MonoRail/Castle.MonoRail.Framework/Providers/DefaultViewComponentDescriptorProvider.cs

   1 // Copyright 2004-2008 Castle Project - http://www.castleproject.org/
   2 //
   3 // Licensed under the Apache License, Version 2.0 (the "License");
   4 // you may not use this file except in compliance with the License.
   5 // You may obtain a copy of the License at
   6 //
   7 //     http://www.apache.org/licenses/LICENSE-2.0
   8 //
   9 // Unless required by applicable law or agreed to in writing, software
  10 // distributed under the License is distributed on an "AS IS" BASIS,
  11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 // See the License for the specific language governing permissions and
  13 // limitations under the License.
  14
  15 namespace Castle.MonoRail.Framework.Providers
  16 {
  17         using System;
  18         using System.Collections.Generic;
  19         using Castle.MonoRail.Framework;
  20         using Descriptors;
  21         using ViewComponents;
  22
  23         /// <summary>
  24         /// Creates <see cref="ViewComponentDescriptor"/> from attributes
  25         /// associated with the <see cref="ViewComponent"/>
  26         /// </summary>
  27         public class DefaultViewComponentDescriptorProvider : IViewComponentDescriptorProvider
  28         {
  29                 private readonly IDictionary<Type, ViewComponentDescriptor> type2Desc =
  30                         new Dictionary<Type, ViewComponentDescriptor>();
  31
  32                 /// <summary>
  33                 /// Services the specified provider.
  34                 /// </summary>
  35                 /// <param name="provider">The provider.</param>
  36                 public void Service(IMonoRailServices provider)
  37                 {
  38                 }
  39
  40                 /// <summary>
  41                 /// Creates a <see cref="ViewComponentDescriptor"/> by inspecting the
  42                 /// specified view component type.
  43                 /// </summary>
  44                 /// <param name="viewComponentType">Type of the view component.</param>
  45                 /// <returns></returns>
  46                 public ViewComponentDescriptor Collect(Type viewComponentType)
  47                 {
  48                         if (viewComponentType == null) throw new ArgumentNullException("viewComponentType");
  49
  50                         if (type2Desc.ContainsKey(viewComponentType))
  51                         {
  52                                 return type2Desc[viewComponentType];
  53                         }
  54
  55                         object[] attrs = viewComponentType.GetCustomAttributes(typeof(ViewComponentDetailsAttribute), true);
  56
  57                         ViewComponentDescriptor descriptor;
  58
  59                         if (attrs.Length == 0)
  60                         {
  61                                 descriptor = ViewComponentDescriptor.Empty;
  62                         }
  63                         else
  64                         {
  65                                 ViewComponentDetailsAttribute details = (ViewComponentDetailsAttribute) attrs[0];
  66
  67                                 IViewComponentCacheKeyGenerator generator = null;
  68
  69                                 if (details.Cache == ViewComponentCache.Always)
  70                                 {
  71                                         generator = new AlwaysCacheKeyGenerator();
  72                                 }
  73                                 else if (details.CacheKeyFactory != null)
  74                                 {
  75                                         try
  76                                         {
  77                                                 generator = (IViewComponentCacheKeyGenerator)
  78                                                             Activator.CreateInstance(details.CacheKeyFactory);
  79                                         }
  80                                         catch(Exception ex)
  81                                         {
  82                                                 throw new MonoRailException(
  83                                                         "Could not instantiate IViewComponentCacheKeyGenerator implementation or " +
  84                                                         "it does not implement this interface. Type: " + details.CacheKeyFactory.FullName, ex);
  85                                         }
  86                                 }
  87
  88                                 descriptor = new ViewComponentDescriptor(details.Cache != ViewComponentCache.Disabled, details.Cache, generator);
  89                         }
  90
  91                         type2Desc[viewComponentType] = descriptor;
  92
  93                         return descriptor;
  94                 }
  95         }
  96 }