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# qlock_qws.h

This is the verbatim text of the qlock_qws.h include file. It is provided only for illustration; the copyright remains with Trolltech.

    /****************************************************************************
    ** $Id:  qt/qlock_qws.h   3.1.0-b2   edited Jun 22 2001 $
    **
    ** Definition of QLock class. This manages interprocess locking
    **
    ** Created : 20000406
    **
    ** Copyright (C) 1992-2000 Trolltech AS.  All rights reserved.
    **
    ** This file is part of the kernel module of the Qt GUI Toolkit.
    **
    ** This file may be distributed and/or modified under the terms of the
    ** GNU General Public License version 2 as published by the Free Software
    ** Foundation and appearing in the file LICENSE.GPL included in the
    ** packaging of this file.
    **
    ** Licensees holding valid Qt Enterprise Edition or Qt Professional Edition
    ** licenses for Qt/Embedded may use this file in accordance with the
    ** Qt Embedded Commercial License Agreement provided with the Software.
    **
    ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
    ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
    **
    ** See http://www.trolltech.com/pricing.html or email sales@trolltech.com for
    **   information about Qt Commercial License Agreements.
    ** See http://www.trolltech.com/gpl/ for GPL licensing information.
    **
    ** Contact info@trolltech.com if any conditions of this licensing are
    ** not clear to you.
    **
    **********************************************************************/

    #ifndef QLOCK_QWS_H
    #define QLOCK_QWS_H

    #ifndef QT_H
    #include <qstring.h>
    #endif // QT_H

    class QLockData;

    class QLock
    {
    public:
        QLock( const QString &filename, char id, bool create = FALSE );
        ~QLock();

        enum Type { Read, Write };

        bool isValid() const;
        void lock( Type type );
        void unlock();
        bool locked() const;

    private:
        Type type;
        QLockData *data;
    };

    // Nice class for ensuring the lock is released.
    // Just create one on the stack and the lock is automatically released
    // when QLockHolder is destructed.
    class QLockHolder
    {
    public:
        QLockHolder( QLock *l, QLock::Type type ) : qlock(l) {
    	qlock->lock( type );
        }
        ~QLockHolder() { if ( locked() ) qlock->unlock(); }

        void lock( QLock::Type type ) { qlock->lock( type ); }
        void unlock() { qlock->unlock(); }
        bool locked() const { return qlock->locked(); }

    private:
        QLock *qlock;
    };

    #endif