mcs/class/corlib/System/MulticastDelegate.cs

   1 //
   2 // System.MultiCastDelegate.cs
   3 //
   4 // Authors:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //   Daniel Stodden (stodden@in.tum.de)
   7 //
   8 // (C) Ximian, Inc.  http://www.ximian.com
   9 //
  10
  11 //
  12 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  13 //
  14 // Permission is hereby granted, free of charge, to any person obtaining
  15 // a copy of this software and associated documentation files (the
  16 // "Software"), to deal in the Software without restriction, including
  17 // without limitation the rights to use, copy, modify, merge, publish,
  18 // distribute, sublicense, and/or sell copies of the Software, and to
  19 // permit persons to whom the Software is furnished to do so, subject to
  20 // the following conditions:
  21 //
  22 // The above copyright notice and this permission notice shall be
  23 // included in all copies or substantial portions of the Software.
  24 //
  25 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  26 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  27 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  28 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  29 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  30 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  31 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  32 //
  33
  34 using System.Collections;
  35 using System.Collections.Generic;
  36 using System.Runtime.Serialization;
  37 using System.Runtime.InteropServices;
  38
  39 namespace System
  40 {
  41         [System.Runtime.InteropServices.ComVisible (true)]
  42         [Serializable]
  43         [StructLayout (LayoutKind.Sequential)]
  44         public abstract class MulticastDelegate : Delegate
  45         {
  46                 Delegate[] delegates;
  47
  48                 protected MulticastDelegate (object target, string method)
  49                         : base (target, method)
  50                 {
  51                 }
  52
  53                 protected MulticastDelegate (Type target, string method)
  54                         : base (target, method)
  55                 {
  56                 }
  57
  58                 public override void GetObjectData (SerializationInfo info, StreamingContext context)
  59                 {
  60                         base.GetObjectData  (info, context);
  61                 }
  62
  63                 protected sealed override object DynamicInvokeImpl (object[] args)
  64                 {
  65                         if (delegates == null) {
  66                                 return base.DynamicInvokeImpl (args);
  67                         } else {
  68                                 object r;
  69                                 int i = 0, len = delegates.Length;
  70                                 do {
  71                                         r = delegates [i].DynamicInvoke (args);
  72                                 } while (++i < len);
  73                                 return r;
  74                         }
  75                 }
  76
  77                 // <remarks>
  78                 //   Equals: two multicast delegates are equal if their base is equal
  79                 //   and their invocations list is equal.
  80                 // </remarks>
  81                 public sealed override bool Equals (object obj)
  82                 {
  83                         if (!base.Equals (obj))
  84                                 return false;
  85
  86                         MulticastDelegate d = obj as MulticastDelegate;
  87                         if (d == null)
  88                                 return false;
  89
  90                         if (delegates == null && d.delegates == null) {
  91                                 return true;
  92                         } else if (delegates == null ^ d.delegates == null) {
  93                                 return false;
  94                         } else {
  95                                 if (delegates.Length != d.delegates.Length)
  96                                         return false;
  97
  98                                 for (int i = 0; i < delegates.Length; ++i) {
  99                                         if (!delegates [i].Equals (d.delegates [i]))
 100                                                 return false;
 101                                 }
 102
 103                                 return true;
 104                         }
 105                 }
 106
 107                 //
 108                 // FIXME: This could use some improvements.
 109                 //
 110                 public sealed override int GetHashCode ()
 111                 {
 112                         return base.GetHashCode ();
 113                 }
 114
 115                 // <summary>
 116                 //   Return, in order of invocation, the invocation list
 117                 //   of a MulticastDelegate
 118                 // </summary>
 119                 public sealed override Delegate[] GetInvocationList ()
 120                 {
 121                         if (delegates != null)
 122                                 return (Delegate[]) delegates.Clone ();
 123                         else
 124                                 return new Delegate[1] { this };
 125                 }
 126
 127                 // <summary>
 128                 //   Combines this MulticastDelegate with the (Multicast)Delegate `follow'.
 129                 //   This does _not_ combine with Delegates. ECMA states the whole delegate
 130                 //   thing should have better been a simple System.Delegate class.
 131                 //   Compiler generated delegates are always MulticastDelegates.
