mcs/class/referencesource/System.Activities.Presentation/System.Activities.Presentation/System/Activities/Presentation/Base/Core/Internal/PropertyEditing/Editors/EditorUtilities.cs

   1 //----------------------------------------------------------------
   2 // Copyright (c) Microsoft Corporation.  All rights reserved.
   3 //----------------------------------------------------------------
   4 namespace System.Activities.Presentation.Internal.PropertyEditing.Editors
   5 {
   6     using System;
   7     using System.Collections;
   8     using System.Globalization;
   9     using System.Reflection;
  10     using System.Activities.Presentation.PropertyEditing;
  11     using System.Activities.Presentation.Internal.PropertyEditing.FromExpression.Framework.PropertyInspector;
  12
  13     // <summary>
  14     // Collection of utilities used by the various value editors
  15     // </summary>
  16     internal static class EditorUtilities
  17     {
  18
  19         // Key = Type, Value = bool
  20         private static Hashtable _cachedLookups = new Hashtable();
  21
  22         // <summary>
  23         // Checks to see whether the specified Type is concrete and has a default constructor.
  24         // That information if both returned and cached for future reference.
  25         //
  26         // NOTE: This method does not handle structs correctly because it will return FALSE
  27         // for struct types, which is incorrect.  However, this bug has its counter-part in
  28         // System.Activities.Presentation.dll where the default NewItemFactory only instantiates
  29         // non-struct classes.  Both of these need to be fixed at the same time because
  30         // they are used in conjunction.  However, MWD is currently locked.
  31         //
  32         // </summary>
  33         // <param name="type">Type to verify</param>
  34         // <returns>True if the specified type is concrete and has a default constructor,
  35         // false otherwise.</returns>
  36         public static bool IsConcreteWithDefaultCtor(Type type)
  37         {
  38
  39             object returnValue = _cachedLookups[type];
  40             if (returnValue == null)
  41             {
  42                 if (type == null || type.IsAbstract)
  43                 {
  44                     returnValue = false;
  45                 }
  46                 else
  47                 {
  48                     ConstructorInfo defaultCtor = type.GetConstructor(Type.EmptyTypes);
  49                     returnValue = (defaultCtor != null && defaultCtor.IsPublic);
  50                 }
  51
  52                 _cachedLookups[type] = returnValue;
  53             }
  54
  55             return (bool)returnValue;
  56         }
  57
  58         // <summary>
  59         // Substitutes user-friendly display names for values of properties
  60         // </summary>
  61         // <param name="item">Item to attempt to identify</param>
  62         // <returns>String value for the item (guaranteed to be non-null)</returns>
  63         public static string GetDisplayName(object item)
  64         {
  65             if (item == null)
  66             {
  67                 return string.Empty;
  68             }
  69
  70             // Display a user-friendly string for PropertyValues
  71             PropertyValue propertyValue = item as PropertyValue;
  72             if (propertyValue != null)
  73             {
  74                 return PropertyValueToDisplayNameConverter.Instance.Convert(
  75                     propertyValue, typeof(string), null, CultureInfo.CurrentCulture).ToString();
  76             }
  77
  78             // Display a user-friendly string for NewItemFactoryTypeModels
  79             NewItemFactoryTypeModel model = item as NewItemFactoryTypeModel;
  80             if (model != null)
  81             {
  82                 return NewItemFactoryTypeModelToDisplayNameConverter.Instance.Convert(
  83                     model, typeof(string), null, CultureInfo.CurrentCulture).ToString();
  84             }
  85
  86             // Otherwise, resort to ToString() implementation
  87             return item.ToString();
  88         }
  89
  90         // <summary>
  91         // Tests whether a type t is a nullable enum type
  92         // </summary>
  93         // <param name="t">The type object to be tested</param>
  94         // <returns>A bool indicating the test result</returns>
  95         public static bool IsNullableEnumType(Type t)
  96         {
  97             if (t.IsGenericType && t.GetGenericTypeDefinition() == typeof(Nullable<>))
  98             {
  99                 Type[] genericArgs = t.GetGenericArguments();
 100                 if (genericArgs != null && genericArgs.Length == 1)
 101                 {
 102                     return genericArgs[0].IsEnum;
 103                 }
 104             }
 105
 106             return false;
 107         }
 108
 109         public const string NullString = "(null)";
 110     }
 111 }