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                 private MulticastDelegate prev;
  47                 private MulticastDelegate kpm_next;
  48
  49                 protected MulticastDelegate (object target, string method)
  50                         : base (target, method)
  51                 {
  52                         prev = null;
  53                 }
  54
  55                 protected MulticastDelegate (Type target, string method)
  56                         : base (target, method)
  57                 {
  58                         prev = null;
  59                 }
  60
  61                 public override void GetObjectData (SerializationInfo info, StreamingContext context)
  62                 {
  63                         base.GetObjectData  (info, context);
  64                 }
  65
  66
  67                 protected sealed override object DynamicInvokeImpl (object[] args)
  68                 {
  69                         if (prev != null)
  70                                 prev.DynamicInvokeImpl (args);
  71
  72                         return base.DynamicInvokeImpl (args);
  73                 }
  74
  75                 internal bool HasSingleTarget {
  76                         get { return prev == null; }
  77                 }
  78                 // <remarks>
  79                 //   Equals: two multicast delegates are equal if their base is equal
  80                 //   and their invocations list is equal.
  81                 // </remarks>
  82                 public sealed override bool Equals (object obj)
  83                 {
  84                         if (!base.Equals (obj))
  85                                 return false;
  86
  87                         MulticastDelegate d = obj as MulticastDelegate;
  88                         if (d == null)
  89                                 return false;
  90
  91                         MulticastDelegate this_prev = this.prev;
  92                         MulticastDelegate obj_prev = d.prev;
  93
  94                         do {
  95                                 if (this_prev == null)
  96                                         return obj_prev == null;
  97
  98                                 if (!this_prev.Compare (obj_prev))
  99                                         return false;
 100
 101                                 this_prev = this_prev.prev;
 102                                 obj_prev = obj_prev.prev;
 103                         } while (true);
 104                 }
 105
 106                 //
 107                 // FIXME: This could use some improvements.
 108                 //
 109                 public sealed override int GetHashCode ()
 110                 {
 111                         return base.GetHashCode ();
 112                 }
 113
 114                 // <summary>
 115                 //   Return, in order of invocation, the invocation list
 116                 //   of a MulticastDelegate
 117                 // </summary>
 118                 public sealed override Delegate[] GetInvocationList ()
 119                 {
 120                         MulticastDelegate d;
 121                         d = (MulticastDelegate) this.Clone ();
 122                         for (d.kpm_next = null; d.prev != null; d = d.prev)
 123                                 d.prev.kpm_next = d;
 124
 125                         if (d.kpm_next == null) {
 126                                 MulticastDelegate other = (MulticastDelegate) d.Clone ();
 127                                 other.prev = null;
 128                                 other.kpm_next = null;
 129                                 return new Delegate [1] { other };
 130                         }
 131
 132                         var list = new List<Delegate> ();
 133                         for (; d != null; d = d.kpm_next) {
 134                                 MulticastDelegate other = (MulticastDelegate) d.Clone ();
 135                                 other.prev = null;
 136                                 other.kpm_next = null;
 137                                 list.Add (other);
 138                         }
 139
 140                         return list.ToArray ();
 141                 }
 142
 143                 // <summary>
 144                 //   Combines this MulticastDelegate with the (Multicast)Delegate `follow'.
 145                 //   This does _not_ combine with Delegates. ECMA states the whole delegate
 146                 //   thing should have better been a simple System.Delegate class.
 147                 //   Compiler generated delegates are always MulticastDelegates.
 148                 // </summary>
 149                 protected sealed override Delegate CombineImpl (Delegate follow)
 150                 {
 151                         MulticastDelegate combined, orig, clone;
 152
 153                         if (this.GetType() != follow.GetType ())
 154                                 throw new ArgumentException (Locale.GetText ("Incompatible Delegate Types. First is {0} second is {1}.", this.GetType ().FullName, follow.GetType ().FullName));
 155
 156                         combined = (MulticastDelegate)follow.Clone ();
 157                         combined.SetMulticastInvoke ();
 158
 159                         for (clone = combined, orig = ((MulticastDelegate)follow).prev; orig != null; orig = orig.prev) {
 160
 161                                 clone.prev = (MulticastDelegate)orig.Clone ();
 162                                 clone = clone.prev;
 163                         }
 164
 165                         clone.SetMulticastInvoke ();
 166                         clone.prev = (MulticastDelegate)this.Clone ();
 167
 168                         for (clone = clone.prev, orig = this.prev; orig != null; orig = orig.prev) {
 169
 170                                 clone.prev = (MulticastDelegate)orig.Clone ();
 171                                 clone = clone.prev;
 172                         }
 173
 174                         return combined;
 175                 }
 176
 177                 private bool BaseEquals (MulticastDelegate value)
 178                 {
 179                         return base.Equals (value);
 180                 }
 181
 182                 /*
 183                  * Perform a slightly crippled version of
 184                  * Knuth-Pratt-Morris over MulticastDelegate chains.
