Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/UI/SupportsEventValidationAttribute.cs

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+//------------------------------------------------------------------------------
+// <copyright file="SupportsEventValidation.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+/*
+ */
+namespace System.Web.UI {
+
+    using System;
+    using System.Collections;
+    using System.ComponentModel;
+    using System.Diagnostics;
+
+    /// <devdoc>
+    /// <para></para>
+    /// </devdoc>
+    [AttributeUsage(AttributeTargets.Class, AllowMultiple=false)]
+    public sealed class SupportsEventValidationAttribute : Attribute {
+
+        private static Hashtable _typesSupportsEventValidation;        
+
+        static SupportsEventValidationAttribute() {
+            // Create a synchronized wrapper
+            _typesSupportsEventValidation = Hashtable.Synchronized(new Hashtable());
+        }
+
+        public SupportsEventValidationAttribute() {
+        }
+
+        internal static bool SupportsEventValidation(Type type) {
+            object result = _typesSupportsEventValidation[type];
+            if (result != null) {
+                return (bool)result;
+            }
+
+            // Check the attributes on the type to see if it supports SupportsEventValidationAttribute
+            // Note that this attribute does not inherit from the base class, since derived classes may 
+            // not be able to validate properly.
+            object[] attribs = type.GetCustomAttributes(typeof(SupportsEventValidationAttribute), false /* inherits */);
+            bool supportsEventValidation = ((attribs != null) && (attribs.Length > 0));
+            _typesSupportsEventValidation[type] = supportsEventValidation;
+
+            return supportsEventValidation;
+        }
+    }
+}
+