc, db, attachFunc, 0, 0);
  sqlite3CreateFunc(db, "sqlite_detach", 1, enc, db, detachFunc, 0, 0);
}

/*
** Initialize a DbFixer structure.  This routine must be called prior
** to passing the structure to one of the sqliteFixAAAA() routines below.
**
** The return value indicates whether or not fixation is required.  TRUE
** means we do need to fix the database references, FALSE means we do not.
*/
int sqlite3FixInit(
  DbFixer *pFix,      /* The fixer to be initialized */
  Parse *pParse,      /* Error messages will be written here */
  int iDb,            /* This is the database that must be used */
  const char *zType,  /* "view", "trigger", or "index" */
  const Token *pName  /* Name of the view, trigger, or index */
){
  sqlite3 *db;

  if( iDb<0 || iDb==1 ) return 0;
  db = pParse->db;
  assert( db->nDb>iDb );
  pFix->pParse = pParse;
  pFix->zDb = db->aDb[iDb].zName;
  pFix->zType = zType;
  pFix->pName = pName;
  return 1;
}

/*
** The following set of routines walk through the parse tree and assign
** a specific database to all table references where the database name
** was left unspecified in the original SQL statement.  The pFix structure
** must have been initialized by a prior call to sqlite3FixInit().
**
** These routines are used to make sure that an index, trigger, or
** view in one database does not refer to objects in a different database.
** (Exception: indices, triggers, and views in the TEMP database are
** allowed to refer to anything.)  If a reference is explicitly made
** to an object in a different database, an error message is added to
** pParse->zErrMsg and these routines return non-zero.  If everything
** checks out, these routines return 0.
*/
int sqlite3FixSrcList(
  DbFixer *pFix,       /* Context of the fixation */
  SrcList *pList       /* The Source list to check and modify */
){
  int i;
  const char *zDb;
  struct SrcList_item *pItem;

  if( pList==0 ) return 0;
  zDb = pFix->zDb;
  for(i=0, pItem=pList->a; i<pList->nSrc; i++, pItem++){
    if( pItem->zDatabase==0 ){
      pItem->zDatabase = sqliteStrDup(zDb);
    }else if( sqlite3StrICmp(pItem->zDatabase,zDb)!=0 ){
      sqlite3ErrorMsg(pFix->pParse,
         "%s %T cannot reference objects in database %s",
         pFix->zType, pFix->pName, pItem->zDatabase);
      return 1;
    }
#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_TRIGGER)
    if( sqlite3FixSelect(pFix, pItem->pSelect) ) return 1;
    if( sqlite3FixExpr(pFix, pItem->pOn) ) return 1;
#endif
  }
  return 0;
}
#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_TRIGGER)
int sqlite3FixSelect(
  DbFixer *pFix,       /* Context of the fixation */
  Select *pSelect      /* The SELECT statement to be fixed to one database */
){
  while( pSelect ){
    if( sqlite3FixExprList(pFix, pSelect->pEList) ){
      return 1;
    }
    if( sqlite3FixSrcList(pFix, pSelect->pSrc) ){
      return 1;
    }
    if( sqlite3FixExpr(pFix, pSelect->pWhere) ){
      return 1;
    }
    if( sqlite3FixExpr(pFix, pSelect->pHaving) ){
      return 1;
    }
    pSelect = pSelect->pPrior;
  }
  return 0;
}
int sqlite3FixExpr(
  DbFixer *pFix,     /* Context of the fixation */
  Expr *pExpr        /* The expression to be fixed to one database */
){
  while( pExpr ){
    if( sqlite3FixSelect(pFix, pExpr->pSelect) ){
      return 1;
    }
    if( sqlite3FixExprList(pFix, pExpr->pList) ){
      return 1;
    }
    if( sqlite3FixExpr(pFix, pExpr->pRight) ){
      return 1;
    }
    pExpr = pExpr->pLeft;
  }
  return 0;
}
int sqlite3FixExprList(
  DbFixer *pFix,     /* Context of the fixation */
  ExprList *pList    /* The expression to be fixed to one database */
){
  int i;
  struct ExprList_item *pItem;
  if( pList==0 ) return 0;
  for(i=0, pItem=pList->a; i<pList->nExpr; i++, pItem++){
    if( sqlite3FixExpr(pFix, pItem->pExpr) ){
      return 1;
    }
  }
  return 0;
}
#endif

#ifndef SQLITE_OMIT_TRIGGER
int sqlite3FixTriggerStep(
  DbFixer *pFix,     /* Context of the fixation */
  TriggerStep *pStep /* The trigger step be fixed to one database */
){
  while( pStep ){
    if( sqlite3FixSelect(pFix, pStep->pSelect) ){
      return 1;
    }
    if( sqlite3FixExpr(pFix, pStep->pWhere) ){
      return 1;
    }
    if( sqlite3FixExprList(pFix, pStep->pExprList) ){
      return 1;
    }
    pStep = pStep->pNext;
  }
  return 0;
}
#endif
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Deleted SQLite.Interop/src/auth.c.

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/*
** 2003 January 11
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used to implement the sqlite3_set_authorizer()
** API.  This facility is an optional feature of the library.  Embedded
** systems that do not need this facility may omit it by recompiling
** the library with -DSQLITE_OMIT_AUTHORIZATION=1
**
** $Id: auth.c,v 1.25 2007/01/30 15:20:47 rmsimpson Exp $
*/
#include "sqliteInt.h"

/*
** All of the code in this file may be omitted by defining a single
** macro.
*/
#ifndef SQLITE_OMIT_AUTHORIZATION

/*
** Set or clear the access authorization function.
**
** The access authorization function is be called during the compilation
** phase to verify that the user has read and/or write access permission on
** various fields of the database.  The first argument to the auth function
** is a copy of the 3rd argument to this routine.  The second argument
** to the auth function is one of these constants:
**
**       SQLITE_CREATE_INDEX
**       SQLITE_CREATE_TABLE
**       SQLITE_CREATE_TEMP_INDEX
**       SQLITE_CREATE_TEMP_TABLE
**       SQLITE_CREATE_TEMP_TRIGGER
**       SQLITE_CREATE_TEMP_VIEW
**       SQLITE_CREATE_TRIGGER
**       SQLITE_CREATE_VIEW
**       SQLITE_DELETE
**       SQLITE_DROP_INDEX
**       SQLITE_DROP_TABLE
**       SQLITE_DROP_TEMP_INDEX
**       SQLITE_DROP_TEMP_TABLE
**       SQLITE_DROP_TEMP_TRIGGER
**       SQLITE_DROP_TEMP_VIEW
**       SQLITE_DROP_TRIGGER
**       SQLITE_DROP_VIEW
**       SQLITE_INSERT
**       SQLITE_PRAGMA
**       SQLITE_READ
**       SQLITE_SELECT
**       SQLITE_TRANSACTION
**       SQLITE_UPDATE
**
** The third and fourth arguments to the auth function are the name of
** the table and the column that are being accessed.  The auth function
** should return either SQLITE_OK, SQLITE_DENY, or SQLITE_IGNORE.  If
** SQLITE_OK is returned, it means that access is allowed.  SQLITE_DENY
** means that the SQL statement will never-run - the sqlite3_exec() call
** will return with an error.  SQLITE_IGNORE means that the SQL statement
** should run but attempts to read the specified column will return NULL
** and attempts to write the column will be ignored.
**
** Setting the auth function to NULL disables this hook.  The default
** setting of the auth function is NULL.
*/
int sqlite3_set_authorizer(
  sqlite3 *db,
  int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),
  void *pArg
){
  db->xAuth = xAuth;
  db->pAuthArg = pArg;
  sqlite3ExpirePreparedStatements(db);
  return SQLITE_OK;
}

/*
** Write an error message into pParse->zErrMsg that explains that the
** user-supplied authorization function returned an illegal value.
*/
static void sqliteAuthBadReturnCode(Parse *pParse, int rc){
  sqlite3ErrorMsg(pParse, "illegal return value (%d) from the "
    "authorization function - should be SQLITE_OK, SQLITE_IGNORE, "
    "or SQLITE_DENY", rc);
  pParse->rc = SQLITE_ERROR;
}

/*
** The pExpr should be a TK_COLUMN expression.  The table referred to
** is in pTabList or else it is the NEW or OLD table of a trigger.  
** Check to see if it is OK to read this particular column.
**
** If the auth function returns SQLITE_IGNORE, change the TK_COLUMN 
** instruction into a TK_NULL.  If the auth function returns SQLITE_DENY,
** then generate an error.
*/
void sqlite3AuthRead(
  Parse *pParse,        /* The parser context */
  Expr *pExpr,          /* The expression to check authorization on */
  SrcList *pTabList     /* All table that pExpr might refer to */
){
  sqlite3 *db = pParse->db;
  int rc;
  Table *pTab;          /* The table being read */
  const char *zCol;     /* Name of the column of the table */
  int iSrc;             /* Index in pTabList->a[] of table being read */
  const char *zDBase;   /* Name of database being accessed */
  TriggerStack *pStack; /* The stack of current triggers */
  int iDb;              /* The index of the database the expression refers to */

  if( db->xAuth==0 ) return;
  if( pExpr->op==TK_AS ) return;
  assert( pExpr->op==TK_COLUMN );
  iDb = sqlite3SchemaToIndex(pParse->db, pExpr->pSchema);
  if( iDb<0 ){
    /* An attempt to read a column out of a subquery or other
    ** temporary table. */
    return;
  }
  for(iSrc=0; pTabList && iSrc<pTabList->nSrc; iSrc++){
    if( pExpr->iTable==pTabList->a[iSrc].iCursor ) break;
  }
  if( iSrc>=0 && pTabList && iSrc<pTabList->nSrc ){
    pTab = pTabList->a[iSrc].pTab;
  }else if( (pStack = pParse->trigStack)!=0 ){
    /* This must be an attempt to read the NEW or OLD pseudo-tables
    ** of a trigger.
    */
    assert( pExpr->iTable==pStack->newIdx || pExpr->iTable==pStack->oldIdx );
    pTab = pStack->pTab;
  }else{
    return;
  }
  if( pTab==0 ) return;
  if( pExpr->iColumn>=0 ){
    assert( pExpr->iColumn<pTab->nCol );
    zCol = pTab->aCol[pExpr->iColumn].zName;
  }else if( pTab->iPKey>=0 ){
    assert( pTab->iPKey<pTab->nCol );
    zCol = pTab->aCol[pTab->iPKey].zName;
  }else{
    zCol = "ROWID";
  }
  assert( iDb>=0 && iDb<db->nDb );
  zDBase = db->aDb[iDb].zName;
  rc = db->xAuth(db->pAuthArg, SQLITE_READ, pTab->zName, zCol, zDBase, 
                 pParse->zAuthContext);
  if( rc==SQLITE_IGNORE ){
    pExpr->op = TK_NULL;
  }else if( rc==SQLITE_DENY ){
    if( db->nDb>2 || iDb!=0 ){
      sqlite3ErrorMsg(pParse, "access to %s.%s.%s is prohibited", 
         zDBase, pTab->zName, zCol);
    }else{
      sqlite3ErrorMsg(pParse, "access to %s.%s is prohibited",pTab->zName,zCol);
    }
    pParse->rc = SQLITE_AUTH;
  }else if( rc!=SQLITE_OK ){
    sqliteAuthBadReturnCode(pParse, rc);
  }
}

/*
** Do an authorization check using the code and arguments given.  Return
** either SQLITE_OK (zero) or SQLITE_IGNORE or SQLITE_DENY.  If SQLITE_DENY
** is returned, then the error count and error message in pParse are
** modified appropriately.
*/
int sqlite3AuthCheck(
  Parse *pParse,
  int code,
  const char *zArg1,
  const char *zArg2,
  const char *zArg3
){
  sqlite3 *db = pParse->db;
  int rc;

  /* Don't do any authorization checks if the database is initialising
  ** or if the parser is being invoked from within sqlite3_declare_vtab.
  */
  if( db->init.busy || IN_DECLARE_VTAB ){
    return SQLITE_OK;
  }

  if( db->xAuth==0 ){
    return SQLITE_OK;
  }
  rc = db->xAuth(db->pAuthArg, code, zArg1, zArg2, zArg3, pParse->zAuthContext);
  if( rc==SQLITE_DENY ){
    sqlite3ErrorMsg(pParse, "not authorized");
    pParse->rc = SQLITE_AUTH;
  }else if( rc!=SQLITE_OK && rc!=SQLITE_IGNORE ){
    rc = SQLITE_DENY;
    sqliteAuthBadReturnCode(pParse, rc);
  }
  return rc;
}

/*
** Push an authorization context.  After this routine is called, the
** zArg3 argument to authorization callbacks will be zContext until
** popped.  Or if pParse==0, this routine is a no-op.
*/
void sqlite3AuthContextPush(
  Parse *pParse,
  AuthContext *pContext, 
  const char *zContext
){
  pContext->pParse = pParse;
  if( pParse ){
    pContext->zAuthContext = pParse->zAuthContext;
    pParse->zAuthContext = zContext;
  }
}

/*
** Pop an authorization context that was previously pushed
** by sqlite3AuthContextPush
*/
void sqlite3AuthContextPop(AuthContext *pContext){
  if( pContext->pParse ){
    pContext->pParse->zAuthContext = pContext->zAuthContext;
    pContext->pParse = 0;
  }
}

#endif /* SQLITE_OMIT_AUTHORIZATION */
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Deleted SQLite.Interop/src/btree.c.

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/*
** 2004 April 6
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** $Id: btree.c,v 1.28 2007/01/30 15:20:47 rmsimpson Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
**
**     Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3:
**     "Sorting And Searching", pages 473-480. Addison-Wesley
**     Publishing Company, Reading, Massachusetts.
**
** The basic idea is that each page of the file contains N database
** entries and N+1 pointers to subpages.
**
**   ----------------------------------------------------------------
**   |  Ptr(0) | Key(0) | Ptr(1) | Key(1) | ... | Key(N) | Ptr(N+1) |
**   ----------------------------------------------------------------
**
** All of the keys on the page that Ptr(0) points to have values less
** than Key(0).  All of the keys on page Ptr(1) and its subpages have
** values greater than Key(0) and less than Key(1).  All of the keys
** on Ptr(N+1) and its subpages have values greater than Key(N).  And
** so forth.
**
** Finding a particular key requires reading O(log(M)) pages from the 
** disk where M is the number of entries in the tree.
**
** In this implementation, a single file can hold one or more separate 
** BTrees.  Each BTree is identified by the index of its root page.  The
** key and data for any entry are combined to form the "payload".  A
** fixed amount of payload can be carried directly on the database
** page.  If the payload is larger than the preset amount then surplus
** bytes are stored on overflow pages.  The payload for an entry
** and the preceding pointer are combined to form a "Cell".  Each 
** page has a small header which contains the Ptr(N+1) pointer and other
** information such as the size of key and data.
**
** FORMAT DETAILS
**
** The file is divided into pages.  The first page is called page 1,
** the second is page 2, and so forth.  A page number of zero indicates
** "no such page".  The page size can be anything between 512 and 65536.
** Each page can be either a btree page, a freelist page or an overflow
** page.
**
** The first page is always a btree page.  The first 100 bytes of the first
** page contain a special header (the "file header") that describes the file.
** The format of the file header is as follows:
**
**   OFFSET   SIZE    DESCRIPTION
**      0      16     Header string: "SQLite format 3\000"
**     16       2     Page size in bytes.  
**     18       1     File format write version
**     19       1     File format read version
**     20       1     Bytes of unused space at the end of each page
**     21       1     Max embedded payload fraction
**     22       1     Min embedded payload fraction
**     23       1     Min leaf payload fraction
**     24       4     File change counter
**     28       4     Reserved for future use
**     32       4     First freelist page
**     36       4     Number of freelist pages in the file
**     40      60     15 4-byte meta values passed to higher layers
**
** All of the integer values are big-endian (most significant byte first).
**
** The file change counter is incremented when the database is changed more
** than once within the same second.  This counter, together with the
** modification time of the file, allows other processes to know
** when the file has changed and thus when they need to flush their
** cache.
**
** The max embedded payload fraction is the amount of the total usable
** space in a page that can be consumed by a single cell for standard
** B-tree (non-LEAFDATA) tables.  A value of 255 means 100%.  The default
** is to limit the maximum cell size so that at least 4 cells will fit
** on one page.  Thus the default max embedded payload fraction is 64.
**
** If the payload for a cell is larger than the max payload, then extra
** payload is spilled to overflow pages.  Once an overflow page is allocated,
** as many bytes as possible are moved into the overflow pages without letting
** the cell size drop below the min embedded payload fraction.
**
** The min leaf payload fraction is like the min embedded payload fraction
** except that it applies to leaf nodes in a LEAFDATA tree.  The maximum
** payload fraction for a LEAFDATA tree is always 100% (or 255) and it
** not specified in the header.
**
** Each btree pages is divided into three sections:  The header, the
** cell pointer array, and the cell area area.  Page 1 also has a 100-byte
** file header that occurs before the page header.
**
**      |----------------|
**      | file header    |   100 bytes.  Page 1 only.
**      |----------------|
**      | page header    |   8 bytes for leaves.  12 bytes for interior nodes
**      |----------------|
**      | cell pointer   |   |  2 bytes per cell.  Sorted order.
**      | array          |   |  Grows downward
**      |                |   v
**      |----------------|
**      | unallocated    |
**      | space          |
**      |----------------|   ^  Grows upwards
**      | cell content   |   |  Arbitrary order interspersed with freeblocks.
**      | area           |   |  and free space fragments.
**      |----------------|
**
** The page headers looks like this:
**
**   OFFSET   SIZE     DESCRIPTION
**      0       1      Flags. 1: intkey, 2: zerodata, 4: leafdata, 8: leaf
**      1       2      byte offset to the first freeblock
**      3       2      number of cells on this page
**      5       2      first byte of the cell content area
**      7       1      number of fragmented free bytes
**      8       4      Right child (the Ptr(N+1) value).  Omitted on leaves.
**
** The flags define the format of this btree page.  The leaf flag means that
** this page has no children.  The zerodata flag means that this page carries
** only keys and no data.  The intkey flag means that the key is a integer
** which is stored in the key size entry of the cell header rather than in
** the payload area.
**
** The cell pointer array begins on the first byte after the page header.
** The cell pointer array contains zero or more 2-byte numbers which are
** offsets from the beginning of the page to the cell content in the cell
** content area.  The cell pointers occur in sorted order.  The system strives
** to keep free space after the last cell pointer so that new cells can
** be easily added without having to defragment the page.
**
** Cell content is stored at the very end of the page and grows toward the
** beginning of the page.
**
** Unused space within the cell content area is collected into a linked list of
** freeblocks.  Each freeblock is at least 4 bytes in size.  The byte offset
** to the first freeblock is given in the header.  Freeblocks occur in
** increasing order.  Because a freeblock must be at least 4 bytes in size,
** any group of 3 or fewer unused bytes in the cell content area cannot
** exist on the freeblock chain.  A group of 3 or fewer free bytes is called
** a fragment.  The total number of bytes in all fragments is recorded.
** in the page header at offset 7.
**
**    SIZE    DESCRIPTION
**      2     Byte offset of the next freeblock
**      2     Bytes in this freeblock
**
** Cells are of variable length.  Cells are stored in the cell content area at
** the end of the page.  Pointers to the cells are in the cell pointer array
** that immediately follows the page header.  Cells is not necessarily
** contiguous or in order, but cell pointers are contiguous and in order.
**
** Cell content makes use of variable length integers.  A variable
** length integer is 1 to 9 bytes where the lower 7 bits of each 
** byte are used.  The integer consists of all bytes that have bit 8 set and
** the first byte with bit 8 clear.  The most significant byte of the integer
** appears first.  A variable-length integer may not be more than 9 bytes long.
** As a special case, all 8 bytes of the 9th byte are used as data.  This
** allows a 64-bit integer to be encoded in 9 bytes.
**
**    0x00                      becomes  0x00000000
**    0x7f                      becomes  0x0000007f
**    0x81 0x00                 becomes  0x00000080
**    0x82 0x00                 becomes  0x00000100
**    0x80 0x7f                 becomes  0x0000007f
**    0x8a 0x91 0xd1 0xac 0x78  becomes  0x12345678
**    0x81 0x81 0x81 0x81 0x01  becomes  0x10204081
**
** Variable length integers are used for rowids and to hold the number of
** bytes of key and data in a btree cell.
**
** The content of a cell looks like this:
**
**    SIZE    DESCRIPTION
**      4     Page number of the left child. Omitted if leaf flag is set.
**     var    Number of bytes of data. Omitted if the zerodata flag is set.
**     var    Number of bytes of key. Or the key itself if intkey flag is set.
**      *     Payload
**      4     First page of the overflow chain.  Omitted if no overflow
**
** Overflow pages form a linked list.  Each page except the last is completely
** filled with data (pagesize - 4 bytes).  The last page can have as little
** as 1 byte of data.
**
**    SIZE    DESCRIPTION
**      4     Page number of next overflow page
**      *     Data
**
** Freelist pages come in two subtypes: trunk pages and leaf pages.  The
** file header points to first in a linked list of trunk page.  Each trunk
** page points to multiple leaf pages.  The content of a leaf page is
** unspecified.  A trunk page looks like this:
**
**    SIZE    DESCRIPTION
**      4     Page number of next trunk page
**      4     Number of leaf pointers on this page
**      *     zero or more pages numbers of leaves
*/
#include "sqliteInt.h"
#include "pager.h"
#include "btree.h"
#include "os.h"
#include <assert.h>

