InversionOfControl/Castle.MicroKernel/Registration/Strategies/ServiceDescriptor.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.MicroKernel.Registration
  16 {
  17         using System;
  18
  19         /// <summary>
  20         /// Describes how to select a types service.
  21         /// </summary>
  22         /// <typeparam name="T">The base type to match against.</typeparam>
  23         public class ServiceDescriptor<T>
  24         {
  25                 public delegate Type ServiceSelector(Type type);
  26
  27                 private readonly TypesDescriptor<T> typesDescriptor;
  28                 private ServiceSelector serviceSelector;
  29
  30                 internal ServiceDescriptor(TypesDescriptor<T> typesDescriptor)
  31                 {
  32                         this.typesDescriptor = typesDescriptor;
  33                 }
  34
  35                 /// <summary>
  36                 /// Uses the base type matched on.
  37                 /// </summary>
  38                 /// <returns></returns>
  39                 public TypesDescriptor<T> Base()
  40                 {
  41                         return Select(delegate(Type type)
  42                         {
  43                                 return typeof(T);
  44                         });
  45                 }
  46
  47                 /// <summary>
  48                 /// Uses the first interface of a type.
  49                 /// </summary>
  50                 /// <returns></returns>
  51                 public TypesDescriptor<T> FirstInterface()
  52                 {
  53                         return Select(delegate(Type type)
  54                         {
  55                                 Type[] interfaces = type.GetInterfaces();
  56                                 if (interfaces.Length > 0)
  57                                 {
  58                                         return interfaces[0];
  59                                 }
  60                                 return null;
  61                         });
  62                 }
  63
  64                 /// <summary>
  65                 /// Assigns a custom service selection strategy.
  66                 /// </summary>
  67                 /// <param name="selector"></param>
  68                 /// <returns></returns>
  69                 public TypesDescriptor<T> Select(ServiceSelector selector)
  70                 {
  71                         this.serviceSelector = selector;
  72                         return typesDescriptor;
  73                 }
  74
  75                 internal Type GetService(Type type)
  76                 {
  77                         if (serviceSelector != null)
  78                         {
  79                                 return serviceSelector(type) ?? type;
  80                         }
  81                         return type;
  82                 }
  83         }
  84 }