2 // System.Runtime.Serialization.ObjectIDGenerator.cs
4 // Author: Duncan Mak (duncan@ximian.com)
5 // Lluis Sanchez (lsg@ctv.es)
8 // Copyright (C) 2004,2006 Novell, Inc (http://www.novell.com)
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:
18 // The above copyright notice and this permission notice shall be
19 // included in all copies or substantial portions of the Software.
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.
30 using System.Collections;
32 namespace System.Runtime.Serialization
35 [MonoTODO ("Serialization format not compatible with.NET")]
37 [System.Runtime.InteropServices.ComVisibleAttribute (true)]
39 public class ObjectIDGenerator
43 long current; // this is the current ID, starts at 1
44 static InstanceComparer comparer = new InstanceComparer ();
47 // ObjectIDGenerator must generate a new id for each object instance.
48 // If two objects have the same state (i.e. the method Equals() returns true),
49 // each one should have a different id.
50 // Thus, the object instance cannot be directly used as key of the hashtable.
51 // InstanceComparer compares object references instead of object content
52 // (unless the object is inmutable, like strings).
54 class InstanceComparer: IComparer, IHashCodeProvider
56 int IComparer.Compare (object o1, object o2)
59 return o1.Equals(o2) ? 0 : 1;
61 return (o1 == o2) ? 0 : 1;
64 int IHashCodeProvider.GetHashCode (object o)
66 return object.InternalGetHashCode (o);
71 public ObjectIDGenerator ()
74 table = new Hashtable (comparer, comparer);
79 public virtual long GetId (object obj, out bool firstTime)
82 throw new ArgumentNullException ("obj");
84 object val = table [obj];
92 table.Add (obj, current);
97 public virtual long HasId (object obj, out bool firstTime)
100 throw new ArgumentNullException ("obj");
102 object val = table [obj];
110 return 0L; // 0 is the null ID
116 get { return current ++; }