/* Round up a number to the next larger multiple of 8.  This is used
** to force 8-byte alignment on 64-bit architectures.
*/
#define ROUND8(x)   ((x+7)&~7)


/* The following value is the maximum cell size assuming a maximum page
** size give above.
*/
#define MX_CELL_SIZE(pBt)  (pBt->pageSize-8)

/* The maximum number of cells on a single page of the database.  This
** assumes a minimum cell size of 3 bytes.  Such small cells will be
** exceedingly rare, but they are possible.
*/
#define MX_CELL(pBt) ((pBt->pageSize-8)/3)

/* Forward declarations */
typedef struct MemPage MemPage;
typedef struct BtLock BtLock;

/*
** This is a magic string that appears at the beginning of every
** SQLite database in order to identify the file as a real database.
**
** You can change this value at compile-time by specifying a
** -DSQLITE_FILE_HEADER="..." on the compiler command-line.  The
** header must be exactly 16 bytes including the zero-terminator so
** the string itself should be 15 characters long.  If you change
** the header, then your custom library will not be able to read 
** databases generated by the standard tools and the standard tools
** will not be able to read databases created by your custom library.
*/
#ifndef SQLITE_FILE_HEADER /* 123456789 123456 */
#  define SQLITE_FILE_HEADER "SQLite format 3"
#endif
static const char zMagicHeader[] = SQLITE_FILE_HEADER;

/*
** Page type flags.  An ORed combination of these flags appear as the
** first byte of every BTree page.
*/
#define PTF_INTKEY    0x01
#define PTF_ZERODATA  0x02
#define PTF_LEAFDATA  0x04
#define PTF_LEAF      0x08

/*
** As each page of the file is loaded into memory, an instance of the following
** structure is appended and initialized to zero.  This structure stores
** information about the page that is decoded from the raw file page.
**
** The pParent field points back to the parent page.  This allows us to
** walk up the BTree from any leaf to the root.  Care must be taken to
** unref() the parent page pointer when this page is no longer referenced.
** The pageDestructor() routine handles that chore.
*/
struct MemPage {
  u8 isInit;           /* True if previously initialized. MUST BE FIRST! */
  u8 idxShift;         /* True if Cell indices have changed */
  u8 nOverflow;        /* Number of overflow cell bodies in aCell[] */
  u8 intKey;           /* True if intkey flag is set */
  u8 leaf;             /* True if leaf flag is set */
  u8 zeroData;         /* True if table stores keys only */
  u8 leafData;         /* True if tables stores data on leaves only */
  u8 hasData;          /* True if this page stores data */
  u8 hdrOffset;        /* 100 for page 1.  0 otherwise */
  u8 childPtrSize;     /* 0 if leaf==1.  4 if leaf==0 */
  u16 maxLocal;        /* Copy of Btree.maxLocal or Btree.maxLeaf */
  u16 minLocal;        /* Copy of Btree.minLocal or Btree.minLeaf */
  u16 cellOffset;      /* Index in aData of first cell pointer */
  u16 idxParent;       /* Index in parent of this node */
  u16 nFree;           /* Number of free bytes on the page */
  u16 nCell;           /* Number of cells on this page, local and ovfl */
  struct _OvflCell {   /* Cells that will not fit on aData[] */
    u8 *pCell;          /* Pointers to the body of the overflow cell */
    u16 idx;            /* Insert this cell before idx-th non-overflow cell */
  } aOvfl[5];
  BtShared *pBt;       /* Pointer back to BTree structure */
  u8 *aData;           /* Pointer back to the start of the page */
  Pgno pgno;           /* Page number for this page */
  MemPage *pParent;    /* The parent of this page.  NULL for root */
};

/*
** The in-memory image of a disk page has the auxiliary information appended
** to the end.  EXTRA_SIZE is the number of bytes of space needed to hold
** that extra information.
*/
#define EXTRA_SIZE sizeof(MemPage)

/* Btree handle */
struct Btree {
  sqlite3 *pSqlite;
  BtShared *pBt;
  u8 inTrans;            /* TRANS_NONE, TRANS_READ or TRANS_WRITE */
};

/*
** Btree.inTrans may take one of the following values.
**
** If the shared-data extension is enabled, there may be multiple users
** of the Btree structure. At most one of these may open a write transaction,
** but any number may have active read transactions. Variable Btree.pDb 
** points to the handle that owns any current write-transaction.
*/
#define TRANS_NONE  0
#define TRANS_READ  1
#define TRANS_WRITE 2

/*
** Everything we need to know about an open database
*/
struct BtShared {
  Pager *pPager;        /* The page cache */
  BtCursor *pCursor;    /* A list of all open cursors */
  MemPage *pPage1;      /* First page of the database */
  u8 inStmt;            /* True if we are in a statement subtransaction */
  u8 readOnly;          /* True if the underlying file is readonly */
  u8 maxEmbedFrac;      /* Maximum payload as % of total page size */
  u8 minEmbedFrac;      /* Minimum payload as % of total page size */
  u8 minLeafFrac;       /* Minimum leaf payload as % of total page size */
  u8 pageSizeFixed;     /* True if the page size can no longer be changed */
#ifndef SQLITE_OMIT_AUTOVACUUM
  u8 autoVacuum;        /* True if database supports auto-vacuum */
#endif
  u16 pageSize;         /* Total number of bytes on a page */
  u16 usableSize;       /* Number of usable bytes on each page */
  int maxLocal;         /* Maximum local payload in non-LEAFDATA tables */
  int minLocal;         /* Minimum local payload in non-LEAFDATA tables */
  int maxLeaf;          /* Maximum local payload in a LEAFDATA table */
  int minLeaf;          /* Minimum local payload in a LEAFDATA table */
  BusyHandler *pBusyHandler;   /* Callback for when there is lock contention */
  u8 inTransaction;     /* Transaction state */
  int nRef;             /* Number of references to this structure */
  int nTransaction;     /* Number of open transactions (read + write) */
  void *pSchema;        /* Pointer to space allocated by sqlite3BtreeSchema() */
  void (*xFreeSchema)(void*);  /* Destructor for BtShared.pSchema */
#ifndef SQLITE_OMIT_SHARED_CACHE
  BtLock *pLock;        /* List of locks held on this shared-btree struct */
  BtShared *pNext;      /* Next in ThreadData.pBtree linked list */
#endif
};

/*
** An instance of the following structure is used to hold information
** about a cell.  The parseCellPtr() function fills in this structure
** based on information extract from the raw disk page.
*/
typedef struct CellInfo CellInfo;
struct CellInfo {
  u8 *pCell;     /* Pointer to the start of cell content */
  i64 nKey;      /* The key for INTKEY tables, or number of bytes in key */
  u32 nData;     /* Number of bytes of data */
  u16 nHeader;   /* Size of the cell content header in bytes */
  u16 nLocal;    /* Amount of payload held locally */
  u16 iOverflow; /* Offset to overflow page number.  Zero if no overflow */
  u16 nSize;     /* Size of the cell content on the main b-tree page */
};

/*
** A cursor is a pointer to a particular entry in the BTree.
** The entry is identified by its MemPage and the index in
** MemPage.aCell[] of the entry.
*/
struct BtCursor {
  Btree *pBtree;            /* The Btree to which this cursor belongs */
  BtCursor *pNext, *pPrev;  /* Forms a linked list of all cursors */
  int (*xCompare)(void*,int,const void*,int,const void*); /* Key comp func */
  void *pArg;               /* First arg to xCompare() */
  Pgno pgnoRoot;            /* The root page of this tree */
  MemPage *pPage;           /* Page that contains the entry */
  int idx;                  /* Index of the entry in pPage->aCell[] */
  CellInfo info;            /* A parse of the cell we are pointing at */
  u8 wrFlag;                /* True if writable */
  u8 eState;                /* One of the CURSOR_XXX constants (see below) */
  void *pKey;      /* Saved key that was cursor's last known position */
  i64 nKey;        /* Size of pKey, or last integer key */
  int skip;        /* (skip<0) -> Prev() is a no-op. (skip>0) -> Next() is */
};

/*
** Potential values for BtCursor.eState.
**
** CURSOR_VALID:
**   Cursor points to a valid entry. getPayload() etc. may be called.
**
** CURSOR_INVALID:
**   Cursor does not point to a valid entry. This can happen (for example) 
**   because the table is empty or because BtreeCursorFirst() has not been
**   called.
**
** CURSOR_REQUIRESEEK:
**   The table that this cursor was opened on still exists, but has been 
**   modified since the cursor was last used. The cursor position is saved
**   in variables BtCursor.pKey and BtCursor.nKey. When a cursor is in 
**   this state, restoreOrClearCursorPosition() can be called to attempt to
**   seek the cursor to the saved position.
*/
#define CURSOR_INVALID           0
#define CURSOR_VALID             1
#define CURSOR_REQUIRESEEK       2

/*
** The TRACE macro will print high-level status information about the
** btree operation when the global variable sqlite3_btree_trace is
** enabled.
*/
#if SQLITE_TEST
# define TRACE(X)   if( sqlite3_btree_trace )\
/*                        { sqlite3DebugPrintf X; fflush(stdout); } */ \
{ printf X; fflush(stdout); }
int sqlite3_btree_trace=0;  /* True to enable tracing */
#else
# define TRACE(X)
#endif

/*
** Forward declaration
*/
static int checkReadLocks(Btree*,Pgno,BtCursor*);

/*
** Read or write a two- and four-byte big-endian integer values.
*/
static u32 get2byte(unsigned char *p){
  return (p[0]<<8) | p[1];
}
static u32 get4byte(unsigned char *p){
  return (p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];
}
static void put2byte(unsigned char *p, u32 v){
  p[0] = v>>8;
  p[1] = v;
}
static void put4byte(unsigned char *p, u32 v){
  p[0] = v>>24;
  p[1] = v>>16;
  p[2] = v>>8;
  p[3] = v;
}

/*
** Routines to read and write variable-length integers.  These used to
** be defined locally, but now we use the varint routines in the util.c
** file.
*/
#define getVarint    sqlite3GetVarint
/* #define getVarint32  sqlite3GetVarint32 */
#define getVarint32(A,B)  ((*B=*(A))<=0x7f?1:sqlite3GetVarint32(A,B))
#define putVarint    sqlite3PutVarint

/* The database page the PENDING_BYTE occupies. This page is never used.
** TODO: This macro is very similary to PAGER_MJ_PGNO() in pager.c. They
** should possibly be consolidated (presumably in pager.h).
**
** If disk I/O is omitted (meaning that the database is stored purely
** in memory) then there is no pending byte.
*/
#ifdef SQLITE_OMIT_DISKIO
# define PENDING_BYTE_PAGE(pBt)  0x7fffffff
#else
# define PENDING_BYTE_PAGE(pBt) ((PENDING_BYTE/(pBt)->pageSize)+1)
#endif

/*
** A linked list of the following structures is stored at BtShared.pLock.
** Locks are added (or upgraded from READ_LOCK to WRITE_LOCK) when a cursor 
** is opened on the table with root page BtShared.iTable. Locks are removed
** from this list when a transaction is committed or rolled back, or when
** a btree handle is closed.
*/
struct BtLock {
  Btree *pBtree;        /* Btree handle holding this lock */
  Pgno iTable;          /* Root page of table */
  u8 eLock;             /* READ_LOCK or WRITE_LOCK */
  BtLock *pNext;        /* Next in BtShared.pLock list */
};

/* Candidate values for BtLock.eLock */
#define READ_LOCK     1
#define WRITE_LOCK    2

#ifdef SQLITE_OMIT_SHARED_CACHE
  /*
  ** The functions queryTableLock(), lockTable() and unlockAllTables()
  ** manipulate entries in the BtShared.pLock linked list used to store
  ** shared-cache table level locks. If the library is compiled with the
  ** shared-cache feature disabled, then there is only ever one user
  ** of each BtShared structure and so this locking is not necessary. 
  ** So define the lock related functions as no-ops.
  */
  #define queryTableLock(a,b,c) SQLITE_OK
  #define lockTable(a,b,c) SQLITE_OK
  #define unlockAllTables(a)
#else


/*
** Query to see if btree handle p may obtain a lock of type eLock 
** (READ_LOCK or WRITE_LOCK) on the table with root-page iTab. Return
** SQLITE_OK if the lock may be obtained (by calling lockTable()), or
** SQLITE_LOCKED if not.
*/
static int queryTableLock(Btree *p, Pgno iTab, u8 eLock){
  BtShared *pBt = p->pBt;
  BtLock *pIter;

  /* This is a no-op if the shared-cache is not enabled */
  if( 0==sqlite3ThreadDataReadOnly()->useSharedData ){
    return SQLITE_OK;
  }

  /* This (along with lockTable()) is where the ReadUncommitted flag is
  ** dealt with. If the caller is querying for a read-lock and the flag is
  ** set, it is unconditionally granted - even if there are write-locks
  ** on the table. If a write-lock is requested, the ReadUncommitted flag
  ** is not considered.
  **
  ** In function lockTable(), if a read-lock is demanded and the 
  ** ReadUncommitted flag is set, no entry is added to the locks list 
  ** (BtShared.pLock).
  **
  ** To summarize: If the ReadUncommitted flag is set, then read cursors do
  ** not create or respect table locks. The locking procedure for a 
  ** write-cursor does not change.
  */
  if( 
    !p->pSqlite || 
    0==(p->pSqlite->flags&SQLITE_ReadUncommitted) || 
    eLock==WRITE_LOCK ||
    iTab==MASTER_ROOT
  ){
    for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
      if( pIter->pBtree!=p && pIter->iTable==iTab && 
          (pIter->eLock!=eLock || eLock!=READ_LOCK) ){
        return SQLITE_LOCKED;
      }
    }
  }
  return SQLITE_OK;
}

/*
** Add a lock on the table with root-page iTable to the shared-btree used
** by Btree handle p. Parameter eLock must be either READ_LOCK or 
** WRITE_LOCK.
**
** SQLITE_OK is returned if the lock is added successfully. SQLITE_BUSY and
** SQLITE_NOMEM may also be returned.
*/
static int lockTable(Btree *p, Pgno iTable, u8 eLock){
  BtShared *pBt = p->pBt;
  BtLock *pLock = 0;
  BtLock *pIter;

  /* This is a no-op if the shared-cache is not enabled */
  if( 0==sqlite3ThreadDataReadOnly()->useSharedData ){
    return SQLITE_OK;
  }

  assert( SQLITE_OK==queryTableLock(p, iTable, eLock) );

  /* If the read-uncommitted flag is set and a read-lock is requested,
  ** return early without adding an entry to the BtShared.pLock list. See
  ** comment in function queryTableLock() for more info on handling 
  ** the ReadUncommitted flag.
  */
  if( 
    (p->pSqlite) && 
    (p->pSqlite->flags&SQLITE_ReadUncommitted) && 
    (eLock==READ_LOCK) &&
    iTable!=MASTER_ROOT
  ){
    return SQLITE_OK;
  }

  /* First search the list for an existing lock on this table. */
  for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
    if( pIter->iTable==iTable && pIter->pBtree==p ){
      pLock = pIter;
      break;
    }
  }

  /* If the above search did not find a BtLock struct associating Btree p
  ** with table iTable, allocate one and link it into the list.
  */
  if( !pLock ){
    pLock = (BtLock *)sqliteMalloc(sizeof(BtLock));
    if( !pLock ){
      return SQLITE_NOMEM;
    }
    pLock->iTable = iTable;
    pLock->pBtree = p;
    pLock->pNext = pBt->pLock;
    pBt->pLock = pLock;
  }

  /* Set the BtLock.eLock variable to the maximum of the current lock
  ** and the requested lock. This means if a write-lock was already held
  ** and a read-lock requested, we don't incorrectly downgrade the lock.
  */
  assert( WRITE_LOCK>READ_LOCK );
  if( eLock>pLock->eLock ){
    pLock->eLock = eLock;
  }

  return SQLITE_OK;
}

/*
** Release all the table locks (locks obtained via calls to the lockTable()
** procedure) held by Btree handle p.
*/
static void unlockAllTables(Btree *p){
  BtLock **ppIter = &p->pBt->pLock;

  /* If the shared-cache extension is not enabled, there should be no
  ** locks in the BtShared.pLock list, making this procedure a no-op. Assert
  ** that this is the case.
  */
  assert( sqlite3ThreadDataReadOnly()->useSharedData || 0==*ppIter );

  while( *ppIter ){
    BtLock *pLock = *ppIter;
    if( pLock->pBtree==p ){
      *ppIter = pLock->pNext;
      sqliteFree(pLock);
    }else{
      ppIter = &pLock->pNext;
    }
  }
}
#endif /* SQLITE_OMIT_SHARED_CACHE */

static void releasePage(MemPage *pPage);  /* Forward reference */

/*
** Save the current cursor position in the variables BtCursor.nKey 
** and BtCursor.pKey. The cursor's state is set to CURSOR_REQUIRESEEK.
*/
static int saveCursorPosition(BtCursor *pCur){
  int rc;

  assert( CURSOR_VALID==pCur->eState );
  assert( 0==pCur->pKey );

  rc = sqlite3BtreeKeySize(pCur, &pCur->nKey);

  /* If this is an intKey table, then the above call to BtreeKeySize()
  ** stores the integer key in pCur->nKey. In this case this value is
  ** all that is required. Otherwise, if pCur is not open on an intKey
  ** table, then malloc space for and store the pCur->nKey bytes of key 
  ** data.
  */
  if( rc==SQLITE_OK && 0==pCur->pPage->intKey){
    void *pKey = sqliteMalloc(pCur->nKey);
    if( pKey ){
      rc = sqlite3BtreeKey(pCur, 0, pCur->nKey, pKey);
      if( rc==SQLITE_OK ){
        pCur->pKey = pKey;
      }else{
        sqliteFree(pKey);
      }
    }else{
      rc = SQLITE_NOMEM;
    }
  }
  assert( !pCur->pPage->intKey || !pCur->pKey );

  if( rc==SQLITE_OK ){
    releasePage(pCur->pPage);
    pCur->pPage = 0;
    pCur->eState = CURSOR_REQUIRESEEK;
  }

  return rc;
}

/*
** Save the positions of all cursors except pExcept open on the table 
** with root-page iRoot. Usually, this is called just before cursor
** pExcept is used to modify the table (BtreeDelete() or BtreeInsert()).
*/
static int saveAllCursors(BtShared *pBt, Pgno iRoot, BtCursor *pExcept){
  BtCursor *p;
  for(p=pBt->pCursor; p; p=p->pNext){
    if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) && 
        p->eState==CURSOR_VALID ){
      int rc = saveCursorPosition(p);
      if( SQLITE_OK!=rc ){
        return rc;
      }
    }
  }
  return SQLITE_OK;
}

/*
** Restore the cursor to the position it was in (or as close to as possible)
** when saveCursorPosition() was called. Note that this call deletes the 
** saved position info stored by saveCursorPosition(), so there can be
** at most one effective restoreOrClearCursorPosition() call after each 
** saveCursorPosition().
**
** If the second argument argument - doSeek - is false, then instead of 
** returning the cursor to it's saved position, any saved position is deleted
** and the cursor state set to CURSOR_INVALID.
*/
static int restoreOrClearCursorPositionX(BtCursor *pCur, int doSeek){
  int rc = SQLITE_OK;
  assert( pCur->eState==CURSOR_REQUIRESEEK );
  pCur->eState = CURSOR_INVALID;
  if( doSeek ){
    rc = sqlite3BtreeMoveto(pCur, pCur->pKey, pCur->nKey, &pCur->skip);
  }
  if( rc==SQLITE_OK ){
    sqliteFree(pCur->pKey);
    pCur->pKey = 0;
    assert( CURSOR_VALID==pCur->eState || CURSOR_INVALID==pCur->eState );
  }
  return rc;
}

