109 lines
3.7 KiB
C#
109 lines
3.7 KiB
C#
//---------------------------------------------------------------------
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// <copyright file="BindingContext.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 [....]
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//---------------------------------------------------------------------
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using CqtExpression = System.Data.Common.CommandTrees.DbExpression;
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using LinqExpression = System.Linq.Expressions.Expression;
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using System.Linq.Expressions;
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using System.Collections.ObjectModel;
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using System.Linq;
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using System.Collections.Generic;
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using System.Data.Common.CommandTrees;
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using System.Data.Metadata.Edm;
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using System.Reflection;
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using System.Data.Common.EntitySql;
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using System.Diagnostics;
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using System.Data.Common;
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using System.Globalization;
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namespace System.Data.Objects.ELinq
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{
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/// <summary>
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/// Class containing binding information for an expression converter (associating CQT bindings
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/// with LINQ lambda parameter or LINQ sub-expressions)
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/// </summary>
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/// <remarks>
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/// Usage pattern:
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/// <code>
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/// BindingContext context = ...;
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///
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/// // translate a "Where" lamba expression input.Where(i => i.X > 2);
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/// LambdaExpression whereLambda = ...;
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/// CqtExpression inputCqt = Translate(whereLambda.Arguments[1]);
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/// CqtExpression inputBinding = CreateExpressionBinding(inputCqt).Var;
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///
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/// // push the scope defined by the parameter
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/// context.PushBindingScope(new KeyValuePair{ParameterExpression, CqtExpression}(whereLambda.Parameters[0], inputBinding));
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///
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/// // translate the expression in this context
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/// CqtExpression result = Translate(whereLambda.Expression);
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///
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/// // pop the scope
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/// context.PopBindingScope();
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/// </code>
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/// </remarks>
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internal sealed class BindingContext
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{
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private readonly Stack<Binding> _scopes;
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/// <summary>
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/// Initialize a new binding context
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/// </summary>
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internal BindingContext()
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{
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_scopes = new Stack<Binding>();
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}
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/// <summary>
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/// Set up a new binding scope where parameter expressions map to their paired CQT expressions.
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/// </summary>
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/// <param name="binding">DbExpression/LinqExpression binding</param>
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internal void PushBindingScope(Binding binding)
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{
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_scopes.Push(binding);
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}
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/// <summary>
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/// Removes a scope when leaving a particular sub-expression.
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/// </summary>
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/// <returns>Scope.</returns>
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internal void PopBindingScope()
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{
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_scopes.Pop();
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}
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internal bool TryGetBoundExpression(Expression linqExpression, out CqtExpression cqtExpression)
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{
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cqtExpression = _scopes
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.Where(binding => binding.LinqExpression == linqExpression)
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.Select(binding => binding.CqtExpression)
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.FirstOrDefault();
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return cqtExpression != null;
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}
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}
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/// <summary>
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/// Class describing a LINQ parameter and its bound expression. For instance, in
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///
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/// products.Select(p => p.ID)
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///
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/// the 'products' query is the bound expression, and 'p' is the parameter.
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/// </summary>
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internal sealed class Binding
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{
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internal Binding(Expression linqExpression, CqtExpression cqtExpression)
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{
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EntityUtil.CheckArgumentNull(linqExpression, "linqExpression");
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EntityUtil.CheckArgumentNull(cqtExpression, "cqtExpression");
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LinqExpression = linqExpression;
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CqtExpression = cqtExpression;
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}
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internal readonly Expression LinqExpression;
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internal readonly CqtExpression CqtExpression;
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}
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}
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