Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Data.Entity/System/Data/Objects/ELinq/BindingContext.cs

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