#define restoreOrClearCursorPosition(p,x) \
  (p->eState==CURSOR_REQUIRESEEK?restoreOrClearCursorPositionX(p,x):SQLITE_OK)

#ifndef SQLITE_OMIT_AUTOVACUUM
/*
** These macros define the location of the pointer-map entry for a 
** database page. The first argument to each is the number of usable
** bytes on each page of the database (often 1024). The second is the
** page number to look up in the pointer map.
**
** PTRMAP_PAGENO returns the database page number of the pointer-map
** page that stores the required pointer. PTRMAP_PTROFFSET returns
** the offset of the requested map entry.
**
** If the pgno argument passed to PTRMAP_PAGENO is a pointer-map page,
** then pgno is returned. So (pgno==PTRMAP_PAGENO(pgsz, pgno)) can be
** used to test if pgno is a pointer-map page. PTRMAP_ISPAGE implements
** this test.
*/
#define PTRMAP_PAGENO(pBt, pgno) ptrmapPageno(pBt, pgno)
#define PTRMAP_PTROFFSET(pBt, pgno) (5*(pgno-ptrmapPageno(pBt, pgno)-1))
#define PTRMAP_ISPAGE(pBt, pgno) (PTRMAP_PAGENO((pBt),(pgno))==(pgno))

static Pgno ptrmapPageno(BtShared *pBt, Pgno pgno){
  int nPagesPerMapPage = (pBt->usableSize/5)+1;
  int iPtrMap = (pgno-2)/nPagesPerMapPage;
  int ret = (iPtrMap*nPagesPerMapPage) + 2; 
  if( ret==PENDING_BYTE_PAGE(pBt) ){
    ret++;
  }
  return ret;
}

/*
** The pointer map is a lookup table that identifies the parent page for
** each child page in the database file.  The parent page is the page that
** contains a pointer to the child.  Every page in the database contains
** 0 or 1 parent pages.  (In this context 'database page' refers
** to any page that is not part of the pointer map itself.)  Each pointer map
** entry consists of a single byte 'type' and a 4 byte parent page number.
** The PTRMAP_XXX identifiers below are the valid types.
**
** The purpose of the pointer map is to facility moving pages from one
** position in the file to another as part of autovacuum.  When a page
** is moved, the pointer in its parent must be updated to point to the
** new location.  The pointer map is used to locate the parent page quickly.
**
** PTRMAP_ROOTPAGE: The database page is a root-page. The page-number is not
**                  used in this case.
**
** PTRMAP_FREEPAGE: The database page is an unused (free) page. The page-number 
**                  is not used in this case.
**
** PTRMAP_OVERFLOW1: The database page is the first page in a list of 
**                   overflow pages. The page number identifies the page that
**                   contains the cell with a pointer to this overflow page.
**
** PTRMAP_OVERFLOW2: The database page is the second or later page in a list of
**                   overflow pages. The page-number identifies the previous
**                   page in the overflow page list.
**
** PTRMAP_BTREE: The database page is a non-root btree page. The page number
**               identifies the parent page in the btree.
*/
#define PTRMAP_ROOTPAGE 1
#define PTRMAP_FREEPAGE 2
#define PTRMAP_OVERFLOW1 3
#define PTRMAP_OVERFLOW2 4
#define PTRMAP_BTREE 5

/*
** Write an entry into the pointer map.
**
** This routine updates the pointer map entry for page number 'key'
** so that it maps to type 'eType' and parent page number 'pgno'.
** An error code is returned if something goes wrong, otherwise SQLITE_OK.
*/
static int ptrmapPut(BtShared *pBt, Pgno key, u8 eType, Pgno parent){
  u8 *pPtrmap;    /* The pointer map page */
  Pgno iPtrmap;   /* The pointer map page number */
  int offset;     /* Offset in pointer map page */
  int rc;

  /* The master-journal page number must never be used as a pointer map page */
  assert( 0==PTRMAP_ISPAGE(pBt, PENDING_BYTE_PAGE(pBt)) );

  assert( pBt->autoVacuum );
  if( key==0 ){
    return SQLITE_CORRUPT_BKPT;
  }
  iPtrmap = PTRMAP_PAGENO(pBt, key);
  rc = sqlite3pager_get(pBt->pPager, iPtrmap, (void **)&pPtrmap);
  if( rc!=SQLITE_OK ){
    return rc;
  }
  offset = PTRMAP_PTROFFSET(pBt, key);

  if( eType!=pPtrmap[offset] || get4byte(&pPtrmap[offset+1])!=parent ){
    TRACE(("PTRMAP_UPDATE: %d->(%d,%d)\n", key, eType, parent));
    rc = sqlite3pager_write(pPtrmap);
    if( rc==SQLITE_OK ){
      pPtrmap[offset] = eType;
      put4byte(&pPtrmap[offset+1], parent);
    }
  }

  sqlite3pager_unref(pPtrmap);
  return rc;
}

/*
** Read an entry from the pointer map.
**
** This routine retrieves the pointer map entry for page 'key', writing
** the type and parent page number to *pEType and *pPgno respectively.
** An error code is returned if something goes wrong, otherwise SQLITE_OK.
*/
static int ptrmapGet(BtShared *pBt, Pgno key, u8 *pEType, Pgno *pPgno){
  int iPtrmap;       /* Pointer map page index */
  u8 *pPtrmap;       /* Pointer map page data */
  int offset;        /* Offset of entry in pointer map */
  int rc;

  iPtrmap = PTRMAP_PAGENO(pBt, key);
  rc = sqlite3pager_get(pBt->pPager, iPtrmap, (void **)&pPtrmap);
  if( rc!=0 ){
    return rc;
  }

  offset = PTRMAP_PTROFFSET(pBt, key);
  assert( pEType!=0 );
  *pEType = pPtrmap[offset];
  if( pPgno ) *pPgno = get4byte(&pPtrmap[offset+1]);

  sqlite3pager_unref(pPtrmap);
  if( *pEType<1 || *pEType>5 ) return SQLITE_CORRUPT_BKPT;
  return SQLITE_OK;
}

#endif /* SQLITE_OMIT_AUTOVACUUM */

/*
** Given a btree page and a cell index (0 means the first cell on
** the page, 1 means the second cell, and so forth) return a pointer
** to the cell content.
**
** This routine works only for pages that do not contain overflow cells.
*/
static u8 *findCell(MemPage *pPage, int iCell){
  u8 *data = pPage->aData;
  assert( iCell>=0 );
  assert( iCell<get2byte(&data[pPage->hdrOffset+3]) );
  return data + get2byte(&data[pPage->cellOffset+2*iCell]);
}

/*
** This a more complex version of findCell() that works for
** pages that do contain overflow cells.  See insert
*/
static u8 *findOverflowCell(MemPage *pPage, int iCell){
  int i;
  for(i=pPage->nOverflow-1; i>=0; i--){
    int k;
    struct _OvflCell *pOvfl;
    pOvfl = &pPage->aOvfl[i];
    k = pOvfl->idx;
    if( k<=iCell ){
      if( k==iCell ){
        return pOvfl->pCell;
      }
      iCell--;
    }
  }
  return findCell(pPage, iCell);
}

/*
** Parse a cell content block and fill in the CellInfo structure.  There
** are two versions of this function.  parseCell() takes a cell index
** as the second argument and parseCellPtr() takes a pointer to the
** body of the cell as its second argument.
*/
static void parseCellPtr(
  MemPage *pPage,         /* Page containing the cell */
  u8 *pCell,              /* Pointer to the cell text. */
  CellInfo *pInfo         /* Fill in this structure */
){
  int n;                  /* Number bytes in cell content header */
  u32 nPayload;           /* Number of bytes of cell payload */

  pInfo->pCell = pCell;
  assert( pPage->leaf==0 || pPage->leaf==1 );
  n = pPage->childPtrSize;
  assert( n==4-4*pPage->leaf );
  if( pPage->hasData ){
    n += getVarint32(&pCell[n], &nPayload);
  }else{
    nPayload = 0;
  }
  pInfo->nData = nPayload;
  if( pPage->intKey ){
    n += getVarint(&pCell[n], (u64 *)&pInfo->nKey);
  }else{
    u32 x;
    n += getVarint32(&pCell[n], &x);
    pInfo->nKey = x;
    nPayload += x;
  }
  pInfo->nHeader = n;
  if( nPayload<=pPage->maxLocal ){
    /* This is the (easy) common case where the entire payload fits
    ** on the local page.  No overflow is required.
    */
    int nSize;          /* Total size of cell content in bytes */
    pInfo->nLocal = nPayload;
    pInfo->iOverflow = 0;
    nSize = nPayload + n;
    if( nSize<4 ){
      nSize = 4;        /* Minimum cell size is 4 */
    }
    pInfo->nSize = nSize;
  }else{
    /* If the payload will not fit completely on the local page, we have
    ** to decide how much to store locally and how much to spill onto
    ** overflow pages.  The strategy is to minimize the amount of unused
    ** space on overflow pages while keeping the amount of local storage
    ** in between minLocal and maxLocal.
    **
    ** Warning:  changing the way overflow payload is distributed in any
    ** way will result in an incompatible file format.
    */
    int minLocal;  /* Minimum amount of payload held locally */
    int maxLocal;  /* Maximum amount of payload held locally */
    int surplus;   /* Overflow payload available for local storage */

    minLocal = pPage->minLocal;
    maxLocal = pPage->maxLocal;
    surplus = minLocal + (nPayload - minLocal)%(pPage->pBt->usableSize - 4);
    if( surplus <= maxLocal ){
      pInfo->nLocal = surplus;
    }else{
      pInfo->nLocal = minLocal;
    }
    pInfo->iOverflow = pInfo->nLocal + n;
    pInfo->nSize = pInfo->iOverflow + 4;
  }
}
static void parseCell(
  MemPage *pPage,         /* Page containing the cell */
  int iCell,              /* The cell index.  First cell is 0 */
  CellInfo *pInfo         /* Fill in this structure */
){
  parseCellPtr(pPage, findCell(pPage, iCell), pInfo);
}

/*
** Compute the total number of bytes that a Cell needs in the cell
** data area of the btree-page.  The return number includes the cell
** data header and the local payload, but not any overflow page or
** the space used by the cell pointer.
*/
#ifndef NDEBUG
static int cellSize(MemPage *pPage, int iCell){
  CellInfo info;
  parseCell(pPage, iCell, &info);
  return info.nSize;
}
#endif
static int cellSizePtr(MemPage *pPage, u8 *pCell){
  CellInfo info;
  parseCellPtr(pPage, pCell, &info);
  return info.nSize;
}

#ifndef SQLITE_OMIT_AUTOVACUUM
/*
** If the cell pCell, part of page pPage contains a pointer
** to an overflow page, insert an entry into the pointer-map
** for the overflow page.
*/
static int ptrmapPutOvflPtr(MemPage *pPage, u8 *pCell){
  if( pCell ){
    CellInfo info;
    parseCellPtr(pPage, pCell, &info);
    if( (info.nData+(pPage->intKey?0:info.nKey))>info.nLocal ){
      Pgno ovfl = get4byte(&pCell[info.iOverflow]);
      return ptrmapPut(pPage->pBt, ovfl, PTRMAP_OVERFLOW1, pPage->pgno);
    }
  }
  return SQLITE_OK;
}
/*
** If the cell with index iCell on page pPage contains a pointer
** to an overflow page, insert an entry into the pointer-map
** for the overflow page.
*/
static int ptrmapPutOvfl(MemPage *pPage, int iCell){
  u8 *pCell;
  pCell = findOverflowCell(pPage, iCell);
  return ptrmapPutOvflPtr(pPage, pCell);
}
#endif


/* A bunch of assert() statements to check the transaction state variables
** of handle p (type Btree*) are internally consistent.
*/
#define btreeIntegrity(p) \
  assert( p->inTrans!=TRANS_NONE || p->pBt->nTransaction<p->pBt->nRef ); \
  assert( p->pBt->nTransaction<=p->pBt->nRef ); \
  assert( p->pBt->inTransaction!=TRANS_NONE || p->pBt->nTransaction==0 ); \
  assert( p->pBt->inTransaction>=p->inTrans ); 

/*
** Defragment the page given.  All Cells are moved to the
** end of the page and all free space is collected into one
** big FreeBlk that occurs in between the header and cell
** pointer array and the cell content area.
*/
static int defragmentPage(MemPage *pPage){
  int i;                     /* Loop counter */
  int pc;                    /* Address of a i-th cell */
  int addr;                  /* Offset of first byte after cell pointer array */
  int hdr;                   /* Offset to the page header */
  int size;                  /* Size of a cell */
  int usableSize;            /* Number of usable bytes on a page */
  int cellOffset;            /* Offset to the cell pointer array */
  int brk;                   /* Offset to the cell content area */
  int nCell;                 /* Number of cells on the page */
  unsigned char *data;       /* The page data */
  unsigned char *temp;       /* Temp area for cell content */

  assert( sqlite3pager_iswriteable(pPage->aData) );
  assert( pPage->pBt!=0 );
  assert( pPage->pBt->usableSize <= SQLITE_MAX_PAGE_SIZE );
  assert( pPage->nOverflow==0 );
  temp = sqliteMalloc( pPage->pBt->pageSize );
  if( temp==0 ) return SQLITE_NOMEM;
  data = pPage->aData;
  hdr = pPage->hdrOffset;
  cellOffset = pPage->cellOffset;
  nCell = pPage->nCell;
  assert( nCell==get2byte(&data[hdr+3]) );
  usableSize = pPage->pBt->usableSize;
  brk = get2byte(&data[hdr+5]);
  memcpy(&temp[brk], &data[brk], usableSize - brk);
  brk = usableSize;
  for(i=0; i<nCell; i++){
    u8 *pAddr;     /* The i-th cell pointer */
    pAddr = &data[cellOffset + i*2];
    pc = get2byte(pAddr);
    assert( pc<pPage->pBt->usableSize );
    size = cellSizePtr(pPage, &temp[pc]);
    brk -= size;
    memcpy(&data[brk], &temp[pc], size);
    put2byte(pAddr, brk);
  }
  assert( brk>=cellOffset+2*nCell );
  put2byte(&data[hdr+5], brk);
  data[hdr+1] = 0;
  data[hdr+2] = 0;
  data[hdr+7] = 0;
  addr = cellOffset+2*nCell;
  memset(&data[addr], 0, brk-addr);
  sqliteFree(temp);
  return SQLITE_OK;
}

/*
** Allocate nByte bytes of space on a page.
**
** Return the index into pPage->aData[] of the first byte of
** the new allocation. Or return 0 if there is not enough free
** space on the page to satisfy the allocation request.
**
** If the page contains nBytes of free space but does not contain
** nBytes of contiguous free space, then this routine automatically
** calls defragementPage() to consolidate all free space before 
** allocating the new chunk.
*/
static int allocateSpace(MemPage *pPage, int nByte){
  int addr, pc, hdr;
  int size;
  int nFrag;
  int top;
  int nCell;
  int cellOffset;
  unsigned char *data;
  
  data = pPage->aData;
  assert( sqlite3pager_iswriteable(data) );
  assert( pPage->pBt );
  if( nByte<4 ) nByte = 4;
  if( pPage->nFree<nByte || pPage->nOverflow>0 ) return 0;
  pPage->nFree -= nByte;
  hdr = pPage->hdrOffset;

  nFrag = data[hdr+7];
  if( nFrag<60 ){
    /* Search the freelist looking for a slot big enough to satisfy the
    ** space request. */
    addr = hdr+1;
    while( (pc = get2byte(&data[addr]))>0 ){
      size = get2byte(&data[pc+2]);
      if( size>=nByte ){
        if( size<nByte+4 ){
          memcpy(&data[addr], &data[pc], 2);
          data[hdr+7] = nFrag + size - nByte;
          return pc;
        }else{
          put2byte(&data[pc+2], size-nByte);
          return pc + size - nByte;
        }
      }
      addr = pc;
    }
  }

  /* Allocate memory from the gap in between the cell pointer array
  ** and the cell content area.
  */
  top = get2byte(&data[hdr+5]);
  nCell = get2byte(&data[hdr+3]);
  cellOffset = pPage->cellOffset;
  if( nFrag>=60 || cellOffset + 2*nCell > top - nByte ){
    if( defragmentPage(pPage) ) return 0;
    top = get2byte(&data[hdr+5]);
  }
  top -= nByte;
  assert( cellOffset + 2*nCell <= top );
  put2byte(&data[hdr+5], top);
  return top;
}

/*
** Return a section of the pPage->aData to the freelist.
** The first byte of the new free block is pPage->aDisk[start]
** and the size of the block is "size" bytes.
**
** Most of the effort here is involved in coalesing adjacent
** free blocks into a single big free block.
*/
static void freeSpace(MemPage *pPage, int start, int size){
  int addr, pbegin, hdr;
  unsigned char *data = pPage->aData;

  assert( pPage->pBt!=0 );
  assert( sqlite3pager_iswriteable(data) );
  assert( start>=pPage->hdrOffset+6+(pPage->leaf?0:4) );
  assert( (start + size)<=pPage->pBt->usableSize );
  if( size<4 ) size = 4;

#ifdef SQLITE_SECURE_DELETE
  /* Overwrite deleted information with zeros when the SECURE_DELETE 
  ** option is enabled at compile-time */
  memset(&data[start], 0, size);
#endif

  /* Add the space back into the linked list of freeblocks */
  hdr = pPage->hdrOffset;
  addr = hdr + 1;
  while( (pbegin = get2byte(&data[addr]))<start && pbegin>0 ){
    assert( pbegin<=pPage->pBt->usableSize-4 );
    assert( pbegin>addr );
    addr = pbegin;
  }
  assert( pbegin<=pPage->pBt->usableSize-4 );
  assert( pbegin>addr || pbegin==0 );
  put2byte(&data[addr], start);
  put2byte(&data[start], pbegin);
  put2byte(&data[start+2], size);
  pPage->nFree += size;

  /* Coalesce adjacent free blocks */
  addr = pPage->hdrOffset + 1;
  while( (pbegin = get2byte(&data[addr]))>0 ){
    int pnext, psize;
    assert( pbegin>addr );
    assert( pbegin<=pPage->pBt->usableSize-4 );
    pnext = get2byte(&data[pbegin]);
    psize = get2byte(&data[pbegin+2]);
    if( pbegin + psize + 3 >= pnext && pnext>0 ){
      int frag = pnext - (pbegin+psize);
      assert( frag<=data[pPage->hdrOffset+7] );
      data[pPage->hdrOffset+7] -= frag;
      put2byte(&data[pbegin], get2byte(&data[pnext]));
      put2byte(&data[pbegin+2], pnext+get2byte(&data[pnext+2])-pbegin);
    }else{
      addr = pbegin;
    }
  }

  /* If the cell content area begins with a freeblock, remove it. */
  if( data[hdr+1]==data[hdr+5] && data[hdr+2]==data[hdr+6] ){
    int top;
    pbegin = get2byte(&data[hdr+1]);
    memcpy(&data[hdr+1], &data[pbegin], 2);
    top = get2byte(&data[hdr+5]);
    put2byte(&data[hdr+5], top + get2byte(&data[pbegin+2]));
  }
}

/*
** Decode the flags byte (the first byte of the header) for a page
** and initialize fields of the MemPage structure accordingly.
*/
static void decodeFlags(MemPage *pPage, int flagByte){
  BtShared *pBt;     /* A copy of pPage->pBt */

  assert( pPage->hdrOffset==(pPage->pgno==1 ? 100 : 0) );
  pPage->intKey = (flagByte & (PTF_INTKEY|PTF_LEAFDATA))!=0;
  pPage->zeroData = (flagByte & PTF_ZERODATA)!=0;
  pPage->leaf = (flagByte & PTF_LEAF)!=0;
  pPage->childPtrSize = 4*(pPage->leaf==0);
  pBt = pPage->pBt;
  if( flagByte & PTF_LEAFDATA ){
    pPage->leafData = 1;
    pPage->maxLocal = pBt->maxLeaf;
    pPage->minLocal = pBt->minLeaf;
  }else{
    pPage->leafData = 0;
    pPage->maxLocal = pBt->maxLocal;
    pPage->minLocal = pBt->minLocal;
  }
  pPage->hasData = !(pPage->zeroData || (!pPage->leaf && pPage->leafData));
}

