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