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.Runtime.Serialization;
  36
  37 namespace System
  38 {
  39         public abstract class MulticastDelegate : Delegate
  40         {
  41                 private MulticastDelegate prev;
  42                 private MulticastDelegate kpm_next;
  43
  44                 protected MulticastDelegate (object target, string method)
  45                         : base (target, method)
  46                 {
  47                         prev = null;
  48                 }
  49
  50                 protected MulticastDelegate (Type target_type, string method)
  51                         : base (target_type, method)
  52                 {
  53                         prev = null;
  54                 }
  55
  56                 public override void GetObjectData (SerializationInfo info, StreamingContext context)
  57                 {
  58                         base.GetObjectData  (info, context);
  59                 }
  60
  61
  62                 protected override object DynamicInvokeImpl (object[] args)
  63                 {
  64                         if (prev != null)
  65                                 prev.DynamicInvokeImpl (args);
  66
  67                         return base.DynamicInvokeImpl (args);
  68                 }
  69
  70                 // <remarks>
  71                 //   Equals: two multicast delegates are equal if their base is equal
  72                 //   and their invocations list is equal.
  73                 // </remarks>
  74                 public override bool Equals (object o)
  75                 {
  76                         if (!base.Equals (o))
  77                                 return false;
  78
  79                         MulticastDelegate d = (MulticastDelegate) o;
  80
  81                         if (this.prev == null) {
  82                                 if (d.prev == null)
  83                                         return true;
  84                                 else
  85                                         return false;
  86                         }
  87
  88                         return this.prev.Equals (d.prev);
  89                 }
  90
  91                 //
  92                 // FIXME: This could use some improvements.
  93                 //
  94                 public override int GetHashCode ()
  95                 {
  96                         return base.GetHashCode ();
  97                 }
  98
  99                 // <summary>
 100                 //   Return, in order of invocation, the invocation list
 101                 //   of a MulticastDelegate
 102                 // </summary>
 103                 public override Delegate[] GetInvocationList ()
 104                 {
 105                         MulticastDelegate d;
 106                         for (d = (MulticastDelegate) this.Clone (); d.prev != null; d = d.prev)
 107                                 d.prev.kpm_next = d;
 108
 109                         if (d.kpm_next == null) {
 110                                 MulticastDelegate other = (MulticastDelegate) d.Clone ();
 111                                 other.prev = null;
 112                                 other.kpm_next = null;
 113                                 return new Delegate [1] { other };
 114                         }
 115
 116                         ArrayList list = new ArrayList ();
 117                         for (; d != null; d = d.kpm_next) {
 118                                 MulticastDelegate other = (MulticastDelegate) d.Clone ();
 119                                 other.prev = null;
 120                                 other.kpm_next = null;
 121                                 list.Add (other);
 122                         }
 123
 124                         return (Delegate []) list.ToArray (typeof (Delegate));
 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 override Delegate CombineImpl (Delegate follow)
 134                 {
 135                         MulticastDelegate combined, orig, clone;
 136
 137                         if (this.GetType() != follow.GetType ())
 138                                 throw new ArgumentException (Locale.GetText ("Incompatible Delegate Types."));
 139
 140                         combined = (MulticastDelegate)follow.Clone ();
 141
 142                         for (clone = combined, orig = ((MulticastDelegate)follow).prev; orig != null; orig = orig.prev) {
 143
 144                                 clone.prev = (MulticastDelegate)orig.Clone ();
 145                                 clone = clone.prev;
 146                         }
 147
 148                         clone.prev = (MulticastDelegate)this.Clone ();
 149
 150                         for (clone = clone.prev, orig = this.prev; orig != null; orig = orig.prev) {
 151
 152                                 clone.prev = (MulticastDelegate)orig.Clone ();
 153                                 clone = clone.prev;
 154                         }
 155
 156                         return combined;
 157                 }
 158
 159                 private bool BaseEquals (MulticastDelegate value)
 160                 {
 161                         return base.Equals (value);
 162                 }
 163
 164                 /*
 165                  * Perform a slightly crippled version of
 166                  * Knuth-Pratt-Morris over MulticastDelegate chains.
 167                  * Border values are set as pointers in kpm_next;
 168                  * Generally, KPM border arrays are length n+1 for
 169                  * strings of n. This one works with length n at the
 170                  * expense of a few additional comparisions.
 171                  */
 172                 private static MulticastDelegate KPM (MulticastDelegate needle, MulticastDelegate haystack,
 173                                                       out MulticastDelegate tail)
 174                 {
 175                         MulticastDelegate nx, hx;
 176
 177                         // preprocess
 178                         hx = needle;
 179                         nx = needle.kpm_next = null;
 180                         do {
 181                                 while ((nx != null) && (!nx.BaseEquals (hx)))
 182                                         nx = nx.kpm_next;
 183
 184                                 hx = hx.prev;
 185                                 if (hx == null)
 186                                         break;
 187
 188                                 nx = nx == null ? needle : nx.prev;
 189                                 if (hx.BaseEquals (nx))
 190                                         hx.kpm_next = nx.kpm_next;
 191                                 else
 192                                         hx.kpm_next = nx;
 193
 194                         } while (true);
 195
 196                         // match
 197                         MulticastDelegate match = haystack;
 198                         nx = needle;
 199                         hx = haystack;
 200                         do {
 201                                 while (nx != null && !nx.BaseEquals (hx)) {
 202                                         nx = nx.kpm_next;
 203                                         match = match.prev;
 204                                 }
 205
 206                                 nx = nx == null ? needle : nx.prev;
 207                                 if (nx == null) {
 208                                         // bingo
 209                                         tail = hx.prev;
 210                                         return match;
 211                                 }
 212
 213                                 hx = hx.prev;
 214                         } while (hx != null);
 215
 216                         tail = null;
 217                         return null;
 218                 }
 219
 220                 protected override Delegate RemoveImpl (Delegate value)
 221                 {
 222                         if (value == null)
 223                                 return this;
 224
 225                         // match this with value
 226                         MulticastDelegate head, tail;
 227                         head = KPM ((MulticastDelegate)value, this, out tail);
 228                         if (head == null)
 229                                 return this;
 230
 231                         // duplicate chain without head..tail
 232                         MulticastDelegate prev = null, retval = null, orig;
 233                         for (orig = this; (object)orig != (object)head; orig = orig.prev) {
 234                                 MulticastDelegate clone = (MulticastDelegate)orig.Clone ();
 235                                 if (prev != null)
 236                                         prev.prev = clone;
 237                                 else
 238                                         retval = clone;
 239                                 prev = clone;
 240                         }
 241                         for (orig = tail; (object)orig != null; orig = orig.prev) {
 242                                 MulticastDelegate clone = (MulticastDelegate)orig.Clone ();
 243                                 if (prev != null)
 244                                         prev.prev = clone;
 245                                 else
 246                                         retval = clone;
 247                                 prev = clone;
 248                         }
 249                         if (prev != null)
 250                                 prev.prev = null;
 251
 252                         return retval;
 253                 }
 254
 255                 public static bool operator == (MulticastDelegate a, MulticastDelegate b)
 256                 {
 257                         if ((object)a == null) {
 258                                 if ((object)b == null)
 259                                         return true;
 260                                 return false;
 261                         }
 262                         return a.Equals (b);
 263                 }
 264
 265                 public static bool operator != (MulticastDelegate a, MulticastDelegate b)
 266                 {
 267                         return !(a == b);
 268                 }
 269         }
 270 }