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                 // Some high-performance applications use this internal property
  78                 // to avoid using a slow path to determine if there is more than one handler
  79                 // This brings an API that we removed in f410e545e2db0e0dc338673a6b10a5cfd2d3340f
  80                 // which some users depeneded on
  81                 //
  82                 // This is an example of code that used this:
  83                 // https://gist.github.com/migueldeicaza/cd99938c2a4372e7e5d5
  84                 //
  85                 // Do not remove this API
  86                 internal bool HasSingleTarget => delegates == null;
  87
  88                 // <remarks>
  89                 //   Equals: two multicast delegates are equal if their base is equal
  90                 //   and their invocations list is equal.
  91                 // </remarks>
  92                 public sealed override bool Equals (object obj)
  93                 {
  94                         if (!base.Equals (obj))
  95                                 return false;
  96
  97                         MulticastDelegate d = obj as MulticastDelegate;
  98                         if (d == null)
  99                                 return false;
 100
 101                         if (delegates == null && d.delegates == null) {
 102                                 return true;
 103                         } else if (delegates == null ^ d.delegates == null) {
 104                                 return false;
 105                         } else {
 106                                 if (delegates.Length != d.delegates.Length)
 107                                         return false;
 108
 109                                 for (int i = 0; i < delegates.Length; ++i) {
 110                                         if (!delegates [i].Equals (d.delegates [i]))
 111                                                 return false;
 112                                 }
 113
 114                                 return true;
 115                         }
 116                 }
 117
 118                 //
 119                 // FIXME: This could use some improvements.
 120                 //
 121                 public sealed override int GetHashCode ()
 122                 {
 123                         return base.GetHashCode ();
 124                 }
 125
 126                 // <summary>
 127                 //   Return, in order of invocation, the invocation list
 128                 //   of a MulticastDelegate
 129                 // </summary>
 130                 public sealed override Delegate[] GetInvocationList ()
 131                 {
 132                         if (delegates != null)
 133                                 return (Delegate[]) delegates.Clone ();
 134                         else
 135                                 return new Delegate[1] { this };
 136                 }
 137
 138                 // <summary>
 139                 //   Combines this MulticastDelegate with the (Multicast)Delegate `follow'.
 140                 //   This does _not_ combine with Delegates. ECMA states the whole delegate
 141                 //   thing should have better been a simple System.Delegate class.
 142                 //   Compiler generated delegates are always MulticastDelegates.
 143                 // </summary>
 144                 protected sealed override Delegate CombineImpl (Delegate follow)
 145                 {
 146                         if (follow == null)
 147                                 return this;
 148
 149                         MulticastDelegate other = (MulticastDelegate) follow;
 150
 151                         MulticastDelegate ret = AllocDelegateLike_internal (this);
 152
 153                         if (delegates == null && other.delegates == null) {
 154                                 ret.delegates = new Delegate [2] { this, other };
 155                         } else if (delegates == null) {
 156                                 ret.delegates = new Delegate [1 + other.delegates.Length];
 157
 158                                 ret.delegates [0] = this;
 159                                 Array.Copy (other.delegates, 0, ret.delegates, 1, other.delegates.Length);
 160                         } else if (other.delegates == null) {
 161                                 ret.delegates = new Delegate [delegates.Length + 1];
 162
 163                                 Array.Copy (delegates, 0, ret.delegates, 0, delegates.Length);
 164                                 ret.delegates [ret.delegates.Length - 1] = other;
 165                         } else {
 166                                 ret.delegates = new Delegate [delegates.Length + other.delegates.Length];
 167
 168                                 Array.Copy (delegates, 0, ret.delegates, 0, delegates.Length);
 169                                 Array.Copy (other.delegates, 0, ret.delegates, delegates.Length, other.delegates.Length);
 170                         }
 171
 172                         return ret;
 173                 }
 174
 175                 protected sealed override Delegate RemoveImpl (Delegate value)
 176                 {
 177                         if (value == null)
 178                                 return this;
 179
 180                         MulticastDelegate other = (MulticastDelegate) value;
 181
 182                         if (delegates == null && other.delegates == null) {
 183                                 /* if they are not equal and the current one is not
 184                                  * a multicastdelegate then we cannot delete it */
 185                                 return this.Equals (other) ? null : this;
 186                         } else if (delegates == null) {
 187                                 foreach (var d in other.delegates) {
 188                                         if (this.Equals (d))
 189                                                 return null;
 190                                 }
 191                                 return this;
 192                         } else if (other.delegates == null) {
 193                                 int idx = Array.LastIndexOf (delegates, other);
 194                                 if (idx == -1)
 195                                         return this;
 196
 197                                 if (delegates.Length <= 1) {
 198                                         /* delegates.Length should never be equal or
 199                                          * lower than 1, it should be 2 or greater */
 200                                         throw new InvalidOperationException ();
 201                                 }
 202
 203                                 if (delegates.Length == 2)
 204                                         return delegates [idx == 0 ? 1 : 0];
 205
 206                                 MulticastDelegate ret = AllocDelegateLike_internal (this);
 207                                 ret.delegates = new Delegate [delegates.Length - 1];
 208
 209                                 Array.Copy (delegates, ret.delegates, idx);
 210                                 Array.Copy (delegates, idx + 1, ret.delegates, idx, delegates.Length - idx - 1);
 211
 212                                 return ret;
 213                         } else {
 214                                 /* wild case : remove MulticastDelegate from MulticastDelegate
 215                                  * complexity is O(m * n), with n the number of elements in
 216                                  * this.delegates and m the number of elements in other.delegates */
 217                                 MulticastDelegate ret = AllocDelegateLike_internal (this);
 218                                 ret.delegates = new Delegate [delegates.Length];
 219
 220                                 /* we should use a set with O(1) lookup complexity
 221                                  * but HashSet is implemented in System.Core.dll */
 222                                 List<Delegate> other_delegates = new List<Delegate> ();
 223                                 for (int i = 0; i < other.delegates.Length; ++i)
 224                                         other_delegates.Add (other.delegates [i]);
 225
 226                                 int idx = delegates.Length;
 227
 228                                 /* we need to remove elements from the end to the beginning, as
 229                                  * the addition and removal of delegates behaves like a stack */
 230                                 for (int i = delegates.Length - 1; i >= 0; --i) {
 231                                         /* if delegates[i] is not in other_delegates,
 232                                          * then we can safely add it to ret.delegates
 233                                          * otherwise we remove it from other_delegates */
 234                                         if (!other_delegates.Remove (delegates [i]))
 235                                                 ret.delegates [--idx] = delegates [i];
 236                                 }
 237
 238                                 /* the elements are at the end of the array, we
 239                                  * need to move them back to the beginning of it */
 240                                 int count = delegates.Length - idx;
 241                                 Array.Copy (ret.delegates, idx, ret.delegates, 0, count);
 242
 243                                 if (count == 0)
 244                                         return null;
 245
 246                                 if (count == 1)
 247                                         return ret.delegates [0];
 248
 249                                 if (count != delegates.Length)
 250                                         Array.Resize (ref ret.delegates, count);
 251
 252                                 return ret;
 253                         }
 254                 }
 255
 256                 public static bool operator == (MulticastDelegate d1, MulticastDelegate d2)
 257                 {
 258                         if (d1 == null)
 259                                 return d2 == null;
 260
 261                         return d1.Equals (d2);
 262                 }
 263
 264                 public static bool operator != (MulticastDelegate d1, MulticastDelegate d2)
 265                 {
 266                         if (d1 == null)
 267                                 return d2 != null;
 268
 269                         return !d1.Equals (d2);
 270                 }
 271         }
 272 }