 185                  * Border values are set as pointers in kpm_next;
 186                  * Generally, KPM border arrays are length n+1 for
 187                  * strings of n. This one works with length n at the
 188                  * expense of a few additional comparisions.
 189                  */
 190                 private static MulticastDelegate KPM (MulticastDelegate needle, MulticastDelegate haystack,
 191                                                       out MulticastDelegate tail)
 192                 {
 193                         MulticastDelegate nx, hx;
 194
 195                         // preprocess
 196                         hx = needle;
 197                         nx = needle.kpm_next = null;
 198                         do {
 199                                 while ((nx != null) && (!nx.BaseEquals (hx)))
 200                                         nx = nx.kpm_next;
 201
 202                                 hx = hx.prev;
 203                                 if (hx == null)
 204                                         break;
 205
 206                                 nx = nx == null ? needle : nx.prev;
 207                                 if (hx.BaseEquals (nx))
 208                                         hx.kpm_next = nx.kpm_next;
 209                                 else
 210                                         hx.kpm_next = nx;
 211
 212                         } while (true);
 213
 214                         // match
 215                         MulticastDelegate match = haystack;
 216                         nx = needle;
 217                         hx = haystack;
 218                         do {
 219                                 while (nx != null && !nx.BaseEquals (hx)) {
 220                                         nx = nx.kpm_next;
 221                                         match = match.prev;
 222                                 }
 223
 224                                 nx = nx == null ? needle : nx.prev;
 225                                 if (nx == null) {
 226                                         // bingo
 227                                         tail = hx.prev;
 228                                         return match;
 229                                 }
 230
 231                                 hx = hx.prev;
 232                         } while (hx != null);
 233
 234                         tail = null;
 235                         return null;
 236                 }
 237
 238                 protected sealed override Delegate RemoveImpl (Delegate value)
 239                 {
 240                         if (value == null)
 241                                 return this;
 242
 243                         // match this with value
 244                         MulticastDelegate head, tail;
 245                         head = KPM ((MulticastDelegate)value, this, out tail);
 246                         if (head == null)
 247                                 return this;
 248
 249                         // duplicate chain without head..tail
 250                         MulticastDelegate prev = null, retval = null, orig;
 251                         for (orig = this; (object)orig != (object)head; orig = orig.prev) {
 252                                 MulticastDelegate clone = (MulticastDelegate)orig.Clone ();
 253                                 if (prev != null)
 254                                         prev.prev = clone;
 255                                 else
 256                                         retval = clone;
 257                                 prev = clone;
 258                         }
 259                         for (orig = tail; (object)orig != null; orig = orig.prev) {
 260                                 MulticastDelegate clone = (MulticastDelegate)orig.Clone ();
 261                                 if (prev != null)
 262                                         prev.prev = clone;
 263                                 else
 264                                         retval = clone;
 265                                 prev = clone;
 266                         }
 267                         if (prev != null)
 268                                 prev.prev = null;
 269
 270                         return retval;
 271                 }
 272
 273                 public static bool operator == (MulticastDelegate d1, MulticastDelegate d2)
 274                 {
 275                         if (d1 == null)
 276                                 return d2 == null;
 277
 278                         return d1.Equals (d2);
 279                 }
 280
 281                 public static bool operator != (MulticastDelegate d1, MulticastDelegate d2)
 282                 {
 283                         if (d1 == null)
 284                                 return d2 != null;
 285
 286                         return !d1.Equals (d2);
 287                 }
 288         }
 289 }