Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Data.Entity/System/Data/SqlClient/SqlGen/JoinSymbol.cs

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+//---------------------------------------------------------------------
+// <copyright file="JoinSymbol.cs" company="Microsoft">
+//      Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//
+// @owner  [....]
+// @backupOwner [....]
+//---------------------------------------------------------------------
+
+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);
+            }
+        }
+    }
+}