mcs/class/referencesource/System.Activities.Presentation/System.Activities.Presentation/System/Activities/Presentation/Base/Core/Internal/PropertyEditing/FromExpression/Framework/Data/IsNullConverter.cs

   1 // -------------------------------------------------------------------
   2 // Copyright (c) Microsoft Corporation. All Rights Reserved.
   3 // -------------------------------------------------------------------
   4 //From \\authoring\Sparkle\Source\1.0.1083.0\Common\Source\Framework\Data
   5 namespace System.Activities.Presentation.Internal.PropertyEditing.FromExpression.Framework.Data
   6 {
   7     using System;
   8     using System.ComponentModel;
   9     using System.Diagnostics;
  10     using System.Globalization;
  11     using System.Windows.Data;
  12     using System.Diagnostics.CodeAnalysis;
  13
  14     // <summary>
  15     // (nullable-to-bool) Returns true if the value is null, false otherwise.
  16     // </summary>
  17     [SuppressMessage("Microsoft.Performance", "CA1812:AvoidUninstantiatedInternalClasses")]
  18     internal class IsNullConverter : IValueConverter
  19     {
  20         // IValueConverter Members
  21         public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
  22         {
  23             return value == null;
  24         }
  25
  26         public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
  27         {
  28             Debug.Fail("IsNullConverter can only be used for BindType=OneWay");
  29             return null;
  30         }
  31     }
  32 }