Imported Upstream version 5.2.0.179

Former-commit-id: a536d4f20e27294d8bbc2184d75f3a22364f7ba1

external/entityframework/samples/Provider/SampleEntityFrameworkProvider/SqlGeneration/Symbol.cs

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+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
+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 SampleEntityFrameworkProvider
+{
+    /// <summary>
+    /// <see cref="SymbolTable"/>
+    /// This class represents an extent/nested select statement,
+    /// or a column.
+    ///
+    /// The important fields are Name, Type and NewName.
+    /// NewName starts off the same as Name, and is then modified as necessary.
+    ///
+    ///
+    /// The rest are used by special symbols.
+    /// e.g. NeedsRenaming is used by columns to indicate that a new name must
+    /// be picked for the column in the second phase of translation.
+    ///
+    /// IsUnnest is used by symbols for a collection expression used as a from clause.
+    /// This allows <see cref="SqlGenerator.AddFromSymbol(SqlSelectStatement, string, Symbol, bool)"/> to add the column list
+    /// after the alias.
+    ///
+    /// </summary>
+    class Symbol : ISqlFragment
+    {
+        private Dictionary<string, Symbol> columns = new Dictionary<string, Symbol>(StringComparer.CurrentCultureIgnoreCase);
+        internal Dictionary<string, Symbol> Columns
+        {
+            get { return columns; }
+        }
+
+        private bool needsRenaming = false;
+        internal bool NeedsRenaming
+        {
+            get { return needsRenaming; }
+            set { needsRenaming = value; }
+        }
+
+        bool isUnnest = false;
+        internal bool IsUnnest
+        {
+            get { return isUnnest; }
+            set { isUnnest = value; }
+        }
+
+        string name;
+        public string Name
+        {
+            get { return name; }
+        }
+
+        string newName;
+        public string NewName
+        {
+            get { return newName; }
+            set { newName = value; }
+        }
+
+        private TypeUsage type;
+        internal TypeUsage Type
+        {
+            get { return type; }
+            set { type = value; }
+        }
+
+        public Symbol(string name, TypeUsage type)
+        {
+            this.name = name;
+            this.newName = name;
+            this.Type = type;
+        }
+
+        #region ISqlFragment Members
+
+        /// <summary>
+        /// Write this symbol out as a string for sql.  This is just
+        /// the new name of the symbol (which could be the same as the old name).
+        ///
+        /// We rename columns here if necessary.
+        /// </summary>
+        /// <param name="writer"></param>
+        /// <param name="sqlGenerator"></param>
+        public void WriteSql(SqlWriter writer, SqlGenerator sqlGenerator)
+        {
+            if (this.NeedsRenaming)
+            {
+                string newName;
+                int i = sqlGenerator.AllColumnNames[this.NewName];
+                do
+                {
+                    ++i;
+                    newName = this.Name + i.ToString(System.Globalization.CultureInfo.InvariantCulture);
+                } while (sqlGenerator.AllColumnNames.ContainsKey(newName));
+                sqlGenerator.AllColumnNames[this.NewName] = i;
+
+                // Prevent it from being renamed repeatedly.
+                this.NeedsRenaming = false;
+                this.NewName = newName;
+
+                // Add this column name to list of known names so that there are no subsequent
+                // collisions
+                sqlGenerator.AllColumnNames[newName] = 0;
+            }
+            writer.Write(SqlGenerator.QuoteIdentifier(this.NewName));
+        }
+
+        #endregion
+    }
+}