 132                 // </summary>
 133                 protected sealed override Delegate CombineImpl (Delegate follow)
 134                 {
 135                         if (follow == null)
 136                                 return this;
 137
 138                         MulticastDelegate other = (MulticastDelegate) follow;
 139
 140                         MulticastDelegate ret = AllocDelegateLike_internal (this);
 141
 142                         if (delegates == null && other.delegates == null) {
 143                                 ret.delegates = new Delegate [2] { this, other };
 144                         } else if (delegates == null) {
 145                                 ret.delegates = new Delegate [1 + other.delegates.Length];
 146
 147                                 ret.delegates [0] = this;
 148                                 Array.Copy (other.delegates, 0, ret.delegates, 1, other.delegates.Length);
 149                         } else if (other.delegates == null) {
 150                                 ret.delegates = new Delegate [delegates.Length + 1];
 151
 152                                 Array.Copy (delegates, 0, ret.delegates, 0, delegates.Length);
 153                                 ret.delegates [ret.delegates.Length - 1] = other;
 154                         } else {
 155                                 ret.delegates = new Delegate [delegates.Length + other.delegates.Length];
 156
 157                                 Array.Copy (delegates, 0, ret.delegates, 0, delegates.Length);
 158                                 Array.Copy (other.delegates, 0, ret.delegates, delegates.Length, other.delegates.Length);
 159                         }
 160
 161                         return ret;
 162                 }
 163
 164                 protected sealed override Delegate RemoveImpl (Delegate value)
 165                 {
 166                         if (value == null)
 167                                 return this;
 168
 169                         MulticastDelegate other = (MulticastDelegate) value;
 170
 171                         if (delegates == null && other.delegates == null) {
 172                                 /* if they are not equal and the current one is not
 173                                  * a multicastdelegate then we cannot delete it */
 174                                 return this.Equals (other) ? null : this;
 175                         } else if (delegates == null) {
 176                                 foreach (var d in other.delegates) {
 177                                         if (this.Equals (d))
 178                                                 return null;
 179                                 }
 180                                 return this;
 181                         } else if (other.delegates == null) {
 182                                 int idx = Array.LastIndexOf (delegates, other);
 183                                 if (idx == -1)
 184                                         return this;
 185
 186                                 if (delegates.Length <= 1) {
 187                                         /* delegates.Length should never be equal or
 188                                          * lower than 1, it should be 2 or greater */
 189                                         throw new InvalidOperationException ();
 190                                 }
 191
 192                                 if (delegates.Length == 2)
 193                                         return delegates [idx == 0 ? 1 : 0];
 194
 195                                 MulticastDelegate ret = AllocDelegateLike_internal (this);
 196                                 ret.delegates = new Delegate [delegates.Length - 1];
 197
 198                                 Array.Copy (delegates, ret.delegates, idx);
 199                                 Array.Copy (delegates, idx + 1, ret.delegates, idx, delegates.Length - idx - 1);
 200
 201                                 return ret;
 202                         } else {
 203                                 /* wild case : remove MulticastDelegate from MulticastDelegate
 204                                  * complexity is O(m * n), with n the number of elements in
 205                                  * this.delegates and m the number of elements in other.delegates */
 206                                 MulticastDelegate ret = AllocDelegateLike_internal (this);
 207                                 ret.delegates = new Delegate [delegates.Length];
 208
 209                                 /* we should use a set with O(1) lookup complexity
 210                                  * but HashSet is implemented in System.Core.dll */
 211                                 List<Delegate> other_delegates = new List<Delegate> ();
 212                                 for (int i = 0; i < other.delegates.Length; ++i)
 213                                         other_delegates.Add (other.delegates [i]);
 214
 215                                 int idx = delegates.Length;
 216
 217                                 /* we need to remove elements from the end to the beginning, as
 218                                  * the addition and removal of delegates behaves like a stack */
 219                                 for (int i = delegates.Length - 1; i >= 0; --i) {
 220                                         /* if delegates[i] is not in other_delegates,
 221                                          * then we can safely add it to ret.delegates
 222                                          * otherwise we remove it from other_delegates */
 223                                         if (!other_delegates.Remove (delegates [i]))
 224                                                 ret.delegates [--idx] = delegates [i];
 225                                 }
 226
 227                                 /* the elements are at the end of the array, we
 228                                  * need to move them back to the beginning of it */
 229                                 int count = delegates.Length - idx;
 230                                 Array.Copy (ret.delegates, idx, ret.delegates, 0, count);
 231
 232                                 if (count == 0)
 233                                         return null;
 234
 235                                 if (count == 1)
 236                                         return ret.delegates [0];
 237
 238                                 if (count != delegates.Length)
 239                                         Array.Resize (ref ret.delegates, count);
 240
 241                                 return ret;
 242                         }
 243                 }
 244
 245                 public static bool operator == (MulticastDelegate d1, MulticastDelegate d2)
 246                 {
 247                         if (d1 == null)
 248                                 return d2 == null;
 249
 250                         return d1.Equals (d2);
 251                 }
 252
 253                 public static bool operator != (MulticastDelegate d1, MulticastDelegate d2)
 254                 {
 255                         if (d1 == null)
 256                                 return d2 != null;
 257
 258                         return !d1.Equals (d2);
 259                 }
 260         }
 261 }