Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Data.Entity/System/Data/Common/CommandTrees/ExpressionBindings.cs

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+//---------------------------------------------------------------------
+// <copyright file="ExpressionBindings.cs" company="Microsoft">
+//      Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//
+// @owner  [....]
+// @backupOwner [....]
+//---------------------------------------------------------------------
+
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+
+using System.Data.Common;
+using System.Data.Common.Utils;
+using System.Data.Metadata.Edm;
+using System.Data.Common.CommandTrees.Internal;
+using System.Data.Common.CommandTrees.ExpressionBuilder;
+
+namespace System.Data.Common.CommandTrees
+{
+    /// <summary>
+    /// Describes a binding for an expression. Conceptually similar to a foreach loop
+    /// in C#. The DbExpression property defines the collection being iterated over,
+    /// while the Var property provides a means to reference the current element
+    /// of the collection during the iteration. DbExpressionBinding is used to describe the set arguments
+    /// to relational expressions such as <see cref="DbFilterExpression"/>, <see cref="DbProjectExpression"/>
+    /// and <see cref="DbJoinExpression"/>.
+    /// </summary>
+    /// <seealso cref="DbExpression"/>
+    /// <seealso cref="Variable"/>
+    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "Db")]
+    public sealed class DbExpressionBinding
+    {
+        private readonly DbExpression _expr;
+        private readonly DbVariableReferenceExpression _varRef;
+        
+        internal DbExpressionBinding(DbExpression input, DbVariableReferenceExpression varRef)
+        {
+            Debug.Assert(input != null, "DbExpressionBinding input cannot be null");
+            Debug.Assert(varRef != null, "DbExpressionBinding variable cannot be null");
+
+            _expr = input;
+            _varRef = varRef;
+        }
+
+        /// <summary>
+        /// Gets the <see cref="DbExpression"/> that defines the input set.
+        /// </summary>
+        public DbExpression Expression { get { return _expr; } }
+        
+        /// <summary>
+        /// Gets the name assigned to the element variable.
+        /// </summary>
+        public string VariableName { get { return _varRef.VariableName; } }
+
+        /// <summary>
+        /// Gets the type metadata of the element variable.
+        /// </summary>
+        public TypeUsage VariableType { get { return _varRef.ResultType; } }
+        
+        /// <summary>
+        /// Gets the <see cref="DbVariableReferenceExpression"/> that references the element variable.
+        /// </summary>
+        public DbVariableReferenceExpression Variable { get { return _varRef;} }
+    }
+
+    /// <summary>
+    /// Defines the binding for the input set to a <see cref="DbGroupByExpression"/>.
+    /// In addition to the properties of <see cref="DbExpressionBinding"/>, DbGroupExpressionBinding
+    /// also provides access to the group element via the <seealso cref="GroupVariable"/> variable reference
+    /// and to the group aggregate via the <seealso cref="GroupAggregate"/> property.
+    /// </summary>
+    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "Db")]
+    public sealed class DbGroupExpressionBinding
+    {
+        private /*readonly*/ DbExpression _expr;
+        private readonly DbVariableReferenceExpression _varRef;
+        private readonly DbVariableReferenceExpression _groupVarRef;
+        private  DbGroupAggregate _groupAggregate;
+        
+        internal DbGroupExpressionBinding(DbExpression input, DbVariableReferenceExpression inputRef, DbVariableReferenceExpression groupRef)
+        {    
+            _expr = input;
+            _varRef = inputRef;
+            _groupVarRef = groupRef;
+        }
+
+        /// <summary>
+        /// Gets the <see cref="DbExpression"/> that defines the input set.
+        /// </summary>
+        public DbExpression Expression { get { return _expr; } }
+                
+        /// <summary>
+        /// Gets the name assigned to the element variable.
+        /// </summary>
+        public string VariableName { get { return _varRef.VariableName; } }
+
+        /// <summary>
+        /// Gets the type metadata of the element variable.
+        /// </summary>
+        public TypeUsage VariableType { get { return _varRef.ResultType; } }
+
+        /// <summary>
+        /// Gets the DbVariableReferenceExpression that references the element variable.
+        /// </summary>
+        public DbVariableReferenceExpression Variable { get { return _varRef; } }
+
+        /// <summary>
+        /// Gets the name assigned to the group element variable.
+        /// </summary>
+        public string GroupVariableName { get { return _groupVarRef.VariableName; } }
+
+        /// <summary>
+        /// Gets the type metadata of the group element variable.
+        /// </summary>
+        public TypeUsage GroupVariableType { get { return _groupVarRef.ResultType; } }
+
+        /// <summary>
+        /// Gets the DbVariableReferenceExpression that references the group element variable.
+        /// </summary>
+        public DbVariableReferenceExpression GroupVariable { get { return _groupVarRef; } }
+
+        /// <summary>
+        /// Gets the DbGroupAggregate that represents the collection of elements of the group. 
+        /// </summary>
+        public DbGroupAggregate GroupAggregate
+        {
+            get
+            {
+                if (_groupAggregate == null)
+                {
+                    _groupAggregate = DbExpressionBuilder.GroupAggregate(this.GroupVariable);                    
+                }
+                return _groupAggregate;
+            }
+        }
+    }
+}