Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Activities/Microsoft/CSharp/Activities/CSharpReference.cs

@@ -0,0 +1,82 @@
+//-----------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//-----------------------------------------------------------------------------
+
+namespace Microsoft.CSharp.Activities
+{
+    using System;
+    using System.Activities;
+    using System.Activities.Expressions;
+    using System.Activities.XamlIntegration;
+    using System.Collections.Generic;
+    using System.ComponentModel;
+    using System.Diagnostics;
+    using System.Linq.Expressions;
+    using System.Windows.Markup;
+
+    [DebuggerStepThrough]
+    [ContentProperty("ExpressionText")]
+    public class CSharpReference<TResult> : CodeActivity<Location<TResult>>, ITextExpression
+    {
+        CompiledExpressionInvoker invoker;
+                
+        public CSharpReference()
+        {
+            this.UseOldFastPath = true;
+        }
+
+        public CSharpReference(string expressionText) :
+            this()
+        {
+            this.ExpressionText = expressionText;
+        }
+
+        public string ExpressionText
+        {
+            get;
+            set;
+        }
+
+        [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
+        public string Language
+        {
+            get
+            {
+                return "C#";
+            }
+        }
+
+        public bool RequiresCompilation
+        {
+            get
+            {
+                return true;
+            }
+        }
+
+        protected override void CacheMetadata(CodeActivityMetadata metadata)
+        {
+            this.invoker = new CompiledExpressionInvoker(this, true, metadata);
+        }
+
+        protected override Location<TResult> Execute(CodeActivityContext context)
+        {
+            Location<TResult> value = (Location<TResult>)this.invoker.InvokeExpression(context);
+
+            return value;
+        }
+
+        public Expression GetExpressionTree()
+        {
+            if (this.IsMetadataCached)
+            {
+                return this.invoker.GetExpressionTree();
+            }
+            else
+            {
+                throw FxTrace.Exception.AsError(new InvalidOperationException(SR.ActivityIsUncached)); 
+            }
+        }
+    }
+}
+