System.Data.SQLite
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//---------------------------------------------------------------------
// <copyright file="JoinSymbol.cs" company="Microsoft">
//      Portions of this file copyright (c) Microsoft Corporation
//      and are released under the Microsoft Pulic License.  See
//      http://archive.msdn.microsoft.com/EFSampleProvider/Project/License.aspx
//      or License.txt for details.
//      All rights reserved.
// </copyright>
//---------------------------------------------------------------------

#if USE_ENTITY_FRAMEWORK_6
namespace System.Data.SQLite.EF6
#else
namespace System.Data.SQLite.Linq
#endif
{
  using System;
  using System.Collections.Generic;

#if USE_ENTITY_FRAMEWORK_6
  using System.Data.Entity.Core.Metadata.Edm;
  using System.Data.Entity.Core.Common.CommandTrees;
#else
  using System.Data.Metadata.Edm;
  using System.Data.Common.CommandTrees;
#endif

  /// <summary>
  /// A Join symbol is a special kind of Symbol.
  /// It has to carry additional information
  /// <list type="bullet">
  /// <item>ColumnList for the list of columns in the select clause if this
  /// symbol represents a sql select statement.  This is set by <see cref="SqlGenerator.AddDefaultColumns"/>. </item>
  /// <item>ExtentList is the list of extents in the select clause.</item>
  /// <item>FlattenedExtentList - if the Join has multiple extents flattened at the 
  /// top level, we need this information to ensure that extent aliases are renamed
  /// correctly in <see cref="SqlSelectStatement.WriteSql"/></item>
  /// <item>NameToExtent has all the extents in ExtentList as a dictionary.
  /// This is used by <see cref="SqlGenerator.Visit(DbPropertyExpression)"/> to flatten
  /// record accesses.</item>
  /// <item>IsNestedJoin - is used to determine whether a JoinSymbol is an 
  /// ordinary join symbol, or one that has a corresponding SqlSelectStatement.</item>
  /// </list>
  /// 
  /// All the lists are set exactly once, and then used for lookups/enumerated.
  /// </summary>
  internal sealed class JoinSymbol : Symbol
  {
    private List<Symbol> columnList;
    internal List<Symbol> ColumnList
    {
      get
      {
        if (null == columnList)
        {
          columnList = new List<Symbol>();
        }
        return columnList;
      }
      set { columnList = value; }
    }

    private List<Symbol> extentList;
    internal List<Symbol> ExtentList
    {
      get { return extentList; }
    }

    private List<Symbol> flattenedExtentList;
    internal List<Symbol> FlattenedExtentList
    {
      get
      {
        if (null == flattenedExtentList)
        {
          flattenedExtentList = new List<Symbol>();
        }
        return flattenedExtentList;
      }
      set { flattenedExtentList = value; }
    }

    private Dictionary<string, Symbol> nameToExtent;
    internal Dictionary<string, Symbol> NameToExtent
    {
      get { return nameToExtent; }
    }

    private bool isNestedJoin;
    internal bool IsNestedJoin
    {
      get { return isNestedJoin; }
      set { isNestedJoin = value; }
    }

    public JoinSymbol(string name, TypeUsage type, List<Symbol> extents)
      : base(name, type)
    {
      extentList = new List<Symbol>(extents.Count);
      nameToExtent = new Dictionary<string, Symbol>(extents.Count, StringComparer.OrdinalIgnoreCase);
      foreach (Symbol symbol in extents)
      {
        this.nameToExtent[symbol.Name] = symbol;
        this.ExtentList.Add(symbol);
      }
    }
  }
}