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/*************************************************************************
*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* Copyright 2000, 2010 Oracle and/or its affiliates.
*
* OpenOffice.org - a multi-platform office productivity suite
*
* This file is part of OpenOffice.org.
*
* OpenOffice.org is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 3
* only, as published by the Free Software Foundation.
*
* OpenOffice.org 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. See the
* GNU Lesser General Public License version 3 for more details
* (a copy is included in the LICENSE file that accompanied this code).
*
* You should have received a copy of the GNU Lesser General Public License
* version 3 along with OpenOffice.org. If not, see
* <http://www.openoffice.org/license.html>
* for a copy of the LGPLv3 License.
*
************************************************************************/
using System;
using unoidl.com.sun.star.uno;
using unoidl.com.sun.star.lang;
namespace uno.util
{
/** An XAdapter implementation that holds a weak reference
(System.WeakReference) to an object.
Clients can register listeners (unoidl.com.sun.star.lang.XReference)
which are notified when the object (the one which is kept weak) is
being finalized. That is, that object is being destroyed because there
are not any hard references to it.
*/
public class WeakAdapter : XAdapter
{
// references the XWeak implementation
private WeakReference m_weakRef;
// contains XReference objects registered by addReference
private delegate void XReference_dispose();
private XReference_dispose m_XReference_dispose;
/** ctor.
@param obj the object that is to be held weakly
*/
public WeakAdapter( Object obj )
{
m_weakRef = new WeakReference( obj );
m_XReference_dispose = null;
}
/** Called by the XWeak implementation (WeakBase) when it is being
finalized. It is only being called once.
The registererd XReference listeners are notified. On notification
they are to unregister themselves. The notification is thread-safe.
However, it is possible to add a listener during the notification
process, which will never receive a notification.
To prevent this, one would have to synchronize this method with
the addReference method. But this can result in deadlocks in a
multithreaded environment.
*/
internal /* non-virtual */ void referentDying()
{
XReference_dispose call;
lock (this)
{
call = m_XReference_dispose;
m_XReference_dispose = null;
}
if (null != call)
call();
}
// XAdapter impl
/** Called to obtain a hard reference o the object which is kept weakly
by this instance.
@return hard reference to the object
*/
public Object queryAdapted()
{
return m_weakRef.Target;
}
/** Called by clients to register listener which are notified when the
weak object is dying.
@param xReference a listener
*/
public void removeReference( XReference xReference )
{
lock (this)
{
m_XReference_dispose -=
new XReference_dispose( xReference.dispose );
}
}
/** Called by clients to unregister listeners.
@param xReference a listener
*/
public void addReference( XReference xReference )
{
lock (this)
{
m_XReference_dispose +=
new XReference_dispose( xReference.dispose );
}
}
}
}
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