Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Activities/System/Activities/Expressions/LambdaValue.cs

@@ -0,0 +1,84 @@
+//-----------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//-----------------------------------------------------------------------------
+
+namespace System.Activities.Expressions
+{
+    using System;
+    using System.Activities.ExpressionParser;
+    using System.Activities.XamlIntegration;
+    using System.Collections.Generic;
+    using System.Diagnostics;
+    using System.Linq.Expressions;
+    using System.Runtime;
+    using System.Windows.Markup;
+
+    // consciously not XAML-friendly since Linq Expressions aren't create-set-use
+    [Fx.Tag.XamlVisible(false)]
+    [DebuggerStepThrough]
+    public sealed class LambdaValue<TResult> : CodeActivity<TResult>, IExpressionContainer, IValueSerializableExpression
+    {
+        Func<ActivityContext, TResult> compiledLambdaValue;
+        Expression<Func<ActivityContext, TResult>> lambdaValue;
+        Expression<Func<ActivityContext, TResult>> rewrittenTree;
+
+        public LambdaValue(Expression<Func<ActivityContext, TResult>> lambdaValue)
+        {
+            if (lambdaValue == null)
+            {
+                throw FxTrace.Exception.ArgumentNull("lambdaValue");
+            }
+            this.lambdaValue = lambdaValue;
+            this.UseOldFastPath = true;
+        }
+
+        // this is called via reflection from Microsoft.CDF.Test.ExpressionUtilities.Activities.ActivityUtilities.ReplaceLambdaValuesInActivityTree
+        internal Expression LambdaExpression
+        {
+            get
+            {
+                return this.lambdaValue;
+            }
+        }
+
+        protected override void CacheMetadata(CodeActivityMetadata metadata)
+        {
+            CodeActivityPublicEnvironmentAccessor publicAccessor = CodeActivityPublicEnvironmentAccessor.Create(metadata);
+
+            // We need to rewrite the tree.
+            Expression newTree;
+            if (ExpressionUtilities.TryRewriteLambdaExpression(this.lambdaValue, out newTree, publicAccessor))
+            {
+                this.rewrittenTree = (Expression<Func<ActivityContext, TResult>>)newTree;
+            }
+            else
+            {
+                this.rewrittenTree = this.lambdaValue;
+            }
+        }
+
+        protected override TResult Execute(CodeActivityContext context)
+        {
+            if (this.compiledLambdaValue == null)
+            {
+                this.compiledLambdaValue = this.rewrittenTree.Compile();
+            }
+            return this.compiledLambdaValue(context);
+        }
+
+        public bool CanConvertToString(IValueSerializerContext context)
+        {
+            return true;
+        }
+
+        public string ConvertToString(IValueSerializerContext context)
+        {
+            // This workflow contains lambda expressions specified in code. 
+            // These expressions are not XAML serializable. 
+            // In order to make your workflow XAML-serializable, 
+            // use either VisualBasicValue/Reference or ExpressionServices.Convert 
+            // This will convert your lambda expressions into expression activities.
+            throw FxTrace.Exception.AsError(new LambdaSerializationException());
+        }
+    }
+}