com.mchange.v1.identicator.WeakIdHashKey Maven / Gradle / Ivy
/*
* Distributed as part of mchange-commons-java 0.2.11
*
* Copyright (C) 2015 Machinery For Change, Inc.
*
* Author: Steve Waldman
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of EITHER:
*
* 1) The GNU Lesser General Public License (LGPL), version 2.1, as
* published by the Free Software Foundation
*
* OR
*
* 2) The Eclipse Public License (EPL), version 1.0
*
* You may choose which license to accept if you wish to redistribute
* or modify this work. You may offer derivatives of this work
* under the license you have chosen, or you may provide the same
* choice of license which you have been offered here.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
*
* You should have received copies of both LGPL v2.1 and EPL v1.0
* along with this software; see the files LICENSE-EPL and LICENSE-LGPL.
* If not, the text of these licenses are currently available at
*
* LGPL v2.1: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
* EPL v1.0: http://www.eclipse.org/org/documents/epl-v10.php
*
*/
package com.mchange.v1.identicator;
import java.lang.ref.*;
// revisit equals() if ever made non-final
final class WeakIdHashKey extends IdHashKey
{
Ref keyRef;
int hash;
public WeakIdHashKey(Object keyObj, Identicator id, ReferenceQueue rq)
{
super( id );
if (keyObj == null)
throw new UnsupportedOperationException("Collection does not accept nulls!");
this.keyRef = new Ref( keyObj, rq );
this.hash = id.hash( keyObj );
}
public Ref getInternalRef()
{ return this.keyRef; }
public Object getKeyObj()
{ return keyRef.get(); }
public boolean equals(Object o)
{
// fast type-exact match for final class
if (o instanceof WeakIdHashKey)
{
WeakIdHashKey other = (WeakIdHashKey) o;
if (this.keyRef == other.keyRef)
return true;
else
{
Object myKeyObj = this.keyRef.get();
Object oKeyObj = other.keyRef.get();
if (myKeyObj == null || oKeyObj == null)
return false;
else
return id.identical( myKeyObj, oKeyObj );
}
}
else
return false;
}
public int hashCode()
{ return hash; }
class Ref extends WeakReference
{
public Ref( Object referant, ReferenceQueue rq )
{ super( referant, rq ); }
WeakIdHashKey getKey()
{ return WeakIdHashKey.this; }
}
}