/*
** Initialize the auxiliary information for a disk block.
**
** The pParent parameter must be a pointer to the MemPage which
** is the parent of the page being initialized.  The root of a
** BTree has no parent and so for that page, pParent==NULL.
**
** Return SQLITE_OK on success.  If we see that the page does
** not contain a well-formed database page, then return 
** SQLITE_CORRUPT.  Note that a return of SQLITE_OK does not
** guarantee that the page is well-formed.  It only shows that
** we failed to detect any corruption.
*/
static int initPage(
  MemPage *pPage,        /* The page to be initialized */
  MemPage *pParent       /* The parent.  Might be NULL */
){
  int pc;            /* Address of a freeblock within pPage->aData[] */
  int hdr;           /* Offset to beginning of page header */
  u8 *data;          /* Equal to pPage->aData */
  BtShared *pBt;        /* The main btree structure */
  int usableSize;    /* Amount of usable space on each page */
  int cellOffset;    /* Offset from start of page to first cell pointer */
  int nFree;         /* Number of unused bytes on the page */
  int top;           /* First byte of the cell content area */

  pBt = pPage->pBt;
  assert( pBt!=0 );
  assert( pParent==0 || pParent->pBt==pBt );
  assert( pPage->pgno==sqlite3pager_pagenumber(pPage->aData) );
  assert( pPage->aData == &((unsigned char*)pPage)[-pBt->pageSize] );
  if( pPage->pParent!=pParent && (pPage->pParent!=0 || pPage->isInit) ){
    /* The parent page should never change unless the file is corrupt */
    return SQLITE_CORRUPT_BKPT;
  }
  if( pPage->isInit ) return SQLITE_OK;
  if( pPage->pParent==0 && pParent!=0 ){
    pPage->pParent = pParent;
    sqlite3pager_ref(pParent->aData);
  }
  hdr = pPage->hdrOffset;
  data = pPage->aData;
  decodeFlags(pPage, data[hdr]);
  pPage->nOverflow = 0;
  pPage->idxShift = 0;
  usableSize = pBt->usableSize;
  pPage->cellOffset = cellOffset = hdr + 12 - 4*pPage->leaf;
  top = get2byte(&data[hdr+5]);
  pPage->nCell = get2byte(&data[hdr+3]);
  if( pPage->nCell>MX_CELL(pBt) ){
    /* To many cells for a single page.  The page must be corrupt */
    return SQLITE_CORRUPT_BKPT;
  }
  if( pPage->nCell==0 && pParent!=0 && pParent->pgno!=1 ){
    /* All pages must have at least one cell, except for root pages */
    return SQLITE_CORRUPT_BKPT;
  }

  /* Compute the total free space on the page */
  pc = get2byte(&data[hdr+1]);
  nFree = data[hdr+7] + top - (cellOffset + 2*pPage->nCell);
  while( pc>0 ){
    int next, size;
    if( pc>usableSize-4 ){
      /* Free block is off the page */
      return SQLITE_CORRUPT_BKPT; 
    }
    next = get2byte(&data[pc]);
    size = get2byte(&data[pc+2]);
    if( next>0 && next<=pc+size+3 ){
      /* Free blocks must be in accending order */
      return SQLITE_CORRUPT_BKPT; 
    }
    nFree += size;
    pc = next;
  }
  pPage->nFree = nFree;
  if( nFree>=usableSize ){
    /* Free space cannot exceed total page size */
    return SQLITE_CORRUPT_BKPT; 
  }

  pPage->isInit = 1;
  return SQLITE_OK;
}

/*
** Set up a raw page so that it looks like a database page holding
** no entries.
*/
static void zeroPage(MemPage *pPage, int flags){
  unsigned char *data = pPage->aData;
  BtShared *pBt = pPage->pBt;
  int hdr = pPage->hdrOffset;
  int first;

  assert( sqlite3pager_pagenumber(data)==pPage->pgno );
  assert( &data[pBt->pageSize] == (unsigned char*)pPage );
  assert( sqlite3pager_iswriteable(data) );
  memset(&data[hdr], 0, pBt->usableSize - hdr);
  data[hdr] = flags;
  first = hdr + 8 + 4*((flags&PTF_LEAF)==0);
  memset(&data[hdr+1], 0, 4);
  data[hdr+7] = 0;
  put2byte(&data[hdr+5], pBt->usableSize);
  pPage->nFree = pBt->usableSize - first;
  decodeFlags(pPage, flags);
  pPage->hdrOffset = hdr;
  pPage->cellOffset = first;
  pPage->nOverflow = 0;
  pPage->idxShift = 0;
  pPage->nCell = 0;
  pPage->isInit = 1;
}

/*
** Get a page from the pager.  Initialize the MemPage.pBt and
** MemPage.aData elements if needed.
*/
static int getPage(BtShared *pBt, Pgno pgno, MemPage **ppPage){
  int rc;
  unsigned char *aData;
  MemPage *pPage;
  rc = sqlite3pager_get(pBt->pPager, pgno, (void**)&aData);
  if( rc ) return rc;
  pPage = (MemPage*)&aData[pBt->pageSize];
  pPage->aData = aData;
  pPage->pBt = pBt;
  pPage->pgno = pgno;
  pPage->hdrOffset = pPage->pgno==1 ? 100 : 0;
  *ppPage = pPage;
  return SQLITE_OK;
}

/*
** Get a page from the pager and initialize it.  This routine
** is just a convenience wrapper around separate calls to
** getPage() and initPage().
*/
static int getAndInitPage(
  BtShared *pBt,          /* The database file */
  Pgno pgno,           /* Number of the page to get */
  MemPage **ppPage,    /* Write the page pointer here */
  MemPage *pParent     /* Parent of the page */
){
  int rc;
  if( pgno==0 ){
    return SQLITE_CORRUPT_BKPT; 
  }
  rc = getPage(pBt, pgno, ppPage);
  if( rc==SQLITE_OK && (*ppPage)->isInit==0 ){
    rc = initPage(*ppPage, pParent);
  }
  return rc;
}

/*
** Release a MemPage.  This should be called once for each prior
** call to getPage.
*/
static void releasePage(MemPage *pPage){
  if( pPage ){
    assert( pPage->aData );
    assert( pPage->pBt );
    assert( &pPage->aData[pPage->pBt->pageSize]==(unsigned char*)pPage );
    sqlite3pager_unref(pPage->aData);
  }
}

/*
** This routine is called when the reference count for a page
** reaches zero.  We need to unref the pParent pointer when that
** happens.
*/
static void pageDestructor(void *pData, int pageSize){
  MemPage *pPage;
  assert( (pageSize & 7)==0 );
  pPage = (MemPage*)&((char*)pData)[pageSize];
  if( pPage->pParent ){
    MemPage *pParent = pPage->pParent;
    pPage->pParent = 0;
    releasePage(pParent);
  }
  pPage->isInit = 0;
}

/*
** During a rollback, when the pager reloads information into the cache
** so that the cache is restored to its original state at the start of
** the transaction, for each page restored this routine is called.
**
** This routine needs to reset the extra data section at the end of the
** page to agree with the restored data.
*/
static void pageReinit(void *pData, int pageSize){
  MemPage *pPage;
  assert( (pageSize & 7)==0 );
  pPage = (MemPage*)&((char*)pData)[pageSize];
  if( pPage->isInit ){
    pPage->isInit = 0;
    initPage(pPage, pPage->pParent);
  }
}

/*
** Open a database file.
** 
** zFilename is the name of the database file.  If zFilename is NULL
** a new database with a random name is created.  This randomly named
** database file will be deleted when sqlite3BtreeClose() is called.
*/
int sqlite3BtreeOpen(
  const char *zFilename,  /* Name of the file containing the BTree database */
  sqlite3 *pSqlite,       /* Associated database handle */
  Btree **ppBtree,        /* Pointer to new Btree object written here */
  int flags               /* Options */
){
  BtShared *pBt;          /* Shared part of btree structure */
  Btree *p;               /* Handle to return */
  int rc;
  int nReserve;
  unsigned char zDbHeader[100];
#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
  const ThreadData *pTsdro;
#endif

  /* Set the variable isMemdb to true for an in-memory database, or 
  ** false for a file-based database. This symbol is only required if
  ** either of the shared-data or autovacuum features are compiled 
  ** into the library.
  */
#if !defined(SQLITE_OMIT_SHARED_CACHE) || !defined(SQLITE_OMIT_AUTOVACUUM)
  #ifdef SQLITE_OMIT_MEMORYDB
    const int isMemdb = 0;
  #else
    const int isMemdb = zFilename && !strcmp(zFilename, ":memory:");
  #endif
#endif

  p = sqliteMalloc(sizeof(Btree));
  if( !p ){
    return SQLITE_NOMEM;
  }
  p->inTrans = TRANS_NONE;
  p->pSqlite = pSqlite;

  /* Try to find an existing Btree structure opened on zFilename. */
#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
  pTsdro = sqlite3ThreadDataReadOnly();
  if( pTsdro->useSharedData && zFilename && !isMemdb ){
    char *zFullPathname = sqlite3OsFullPathname(zFilename);
    if( !zFullPathname ){
      sqliteFree(p);
      return SQLITE_NOMEM;
    }
    for(pBt=pTsdro->pBtree; pBt; pBt=pBt->pNext){
      assert( pBt->nRef>0 );
      if( 0==strcmp(zFullPathname, sqlite3pager_filename(pBt->pPager)) ){
        p->pBt = pBt;
        *ppBtree = p;
        pBt->nRef++;
        sqliteFree(zFullPathname);
        return SQLITE_OK;
      }
    }
    sqliteFree(zFullPathname);
  }
#endif

  /*
  ** The following asserts make sure that structures used by the btree are
  ** the right size.  This is to guard against size changes that result
  ** when compiling on a different architecture.
  */
  assert( sizeof(i64)==8 || sizeof(i64)==4 );
  assert( sizeof(u64)==8 || sizeof(u64)==4 );
  assert( sizeof(u32)==4 );
  assert( sizeof(u16)==2 );
  assert( sizeof(Pgno)==4 );

  pBt = sqliteMalloc( sizeof(*pBt) );
  if( pBt==0 ){
    *ppBtree = 0;
    sqliteFree(p);
    return SQLITE_NOMEM;
  }
  rc = sqlite3pager_open(&pBt->pPager, zFilename, EXTRA_SIZE, flags);
  if( rc==SQLITE_OK ){
    rc = sqlite3pager_read_fileheader(pBt->pPager,sizeof(zDbHeader),zDbHeader);
  }
  if( rc!=SQLITE_OK ){
    if( pBt->pPager ){
      sqlite3pager_close(pBt->pPager);
    }
    sqliteFree(pBt);
    sqliteFree(p);
    *ppBtree = 0;
    return rc;
  }
  p->pBt = pBt;

  sqlite3pager_set_destructor(pBt->pPager, pageDestructor);
  sqlite3pager_set_reiniter(pBt->pPager, pageReinit);
  pBt->pCursor = 0;
  pBt->pPage1 = 0;
  pBt->readOnly = sqlite3pager_isreadonly(pBt->pPager);
  pBt->pageSize = get2byte(&zDbHeader[16]);
  if( pBt->pageSize<512 || pBt->pageSize>SQLITE_MAX_PAGE_SIZE
       || ((pBt->pageSize-1)&pBt->pageSize)!=0 ){
    pBt->pageSize = SQLITE_DEFAULT_PAGE_SIZE;
    pBt->maxEmbedFrac = 64;   /* 25% */
    pBt->minEmbedFrac = 32;   /* 12.5% */
    pBt->minLeafFrac = 32;    /* 12.5% */
#ifndef SQLITE_OMIT_AUTOVACUUM
    /* If the magic name ":memory:" will create an in-memory database, then
    ** do not set the auto-vacuum flag, even if SQLITE_DEFAULT_AUTOVACUUM
    ** is true. On the other hand, if SQLITE_OMIT_MEMORYDB has been defined,
    ** then ":memory:" is just a regular file-name. Respect the auto-vacuum
    ** default in this case.
    */
    if( zFilename && !isMemdb ){
      pBt->autoVacuum = SQLITE_DEFAULT_AUTOVACUUM;
    }
#endif
    nReserve = 0;
  }else{
    nReserve = zDbHeader[20];
    pBt->maxEmbedFrac = zDbHeader[21];
    pBt->minEmbedFrac = zDbHeader[22];
    pBt->minLeafFrac = zDbHeader[23];
    pBt->pageSizeFixed = 1;
#ifndef SQLITE_OMIT_AUTOVACUUM
    pBt->autoVacuum = (get4byte(&zDbHeader[36 + 4*4])?1:0);
#endif
  }
  pBt->usableSize = pBt->pageSize - nReserve;
  assert( (pBt->pageSize & 7)==0 );  /* 8-byte alignment of pageSize */
  sqlite3pager_set_pagesize(pBt->pPager, pBt->pageSize);

#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
  /* Add the new btree to the linked list starting at ThreadData.pBtree.
  ** There is no chance that a malloc() may fail inside of the 
  ** sqlite3ThreadData() call, as the ThreadData structure must have already
  ** been allocated for pTsdro->useSharedData to be non-zero.
  */
  if( pTsdro->useSharedData && zFilename && !isMemdb ){
    pBt->pNext = pTsdro->pBtree;
    sqlite3ThreadData()->pBtree = pBt;
  }
#endif
  pBt->nRef = 1;
  *ppBtree = p;
  return SQLITE_OK;
}

/*
** Close an open database and invalidate all cursors.
*/
int sqlite3BtreeClose(Btree *p){
  BtShared *pBt = p->pBt;
  BtCursor *pCur;

#ifndef SQLITE_OMIT_SHARED_CACHE
  ThreadData *pTsd;
#endif

  /* Close all cursors opened via this handle.  */
  pCur = pBt->pCursor;
  while( pCur ){
    BtCursor *pTmp = pCur;
    pCur = pCur->pNext;
    if( pTmp->pBtree==p ){
      sqlite3BtreeCloseCursor(pTmp);
    }
  }

  /* Rollback any active transaction and free the handle structure.
  ** The call to sqlite3BtreeRollback() drops any table-locks held by
  ** this handle.
  */
  sqlite3BtreeRollback(p);
  sqliteFree(p);

#ifndef SQLITE_OMIT_SHARED_CACHE
  /* If there are still other outstanding references to the shared-btree
  ** structure, return now. The remainder of this procedure cleans 
  ** up the shared-btree.
  */
  assert( pBt->nRef>0 );
  pBt->nRef--;
  if( pBt->nRef ){
    return SQLITE_OK;
  }

  /* Remove the shared-btree from the thread wide list. Call 
  ** ThreadDataReadOnly() and then cast away the const property of the 
  ** pointer to avoid allocating thread data if it is not really required.
  */
  pTsd = (ThreadData *)sqlite3ThreadDataReadOnly();
  if( pTsd->pBtree==pBt ){
    assert( pTsd==sqlite3ThreadData() );
    pTsd->pBtree = pBt->pNext;
  }else{
    BtShared *pPrev;
    for(pPrev=pTsd->pBtree; pPrev && pPrev->pNext!=pBt; pPrev=pPrev->pNext){}
    if( pPrev ){
      assert( pTsd==sqlite3ThreadData() );
      pPrev->pNext = pBt->pNext;
    }
  }
#endif

  /* Close the pager and free the shared-btree structure */
  assert( !pBt->pCursor );
  sqlite3pager_close(pBt->pPager);
  if( pBt->xFreeSchema && pBt->pSchema ){
    pBt->xFreeSchema(pBt->pSchema);
  }
  sqliteFree(pBt->pSchema);
  sqliteFree(pBt);
  return SQLITE_OK;
}

/*
** Change the busy handler callback function.
*/
int sqlite3BtreeSetBusyHandler(Btree *p, BusyHandler *pHandler){
  BtShared *pBt = p->pBt;
  pBt->pBusyHandler = pHandler;
  sqlite3pager_set_busyhandler(pBt->pPager, pHandler);
  return SQLITE_OK;
}

/*
** Change the limit on the number of pages allowed in the cache.
**
** The maximum number of cache pages is set to the absolute
** value of mxPage.  If mxPage is negative, the pager will
** operate asynchronously - it will not stop to do fsync()s
** to insure data is written to the disk surface before
** continuing.  Transactions still work if synchronous is off,
** and the database cannot be corrupted if this program
** crashes.  But if the operating system crashes or there is
** an abrupt power failure when synchronous is off, the database
** could be left in an inconsistent and unrecoverable state.
** Synchronous is on by default so database corruption is not
** normally a worry.
*/
int sqlite3BtreeSetCacheSize(Btree *p, int mxPage){
  BtShared *pBt = p->pBt;
  sqlite3pager_set_cachesize(pBt->pPager, mxPage);
  return SQLITE_OK;
}

/*
** Change the way data is synced to disk in order to increase or decrease
** how well the database resists damage due to OS crashes and power
** failures.  Level 1 is the same as asynchronous (no syncs() occur and
** there is a high probability of damage)  Level 2 is the default.  There
** is a very low but non-zero probability of damage.  Level 3 reduces the
** probability of damage to near zero but with a write performance reduction.
*/
#ifndef SQLITE_OMIT_PAGER_PRAGMAS
int sqlite3BtreeSetSafetyLevel(Btree *p, int level, int fullSync){
  BtShared *pBt = p->pBt;
  sqlite3pager_set_safety_level(pBt->pPager, level, fullSync);
  return SQLITE_OK;
}
#endif

/*
** Return TRUE if the given btree is set to safety level 1.  In other
** words, return TRUE if no sync() occurs on the disk files.
*/
int sqlite3BtreeSyncDisabled(Btree *p){
  BtShared *pBt = p->pBt;
  assert( pBt && pBt->pPager );
  return sqlite3pager_nosync(pBt->pPager);
}

#if !defined(SQLITE_OMIT_PAGER_PRAGMAS) || !defined(SQLITE_OMIT_VACUUM)
/*
** Change the default pages size and the number of reserved bytes per page.
**
** The page size must be a power of 2 between 512 and 65536.  If the page
** size supplied does not meet this constraint then the page size is not
** changed.
**
** Page sizes are constrained to be a power of two so that the region
** of the database file used for locking (beginning at PENDING_BYTE,
** the first byte past the 1GB boundary, 0x40000000) needs to occur
** at the beginning of a page.
**
** If parameter nReserve is less than zero, then the number of reserved
** bytes per page is left unchanged.
*/
int sqlite3BtreeSetPageSize(Btree *p, int pageSize, int nReserve){
  BtShared *pBt = p->pBt;
  if( pBt->pageSizeFixed ){
    return SQLITE_READONLY;
  }
  if( nReserve<0 ){
    nReserve = pBt->pageSize - pBt->usableSize;
  }
  if( pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE &&
        ((pageSize-1)&pageSize)==0 ){
    assert( (pageSize & 7)==0 );
    assert( !pBt->pPage1 && !pBt->pCursor );
    pBt->pageSize = sqlite3pager_set_pagesize(pBt->pPager, pageSize);
  }
  pBt->usableSize = pBt->pageSize - nReserve;
  return SQLITE_OK;
}

/*
** Return the currently defined page size
*/
int sqlite3BtreeGetPageSize(Btree *p){
  return p->pBt->pageSize;
}
int sqlite3BtreeGetReserve(Btree *p){
  return p->pBt->pageSize - p->pBt->usableSize;
}
#endif /* !defined(SQLITE_OMIT_PAGER_PRAGMAS) || !defined(SQLITE_OMIT_VACUUM) */

/*
** Change the 'auto-vacuum' property of the database. If the 'autoVacuum'
** parameter is non-zero, then auto-vacuum mode is enabled. If zero, it
** is disabled. The default value for the auto-vacuum property is 
** determined by the SQLITE_DEFAULT_AUTOVACUUM macro.
*/
int sqlite3BtreeSetAutoVacuum(Btree *p, int autoVacuum){
  BtShared *pBt = p->pBt;;
#ifdef SQLITE_OMIT_AUTOVACUUM
  return SQLITE_READONLY;
#else
  if( pBt->pageSizeFixed ){
    return SQLITE_READONLY;
  }
  pBt->autoVacuum = (autoVacuum?1:0);
  return SQLITE_OK;
#endif
}

/*
** Return the value of the 'auto-vacuum' property. If auto-vacuum is 
** enabled 1 is returned. Otherwise 0.
*/
int sqlite3BtreeGetAutoVacuum(Btree *p){
#ifdef SQLITE_OMIT_AUTOVACUUM
  return 0;
#else
  return p->pBt->autoVacuum;
#endif
}


/*
** Get a reference to pPage1 of the database file.  This will
** also acquire a readlock on that file.
**
** SQLITE_OK is returned on success.  If the file is not a
** well-formed database file, then SQLITE_CORRUPT is returned.
** SQLITE_BUSY is returned if the database is locked.  SQLITE_NOMEM
** is returned if we run out of memory.  SQLITE_PROTOCOL is returned
** if there is a locking protocol violation.
*/
static int lockBtree(BtShared *pBt){
  int rc, pageSize;
  MemPage *pPage1;
  if( pBt->pPage1 ) return SQLITE_OK;
  rc = getPage(pBt, 1, &pPage1);
  if( rc!=SQLITE_OK ) return rc;
  

