Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Configuration/System/Configuration/CallbackValidator.cs

@@ -0,0 +1,49 @@
+//------------------------------------------------------------------------------
+// <copyright file="CallbackValidator.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+using System;
+using System.Collections;
+using System.IO;
+using System.Reflection;
+using System.Security.Permissions;
+using System.Xml;
+using System.Collections.Specialized;
+using System.Globalization;
+using System.ComponentModel;
+using System.Security;
+using System.Text;
+using System.Text.RegularExpressions;
+
+namespace System.Configuration {
+
+    public sealed class CallbackValidator : ConfigurationValidatorBase {
+        Type _type;
+        ValidatorCallback _callback;
+
+        public CallbackValidator(Type type, ValidatorCallback callback) : this(callback) {
+            if (type == null) {
+                throw new ArgumentNullException("type");
+            }
+            _type = type;
+        }
+
+        // Do not check for null type here to handle the callback attribute case
+        internal CallbackValidator(ValidatorCallback callback) {
+            if (callback == null) {
+                throw new ArgumentNullException("callback");
+            }
+            _type = null;
+            _callback = callback;
+        }
+
+        public override bool CanValidate(Type type) {
+            return (type == _type || _type == null);
+        }
+        public override void Validate(object value) {
+            _callback(value);
+        }
+    }
+}