mcs/class/System/System.ComponentModel/EventHandlerList.cs

   1 //
   2 // System.ComponentModel.EventHandlerList.cs
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //   Gonzalo Paniagua Javier (gonzalo@ximian.com)
   7 //
   8 // (C) Ximian, Inc.  http://www.ximian.com
   9 //
  10
  11 //
  12 // Permission is hereby granted, free of charge, to any person obtaining
  13 // a copy of this software and associated documentation files (the
  14 // "Software"), to deal in the Software without restriction, including
  15 // without limitation the rights to use, copy, modify, merge, publish,
  16 // distribute, sublicense, and/or sell copies of the Software, and to
  17 // permit persons to whom the Software is furnished to do so, subject to
  18 // the following conditions:
  19 //
  20 // The above copyright notice and this permission notice shall be
  21 // included in all copies or substantial portions of the Software.
  22 //
  23 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  27 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  28 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  29 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  30 //
  31
  32 using System;
  33 using System.Collections;
  34
  35 #if NET_2_0
  36 using System.Collections.Generic;
  37 #endif
  38
  39 namespace System.ComponentModel {
  40
  41         internal class ListEntry {
  42                 public object key;
  43                 public Delegate value;
  44                 public ListEntry next;
  45         }
  46
  47         // <summary>
  48         //   List of Event delegates.
  49         // </summary>
  50         //
  51         // <remarks>
  52         //   Longer description
  53         // </remarks>
  54         public sealed class EventHandlerList : IDisposable
  55         {
  56                 ListEntry entries;
  57
  58                 Delegate null_entry;
  59
  60                 public EventHandlerList ()
  61                 {
  62                 }
  63
  64                 public Delegate this [object key] {
  65                         get {
  66                                 if (key == null)
  67                                         return null_entry;
  68                                 ListEntry entry = FindEntry (key);
  69                                 if (entry != null)
  70                                         return entry.value;
  71                                 else
  72                                         return null;
  73                         }
  74
  75                         set {
  76                                 AddHandler (key, value);
  77                         }
  78                 }
  79
  80                 public void AddHandler (object key, Delegate value)
  81                 {
  82                         if (key == null) {
  83                                 null_entry = Delegate.Combine (null_entry, value);
  84                                 return;
  85                         }
  86
  87                         ListEntry entry = FindEntry (key);
  88                         if (entry == null) {
  89                                 entry = new ListEntry ();
  90                                 entry.key = key;
  91                                 entry.value = null;
  92                                 entry.next = entries;
  93                                 entries = entry;
  94                         }
  95
  96                         entry.value = Delegate.Combine (entry.value, value);
  97                 }
  98
  99 #if NET_2_0
 100                 public void AddHandlers (EventHandlerList listToAddFrom)
 101                 {
 102                         if (listToAddFrom == null)
 103                                 return;
 104
 105                         ListEntry entry = listToAddFrom.entries;
 106                         while (entry != null) {
 107                                 AddHandler (entry.key, entry.value);
 108                                 entry = entry.next;
 109                         }
 110                 }
 111 #endif
 112
 113                 public void RemoveHandler (object key, Delegate value)
 114                 {
 115                         if (key == null) {
 116                                 null_entry = Delegate.Remove (null_entry, value);
 117                                 return;
 118                         }
 119
 120                         ListEntry entry = FindEntry (key);
 121                         if (entry == null)
 122                                 return;
 123
 124                         entry.value = Delegate.Remove (entry.value, value);
 125                 }
 126
 127                 public void Dispose ()
 128                 {
 129                         entries = null;
 130                 }
 131
 132                 private ListEntry FindEntry (object key)
 133                 {
 134                         ListEntry entry = entries;
 135                         while (entry != null) {
 136                                 if (entry.key == key)
 137                                         return entry;
 138                                 entry = entry.next;
 139                         }
 140
 141                         return null;
 142                 }
 143         }
 144 }
 145