  /* Do some checking to help insure the file we opened really is
  ** a valid database file. 
  */
  rc = SQLITE_NOTADB;
  if( sqlite3pager_pagecount(pBt->pPager)>0 ){
    u8 *page1 = pPage1->aData;
    if( memcmp(page1, zMagicHeader, 16)!=0 ){
      goto page1_init_failed;
    }
    if( page1[18]>1 || page1[19]>1 ){
      goto page1_init_failed;
    }
    pageSize = get2byte(&page1[16]);
    if( ((pageSize-1)&pageSize)!=0 ){
      goto page1_init_failed;
    }
    assert( (pageSize & 7)==0 );
    pBt->pageSize = pageSize;
    pBt->usableSize = pageSize - page1[20];
    if( pBt->usableSize<500 ){
      goto page1_init_failed;
    }
    pBt->maxEmbedFrac = page1[21];
    pBt->minEmbedFrac = page1[22];
    pBt->minLeafFrac = page1[23];
#ifndef SQLITE_OMIT_AUTOVACUUM
    pBt->autoVacuum = (get4byte(&page1[36 + 4*4])?1:0);
#endif
  }

  /* maxLocal is the maximum amount of payload to store locally for
  ** a cell.  Make sure it is small enough so that at least minFanout
  ** cells can will fit on one page.  We assume a 10-byte page header.
  ** Besides the payload, the cell must store:
  **     2-byte pointer to the cell
  **     4-byte child pointer
  **     9-byte nKey value
  **     4-byte nData value
  **     4-byte overflow page pointer
  ** So a cell consists of a 2-byte poiner, a header which is as much as
  ** 17 bytes long, 0 to N bytes of payload, and an optional 4 byte overflow
  ** page pointer.
  */
  pBt->maxLocal = (pBt->usableSize-12)*pBt->maxEmbedFrac/255 - 23;
  pBt->minLocal = (pBt->usableSize-12)*pBt->minEmbedFrac/255 - 23;
  pBt->maxLeaf = pBt->usableSize - 35;
  pBt->minLeaf = (pBt->usableSize-12)*pBt->minLeafFrac/255 - 23;
  if( pBt->minLocal>pBt->maxLocal || pBt->maxLocal<0 ){
    goto page1_init_failed;
  }
  assert( pBt->maxLeaf + 23 <= MX_CELL_SIZE(pBt) );
  pBt->pPage1 = pPage1;
  return SQLITE_OK;

page1_init_failed:
  releasePage(pPage1);
  pBt->pPage1 = 0;
  return rc;
}

/*
** This routine works like lockBtree() except that it also invokes the
** busy callback if there is lock contention.
*/
static int lockBtreeWithRetry(Btree *pRef){
  int rc = SQLITE_OK;
  if( pRef->inTrans==TRANS_NONE ){
    u8 inTransaction = pRef->pBt->inTransaction;
    btreeIntegrity(pRef);
    rc = sqlite3BtreeBeginTrans(pRef, 0);
    pRef->pBt->inTransaction = inTransaction;
    pRef->inTrans = TRANS_NONE;
    if( rc==SQLITE_OK ){
      pRef->pBt->nTransaction--;
    }
    btreeIntegrity(pRef);
  }
  return rc;
}
       

/*
** If there are no outstanding cursors and we are not in the middle
** of a transaction but there is a read lock on the database, then
** this routine unrefs the first page of the database file which 
** has the effect of releasing the read lock.
**
** If there are any outstanding cursors, this routine is a no-op.
**
** If there is a transaction in progress, this routine is a no-op.
*/
static void unlockBtreeIfUnused(BtShared *pBt){
  if( pBt->inTransaction==TRANS_NONE && pBt->pCursor==0 && pBt->pPage1!=0 ){
    if( sqlite3pager_refcount(pBt->pPager)>=1 ){
      if( pBt->pPage1->aData==0 ){
        MemPage *pPage = pBt->pPage1;
        pPage->aData = &((u8*)pPage)[-pBt->pageSize];
        pPage->pBt = pBt;
        pPage->pgno = 1;
      }
      releasePage(pBt->pPage1);
    }
    pBt->pPage1 = 0;
    pBt->inStmt = 0;
  }
}

/*
** Create a new database by initializing the first page of the
** file.
*/
static int newDatabase(BtShared *pBt){
  MemPage *pP1;
  unsigned char *data;
  int rc;
  if( sqlite3pager_pagecount(pBt->pPager)>0 ) return SQLITE_OK;
  pP1 = pBt->pPage1;
  assert( pP1!=0 );
  data = pP1->aData;
  rc = sqlite3pager_write(data);
  if( rc ) return rc;
  memcpy(data, zMagicHeader, sizeof(zMagicHeader));
  assert( sizeof(zMagicHeader)==16 );
  put2byte(&data[16], pBt->pageSize);
  data[18] = 1;
  data[19] = 1;
  data[20] = pBt->pageSize - pBt->usableSize;
  data[21] = pBt->maxEmbedFrac;
  data[22] = pBt->minEmbedFrac;
  data[23] = pBt->minLeafFrac;
  memset(&data[24], 0, 100-24);
  zeroPage(pP1, PTF_INTKEY|PTF_LEAF|PTF_LEAFDATA );
  pBt->pageSizeFixed = 1;
#ifndef SQLITE_OMIT_AUTOVACUUM
  if( pBt->autoVacuum ){
    put4byte(&data[36 + 4*4], 1);
  }
#endif
  return SQLITE_OK;
}

/*
** Attempt to start a new transaction. A write-transaction
** is started if the second argument is nonzero, otherwise a read-
** transaction.  If the second argument is 2 or more and exclusive
** transaction is started, meaning that no other process is allowed
** to access the database.  A preexisting transaction may not be
** upgraded to exclusive by calling this routine a second time - the
** exclusivity flag only works for a new transaction.
**
** A write-transaction must be started before attempting any 
** changes to the database.  None of the following routines 
** will work unless a transaction is started first:
**
**      sqlite3BtreeCreateTable()
**      sqlite3BtreeCreateIndex()
**      sqlite3BtreeClearTable()
**      sqlite3BtreeDropTable()
**      sqlite3BtreeInsert()
**      sqlite3BtreeDelete()
**      sqlite3BtreeUpdateMeta()
**
** If an initial attempt to acquire the lock fails because of lock contention
** and the database was previously unlocked, then invoke the busy handler
** if there is one.  But if there was previously a read-lock, do not
** invoke the busy handler - just return SQLITE_BUSY.  SQLITE_BUSY is 
** returned when there is already a read-lock in order to avoid a deadlock.
**
** Suppose there are two processes A and B.  A has a read lock and B has
** a reserved lock.  B tries to promote to exclusive but is blocked because
** of A's read lock.  A tries to promote to reserved but is blocked by B.
** One or the other of the two processes must give way or there can be
** no progress.  By returning SQLITE_BUSY and not invoking the busy callback
** when A already has a read lock, we encourage A to give up and let B
** proceed.
*/
int sqlite3BtreeBeginTrans(Btree *p, int wrflag){
  BtShared *pBt = p->pBt;
  int rc = SQLITE_OK;

  btreeIntegrity(p);

  /* If the btree is already in a write-transaction, or it
  ** is already in a read-transaction and a read-transaction
  ** is requested, this is a no-op.
  */
  if( p->inTrans==TRANS_WRITE || (p->inTrans==TRANS_READ && !wrflag) ){
    return SQLITE_OK;
  }

  /* Write transactions are not possible on a read-only database */
  if( pBt->readOnly && wrflag ){
    return SQLITE_READONLY;
  }

  /* If another database handle has already opened a write transaction 
  ** on this shared-btree structure and a second write transaction is
  ** requested, return SQLITE_BUSY.
  */
  if( pBt->inTransaction==TRANS_WRITE && wrflag ){
    return SQLITE_BUSY;
  }

  do {
    if( pBt->pPage1==0 ){
      rc = lockBtree(pBt);
    }
  
    if( rc==SQLITE_OK && wrflag ){
      rc = sqlite3pager_begin(pBt->pPage1->aData, wrflag>1);
      if( rc==SQLITE_OK ){
        rc = newDatabase(pBt);
      }
    }
  
    if( rc==SQLITE_OK ){
      if( wrflag ) pBt->inStmt = 0;
    }else{
      unlockBtreeIfUnused(pBt);
    }
  }while( rc==SQLITE_BUSY && pBt->inTransaction==TRANS_NONE &&
          sqlite3InvokeBusyHandler(pBt->pBusyHandler) );

  if( rc==SQLITE_OK ){
    if( p->inTrans==TRANS_NONE ){
      pBt->nTransaction++;
    }
    p->inTrans = (wrflag?TRANS_WRITE:TRANS_READ);
    if( p->inTrans>pBt->inTransaction ){
      pBt->inTransaction = p->inTrans;
    }
  }

  btreeIntegrity(p);
  return rc;
}

#ifndef SQLITE_OMIT_AUTOVACUUM

/*
** Set the pointer-map entries for all children of page pPage. Also, if
** pPage contains cells that point to overflow pages, set the pointer
** map entries for the overflow pages as well.
*/
static int setChildPtrmaps(MemPage *pPage){
  int i;                             /* Counter variable */
  int nCell;                         /* Number of cells in page pPage */
  int rc = SQLITE_OK;                /* Return code */
  BtShared *pBt = pPage->pBt;
  int isInitOrig = pPage->isInit;
  Pgno pgno = pPage->pgno;

  initPage(pPage, 0);
  nCell = pPage->nCell;

  for(i=0; i<nCell; i++){
    u8 *pCell = findCell(pPage, i);

    rc = ptrmapPutOvflPtr(pPage, pCell);
    if( rc!=SQLITE_OK ){
      goto set_child_ptrmaps_out;
    }

    if( !pPage->leaf ){
      Pgno childPgno = get4byte(pCell);
      rc = ptrmapPut(pBt, childPgno, PTRMAP_BTREE, pgno);
      if( rc!=SQLITE_OK ) goto set_child_ptrmaps_out;
    }
  }

  if( !pPage->leaf ){
    Pgno childPgno = get4byte(&pPage->aData[pPage->hdrOffset+8]);
    rc = ptrmapPut(pBt, childPgno, PTRMAP_BTREE, pgno);
  }

set_child_ptrmaps_out:
  pPage->isInit = isInitOrig;
  return rc;
}

/*
** Somewhere on pPage, which is guarenteed to be a btree page, not an overflow
** page, is a pointer to page iFrom. Modify this pointer so that it points to
** iTo. Parameter eType describes the type of pointer to be modified, as 
** follows:
**
** PTRMAP_BTREE:     pPage is a btree-page. The pointer points at a child 
**                   page of pPage.
**
** PTRMAP_OVERFLOW1: pPage is a btree-page. The pointer points at an overflow
**                   page pointed to by one of the cells on pPage.
**
** PTRMAP_OVERFLOW2: pPage is an overflow-page. The pointer points at the next
**                   overflow page in the list.
*/
static int modifyPagePointer(MemPage *pPage, Pgno iFrom, Pgno iTo, u8 eType){
  if( eType==PTRMAP_OVERFLOW2 ){
    /* The pointer is always the first 4 bytes of the page in this case.  */
    if( get4byte(pPage->aData)!=iFrom ){
      return SQLITE_CORRUPT_BKPT;
    }
    put4byte(pPage->aData, iTo);
  }else{
    int isInitOrig = pPage->isInit;
    int i;
    int nCell;

    initPage(pPage, 0);
    nCell = pPage->nCell;

    for(i=0; i<nCell; i++){
      u8 *pCell = findCell(pPage, i);
      if( eType==PTRMAP_OVERFLOW1 ){
        CellInfo info;
        parseCellPtr(pPage, pCell, &info);
        if( info.iOverflow ){
          if( iFrom==get4byte(&pCell[info.iOverflow]) ){
            put4byte(&pCell[info.iOverflow], iTo);
            break;
          }
        }
      }else{
        if( get4byte(pCell)==iFrom ){
          put4byte(pCell, iTo);
          break;
        }
      }
    }
  
    if( i==nCell ){
      if( eType!=PTRMAP_BTREE || 
          get4byte(&pPage->aData[pPage->hdrOffset+8])!=iFrom ){
        return SQLITE_CORRUPT_BKPT;
      }
      put4byte(&pPage->aData[pPage->hdrOffset+8], iTo);
    }

    pPage->isInit = isInitOrig;
  }
  return SQLITE_OK;
}


/*
** Move the open database page pDbPage to location iFreePage in the 
** database. The pDbPage reference remains valid.
*/
static int relocatePage(
  BtShared *pBt,           /* Btree */
  MemPage *pDbPage,        /* Open page to move */
  u8 eType,                /* Pointer map 'type' entry for pDbPage */
  Pgno iPtrPage,           /* Pointer map 'page-no' entry for pDbPage */
  Pgno iFreePage           /* The location to move pDbPage to */
){
  MemPage *pPtrPage;   /* The page that contains a pointer to pDbPage */
  Pgno iDbPage = pDbPage->pgno;
  Pager *pPager = pBt->pPager;
  int rc;

  assert( eType==PTRMAP_OVERFLOW2 || eType==PTRMAP_OVERFLOW1 || 
      eType==PTRMAP_BTREE || eType==PTRMAP_ROOTPAGE );

  /* Move page iDbPage from it's current location to page number iFreePage */
  TRACE(("AUTOVACUUM: Moving %d to free page %d (ptr page %d type %d)\n", 
      iDbPage, iFreePage, iPtrPage, eType));
  rc = sqlite3pager_movepage(pPager, pDbPage->aData, iFreePage);
  if( rc!=SQLITE_OK ){
    return rc;
  }
  pDbPage->pgno = iFreePage;

  /* If pDbPage was a btree-page, then it may have child pages and/or cells
  ** that point to overflow pages. The pointer map entries for all these
  ** pages need to be changed.
  **
  ** If pDbPage is an overflow page, then the first 4 bytes may store a
  ** pointer to a subsequent overflow page. If this is the case, then
  ** the pointer map needs to be updated for the subsequent overflow page.
  */
  if( eType==PTRMAP_BTREE || eType==PTRMAP_ROOTPAGE ){
    rc = setChildPtrmaps(pDbPage);
    if( rc!=SQLITE_OK ){
      return rc;
    }
  }else{
    Pgno nextOvfl = get4byte(pDbPage->aData);
    if( nextOvfl!=0 ){
      rc = ptrmapPut(pBt, nextOvfl, PTRMAP_OVERFLOW2, iFreePage);
      if( rc!=SQLITE_OK ){
        return rc;
      }
    }
  }

  /* Fix the database pointer on page iPtrPage that pointed at iDbPage so
  ** that it points at iFreePage. Also fix the pointer map entry for
  ** iPtrPage.
  */
  if( eType!=PTRMAP_ROOTPAGE ){
    rc = getPage(pBt, iPtrPage, &pPtrPage);
    if( rc!=SQLITE_OK ){
      return rc;
    }
    rc = sqlite3pager_write(pPtrPage->aData);
    if( rc!=SQLITE_OK ){
      releasePage(pPtrPage);
      return rc;
    }
    rc = modifyPagePointer(pPtrPage, iDbPage, iFreePage, eType);
    releasePage(pPtrPage);
    if( rc==SQLITE_OK ){
      rc = ptrmapPut(pBt, iFreePage, eType, iPtrPage);
    }
  }
  return rc;
}

/* Forward declaration required by autoVacuumCommit(). */
static int allocatePage(BtShared *, MemPage **, Pgno *, Pgno, u8);

/*
** This routine is called prior to sqlite3pager_commit when a transaction
** is commited for an auto-vacuum database.
*/
static int autoVacuumCommit(BtShared *pBt, Pgno *nTrunc){
  Pager *pPager = pBt->pPager;
  Pgno nFreeList;            /* Number of pages remaining on the free-list. */
  int nPtrMap;               /* Number of pointer-map pages deallocated */
  Pgno origSize;             /* Pages in the database file */
  Pgno finSize;              /* Pages in the database file after truncation */
  int rc;                    /* Return code */
  u8 eType;
  int pgsz = pBt->pageSize;  /* Page size for this database */
  Pgno iDbPage;              /* The database page to move */
  MemPage *pDbMemPage = 0;   /* "" */
  Pgno iPtrPage;             /* The page that contains a pointer to iDbPage */
  Pgno iFreePage;            /* The free-list page to move iDbPage to */
  MemPage *pFreeMemPage = 0; /* "" */

#ifndef NDEBUG
  int nRef = sqlite3pager_refcount(pPager);
#endif

  assert( pBt->autoVacuum );
  if( PTRMAP_ISPAGE(pBt, sqlite3pager_pagecount(pPager)) ){
    return SQLITE_CORRUPT_BKPT;
  }

  /* Figure out how many free-pages are in the database. If there are no
  ** free pages, then auto-vacuum is a no-op.
  */
  nFreeList = get4byte(&pBt->pPage1->aData[36]);
  if( nFreeList==0 ){
    *nTrunc = 0;
    return SQLITE_OK;
  }

  /* This block figures out how many pages there are in the database
  ** now (variable origSize), and how many there will be after the
  ** truncation (variable finSize).
  **
  ** The final size is the original size, less the number of free pages
  ** in the database, less any pointer-map pages that will no longer
  ** be required, less 1 if the pending-byte page was part of the database
  ** but is not after the truncation.
  **/
  origSize = sqlite3pager_pagecount(pPager);
  if( origSize==PENDING_BYTE_PAGE(pBt) ){
    origSize--;
  }
  nPtrMap = (nFreeList-origSize+PTRMAP_PAGENO(pBt, origSize)+pgsz/5)/(pgsz/5);
  finSize = origSize - nFreeList - nPtrMap;
  if( origSize>PENDING_BYTE_PAGE(pBt) && finSize<=PENDING_BYTE_PAGE(pBt) ){
    finSize--;
  }
  while( PTRMAP_ISPAGE(pBt, finSize) || finSize==PENDING_BYTE_PAGE(pBt) ){
    finSize--;
  }
  TRACE(("AUTOVACUUM: Begin (db size %d->%d)\n", origSize, finSize));

  /* Variable 'finSize' will be the size of the file in pages after
  ** the auto-vacuum has completed (the current file size minus the number
  ** of pages on the free list). Loop through the pages that lie beyond
  ** this mark, and if they are not already on the free list, move them
  ** to a free page earlier in the file (somewhere before finSize).
  */
  for( iDbPage=finSize+1; iDbPage<=origSize; iDbPage++ ){
    /* If iDbPage is a pointer map page, or the pending-byte page, skip it. */
    if( PTRMAP_ISPAGE(pBt, iDbPage) || iDbPage==PENDING_BYTE_PAGE(pBt) ){
      continue;
    }

    rc = ptrmapGet(pBt, iDbPage, &eType, &iPtrPage);
    if( rc!=SQLITE_OK ) goto autovacuum_out;
    if( eType==PTRMAP_ROOTPAGE ){
      rc = SQLITE_CORRUPT_BKPT;
      goto autovacuum_out;
    }

    /* If iDbPage is free, do not swap it.  */
    if( eType==PTRMAP_FREEPAGE ){
      continue;
    }
    rc = getPage(pBt, iDbPage, &pDbMemPage);
    if( rc!=SQLITE_OK ) goto autovacuum_out;

    /* Find the next page in the free-list that is not already at the end 
    ** of the file. A page can be pulled off the free list using the 
    ** allocatePage() routine.
    */
    do{
      if( pFreeMemPage ){
        releasePage(pFreeMemPage);
        pFreeMemPage = 0;
      }
      rc = allocatePage(pBt, &pFreeMemPage, &iFreePage, 0, 0);
      if( rc!=SQLITE_OK ){
        releasePage(pDbMemPage);
        goto autovacuum_out;
      }
      assert( iFreePage<=origSize );
    }while( iFreePage>finSize );
    releasePage(pFreeMemPage);
    pFreeMemPage = 0;

    /* Relocate the page into the body of the file. Note that although the 
    ** page has moved within the database file, the pDbMemPage pointer 
    ** remains valid. This means that this function can run without
    ** invalidating cursors open on the btree. This is important in 
    ** shared-cache mode.
    */
    rc = relocatePage(pBt, pDbMemPage, eType, iPtrPage, iFreePage);
    releasePage(pDbMemPage);
    if( rc!=SQLITE_OK ) goto autovacuum_out;
  }

