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 using System.Collections.Generic;
  35
  36 namespace System.ComponentModel {
  37
  38         internal class ListEntry {
  39                 public object key;
  40                 public Delegate value;
  41                 public ListEntry next;
  42         }
  43
  44         // <summary>
  45         //   List of Event delegates.
  46         // </summary>
  47         //
  48         // <remarks>
  49         //   Longer description
  50         // </remarks>
  51         public sealed class EventHandlerList : IDisposable
  52         {
  53                 ListEntry entries;
  54
  55                 Delegate null_entry;
  56
  57                 public EventHandlerList ()
  58                 {
  59                 }
  60
  61                 public Delegate this [object key] {
  62                         get {
  63                                 if (key == null)
  64                                         return null_entry;
  65                                 ListEntry entry = FindEntry (key);
  66                                 if (entry != null)
  67                                         return entry.value;
  68                                 else
  69                                         return null;
  70                         }
  71
  72                         set {
  73                                 AddHandler (key, value);
  74                         }
  75                 }
  76
  77                 public void AddHandler (object key, Delegate value)
  78                 {
  79                         if (key == null) {
  80                                 null_entry = Delegate.Combine (null_entry, value);
  81                                 return;
  82                         }
  83
  84                         ListEntry entry = FindEntry (key);
  85                         if (entry == null) {
  86                                 entry = new ListEntry ();
  87                                 entry.key = key;
  88                                 entry.value = null;
  89                                 entry.next = entries;
  90                                 entries = entry;
  91                         }
  92
  93                         entry.value = Delegate.Combine (entry.value, value);
  94                 }
  95
  96                 public void AddHandlers (EventHandlerList listToAddFrom)
  97                 {
  98                         if (listToAddFrom == null)
  99                                 return;
 100
 101                         ListEntry entry = listToAddFrom.entries;
 102                         while (entry != null) {
 103                                 AddHandler (entry.key, entry.value);
 104                                 entry = entry.next;
 105                         }
 106                 }
 107
 108                 public void RemoveHandler (object key, Delegate value)
 109                 {
 110                         if (key == null) {
 111                                 null_entry = Delegate.Remove (null_entry, value);
 112                                 return;
 113                         }
 114
 115                         ListEntry entry = FindEntry (key);
 116                         if (entry == null)
 117                                 return;
 118
 119                         entry.value = Delegate.Remove (entry.value, value);
 120                 }
 121
 122                 public void Dispose ()
 123                 {
 124                         entries = null;
 125                 }
 126
 127                 private ListEntry FindEntry (object key)
 128                 {
 129                         ListEntry entry = entries;
 130                         while (entry != null) {
 131                                 if (entry.key == key)
 132                                         return entry;
 133                                 entry = entry.next;
 134                         }
 135
 136                         return null;
 137                 }
 138         }
 139 }
 140