69 lines
2.1 KiB
C#
69 lines
2.1 KiB
C#
//---------------------------------------------------------------------
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// <copyright file="SymbolTable.cs" company="Microsoft">
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// Copyright (c) Microsoft Corporation. All rights reserved.
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// </copyright>
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//
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// @owner Microsoft
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// @backupOwner Microsoft
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//---------------------------------------------------------------------
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using System;
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.IO;
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using System.Text;
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using System.Data.SqlClient;
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using System.Data.Metadata.Edm;
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using System.Data.Common.CommandTrees;
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namespace System.Data.SqlClient.SqlGen
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{
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/// <summary>
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/// The symbol table is quite primitive - it is a stack with a new entry for
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/// each scope. Lookups search from the top of the stack to the bottom, until
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/// an entry is found.
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///
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/// The symbols are of the following kinds
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/// <list type="bullet">
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/// <item><see cref="Symbol"/> represents tables (extents/nested selects/unnests)</item>
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/// <item><see cref="JoinSymbol"/> represents Join nodes</item>
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/// <item><see cref="Symbol"/> columns.</item>
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/// </list>
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///
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/// Symbols represent names <see cref="SqlGenerator.Visit(DbVariableReferenceExpression)"/> to be resolved,
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/// or things to be renamed.
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/// </summary>
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internal sealed class SymbolTable
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{
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private List<Dictionary<string, Symbol>> symbols = new List<Dictionary<string, Symbol>>();
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internal void EnterScope()
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{
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symbols.Add(new Dictionary<string, Symbol>(StringComparer.OrdinalIgnoreCase));
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}
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internal void ExitScope()
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{
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symbols.RemoveAt(symbols.Count - 1);
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}
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internal void Add(string name, Symbol value)
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{
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symbols[symbols.Count - 1][name] = value;
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}
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internal Symbol Lookup(string name)
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{
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for (int i = symbols.Count - 1; i >= 0; --i)
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{
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if (symbols[i].ContainsKey(name))
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{
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return symbols[i][name];
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}
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}
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return null;
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}
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}
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}
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