  /* The entire free-list has been swapped to the end of the file. So
  ** truncate the database file to finSize pages and consider the
  ** free-list empty.
  */
  rc = sqlite3pager_write(pBt->pPage1->aData);
  if( rc!=SQLITE_OK ) goto autovacuum_out;
  put4byte(&pBt->pPage1->aData[32], 0);
  put4byte(&pBt->pPage1->aData[36], 0);
  *nTrunc = finSize;
  assert( finSize!=PENDING_BYTE_PAGE(pBt) );

autovacuum_out:
  assert( nRef==sqlite3pager_refcount(pPager) );
  if( rc!=SQLITE_OK ){
    sqlite3pager_rollback(pPager);
  }
  return rc;
}
#endif

/*
** Commit the transaction currently in progress.
**
** This will release the write lock on the database file.  If there
** are no active cursors, it also releases the read lock.
*/
int sqlite3BtreeCommit(Btree *p){
  BtShared *pBt = p->pBt;

  btreeIntegrity(p);

  /* If the handle has a write-transaction open, commit the shared-btrees 
  ** transaction and set the shared state to TRANS_READ.
  */
  if( p->inTrans==TRANS_WRITE ){
    int rc;
    assert( pBt->inTransaction==TRANS_WRITE );
    assert( pBt->nTransaction>0 );
    rc = sqlite3pager_commit(pBt->pPager);
    if( rc!=SQLITE_OK ){
      return rc;
    }
    pBt->inTransaction = TRANS_READ;
    pBt->inStmt = 0;
  }
  unlockAllTables(p);

  /* If the handle has any kind of transaction open, decrement the transaction
  ** count of the shared btree. If the transaction count reaches 0, set
  ** the shared state to TRANS_NONE. The unlockBtreeIfUnused() call below
  ** will unlock the pager.
  */
  if( p->inTrans!=TRANS_NONE ){
    pBt->nTransaction--;
    if( 0==pBt->nTransaction ){
      pBt->inTransaction = TRANS_NONE;
    }
  }

  /* Set the handles current transaction state to TRANS_NONE and unlock
  ** the pager if this call closed the only read or write transaction.
  */
  p->inTrans = TRANS_NONE;
  unlockBtreeIfUnused(pBt);

  btreeIntegrity(p);
  return SQLITE_OK;
}

#ifndef NDEBUG
/*
** Return the number of write-cursors open on this handle. This is for use
** in assert() expressions, so it is only compiled if NDEBUG is not
** defined.
*/
static int countWriteCursors(BtShared *pBt){
  BtCursor *pCur;
  int r = 0;
  for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){
    if( pCur->wrFlag ) r++; 
  }
  return r;
}
#endif

#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
/*
** Print debugging information about all cursors to standard output.
*/
void sqlite3BtreeCursorList(Btree *p){
  BtCursor *pCur;
  BtShared *pBt = p->pBt;
  for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){
    MemPage *pPage = pCur->pPage;
    char *zMode = pCur->wrFlag ? "rw" : "ro";
    sqlite3DebugPrintf("CURSOR %p rooted at %4d(%s) currently at %d.%d%s\n",
       pCur, pCur->pgnoRoot, zMode,
       pPage ? pPage->pgno : 0, pCur->idx,
       (pCur->eState==CURSOR_VALID) ? "" : " eof"
    );
  }
}
#endif

/*
** Rollback the transaction in progress.  All cursors will be
** invalided by this operation.  Any attempt to use a cursor
** that was open at the beginning of this operation will result
** in an error.
**
** This will release the write lock on the database file.  If there
** are no active cursors, it also releases the read lock.
*/
int sqlite3BtreeRollback(Btree *p){
  int rc;
  BtShared *pBt = p->pBt;
  MemPage *pPage1;

  rc = saveAllCursors(pBt, 0, 0);
#ifndef SQLITE_OMIT_SHARED_CACHE
  if( rc!=SQLITE_OK ){
    /* This is a horrible situation. An IO or malloc() error occured whilst
    ** trying to save cursor positions. If this is an automatic rollback (as
    ** the result of a constraint, malloc() failure or IO error) then 
    ** the cache may be internally inconsistent (not contain valid trees) so
    ** we cannot simply return the error to the caller. Instead, abort 
    ** all queries that may be using any of the cursors that failed to save.
    */
    while( pBt->pCursor ){
      sqlite3 *db = pBt->pCursor->pBtree->pSqlite;
      if( db ){
        sqlite3AbortOtherActiveVdbes(db, 0);
      }
    }
  }
#endif
  btreeIntegrity(p);
  unlockAllTables(p);

  if( p->inTrans==TRANS_WRITE ){
    int rc2;

    assert( TRANS_WRITE==pBt->inTransaction );
    rc2 = sqlite3pager_rollback(pBt->pPager);
    if( rc2!=SQLITE_OK ){
      rc = rc2;
    }

    /* The rollback may have destroyed the pPage1->aData value.  So
    ** call getPage() on page 1 again to make sure pPage1->aData is
    ** set correctly. */
    if( getPage(pBt, 1, &pPage1)==SQLITE_OK ){
      releasePage(pPage1);
    }
    assert( countWriteCursors(pBt)==0 );
    pBt->inTransaction = TRANS_READ;
  }

  if( p->inTrans!=TRANS_NONE ){
    assert( pBt->nTransaction>0 );
    pBt->nTransaction--;
    if( 0==pBt->nTransaction ){
      pBt->inTransaction = TRANS_NONE;
    }
  }

  p->inTrans = TRANS_NONE;
  pBt->inStmt = 0;
  unlockBtreeIfUnused(pBt);

  btreeIntegrity(p);
  return rc;
}

/*
** Start a statement subtransaction.  The subtransaction can
** can be rolled back independently of the main transaction.
** You must start a transaction before starting a subtransaction.
** The subtransaction is ended automatically if the main transaction
** commits or rolls back.
**
** Only one subtransaction may be active at a time.  It is an error to try
** to start a new subtransaction if another subtransaction is already active.
**
** Statement subtransactions are used around individual SQL statements
** that are contained within a BEGIN...COMMIT block.  If a constraint
** error occurs within the statement, the effect of that one statement
** can be rolled back without having to rollback the entire transaction.
*/
int sqlite3BtreeBeginStmt(Btree *p){
  int rc;
  BtShared *pBt = p->pBt;
  if( (p->inTrans!=TRANS_WRITE) || pBt->inStmt ){
    return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
  }
  assert( pBt->inTransaction==TRANS_WRITE );
  rc = pBt->readOnly ? SQLITE_OK : sqlite3pager_stmt_begin(pBt->pPager);
  pBt->inStmt = 1;
  return rc;
}


/*
** Commit the statment subtransaction currently in progress.  If no
** subtransaction is active, this is a no-op.
*/
int sqlite3BtreeCommitStmt(Btree *p){
  int rc;
  BtShared *pBt = p->pBt;
  if( pBt->inStmt && !pBt->readOnly ){
    rc = sqlite3pager_stmt_commit(pBt->pPager);
  }else{
    rc = SQLITE_OK;
  }
  pBt->inStmt = 0;
  return rc;
}

/*
** Rollback the active statement subtransaction.  If no subtransaction
** is active this routine is a no-op.
**
** All cursors will be invalidated by this operation.  Any attempt
** to use a cursor that was open at the beginning of this operation
** will result in an error.
*/
int sqlite3BtreeRollbackStmt(Btree *p){
  int rc = SQLITE_OK;
  BtShared *pBt = p->pBt;
  sqlite3MallocDisallow();
  if( pBt->inStmt && !pBt->readOnly ){
    rc = sqlite3pager_stmt_rollback(pBt->pPager);
    assert( countWriteCursors(pBt)==0 );
    pBt->inStmt = 0;
  }
  sqlite3MallocAllow();
  return rc;
}

/*
** Default key comparison function to be used if no comparison function
** is specified on the sqlite3BtreeCursor() call.
*/
static int dfltCompare(
  void *NotUsed,             /* User data is not used */
  int n1, const void *p1,    /* First key to compare */
  int n2, const void *p2     /* Second key to compare */
){
  int c;
  c = memcmp(p1, p2, n1<n2 ? n1 : n2);
  if( c==0 ){
    c = n1 - n2;
  }
  return c;
}

/*
** Create a new cursor for the BTree whose root is on the page
** iTable.  The act of acquiring a cursor gets a read lock on 
** the database file.
**
** If wrFlag==0, then the cursor can only be used for reading.
** If wrFlag==1, then the cursor can be used for reading or for
** writing if other conditions for writing are also met.  These
** are the conditions that must be met in order for writing to
** be allowed:
**
** 1:  The cursor must have been opened with wrFlag==1
**
** 2:  No other cursors may be open with wrFlag==0 on the same table
**
** 3:  The database must be writable (not on read-only media)
**
** 4:  There must be an active transaction.
**
** Condition 2 warrants further discussion.  If any cursor is opened
** on a table with wrFlag==0, that prevents all other cursors from
** writing to that table.  This is a kind of "read-lock".  When a cursor
** is opened with wrFlag==0 it is guaranteed that the table will not
** change as long as the cursor is open.  This allows the cursor to
** do a sequential scan of the table without having to worry about
** entries being inserted or deleted during the scan.  Cursors should
** be opened with wrFlag==0 only if this read-lock property is needed.
** That is to say, cursors should be opened with wrFlag==0 only if they
** intend to use the sqlite3BtreeNext() system call.  All other cursors
** should be opened with wrFlag==1 even if they never really intend
** to write.
** 
** No checking is done to make sure that page iTable really is the
** root page of a b-tree.  If it is not, then the cursor acquired
** will not work correctly.
**
** The comparison function must be logically the same for every cursor
** on a particular table.  Changing the comparison function will result
** in incorrect operations.  If the comparison function is NULL, a
** default comparison function is used.  The comparison function is
** always ignored for INTKEY tables.
*/
int sqlite3BtreeCursor(
  Btree *p,                                   /* The btree */
  int iTable,                                 /* Root page of table to open */
  int wrFlag,                                 /* 1 to write. 0 read-only */
  int (*xCmp)(void*,int,const void*,int,const void*), /* Key Comparison func */
  void *pArg,                                 /* First arg to xCompare() */
  BtCursor **ppCur                            /* Write new cursor here */
){
  int rc;
  BtCursor *pCur;
  BtShared *pBt = p->pBt;

  *ppCur = 0;
  if( wrFlag ){
    if( pBt->readOnly ){
      return SQLITE_READONLY;
    }
    if( checkReadLocks(p, iTable, 0) ){
      return SQLITE_LOCKED;
    }
  }

  if( pBt->pPage1==0 ){
    rc = lockBtreeWithRetry(p);
    if( rc!=SQLITE_OK ){
      return rc;
    }
  }
  pCur = sqliteMalloc( sizeof(*pCur) );
  if( pCur==0 ){
    rc = SQLITE_NOMEM;
    goto create_cursor_exception;
  }
  pCur->pgnoRoot = (Pgno)iTable;
  if( iTable==1 && sqlite3pager_pagecount(pBt->pPager)==0 ){
    rc = SQLITE_EMPTY;
    goto create_cursor_exception;
  }
  rc = getAndInitPage(pBt, pCur->pgnoRoot, &pCur->pPage, 0);
  if( rc!=SQLITE_OK ){
    goto create_cursor_exception;
  }

  /* Now that no other errors can occur, finish filling in the BtCursor
  ** variables, link the cursor into the BtShared list and set *ppCur (the
  ** output argument to this function).
  */
  pCur->xCompare = xCmp ? xCmp : dfltCompare;
  pCur->pArg = pArg;
  pCur->pBtree = p;
  pCur->wrFlag = wrFlag;
  pCur->pNext = pBt->pCursor;
  if( pCur->pNext ){
    pCur->pNext->pPrev = pCur;
  }
  pBt->pCursor = pCur;
  pCur->eState = CURSOR_INVALID;
  *ppCur = pCur;

  return SQLITE_OK;
create_cursor_exception:
  if( pCur ){
    releasePage(pCur->pPage);
    sqliteFree(pCur);
  }
  unlockBtreeIfUnused(pBt);
  return rc;
}

#if 0  /* Not Used */
/*
** Change the value of the comparison function used by a cursor.
*/
void sqlite3BtreeSetCompare(
  BtCursor *pCur,     /* The cursor to whose comparison function is changed */
  int(*xCmp)(void*,int,const void*,int,const void*), /* New comparison func */
  void *pArg          /* First argument to xCmp() */
){
  pCur->xCompare = xCmp ? xCmp : dfltCompare;
  pCur->pArg = pArg;
}
#endif

/*
** Close a cursor.  The read lock on the database file is released
** when the last cursor is closed.
*/
int sqlite3BtreeCloseCursor(BtCursor *pCur){
  BtShared *pBt = pCur->pBtree->pBt;
  restoreOrClearCursorPosition(pCur, 0);
  if( pCur->pPrev ){
    pCur->pPrev->pNext = pCur->pNext;
  }else{
    pBt->pCursor = pCur->pNext;
  }
  if( pCur->pNext ){
    pCur->pNext->pPrev = pCur->pPrev;
  }
  releasePage(pCur->pPage);
  unlockBtreeIfUnused(pBt);
  sqliteFree(pCur);
  return SQLITE_OK;
}

/*
** Make a temporary cursor by filling in the fields of pTempCur.
** The temporary cursor is not on the cursor list for the Btree.
*/
static void getTempCursor(BtCursor *pCur, BtCursor *pTempCur){
  memcpy(pTempCur, pCur, sizeof(*pCur));
  pTempCur->pNext = 0;
  pTempCur->pPrev = 0;
  if( pTempCur->pPage ){
    sqlite3pager_ref(pTempCur->pPage->aData);
  }
}

/*
** Delete a temporary cursor such as was made by the CreateTemporaryCursor()
** function above.
*/
static void releaseTempCursor(BtCursor *pCur){
  if( pCur->pPage ){
    sqlite3pager_unref(pCur->pPage->aData);
  }
}

/*
** Make sure the BtCursor.info field of the given cursor is valid.
** If it is not already valid, call parseCell() to fill it in.
**
** BtCursor.info is a cache of the information in the current cell.
** Using this cache reduces the number of calls to parseCell().
*/
static void getCellInfo(BtCursor *pCur){
  if( pCur->info.nSize==0 ){
    parseCell(pCur->pPage, pCur->idx, &pCur->info);
  }else{
#ifndef NDEBUG
    CellInfo info;
    memset(&info, 0, sizeof(info));
    parseCell(pCur->pPage, pCur->idx, &info);
    assert( memcmp(&info, &pCur->info, sizeof(info))==0 );
#endif
  }
}

/*
** Set *pSize to the size of the buffer needed to hold the value of
** the key for the current entry.  If the cursor is not pointing
** to a valid entry, *pSize is set to 0. 
**
** For a table with the INTKEY flag set, this routine returns the key
** itself, not the number of bytes in the key.
*/
int sqlite3BtreeKeySize(BtCursor *pCur, i64 *pSize){
  int rc = restoreOrClearCursorPosition(pCur, 1);
  if( rc==SQLITE_OK ){
    assert( pCur->eState==CURSOR_INVALID || pCur->eState==CURSOR_VALID );
    if( pCur->eState==CURSOR_INVALID ){
      *pSize = 0;
    }else{
      getCellInfo(pCur);
      *pSize = pCur->info.nKey;
    }
  }
  return rc;
}

/*
** Set *pSize to the number of bytes of data in the entry the
** cursor currently points to.  Always return SQLITE_OK.
** Failure is not possible.  If the cursor is not currently
** pointing to an entry (which can happen, for example, if
** the database is empty) then *pSize is set to 0.
*/
int sqlite3BtreeDataSize(BtCursor *pCur, u32 *pSize){
  int rc = restoreOrClearCursorPosition(pCur, 1);
  if( rc==SQLITE_OK ){
    assert( pCur->eState==CURSOR_INVALID || pCur->eState==CURSOR_VALID );
    if( pCur->eState==CURSOR_INVALID ){
      /* Not pointing at a valid entry - set *pSize to 0. */
      *pSize = 0;
    }else{
      getCellInfo(pCur);
      *pSize = pCur->info.nData;
    }
  }
  return rc;
}

/*
** Read payload information from the entry that the pCur cursor is
** pointing to.  Begin reading the payload at "offset" and read
** a total of "amt" bytes.  Put the result in zBuf.
**
** This routine does not make a distinction between key and data.
** It just reads bytes from the payload area.  Data might appear
** on the main page or be scattered out on multiple overflow pages.
*/
static int getPayload(
  BtCursor *pCur,      /* Cursor pointing to entry to read from */
  int offset,          /* Begin reading this far into payload */
  int amt,             /* Read this many bytes */
  unsigned char *pBuf, /* Write the bytes into this buffer */ 
  int skipKey          /* offset begins at data if this is true */
){
  unsigned char *aPayload;
  Pgno nextPage;
  int rc;
  MemPage *pPage;
  BtShared *pBt;
  int ovflSize;
  u32 nKey;

  assert( pCur!=0 && pCur->pPage!=0 );
  assert( pCur->eState==CURSOR_VALID );
  pBt = pCur->pBtree->pBt;
  pPage = pCur->pPage;
  assert( pCur->idx>=0 && pCur->idx<pPage->nCell );
  getCellInfo(pCur);
  aPayload = pCur->info.pCell + pCur->info.nHeader;
  if( pPage->intKey ){
    nKey = 0;
  }else{
    nKey = pCur->info.nKey;
  }
  assert( offset>=0 );
  if( skipKey ){
    offset += nKey;
  }
  if( offset+amt > nKey+pCur->info.nData ){
    return SQLITE_ERROR;
  }
  if( offset<pCur->info.nLocal ){
    int a = amt;
    if( a+offset>pCur->info.nLocal ){
      a = pCur->info.nLocal - offset;
    }
    memcpy(pBuf, &aPayload[offset], a);
    if( a==amt ){
      return SQLITE_OK;
    }
    offset = 0;
    pBuf += a;
    amt -= a;
  }else{
    offset -= pCur->info.nLocal;
  }
  ovflSize = pBt->usableSize - 4;
  if( amt>0 ){
    nextPage = get4byte(&aPayload[pCur->info.nLocal]);
    while( amt>0 && nextPage ){
      rc = sqlite3pager_get(pBt->pPager, nextPage, (void**)&aPayload);
      if( rc!=0 ){
        return rc;
      }
      nextPage = get4byte(aPayload);
      if( offset<ovflSize ){
        int a = amt;
        if( a + offset > ovflSize ){
          a = ovflSize - offset;
        }
        memcpy(pBuf, &aPayload[offset+4], a);
        offset = 0;
        amt -= a;
        pBuf += a;
      }else{
        offset -= ovflSize;
      }
      sqlite3pager_unref(aPayload);
    }
  }

  if( amt>0 ){
    return SQLITE_CORRUPT_BKPT;
  }
  return SQLITE_OK;
}

/*
** Read part of the key associated with cursor pCur.  Exactly
** "amt" bytes will be transfered into pBuf[].  The transfer
** begins at "offset".
**
** Return SQLITE_OK on success or an error code if anything goes
** wrong.  An error is returned if "offset+amt" is larger than
** the available payload.
*/
int sqlite3BtreeKey(BtCursor *pCur, u32 offset, u32 amt, void *pBuf){
  int rc = restoreOrClearCursorPosition(pCur, 1);
  if( rc==SQLITE_OK ){
    assert( pCur->eState==CURSOR_VALID );
    assert( pCur->pPage!=0 );
    if( pCur->pPage->intKey ){
      return SQLITE_CORRUPT_BKPT;
    }
    assert( pCur->pPage->intKey==0 );
    assert( pCur->idx>=0 && pCur->idx<pCur->pPage->nCell );
    rc = getPayload(pCur, offset, amt, (unsigned char*)pBuf, 0);
  }
  return rc;
}

/*
** Read part of the data associated with cursor pCur.  Exactly
** "amt" bytes will be transfered into pBuf[].  The transfer
** begins at "offset".
**
** Return SQLITE_OK on success or an error code if anything goes
** wrong.  An error is returned if "offset+amt" is larger than
** the available payload.
*/
int sqlite3BtreeData(BtCursor *pCur, u32 offset, u32 amt, void *pBuf){
  int rc = restoreOrClearCursorPosition(pCur, 1);
  if( rc==SQLITE_OK ){
    assert( pCur->eState==CURSOR_VALID );
    assert( pCur->pPage!=0 );
    assert( pCur->idx>=0 && pCur->idx<pCur->pPage->nCell );
    rc = getPayload(pCur, offset, amt, pBuf, 1);
  }
  return rc;
}

