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//
// System.Runtime.Serialization.ObjectIDGenerator.cs
//
// Author: Duncan Mak (duncan@ximian.com)
// Lluis Sanchez (lsg@ctv.es)
//
// (C) Ximian, Inc.
// Copyright (C) 2004,2006 Novell, Inc (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System.Collections;
namespace System.Runtime.Serialization
{
[Serializable]
[MonoTODO ("Serialization format not compatible with.NET")]
#if NET_2_0
[System.Runtime.InteropServices.ComVisibleAttribute (true)]
#endif
public class ObjectIDGenerator
{
// Private field
Hashtable table;
long current; // this is the current ID, starts at 1
static InstanceComparer comparer = new InstanceComparer ();
// ObjectIDGenerator must generate a new id for each object instance.
// If two objects have the same state (i.e. the method Equals() returns true),
// each one should have a different id.
// Thus, the object instance cannot be directly used as key of the hashtable.
// InstanceComparer compares object references instead of object content
// (unless the object is inmutable, like strings).
class InstanceComparer: IComparer, IHashCodeProvider
{
int IComparer.Compare (object o1, object o2)
{
if (o1 is string)
return o1.Equals(o2) ? 0 : 1;
else
return (o1 == o2) ? 0 : 1;
}
int IHashCodeProvider.GetHashCode (object o)
{
return object.InternalGetHashCode (o);
}
}
// constructor
public ObjectIDGenerator ()
: base ()
{
table = new Hashtable (comparer, comparer);
current = 1;
}
// Methods
public virtual long GetId (object obj, out bool firstTime)
{
if (obj == null)
throw new ArgumentNullException ("obj");
object val = table [obj];
if (val != null) {
firstTime = false;
return (long) val;
} else {
firstTime = true;
table.Add (obj, current);
return current ++;
}
}
public virtual long HasId (object obj, out bool firstTime)
{
if (obj == null)
throw new ArgumentNullException ("obj");
object val = table [obj];
if (val != null) {
firstTime = false;
return (long) val;
} else {
firstTime = true;
return 0L; // 0 is the null ID
}
}
internal long NextId
{
get { return current ++; }
}
}
}
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