mcs/class/System/System.ComponentModel.Design.Serialization/MemberRelationshipService.cs

   1 //
   2 // System.ComponentModel.Design.Serialization.MemberRelationshipService
   3 //
   4 // Authors:
   5 //        Ivan N. Zlatev (contact@i-nZ.net)
   6 //
   7 // (C) 2007 Ivan N. Zlatev
   8
   9 //
  10 // Permission is hereby granted, free of charge, to any person obtaining
  11 // a copy of this software and associated documentation files (the
  12 // "Software"), to deal in the Software without restriction, including
  13 // without limitation the rights to use, copy, modify, merge, publish,
  14 // distribute, sublicense, and/or sell copies of the Software, and to
  15 // permit persons to whom the Software is furnished to do so, subject to
  16 // the following conditions:
  17 //
  18 // The above copyright notice and this permission notice shall be
  19 // included in all copies or substantial portions of the Software.
  20 //
  21 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  22 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  23 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  24 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  25 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  26 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  27 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  28 //
  29
  30
  31 using System;
  32 using System.CodeDom;
  33 using System.ComponentModel;
  34 using System.Collections;
  35
  36 namespace System.ComponentModel.Design.Serialization
  37 {
  38         public abstract class MemberRelationshipService
  39         {
  40
  41                 // MSDN: The default implementation stores relationships in a dictionary using weak references
  42                 //       so the relationship table does not keep objects alive.
  43                 //
  44                 private class MemberRelationshipWeakEntry
  45                 {
  46
  47                         private WeakReference _ownerWeakRef;
  48                         private MemberDescriptor _member;
  49
  50                         public MemberRelationshipWeakEntry (MemberRelationship relation)
  51                         {
  52                                 _ownerWeakRef = new WeakReference (relation.Owner);
  53                                 _member = relation.Member;
  54                         }
  55
  56                         public object Owner {
  57                                 get {
  58                                         if (_ownerWeakRef.IsAlive)
  59                                                 return _ownerWeakRef.Target;
  60                                         return null;
  61                                 }
  62                         }
  63
  64                         public MemberDescriptor Member {
  65                                 get { return _member; }
  66                         }
  67
  68                         public static bool operator == (MemberRelationshipWeakEntry left, MemberRelationshipWeakEntry right)
  69                         {
  70                                 if (left.Owner == right.Owner && left.Member == right.Member)
  71                                         return true;
  72                                 else
  73                                         return false;
  74                         }
  75
  76                         public static bool operator != (MemberRelationshipWeakEntry left, MemberRelationshipWeakEntry right)
  77                         {
  78                                 return !(left == right);
  79                         }
  80
  81                         public override int GetHashCode ()
  82                         {
  83                                 if (this.Owner != null && _member != null)
  84                                         return _member.GetHashCode () ^ _ownerWeakRef.Target.GetHashCode ();
  85                                 return base.GetHashCode ();
  86                         }
  87
  88                         public override bool Equals (object o)
  89                         {
  90                                 if (o is MemberRelationshipWeakEntry) {
  91                                         return ((MemberRelationshipWeakEntry) o) == this;
  92                                 }
  93                                 return false;
  94                         }
  95                 }
  96
  97                 private Hashtable _relations;
  98
  99                 protected MemberRelationshipService ()
 100                 {
 101                         _relations = new Hashtable ();
 102                 }
 103
 104                 public abstract bool SupportsRelationship (MemberRelationship source, MemberRelationship relationship);
 105
 106                 protected virtual MemberRelationship GetRelationship (MemberRelationship source)
 107                 {
 108                         if (source.IsEmpty)
 109                                 throw new ArgumentNullException ("source");
 110
 111                         MemberRelationshipWeakEntry entry = _relations[new MemberRelationshipWeakEntry (source)] as MemberRelationshipWeakEntry;
 112                         if (entry != null)
 113                                 return new MemberRelationship (entry.Owner, entry.Member);
 114                         return MemberRelationship.Empty;
 115                 }
 116
 117                 protected virtual void SetRelationship (MemberRelationship source, MemberRelationship relationship)
 118                 {
 119                         if (source.IsEmpty)
 120                                 throw new ArgumentNullException ("source");
 121
 122                         if (!relationship.IsEmpty && !this.SupportsRelationship (source, relationship))
 123                                 throw new ArgumentException ("Relationship not supported.");
 124
 125                         _relations[new MemberRelationshipWeakEntry (source)] = new MemberRelationshipWeakEntry (relationship);
 126                 }
 127
 128                 public MemberRelationship this [object owner, MemberDescriptor member] {
 129                         get { return GetRelationship (new MemberRelationship (owner,  member)); }
 130                         set { SetRelationship (new MemberRelationship (owner,  member), value); }
 131                 }
 132
 133                 public MemberRelationship this [MemberRelationship source] {
 134                         get { return GetRelationship (source); }
 135                         set { SetRelationship (source, value); }
 136                 }
 137         }
 138 }