/*
** Return a pointer to payload information from the entry that the 
** pCur cursor is pointing to.  The pointer is to the beginning of
** the key if skipKey==0 and it points to the beginning of data if
** skipKey==1.  The number of bytes of available key/data is written
** into *pAmt.  If *pAmt==0, then the value returned will not be
** a valid pointer.
**
** This routine is an optimization.  It is common for the entire key
** and data to fit on the local page and for there to be no overflow
** pages.  When that is so, this routine can be used to access the
** key and data without making a copy.  If the key and/or data spills
** onto overflow pages, then getPayload() must be used to reassembly
** the key/data and copy it into a preallocated buffer.
**
** The pointer returned by this routine looks directly into the cached
** page of the database.  The data might change or move the next time
** any btree routine is called.
*/
static const unsigned char *fetchPayload(
  BtCursor *pCur,      /* Cursor pointing to entry to read from */
  int *pAmt,           /* Write the number of available bytes here */
  int skipKey          /* read beginning at data if this is true */
){
  unsigned char *aPayload;
  MemPage *pPage;
  u32 nKey;
  int nLocal;

  assert( pCur!=0 && pCur->pPage!=0 );
  assert( pCur->eState==CURSOR_VALID );
  pPage = pCur->pPage;
  assert( pCur->idx>=0 && pCur->idx<pPage->nCell );
  getCellInfo(pCur);
  aPayload = pCur->info.pCell;
  aPayload += pCur->info.nHeader;
  if( pPage->intKey ){
    nKey = 0;
  }else{
    nKey = pCur->info.nKey;
  }
  if( skipKey ){
    aPayload += nKey;
    nLocal = pCur->info.nLocal - nKey;
  }else{
    nLocal = pCur->info.nLocal;
    if( nLocal>nKey ){
      nLocal = nKey;
    }
  }
  *pAmt = nLocal;
  return aPayload;
}


/*
** For the entry that cursor pCur is point to, return as
** many bytes of the key or data as are available on the local
** b-tree page.  Write the number of available bytes into *pAmt.
**
** The pointer returned is ephemeral.  The key/data may move
** or be destroyed on the next call to any Btree routine.
**
** These routines is used to get quick access to key and data
** in the common case where no overflow pages are used.
*/
const void *sqlite3BtreeKeyFetch(BtCursor *pCur, int *pAmt){
  if( pCur->eState==CURSOR_VALID ){
    return (const void*)fetchPayload(pCur, pAmt, 0);
  }
  return 0;
}
const void *sqlite3BtreeDataFetch(BtCursor *pCur, int *pAmt){
  if( pCur->eState==CURSOR_VALID ){
    return (const void*)fetchPayload(pCur, pAmt, 1);
  }
  return 0;
}


/*
** Move the cursor down to a new child page.  The newPgno argument is the
** page number of the child page to move to.
*/
static int moveToChild(BtCursor *pCur, u32 newPgno){
  int rc;
  MemPage *pNewPage;
  MemPage *pOldPage;
  BtShared *pBt = pCur->pBtree->pBt;

  assert( pCur->eState==CURSOR_VALID );
  rc = getAndInitPage(pBt, newPgno, &pNewPage, pCur->pPage);
  if( rc ) return rc;
  pNewPage->idxParent = pCur->idx;
  pOldPage = pCur->pPage;
  pOldPage->idxShift = 0;
  releasePage(pOldPage);
  pCur->pPage = pNewPage;
  pCur->idx = 0;
  pCur->info.nSize = 0;
  if( pNewPage->nCell<1 ){
    return SQLITE_CORRUPT_BKPT;
  }
  return SQLITE_OK;
}

/*
** Return true if the page is the virtual root of its table.
**
** The virtual root page is the root page for most tables.  But
** for the table rooted on page 1, sometime the real root page
** is empty except for the right-pointer.  In such cases the
** virtual root page is the page that the right-pointer of page
** 1 is pointing to.
*/
static int isRootPage(MemPage *pPage){
  MemPage *pParent = pPage->pParent;
  if( pParent==0 ) return 1;
  if( pParent->pgno>1 ) return 0;
  if( get2byte(&pParent->aData[pParent->hdrOffset+3])==0 ) return 1;
  return 0;
}

/*
** Move the cursor up to the parent page.
**
** pCur->idx is set to the cell index that contains the pointer
** to the page we are coming from.  If we are coming from the
** right-most child page then pCur->idx is set to one more than
** the largest cell index.
*/
static void moveToParent(BtCursor *pCur){
  MemPage *pParent;
  MemPage *pPage;
  int idxParent;

  assert( pCur->eState==CURSOR_VALID );
  pPage = pCur->pPage;
  assert( pPage!=0 );
  assert( !isRootPage(pPage) );
  pParent = pPage->pParent;
  assert( pParent!=0 );
  idxParent = pPage->idxParent;
  sqlite3pager_ref(pParent->aData);
  releasePage(pPage);
  pCur->pPage = pParent;
  pCur->info.nSize = 0;
  assert( pParent->idxShift==0 );
  pCur->idx = idxParent;
}

/*
** Move the cursor to the root page
*/
static int moveToRoot(BtCursor *pCur){
  MemPage *pRoot;
  int rc = SQLITE_OK;
  BtShared *pBt = pCur->pBtree->pBt;

  restoreOrClearCursorPosition(pCur, 0);
  pRoot = pCur->pPage;
  if( pRoot && pRoot->pgno==pCur->pgnoRoot ){
    assert( pRoot->isInit );
  }else{
    if( 
      SQLITE_OK!=(rc = getAndInitPage(pBt, pCur->pgnoRoot, &pRoot, 0))
    ){
      pCur->eState = CURSOR_INVALID;
      return rc;
    }
    releasePage(pCur->pPage);
    pCur->pPage = pRoot;
  }
  pCur->idx = 0;
  pCur->info.nSize = 0;
  if( pRoot->nCell==0 && !pRoot->leaf ){
    Pgno subpage;
    assert( pRoot->pgno==1 );
    subpage = get4byte(&pRoot->aData[pRoot->hdrOffset+8]);
    assert( subpage>0 );
    pCur->eState = CURSOR_VALID;
    rc = moveToChild(pCur, subpage);
  }
  pCur->eState = ((pCur->pPage->nCell>0)?CURSOR_VALID:CURSOR_INVALID);
  return rc;
}

/*
** Move the cursor down to the left-most leaf entry beneath the
** entry to which it is currently pointing.
**
** The left-most leaf is the one with the smallest key - the first
** in ascending order.
*/
static int moveToLeftmost(BtCursor *pCur){
  Pgno pgno;
  int rc;
  MemPage *pPage;

  assert( pCur->eState==CURSOR_VALID );
  while( !(pPage = pCur->pPage)->leaf ){
    assert( pCur->idx>=0 && pCur->idx<pPage->nCell );
    pgno = get4byte(findCell(pPage, pCur->idx));
    rc = moveToChild(pCur, pgno);
    if( rc ) return rc;
  }
  return SQLITE_OK;
}

/*
** Move the cursor down to the right-most leaf entry beneath the
** page to which it is currently pointing.  Notice the difference
** between moveToLeftmost() and moveToRightmost().  moveToLeftmost()
** finds the left-most entry beneath the *entry* whereas moveToRightmost()
** finds the right-most entry beneath the *page*.
**
** The right-most entry is the one with the largest key - the last
** key in ascending order.
*/
static int moveToRightmost(BtCursor *pCur){
  Pgno pgno;
  int rc;
  MemPage *pPage;

  assert( pCur->eState==CURSOR_VALID );
  while( !(pPage = pCur->pPage)->leaf ){
    pgno = get4byte(&pPage->aData[pPage->hdrOffset+8]);
    pCur->idx = pPage->nCell;
    rc = moveToChild(pCur, pgno);
    if( rc ) return rc;
  }
  pCur->idx = pPage->nCell - 1;
  pCur->info.nSize = 0;
  return SQLITE_OK;
}

/* Move the cursor to the first entry in the table.  Return SQLITE_OK
** on success.  Set *pRes to 0 if the cursor actually points to something
** or set *pRes to 1 if the table is empty.
*/
int sqlite3BtreeFirst(BtCursor *pCur, int *pRes){
  int rc;
  rc = moveToRoot(pCur);
  if( rc ) return rc;
  if( pCur->eState==CURSOR_INVALID ){
    assert( pCur->pPage->nCell==0 );
    *pRes = 1;
    return SQLITE_OK;
  }
  assert( pCur->pPage->nCell>0 );
  *pRes = 0;
  rc = moveToLeftmost(pCur);
  return rc;
}

/* Move the cursor to the last entry in the table.  Return SQLITE_OK
** on success.  Set *pRes to 0 if the cursor actually points to something
** or set *pRes to 1 if the table is empty.
*/
int sqlite3BtreeLast(BtCursor *pCur, int *pRes){
  int rc;
  rc = moveToRoot(pCur);
  if( rc ) return rc;
  if( CURSOR_INVALID==pCur->eState ){
    assert( pCur->pPage->nCell==0 );
    *pRes = 1;
    return SQLITE_OK;
  }
  assert( pCur->eState==CURSOR_VALID );
  *pRes = 0;
  rc = moveToRightmost(pCur);
  return rc;
}

/* Move the cursor so that it points to an entry near pKey/nKey.
** Return a success code.
**
** For INTKEY tables, only the nKey parameter is used.  pKey is
** ignored.  For other tables, nKey is the number of bytes of data
** in pKey.  The comparison function specified when the cursor was
** created is used to compare keys.
**
** If an exact match is not found, then the cursor is always
** left pointing at a leaf page which would hold the entry if it
** were present.  The cursor might point to an entry that comes
** before or after the key.
**
** The result of comparing the key with the entry to which the
** cursor is written to *pRes if pRes!=NULL.  The meaning of
** this value is as follows:
**
**     *pRes<0      The cursor is left pointing at an entry that
**                  is smaller than pKey or if the table is empty
**                  and the cursor is therefore left point to nothing.
**
**     *pRes==0     The cursor is left pointing at an entry that
**                  exactly matches pKey.
**
**     *pRes>0      The cursor is left pointing at an entry that
**                  is larger than pKey.
*/
int sqlite3BtreeMoveto(BtCursor *pCur, const void *pKey, i64 nKey, int *pRes){
  int rc;
  int tryRightmost;
  rc = moveToRoot(pCur);
  if( rc ) return rc;
  assert( pCur->pPage );
  assert( pCur->pPage->isInit );
  tryRightmost = pCur->pPage->intKey;
  if( pCur->eState==CURSOR_INVALID ){
    *pRes = -1;
    assert( pCur->pPage->nCell==0 );
    return SQLITE_OK;
  }
  for(;;){
    int lwr, upr;
    Pgno chldPg;
    MemPage *pPage = pCur->pPage;
    int c = -1;  /* pRes return if table is empty must be -1 */
    lwr = 0;
    upr = pPage->nCell-1;
    if( !pPage->intKey && pKey==0 ){
      return SQLITE_CORRUPT_BKPT;
    }
    while( lwr<=upr ){
      void *pCellKey;
      i64 nCellKey;
      pCur->idx = (lwr+upr)/2;
      pCur->info.nSize = 0;
      if( pPage->intKey ){
        u8 *pCell;
        if( tryRightmost ){
          pCur->idx = upr;
        }
        pCell = findCell(pPage, pCur->idx) + pPage->childPtrSize;
        if( pPage->hasData ){
          u32 dummy;
          pCell += getVarint32(pCell, &dummy);
        }
        getVarint(pCell, (u64 *)&nCellKey);
        if( nCellKey<nKey ){
          c = -1;
        }else if( nCellKey>nKey ){
          c = +1;
          tryRightmost = 0;
        }else{
          c = 0;
        }
      }else{
        int available;
        pCellKey = (void *)fetchPayload(pCur, &available, 0);
        nCellKey = pCur->info.nKey;
        if( available>=nCellKey ){
          c = pCur->xCompare(pCur->pArg, nCellKey, pCellKey, nKey, pKey);
        }else{
          pCellKey = sqliteMallocRaw( nCellKey );
          if( pCellKey==0 ) return SQLITE_NOMEM;
          rc = sqlite3BtreeKey(pCur, 0, nCellKey, (void *)pCellKey);
          c = pCur->xCompare(pCur->pArg, nCellKey, pCellKey, nKey, pKey);
          sqliteFree(pCellKey);
          if( rc ) return rc;
        }
      }
      if( c==0 ){
        if( pPage->leafData && !pPage->leaf ){
          lwr = pCur->idx;
          upr = lwr - 1;
          break;
        }else{
          if( pRes ) *pRes = 0;
          return SQLITE_OK;
        }
      }
      if( c<0 ){
        lwr = pCur->idx+1;
      }else{
        upr = pCur->idx-1;
      }
    }
    assert( lwr==upr+1 );
    assert( pPage->isInit );
    if( pPage->leaf ){
      chldPg = 0;
    }else if( lwr>=pPage->nCell ){
      chldPg = get4byte(&pPage->aData[pPage->hdrOffset+8]);
    }else{
      chldPg = get4byte(findCell(pPage, lwr));
    }
    if( chldPg==0 ){
      assert( pCur->idx>=0 && pCur->idx<pCur->pPage->nCell );
      if( pRes ) *pRes = c;
      return SQLITE_OK;
    }
    pCur->idx = lwr;
    pCur->info.nSize = 0;
    rc = moveToChild(pCur, chldPg);
    if( rc ){
      return rc;
    }
  }
  /* NOT REACHED */
}

/*
** Return TRUE if the cursor is not pointing at an entry of the table.
**
** TRUE will be returned after a call to sqlite3BtreeNext() moves
** past the last entry in the table or sqlite3BtreePrev() moves past
** the first entry.  TRUE is also returned if the table is empty.
*/
int sqlite3BtreeEof(BtCursor *pCur){
  /* TODO: What if the cursor is in CURSOR_REQUIRESEEK but all table entries
  ** have been deleted? This API will need to change to return an error code
  ** as well as the boolean result value.
  */
  return (CURSOR_VALID!=pCur->eState);
}

/*
** Advance the cursor to the next entry in the database.  If
** successful then set *pRes=0.  If the cursor
** was already pointing to the last entry in the database before
** this routine was called, then set *pRes=1.
*/
int sqlite3BtreeNext(BtCursor *pCur, int *pRes){
  int rc;
  MemPage *pPage;

#ifndef SQLITE_OMIT_SHARED_CACHE
  rc = restoreOrClearCursorPosition(pCur, 1);
  if( rc!=SQLITE_OK ){
    return rc;
  }
  if( pCur->skip>0 ){
    pCur->skip = 0;
    *pRes = 0;
    return SQLITE_OK;
  }
  pCur->skip = 0;
#endif 

  assert( pRes!=0 );
  pPage = pCur->pPage;
  if( CURSOR_INVALID==pCur->eState ){
    *pRes = 1;
    return SQLITE_OK;
  }
  assert( pPage->isInit );
  assert( pCur->idx<pPage->nCell );

  pCur->idx++;
  pCur->info.nSize = 0;
  if( pCur->idx>=pPage->nCell ){
    if( !pPage->leaf ){
      rc = moveToChild(pCur, get4byte(&pPage->aData[pPage->hdrOffset+8]));
      if( rc ) return rc;
      rc = moveToLeftmost(pCur);
      *pRes = 0;
      return rc;
    }
    do{
      if( isRootPage(pPage) ){
        *pRes = 1;
        pCur->eState = CURSOR_INVALID;
        return SQLITE_OK;
      }
      moveToParent(pCur);
      pPage = pCur->pPage;
    }while( pCur->idx>=pPage->nCell );
    *pRes = 0;
    if( pPage->leafData ){
      rc = sqlite3BtreeNext(pCur, pRes);
    }else{
      rc = SQLITE_OK;
    }
    return rc;
  }
  *pRes = 0;
  if( pPage->leaf ){
    return SQLITE_OK;
  }
  rc = moveToLeftmost(pCur);
  return rc;
}

/*
** Step the cursor to the back to the previous entry in the database.  If
** successful then set *pRes=0.  If the cursor
** was already pointing to the first entry in the database before
** this routine was called, then set *pRes=1.
*/
int sqlite3BtreePrevious(BtCursor *pCur, int *pRes){
  int rc;
  Pgno pgno;
  MemPage *pPage;

#ifndef SQLITE_OMIT_SHARED_CACHE
  rc = restoreOrClearCursorPosition(pCur, 1);
  if( rc!=SQLITE_OK ){
    return rc;
  }
  if( pCur->skip<0 ){
    pCur->skip = 0;
    *pRes = 0;
    return SQLITE_OK;
  }
  pCur->skip = 0;
#endif

  if( CURSOR_INVALID==pCur->eState ){
    *pRes = 1;
    return SQLITE_OK;
  }

  pPage = pCur->pPage;
  assert( pPage->isInit );
  assert( pCur->idx>=0 );
  if( !pPage->leaf ){
    pgno = get4byte( findCell(pPage, pCur->idx) );
    rc = moveToChild(pCur, pgno);
    if( rc ) return rc;
    rc = moveToRightmost(pCur);
  }else{
    while( pCur->idx==0 ){
      if( isRootPage(pPage) ){
        pCur->eState = CURSOR_INVALID;
        *pRes = 1;
        return SQLITE_OK;
      }
      moveToParent(pCur);
      pPage = pCur->pPage;
    }
    pCur->idx--;
    pCur->info.nSize = 0;
    if( pPage->leafData && !pPage->leaf ){
      rc = sqlite3BtreePrevious(pCur, pRes);
    }else{
      rc = SQLITE_OK;
    }
  }
  *pRes = 0;
  return rc;
}

/*
** Allocate a new page from the database file.
**
** The new page is marked as dirty.  (In other words, sqlite3pager_write()
** has already been called on the new page.)  The new page has also
** been referenced and the calling routine is responsible for calling
** sqlite3pager_unref() on the new page when it is done.
**
** SQLITE_OK is returned on success.  Any other return value indicates
** an error.  *ppPage and *pPgno are undefined in the event of an error.
** Do not invoke sqlite3pager_unref() on *ppPage if an error is returned.
**
** If the "nearby" parameter is not 0, then a (feeble) effort is made to 
** locate a page close to the page number "nearby".  This can be used in an
** attempt to keep related pages close to each other in the database file,
** which in turn can make database access faster.
**
** If the "exact" parameter is not 0, and the page-number nearby exists 
** anywhere on the free-list, then it is guarenteed to be returned. This
** is only used by auto-vacuum databases when allocating a new table.
*/
static int allocatePage(
  BtShared *pBt, 
  MemPage **ppPage, 
  Pgno *pPgno, 
  Pgno nearby,
  u8 exact
){
  MemPage *pPage1;
  int rc;
  int n;     /* Number of pages on the freelist */
  int k;     /* Number of leaves on the trunk of the freelist */
  MemPage *pTrunk = 0;
  MemPage *pPrevTrunk = 0;

  pPage1 = pBt->pPage1;
  n = get4byte(&pPage1->aData[36]);
  if( n>0 ){
    /* There are pages on the freelist.  Reuse one of those pages. */
    Pgno iTrunk;
    u8 searchList = 0; /* If the free-list must be searched for 'nearby' */
    
    /* If the 'exact' parameter was true and a query of the pointer-map
    ** shows that the page 'nearby' is somewhere on the free-list, then
    ** the entire-list will be searched for that page.
    */
#ifndef SQLITE_OMIT_AUTOVACUUM
    if( exact ){
      u8 eType;
      assert( nearby>0 );
      assert( pBt->autoVacuum );
      rc = ptrmapGet(pBt, nearby, &eType, 0);
      if( rc ) return rc;
      if( eType==PTRMAP_FREEPAGE ){
        searchList = 1;
      }
      *pPgno = nearby;
    }
#endif

    /* Decrement the free-list count by 1. Set iTrunk to the index of the
    ** first free-list trunk page. iPrevTrunk is initially 1.
    */
    rc = sqlite3pager_write(pPage1->aData);
    if( rc ) return rc;
    put4byte(&pPage1->aData[36], n-1);

