WeakComponentBase.cs

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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 .
 */
 
using System;
using unoidl.com.sun.star.lang;
 
namespace uno.util
{
 
public class WeakComponentBase : WeakBase, XComponent
{
    private delegate void t_disposing( EventObject evt );
    private t_disposing m_disposing = null;
    private bool m_inDispose = false;
    private bool m_disposed = false;
 
    protected bool isDisposed()
    {
        lock (this)
        {
            return m_disposed;
        }
    }
 
    protected void checkUnDisposed()
    {
        if (! isDisposed())
        {
            throw new unoidl.com.sun.star.lang.DisposedException(
                "object already disposed!", this );
        }
    }
    
    ~WeakComponentBase()
    {
        bool doDispose;
        lock (this)
        {
            doDispose = (!m_inDispose && !m_disposed);
        }
        if (doDispose)
        {
            dispose();
        }
    }
    
    protected void preDisposing()
    {
    }
    
    protected void postDisposing()
    {
    }
    
    // XComponent impl
    public void dispose()
    {
        // Determine in a thread-safe way if this is the first call to this
        // method.  Only then we proceed with the notification of event
        // listeners.  It is an error to call this method more than once.
        bool doDispose = false;
        t_disposing call = null;
        lock (this)
        {
            if (! m_inDispose && !m_disposed)
            {
                call = m_disposing;
                m_disposing = null;
                m_inDispose = true;
                doDispose = true;
            }
        }
        // The notification occurs in an unsynchronized block in order to avoid
        // deadlocks if one of the listeners calls back in a different thread on
        // a synchronized method which uses the same object.
        if (doDispose)
        {
            try
            {
                // call sub class
                preDisposing();
                // send disposing notifications to listeners
                if (null != call)
                {
                    EventObject evt = new EventObject( this );
                    call( evt );
                }
                // call sub class
                postDisposing();
            }
            finally
            {
                // finally makes sure that the flags are set ensuring
                // that this function is only called once.
                m_disposed = true;
                m_inDispose = false;
            }
        }
        else
        {
            // in a multithreaded environment, it can't be avoided,
            // that dispose is called twice.
            // However this condition is traced, because it MAY indicate an
            // error.
#if DEBUG
            Console.WriteLine(
                "WeakComponentBase.dispose() - dispose called twice" );
#endif
//             Debug.Fail( "WeakComponentBase.dispose() - dispose called twice" );
        }
    }
    public void addEventListener( XEventListener xListener )
    {
        bool add;
        lock (this)
        {
            add = (! m_inDispose && !m_disposed);
            if (add)
                m_disposing += new t_disposing( xListener.disposing );
        }
        if (! add)
            xListener.disposing( new EventObject( this ) );
    }
    public void removeEventListener( XEventListener xListener )
    {
        lock (this)
        {
            if (! m_inDispose && !m_disposed)
                m_disposing -= new t_disposing( xListener.disposing );
        }
    }
}
 
}