Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System.Web/UI/ViewStateModeByIdAttribute.cs

@@ -0,0 +1,32 @@
+//------------------------------------------------------------------------------
+// <copyright file="ViewStateModeByIdAttribute.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+/*
+ */
+namespace System.Web.UI {
+    using System;
+    using System.Collections;
+    using System.Collections.Generic;
+    using System.ComponentModel;
+
+    [AttributeUsage(AttributeTargets.Class)]
+    public sealed class ViewStateModeByIdAttribute : Attribute {
+        static Hashtable _viewStateIdTypes = Hashtable.Synchronized(new Hashtable());
+
+        public ViewStateModeByIdAttribute() {
+        }
+
+        internal static bool IsEnabled(Type type) {
+            if (!_viewStateIdTypes.ContainsKey(type)) {
+                System.ComponentModel.AttributeCollection attrs = TypeDescriptor.GetAttributes(type);
+                ViewStateModeByIdAttribute attr = (ViewStateModeByIdAttribute)attrs[typeof(ViewStateModeByIdAttribute)];
+                _viewStateIdTypes[type] = (attr != null);
+            }
+            return (bool)_viewStateIdTypes[type];
+        }
+    }
+}
+