    /* The code within this loop is run only once if the 'searchList' variable
    ** is not true. Otherwise, it runs once for each trunk-page on the
    ** free-list until the page 'nearby' is located.
    */
    do {
      pPrevTrunk = pTrunk;
      if( pPrevTrunk ){
        iTrunk = get4byte(&pPrevTrunk->aData[0]);
      }else{
        iTrunk = get4byte(&pPage1->aData[32]);
      }
      rc = getPage(pBt, iTrunk, &pTrunk);
      if( rc ){
        pTrunk = 0;
        goto end_allocate_page;
      }

      k = get4byte(&pTrunk->aData[4]);
      if( k==0 && !searchList ){
        /* The trunk has no leaves and the list is not being searched. 
        ** So extract the trunk page itself and use it as the newly 
        ** allocated page */
        assert( pPrevTrunk==0 );
        rc = sqlite3pager_write(pTrunk->aData);
        if( rc ){
          goto end_allocate_page;
        }
        *pPgno = iTrunk;
        memcpy(&pPage1->aData[32], &pTrunk->aData[0], 4);
        *ppPage = pTrunk;
        pTrunk = 0;
        TRACE(("ALLOCATE: %d trunk - %d free pages left\n", *pPgno, n-1));
      }else if( k>pBt->usableSize/4 - 8 ){
        /* Value of k is out of range.  Database corruption */
        rc = SQLITE_CORRUPT_BKPT;
        goto end_allocate_page;
#ifndef SQLITE_OMIT_AUTOVACUUM
      }else if( searchList && nearby==iTrunk ){
        /* The list is being searched and this trunk page is the page
        ** to allocate, regardless of whether it has leaves.
        */
        assert( *pPgno==iTrunk );
        *ppPage = pTrunk;
        searchList = 0;
        rc = sqlite3pager_write(pTrunk->aData);
        if( rc ){
          goto end_allocate_page;
        }
        if( k==0 ){
          if( !pPrevTrunk ){
            memcpy(&pPage1->aData[32], &pTrunk->aData[0], 4);
          }else{
            memcpy(&pPrevTrunk->aData[0], &pTrunk->aData[0], 4);
          }
        }else{
          /* The trunk page is required by the caller but it contains 
          ** pointers to free-list leaves. The first leaf becomes a trunk
          ** page in this case.
          */
          MemPage *pNewTrunk;
          Pgno iNewTrunk = get4byte(&pTrunk->aData[8]);
          rc = getPage(pBt, iNewTrunk, &pNewTrunk);
          if( rc!=SQLITE_OK ){
            goto end_allocate_page;
          }
          rc = sqlite3pager_write(pNewTrunk->aData);
          if( rc!=SQLITE_OK ){
            releasePage(pNewTrunk);
            goto end_allocate_page;
          }
          memcpy(&pNewTrunk->aData[0], &pTrunk->aData[0], 4);
          put4byte(&pNewTrunk->aData[4], k-1);
          memcpy(&pNewTrunk->aData[8], &pTrunk->aData[12], (k-1)*4);
          releasePage(pNewTrunk);
          if( !pPrevTrunk ){
            put4byte(&pPage1->aData[32], iNewTrunk);
          }else{
            rc = sqlite3pager_write(pPrevTrunk->aData);
            if( rc ){
              goto end_allocate_page;
            }
            put4byte(&pPrevTrunk->aData[0], iNewTrunk);
          }
        }
        pTrunk = 0;
        TRACE(("ALLOCATE: %d trunk - %d free pages left\n", *pPgno, n-1));
#endif
      }else{
        /* Extract a leaf from the trunk */
        int closest;
        Pgno iPage;
        unsigned char *aData = pTrunk->aData;
        rc = sqlite3pager_write(aData);
        if( rc ){
          goto end_allocate_page;
        }
        if( nearby>0 ){
          int i, dist;
          closest = 0;
          dist = get4byte(&aData[8]) - nearby;
          if( dist<0 ) dist = -dist;
          for(i=1; i<k; i++){
            int d2 = get4byte(&aData[8+i*4]) - nearby;
            if( d2<0 ) d2 = -d2;
            if( d2<dist ){
              closest = i;
              dist = d2;
            }
          }
        }else{
          closest = 0;
        }

        iPage = get4byte(&aData[8+closest*4]);
        if( !searchList || iPage==nearby ){
          *pPgno = iPage;
          if( *pPgno>sqlite3pager_pagecount(pBt->pPager) ){
            /* Free page off the end of the file */
            return SQLITE_CORRUPT_BKPT;
          }
          TRACE(("ALLOCATE: %d was leaf %d of %d on trunk %d"
                 ": %d more free pages\n",
                 *pPgno, closest+1, k, pTrunk->pgno, n-1));
          if( closest<k-1 ){
            memcpy(&aData[8+closest*4], &aData[4+k*4], 4);
          }
          put4byte(&aData[4], k-1);
          rc = getPage(pBt, *pPgno, ppPage);
          if( rc==SQLITE_OK ){
            sqlite3pager_dont_rollback((*ppPage)->aData);
            rc = sqlite3pager_write((*ppPage)->aData);
            if( rc!=SQLITE_OK ){
              releasePage(*ppPage);
            }
          }
          searchList = 0;
        }
      }
      releasePage(pPrevTrunk);
      pPrevTrunk = 0;
    }while( searchList );
  }else{
    /* There are no pages on the freelist, so create a new page at the
    ** end of the file */
    *pPgno = sqlite3pager_pagecount(pBt->pPager) + 1;

#ifndef SQLITE_OMIT_AUTOVACUUM
    if( pBt->autoVacuum && PTRMAP_ISPAGE(pBt, *pPgno) ){
      /* If *pPgno refers to a pointer-map page, allocate two new pages
      ** at the end of the file instead of one. The first allocated page
      ** becomes a new pointer-map page, the second is used by the caller.
      */
      TRACE(("ALLOCATE: %d from end of file (pointer-map page)\n", *pPgno));
      assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
      (*pPgno)++;
    }
#endif

    assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
    rc = getPage(pBt, *pPgno, ppPage);
    if( rc ) return rc;
    rc = sqlite3pager_write((*ppPage)->aData);
    if( rc!=SQLITE_OK ){
      releasePage(*ppPage);
    }
    TRACE(("ALLOCATE: %d from end of file\n", *pPgno));
  }

  assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );

end_allocate_page:
  releasePage(pTrunk);
  releasePage(pPrevTrunk);
  return rc;
}

/*
** Add a page of the database file to the freelist.
**
** sqlite3pager_unref() is NOT called for pPage.
*/
static int freePage(MemPage *pPage){
  BtShared *pBt = pPage->pBt;
  MemPage *pPage1 = pBt->pPage1;
  int rc, n, k;

  /* Prepare the page for freeing */
  assert( pPage->pgno>1 );
  pPage->isInit = 0;
  releasePage(pPage->pParent);
  pPage->pParent = 0;

  /* Increment the free page count on pPage1 */
  rc = sqlite3pager_write(pPage1->aData);
  if( rc ) return rc;
  n = get4byte(&pPage1->aData[36]);
  put4byte(&pPage1->aData[36], n+1);

#ifdef SQLITE_SECURE_DELETE
  /* If the SQLITE_SECURE_DELETE compile-time option is enabled, then
  ** always fully overwrite deleted information with zeros.
  */
  rc = sqlite3pager_write(pPage->aData);
  if( rc ) return rc;
  memset(pPage->aData, 0, pPage->pBt->pageSize);
#endif

#ifndef SQLITE_OMIT_AUTOVACUUM
  /* If the database supports auto-vacuum, write an entry in the pointer-map
  ** to indicate that the page is free.
  */
  if( pBt->autoVacuum ){
    rc = ptrmapPut(pBt, pPage->pgno, PTRMAP_FREEPAGE, 0);
    if( rc ) return rc;
  }
#endif

  if( n==0 ){
    /* This is the first free page */
    rc = sqlite3pager_write(pPage->aData);
    if( rc ) return rc;
    memset(pPage->aData, 0, 8);
    put4byte(&pPage1->aData[32], pPage->pgno);
    TRACE(("FREE-PAGE: %d first\n", pPage->pgno));
  }else{
    /* Other free pages already exist.  Retrive the first trunk page
    ** of the freelist and find out how many leaves it has. */
    MemPage *pTrunk;
    rc = getPage(pBt, get4byte(&pPage1->aData[32]), &pTrunk);
    if( rc ) return rc;
    k = get4byte(&pTrunk->aData[4]);
    if( k>=pBt->usableSize/4 - 8 ){
      /* The trunk is full.  Turn the page being freed into a new
      ** trunk page with no leaves. */
      rc = sqlite3pager_write(pPage->aData);
      if( rc ) return rc;
      put4byte(pPage->aData, pTrunk->pgno);
      put4byte(&pPage->aData[4], 0);
      put4byte(&pPage1->aData[32], pPage->pgno);
      TRACE(("FREE-PAGE: %d new trunk page replacing %d\n",
              pPage->pgno, pTrunk->pgno));
    }else{
      /* Add the newly freed page as a leaf on the current trunk */
      rc = sqlite3pager_write(pTrunk->aData);
      if( rc ) return rc;
      put4byte(&pTrunk->aData[4], k+1);
      put4byte(&pTrunk->aData[8+k*4], pPage->pgno);
#ifndef SQLITE_SECURE_DELETE
      sqlite3pager_dont_write(pBt->pPager, pPage->pgno);
#endif
      TRACE(("FREE-PAGE: %d leaf on trunk page %d\n",pPage->pgno,pTrunk->pgno));
    }
    releasePage(pTrunk);
  }
  return rc;
}

/*
** Free any overflow pages associated with the given Cell.
*/
static int clearCell(MemPage *pPage, unsigned char *pCell){
  BtShared *pBt = pPage->pBt;
  CellInfo info;
  Pgno ovflPgno;
  int rc;

  parseCellPtr(pPage, pCell, &info);
  if( info.iOverflow==0 ){
    return SQLITE_OK;  /* No overflow pages. Return without doing anything */
  }
  ovflPgno = get4byte(&pCell[info.iOverflow]);
  while( ovflPgno!=0 ){
    MemPage *pOvfl;
    if( ovflPgno>sqlite3pager_pagecount(pBt->pPager) ){
      return SQLITE_CORRUPT_BKPT;
    }
    rc = getPage(pBt, ovflPgno, &pOvfl);
    if( rc ) return rc;
    ovflPgno = get4byte(pOvfl->aData);
    rc = freePage(pOvfl);
    sqlite3pager_unref(pOvfl->aData);
    if( rc ) return rc;
  }
  return SQLITE_OK;
}

/*
** Create the byte sequence used to represent a cell on page pPage
** and write that byte sequence into pCell[].  Overflow pages are
** allocated and filled in as necessary.  The calling procedure
** is responsible for making sure sufficient space has been allocated
** for pCell[].
**
** Note that pCell does not necessary need to point to the pPage->aData
** area.  pCell might point to some temporary storage.  The cell will
** be constructed in this temporary area then copied into pPage->aData
** later.
*/
static int fillInCell(
  MemPage *pPage,                /* The page that contains the cell */
  unsigned char *pCell,          /* Complete text of the cell */
  const void *pKey, i64 nKey,    /* The key */
  const void *pData,int nData,   /* The data */
  int *pnSize                    /* Write cell size here */
){
  int nPayload;
  const u8 *pSrc;
  int nSrc, n, rc;
  int spaceLeft;
  MemPage *pOvfl = 0;
  MemPage *pToRelease = 0;
  unsigned char *pPrior;
  unsigned char *pPayload;
  BtShared *pBt = pPage->pBt;
  Pgno pgnoOvfl = 0;
  int nHeader;
  CellInfo info;

  /* Fill in the header. */
  nHeader = 0;
  if( !pPage->leaf ){
    nHeader += 4;
  }
  if( pPage->hasData ){
    nHeader += putVarint(&pCell[nHeader], nData);
  }else{
    nData = 0;
  }
  nHeader += putVarint(&pCell[nHeader], *(u64*)&nKey);
  parseCellPtr(pPage, pCell, &info);
  assert( info.nHeader==nHeader );
  assert( info.nKey==nKey );
  assert( info.nData==nData );
  
  /* Fill in the payload */
  nPayload = nData;
  if( pPage->intKey ){
    pSrc = pData;
    nSrc = nData;
    nData = 0;
  }else{
    nPayload += nKey;
    pSrc = pKey;
    nSrc = nKey;
  }
  *pnSize = info.nSize;
  spaceLeft = info.nLocal;
  pPayload = &pCell[nHeader];
  pPrior = &pCell[info.iOverflow];

  while( nPayload>0 ){
    if( spaceLeft==0 ){
#ifndef SQLITE_OMIT_AUTOVACUUM
      Pgno pgnoPtrmap = pgnoOvfl; /* Overflow page pointer-map entry page */
#endif
      rc = allocatePage(pBt, &pOvfl, &pgnoOvfl, pgnoOvfl, 0);
#ifndef SQLITE_OMIT_AUTOVACUUM
      /* If the database supports auto-vacuum, and the second or subsequent
      ** overflow page is being allocated, add an entry to the pointer-map
      ** for that page now. The entry for the first overflow page will be
      ** added later, by the insertCell() routine.
      */
      if( pBt->autoVacuum && pgnoPtrmap!=0 && rc==SQLITE_OK ){
        rc = ptrmapPut(pBt, pgnoOvfl, PTRMAP_OVERFLOW2, pgnoPtrmap);
      }
#endif
      if( rc ){
        releasePage(pToRelease);
        /* clearCell(pPage, pCell); */
        return rc;
      }
      put4byte(pPrior, pgnoOvfl);
      releasePage(pToRelease);
      pToRelease = pOvfl;
      pPrior = pOvfl->aData;
      put4byte(pPrior, 0);
      pPayload = &pOvfl->aData[4];
      spaceLeft = pBt->usableSize - 4;
    }
    n = nPayload;
    if( n>spaceLeft ) n = spaceLeft;
    if( n>nSrc ) n = nSrc;
    assert( pSrc );
    memcpy(pPayload, pSrc, n);
    nPayload -= n;
    pPayload += n;
    pSrc += n;
    nSrc -= n;
    spaceLeft -= n;
    if( nSrc==0 ){
      nSrc = nData;
      pSrc = pData;
    }
  }
  releasePage(pToRelease);
  return SQLITE_OK;
}

/*
** Change the MemPage.pParent pointer on the page whose number is
** given in the second argument so that MemPage.pParent holds the
** pointer in the third argument.
*/
static int reparentPage(BtShared *pBt, Pgno pgno, MemPage *pNewParent, int idx){
  MemPage *pThis;
  unsigned char *aData;

  assert( pNewParent!=0 );
  if( pgno==0 ) return SQLITE_OK;
  assert( pBt->pPager!=0 );
  aData = sqlite3pager_lookup(pBt->pPager, pgno);
  if( aData ){
    pThis = (MemPage*)&aData[pBt->pageSize];
    assert( pThis->aData==aData );
    if( pThis->isInit ){
      if( pThis->pParent!=pNewParent ){
        if( pThis->pParent ) sqlite3pager_unref(pThis->pParent->aData);
        pThis->pParent = pNewParent;
        sqlite3pager_ref(pNewParent->aData);
      }
      pThis->idxParent = idx;
    }
    sqlite3pager_unref(aData);
  }

#ifndef SQLITE_OMIT_AUTOVACUUM
  if( pBt->autoVacuum ){
    return ptrmapPut(pBt, pgno, PTRMAP_BTREE, pNewParent->pgno);
  }
#endif
  return SQLITE_OK;
}



/*
** Change the pParent pointer of all children of pPage to point back
** to pPage.
**
** In other words, for every child of pPage, invoke reparentPage()
** to make sure that each child knows that pPage is its parent.
**
** This routine gets called after you memcpy() one page into
** another.
*/
static int reparentChildPages(MemPage *pPage){
  int i;
  BtShared *pBt = pPage->pBt;
  int rc = SQLITE_OK;

  if( pPage->leaf ) return SQLITE_OK;

  for(i=0; i<pPage->nCell; i++){
    u8 *pCell = findCell(pPage, i);
    if( !pPage->leaf ){
      rc = reparentPage(pBt, get4byte(pCell), pPage, i);
      if( rc!=SQLITE_OK ) return rc;
    }
  }
  if( !pPage->leaf ){
    rc = reparentPage(pBt, get4byte(&pPage->aData[pPage->hdrOffset+8]), 
       pPage, i);
    pPage->idxShift = 0;
  }
  return rc;
}

/*
** Remove the i-th cell from pPage.  This routine effects pPage only.
** The cell content is not freed or deallocated.  It is assumed that
** the cell content has been copied someplace else.  This routine just
** removes the reference to the cell from pPage.
**
** "sz" must be the number of bytes in the cell.
*/
static void dropCell(MemPage *pPage, int idx, int sz){
  int i;          /* Loop counter */
  int pc;         /* Offset to cell content of cell being deleted */
  u8 *data;       /* pPage->aData */
  u8 *ptr;        /* Used to move bytes around within data[] */

  assert( idx>=0 && idx<pPage->nCell );
  assert( sz==cellSize(pPage, idx) );
  assert( sqlite3pager_iswriteable(pPage->aData) );
  data = pPage->aData;
  ptr = &data[pPage->cellOffset + 2*idx];
  pc = get2byte(ptr);
  assert( pc>10 && pc+sz<=pPage->pBt->usableSize );
  freeSpace(pPage, pc, sz);
  for(i=idx+1; i<pPage->nCell; i++, ptr+=2){
    ptr[0] = ptr[2];
    ptr[1] = ptr[3];
  }
  pPage->nCell--;
  put2byte(&data[pPage->hdrOffset+3], pPage->nCell);
  pPage->nFree += 2;
  pPage->idxShift = 1;
}

/*
** Insert a new cell on pPage at cell index "i".  pCell points to the
** content of the cell.
**
** If the cell content will fit on the page, then put it there.  If it
** will not fit, then make a copy of the cell content into pTemp if
** pTemp is not null.  Regardless of pTemp, allocate a new entry
** in pPage->aOvfl[] and make it point to the cell content (either
** in pTemp or the original pCell) and also record its index. 
** Allocating a new entry in pPage->aCell[] implies that 
** pPage->nOverflow is incremented.
**
** If nSkip is non-zero, then do not copy the first nSkip bytes of the
** cell. The caller will overwrite them after this function returns. If
** nSkip is non-zero, then pCell may not point to an invalid memory location 
** (but pCell+nSkip is always valid).
*/
static int insertCell(
  MemPage *pPage,   /* Page into which we are copying */
  int i,            /* New cell becomes the i-th cell of the page */
  u8 *pCell,        /* Content of the new cell */
  int sz,           /* Bytes of content in pCell */
  u8 *pTemp,        /* Temp storage space for pCell, if needed */
  u8 nSkip          /* Do not write the first nSkip bytes of the cell */
){
  int idx;          /* Where to write new cell content in data[] */
  int j;            /* Loop counter */
  int top;          /* First byte of content for any cell in data[] */
  int end;          /* First byte past the last cell pointer in data[] */
  int ins;          /* Index in data[] where new cell pointer is inserted */
  int hdr;          /* Offset into data[] of the page header */
  int cellOffset;   /* Address of first cell pointer in data[] */
  u8 *data;         /* The content of the whole page */
  u8 *ptr;          /* Used for moving information around in data[] */

  assert( i>=0 && i<=pPage->nCell+pPage->nOverflow );
  assert( sz==cellSizePtr(pPage, pCell) );
  assert( sqlite3pager_iswriteable(pPage->aData) );
  if( pPage->nOverflow || sz+2>pPage->nFree ){
    if( pTemp ){
      memcpy(pTemp+nSkip, pCell+nSkip, sz-nSkip);
      pCell = pTemp;
    }
    j = pPage->nOverflow++;
    assert( j<sizeof(pPage->aOvfl)/sizeof(pPage->aOvfl[0]) );
    pPage->aOvfl[j].pCell = pCell;
    pPage->aOvfl[j].idx = i;
    pPage->nFree = 0;
  }else{
    data = pPage->aData;
    hdr = pPage->hdrOffset;
    top = get2byte(&data[hdr+5]);
    cellOffset = pPage->cellOffset;
    end = cellOffset + 2*pPage->nCell + 2;
    ins = cellOffset + 2*i;
    if( end > top - sz ){
      int rc = defragmentPage(pPage);
      if( rc!=SQLITE_OK ) return rc;
      top = get2byte(&data[hdr+5]);
      assert( end + sz <= top );
    }
    idx = allocateSpace(pPage, sz);
    assert( idx>0 );
    assert( end <= get2byte(&data[hdr+5]) );
    pPage->nCell++;
    pPage->nFree -= 2;
    memcpy(&data[idx+nSkip], pCell+nSkip, sz-nSkip);
    for(j=end-2, ptr=&data[j]; j>ins; j-=2, ptr-=2){
      ptr[0] = ptr[-2];
      ptr[1] = ptr[-1];
    }
    put2byte(&data[ins], idx);
    put2byte(&data[hdr+3], pPage->nCell);
    pPage->idxShift = 1;
#ifndef SQLITE_OMIT_AUTOVACUUM