System.Data.SQLite

#define safe_isspace(x) (jsonIsSpace[(unsigned char)x])

#ifndef SQLITE_AMALGAMATION
  /* Unsigned integer types.  These are already defined in the sqliteInt.h,
  ** but the definitions need to be repeated for separate compilation. */
  typedef sqlite3_uint64 u64;
  typedef unsigned int u32;
  typedef unsigned short int u16;
  typedef unsigned char u8;
#endif

/* Objects */
typedef struct JsonString JsonString;
typedef struct JsonNode JsonNode;
typedef struct JsonParse JsonParse;

  u32 nNode;         /* Number of slots of aNode[] used */
  u32 nAlloc;        /* Number of slots of aNode[] allocated */
  JsonNode *aNode;   /* Array of nodes containing the parse */
  const char *zJson; /* Original JSON string */
  u32 *aUp;          /* Index of parent of each node */
  u8 oom;            /* Set to true if out of memory */
  u8 nErr;           /* Number of errors seen */
  u16 iDepth;        /* Nesting depth */
  int nJson;         /* Length of the zJson string in bytes */
};

/*
** Maximum nesting depth of JSON for this implementation.
**
** This limit is needed to avoid a stack overflow in the recursive
** descent parser.  A depth of 2000 is far deeper than any sane JSON
** should go.
*/
#define JSON_MAX_DEPTH  2000

/**************************************************************************
** Utility routines for dealing with JsonString objects
**************************************************************************/

/* Set the JsonString object to an empty string
*/
static void jsonZero(JsonString *p){

