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+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed
+ * with this work for additional information regarding copyright
+ * ownership. The ASF licenses this file to you under the Apache
+ * License, Version 2.0 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of
+ * the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+
+package com.sun.star.lib.uno.helper;
+import java.lang.ref.WeakReference;
+import com.sun.star.uno.XAdapter;
+import com.sun.star.uno.XReference;
+import java.util.List;
+import java.util.Collections;
+import java.util.LinkedList;
+
+/** An XAdapter implementation that holds a weak reference (java.lang.ref.WeakReference)
+ * to an object. Clients can register listener (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 implements XAdapter
+{
+ // references the XWeak implementation
+ private final WeakReference<Object> m_weakRef;
+ // contains XReference objects registered by addReference
+ private final List<XReference> m_xreferenceList;
+
+ /**
+ *@param component the object that is to be held weak
+ */
+ public WeakAdapter(Object component)
+ {
+ m_weakRef= new WeakReference<Object>(component);
+ m_xreferenceList= Collections.synchronizedList( new LinkedList<XReference>());
+ }
+
+ /** Called by the XWeak implementation (WeakBase) when it is being finalized.
+ * It is only being called once.
+ * The registered 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 multi-threaded
+ * environment.
+ */
+ void referentDying()
+ {
+ //synchronized call
+ XReference[] references= m_xreferenceList.toArray(new XReference[m_xreferenceList.size()]);
+ for (int i= references.length; i > 0; i--)
+ {
+ references[i-1].dispose();
+ }
+ }
+
+ /** Method of com.sun.star.uno.XAdapter. It is called to obtain a hard reference
+ * to the object which is kept weak by this instance.
+ * @return hard reference to the object
+ */
+ public Object queryAdapted()
+ {
+ return m_weakRef.get();
+ }
+
+ /** Method of com.sun.star.uno.XAdapter. Called by clients to register listener which
+ * are notified when the weak object is dying.
+ *@param xReference a listener
+ */
+ public void removeReference(XReference xReference)
+ {
+ m_xreferenceList.remove(xReference);
+ }
+
+ /** Method of com.sun.star.uno.XAdapter. Called by clients to unregister listeners.
+ *@param xReference listener
+ */
+ public void addReference(XReference xReference)
+ {
+ m_xreferenceList.add(xReference);
+ }
+}
+