Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System.Activities/System/Activities/Expressions/Equal.cs

@@ -0,0 +1,59 @@
+//----------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//----------------------------------------------------------------
+
+namespace System.Activities.Expressions
+{
+    using System.Activities;
+    using System.Activities.Statements;
+    using System.Linq.Expressions;
+    using System.Activities.Validation;
+    using System.Collections.Generic;
+    using System.ComponentModel;
+    using System.Runtime;
+
+    public sealed class Equal<TLeft, TRight, TResult> : CodeActivity<TResult>
+    {
+        //Lock is not needed for operationFunction here. The reason is that delegates for a given Equal<TLeft, TRight, TResult> are the same.
+        //It's possible that 2 threads are assigning the operationFucntion at the same time. But it's okay because the compiled codes are the same.
+        static Func<TLeft, TRight, TResult> operationFunction;
+
+        [RequiredArgument]
+        [DefaultValue(null)]
+        public InArgument<TLeft> Left
+        {
+            get;
+            set;
+        }
+
+        [RequiredArgument]
+        [DefaultValue(null)]
+        public InArgument<TRight> Right
+        {
+            get;
+            set;
+        }
+
+        protected override void CacheMetadata(CodeActivityMetadata metadata)
+        {
+            BinaryExpressionHelper.OnGetArguments(metadata, this.Left, this.Right);
+
+            if (operationFunction == null)
+            {
+                ValidationError validationError;
+                if (!BinaryExpressionHelper.TryGenerateLinqDelegate(ExpressionType.Equal, out operationFunction, out validationError))
+                {
+                    metadata.AddValidationError(validationError);
+                }
+            }
+        }
+
+        protected override TResult Execute(CodeActivityContext context)
+        {
+            Fx.Assert(operationFunction != null, "OperationFunction must exist.");
+            TLeft leftValue = this.Left.Get(context);
+            TRight rightValue = this.Right.Get(context);
+            return operationFunction(leftValue, rightValue);
+        }
+    }
+}