class/corlib/System.Runtime.Serialization/SurrogateSelector.cs

   1 //
   2 // System.Runtime.Serialization.SurrogateSelector.cs
   3 //
   4 // Author: Duncan Mak (duncan@ximian.com)
   5 //         Lluis Sanchez (lsg@ctv.es)
   6 //
   7 // (C) Ximian, Inc.
   8 //
   9
  10 //
  11 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  12 //
  13 // Permission is hereby granted, free of charge, to any person obtaining
  14 // a copy of this software and associated documentation files (the
  15 // "Software"), to deal in the Software without restriction, including
  16 // without limitation the rights to use, copy, modify, merge, publish,
  17 // distribute, sublicense, and/or sell copies of the Software, and to
  18 // permit persons to whom the Software is furnished to do so, subject to
  19 // the following conditions:
  20 //
  21 // The above copyright notice and this permission notice shall be
  22 // included in all copies or substantial portions of the Software.
  23 //
  24 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  25 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  26 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  27 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  28 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  29 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  30 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  31 //
  32
  33 using System;
  34 using System.Collections;
  35
  36 namespace System.Runtime.Serialization
  37 {
  38         [System.Runtime.InteropServices.ComVisibleAttribute (true)]
  39         public class SurrogateSelector : ISurrogateSelector
  40         {
  41                 // Fields
  42                 Hashtable Surrogates = new Hashtable ();
  43                 ISurrogateSelector nextSelector = null;
  44
  45                 // Constructor
  46                 public SurrogateSelector()
  47                         : base ()
  48                 {
  49                 }
  50
  51                 // Methods
  52                 public virtual void AddSurrogate (Type type,
  53                           StreamingContext context, ISerializationSurrogate surrogate)
  54                 {
  55                         if (type == null || surrogate == null)
  56                                 throw new ArgumentNullException ("Null reference.");
  57
  58                         string currentKey = type.FullName + "#" + context.ToString ();
  59
  60                         if (Surrogates.ContainsKey (currentKey))
  61                                 throw new ArgumentException ("A surrogate for " + type.FullName + " already exists.");
  62
  63                         Surrogates.Add (currentKey, surrogate);
  64                 }
  65
  66                 public virtual void ChainSelector (ISurrogateSelector selector)
  67                 {
  68                         if (selector == null)
  69                                 throw new ArgumentNullException ("Selector is null.");
  70
  71                         // Chain the selector at the beggining of the chain
  72                         // since "The last selector added to the list will be the first one checked"
  73                         // (from MS docs)
  74
  75                         if (nextSelector != null)
  76                                 selector.ChainSelector (nextSelector);
  77
  78                         nextSelector = selector;
  79                 }
  80
  81                 public virtual ISurrogateSelector GetNextSelector ()
  82                 {
  83                         return nextSelector;
  84                 }
  85
  86                 public virtual ISerializationSurrogate GetSurrogate (Type type,
  87                              StreamingContext context, out ISurrogateSelector selector)
  88                 {
  89                         if (type == null)
  90                                 throw new ArgumentNullException ("type is null.");
  91
  92                         // Check this selector, and if the surrogate is not found,
  93                         // check the chained selectors
  94
  95                         string key = type.FullName + "#" + context.ToString ();
  96                         ISerializationSurrogate surrogate = (ISerializationSurrogate) Surrogates [key];
  97
  98                         if (surrogate != null) {
  99                                 selector = this;
 100                                 return surrogate;
 101                         }
 102
 103                         if (nextSelector != null)
 104                                 return nextSelector.GetSurrogate (type, context, out selector);
 105                         else {
 106                                 selector = null;
 107                                 return null;
 108                         }
 109                 }
 110
 111                 public virtual void RemoveSurrogate (Type type, StreamingContext context)
 112                 {
 113                         if (type == null)
 114                                 throw new ArgumentNullException ("type is null.");
 115
 116                         string key = type.FullName + "#" + context.ToString ();
 117                         Surrogates.Remove (key);
 118                 }
 119         }
 120 }