Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

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

@@ -0,0 +1,58 @@
+//----------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//----------------------------------------------------------------
+
+namespace System.Activities.Expressions
+{
+    using System.Activities.Validation;
+    using System.Collections.Generic;
+    using System.Linq.Expressions;
+    using System.Runtime;
+    using System.Collections.ObjectModel;
+    using System.Reflection;
+
+    static class IndexerHelper
+    {
+        public static void OnGetArguments<TItem>(Collection<InArgument> indices, OutArgument<Location<TItem>> result, CodeActivityMetadata metadata)
+        {
+            for (int i = 0; i < indices.Count; i++)
+            {
+                RuntimeArgument indexArgument = new RuntimeArgument("Index" + i, indices[i].ArgumentType, ArgumentDirection.In, true);
+                metadata.Bind(indices[i], indexArgument);
+                metadata.AddArgument(indexArgument);
+            }
+
+            RuntimeArgument resultArgument = new RuntimeArgument("Result", typeof(Location<TItem>), ArgumentDirection.Out);
+            metadata.Bind(result, resultArgument);
+            metadata.AddArgument(resultArgument);
+        }
+        public static void CacheMethod<TOperand, TItem>(Collection<InArgument> indices, ref MethodInfo getMethod, ref MethodInfo setMethod)
+        {
+            Type[] getTypes = new Type[indices.Count];
+            for (int i = 0; i < indices.Count; i++)
+            {
+                getTypes[i] = indices[i].ArgumentType;
+            }
+
+            getMethod = typeof(TOperand).GetMethod("get_Item", getTypes);
+            if (getMethod != null && !getMethod.IsSpecialName)
+            {
+                getMethod = null;
+            }
+
+            Type[] setTypes = new Type[indices.Count + 1];
+            for (int i = 0; i < indices.Count; i++)
+            {
+                setTypes[i] = indices[i].ArgumentType;
+            }
+            setTypes[setTypes.Length - 1] = typeof(TItem);
+            setMethod = typeof(TOperand).GetMethod("set_Item", setTypes);
+            if (setMethod != null && !setMethod.IsSpecialName)
+            {
+                setMethod = null;
+            }
+        }
+
+    }
+
+}