*/
static int jsonParseValue(JsonParse *pParse, u32 i){
  char c;
  u32 j;
  int iThis;
  int x;
  JsonNode *pNode;
  const char *z = pParse->zJson;
  while( safe_isspace(z[i]) ){ i++; }
  if( (c = z[i])=='{' ){
    /* Parse object */
    iThis = jsonParseAddNode(pParse, JSON_OBJECT, 0, 0);
    if( iThis<0 ) return -1;
    for(j=i+1;;j++){
      while( safe_isspace(z[j]) ){ j++; }
      if( ++pParse->iDepth > JSON_MAX_DEPTH ) return -1;
      x = jsonParseValue(pParse, j);
      if( x<0 ){
        pParse->iDepth--;
        if( x==(-2) && pParse->nNode==(u32)iThis+1 ) return j+1;
        return -1;
      }
      if( pParse->oom ) return -1;
      pNode = &pParse->aNode[pParse->nNode-1];
      if( pNode->eType!=JSON_STRING ) return -1;
      pNode->jnFlags |= JNODE_LABEL;
      j = x;
      while( safe_isspace(z[j]) ){ j++; }
      if( z[j]!=':' ) return -1;
      j++;
      x = jsonParseValue(pParse, j);
      pParse->iDepth--;
      if( x<0 ) return -1;
      j = x;
      while( safe_isspace(z[j]) ){ j++; }
      c = z[j];
      if( c==',' ) continue;
      if( c!='}' ) return -1;
      break;
    }
    pParse->aNode[iThis].n = pParse->nNode - (u32)iThis - 1;
    return j+1;
  }else if( c=='[' ){
    /* Parse array */
    iThis = jsonParseAddNode(pParse, JSON_ARRAY, 0, 0);
    if( iThis<0 ) return -1;
    for(j=i+1;;j++){
      while( safe_isspace(z[j]) ){ j++; }
      if( ++pParse->iDepth > JSON_MAX_DEPTH ) return -1;
      x = jsonParseValue(pParse, j);
      pParse->iDepth--;
      if( x<0 ){
        if( x==(-3) && pParse->nNode==(u32)iThis+1 ) return j+1;
        return -1;
      }
      j = x;
      while( safe_isspace(z[j]) ){ j++; }
      c = z[j];
      if( c==',' ) continue;
      if( c!=']' ) return -1;
      break;
    }
    pParse->aNode[iThis].n = pParse->nNode - (u32)iThis - 1;
    return j+1;
  }else if( c=='"' ){
    /* Parse string */
    u8 jnFlags = 0;
    j = i+1;
    for(;;){
      c = z[j];
      if( (c & ~0x1f)==0 ){
        /* Control characters are not allowed in strings */
        return -1;
      }
      if( c=='\\' ){
        c = z[++j];
        if( c=='"' || c=='\\' || c=='/' || c=='b' || c=='f'
           || c=='n' || c=='r' || c=='t'
           || (c=='u' && jsonIs4Hex(z+j+1)) ){
          jnFlags = JNODE_ESCAPE;
        }else{
          return -1;
        }
      }else if( c=='"' ){
        break;
      }
      j++;
    }
    jsonParseAddNode(pParse, JSON_STRING, j+1-i, &z[i]);
    if( !pParse->oom ) pParse->aNode[pParse->nNode-1].jnFlags = jnFlags;
    return j+1;
  }else if( c=='n'
         && strncmp(z+i,"null",4)==0
         && !safe_isalnum(z[i+4]) ){
    jsonParseAddNode(pParse, JSON_NULL, 0, 0);
    return i+4;
  }else if( c=='t'
         && strncmp(z+i,"true",4)==0
         && !safe_isalnum(z[i+4]) ){
    jsonParseAddNode(pParse, JSON_TRUE, 0, 0);
    return i+4;
  }else if( c=='f'
         && strncmp(z+i,"false",5)==0
         && !safe_isalnum(z[i+5]) ){
    jsonParseAddNode(pParse, JSON_FALSE, 0, 0);
    return i+5;
  }else if( c=='-' || (c>='0' && c<='9') ){
    /* Parse number */
    u8 seenDP = 0;
    u8 seenE = 0;
    assert( '-' < '0' );
    if( c<='0' ){
      j = c=='-' ? i+1 : i;
      if( z[j]=='0' && z[j+1]>='0' && z[j+1]<='9' ) return -1;
    }
    j = i+1;
    for(;; j++){
      c = z[j];
      if( c>='0' && c<='9' ) continue;
      if( c=='.' ){
        if( z[j-1]=='-' ) return -1;
        if( seenDP ) return -1;
        seenDP = 1;
        continue;
      }
      if( c=='e' || c=='E' ){
        if( z[j-1]<'0' ) return -1;
        if( seenE ) return -1;
        seenDP = seenE = 1;
        c = z[j+1];
        if( c=='+' || c=='-' ){
          j++;
          c = z[j+1];
        }
        if( c<'0' || c>'9' ) return -1;
        continue;
      }
      break;
    }
    if( z[j-1]<'0' ) return -1;
    jsonParseAddNode(pParse, seenDP ? JSON_REAL : JSON_INT,
                        j - i, &z[i]);
    return j;
  }else if( c=='}' ){
    return -2;  /* End of {...} */
  }else if( c==']' ){
    return -3;  /* End of [...] */
  }else if( c==0 ){
    return 0;   /* End of file */

  int i;
  memset(pParse, 0, sizeof(*pParse));
  if( zJson==0 ) return 1;
  pParse->zJson = zJson;
  i = jsonParseValue(pParse, 0);
  if( pParse->oom ) i = -1;
  if( i>0 ){
    assert( pParse->iDepth==0 );
    while( safe_isspace(zJson[i]) ) i++;
    if( zJson[i] ) i = -1;
  }
  if( i<=0 ){
    if( pCtx!=0 ){
      if( pParse->oom ){
        sqlite3_result_error_nomem(pCtx);

  jsonReset(&jx);
}

/* This is the RFC 7396 MergePatch algorithm.
*/
static JsonNode *jsonMergePatch(
  JsonParse *pParse,   /* The JSON parser that contains the TARGET */
  u32 iTarget,         /* Node of the TARGET in pParse */
  JsonNode *pPatch     /* The PATCH */
){
  u32 i, j;
  u32 iRoot;
  JsonNode *pTarget;
  if( pPatch->eType!=JSON_OBJECT ){
    return pPatch;