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//---------------------------------------------------------------------
// <copyright file="JoinSymbol.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//
// @owner Microsoft
// @backupOwner Microsoft
//---------------------------------------------------------------------
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Text;
using System.Data.SqlClient;
using System.Data.Metadata.Edm;
using System.Data.Common.CommandTrees;
namespace System.Data.SqlClient.SqlGen
{
/// <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);
}
}
}
}
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