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** This file contains pre-release code and may not be distributed.

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** contained in the Technology Preview License Agreement accompanying

** this package.

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** General Public License version 2.1 as published by the Free Software

** Foundation and appearing in the file LICENSE.LGPL included in the

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****************************************************************************/

#ifndef QGUARD_P_H

#define QGUARD_P_H

//

//  W A R N I N G

//  -------------

//

// This file is not part of the Qt API.  It exists for the convenience

// of qapplication_*.cpp, qwidget*.cpp and qfiledialog.cpp.  This header

// file may change from version to version without notice, or even be removed.

//

// We mean it.

//

#include "QtCore/qglobal.h"

QT_BEGIN_NAMESPACE

class QObject;

template<class T>

class QGuard

{

    QObject *o;

    QGuard<QObject> *next;

    QGuard<QObject> **prev;

    friend void q_guard_addGuard(QGuard<QObject> *);

    friend void q_guard_removeGuard(QGuard<QObject> *);

    friend class QObjectPrivate;

public:

    inline QGuard();

    inline QGuard(T *);

    inline QGuard(const QGuard<T> &);

    inline virtual ~QGuard();

    inline QGuard<T> &operator=(const QGuard<T> &o);

    inline QGuard<T> &operator=(T *);

    inline bool isNull() const

        { return !o; }

    inline T* operator->() const

        { return static_cast<T*>(const_cast<QObject*>(o)); }

    inline T& operator*() const

        { return *static_cast<T*>(const_cast<QObject*>(o)); }

    inline operator T*() const

        { return static_cast<T*>(const_cast<QObject*>(o)); }

    inline T* data() const

        { return static_cast<T*>(const_cast<QObject*>(o)); }

protected:

    virtual void objectDestroyed(T *) {}

};

QT_END_NAMESPACE

#include "private/qobject_p.h"

QT_BEGIN_NAMESPACE

inline void q_guard_addGuard(QGuard<QObject> *);

inline void q_guard_removeGuard(QGuard<QObject> *);

template<class T>

QGuard<T>::QGuard()

: o(0), next(0), prev(0)

{

}

template<class T>

QGuard<T>::QGuard(T *g)

: o(g), next(0), prev(0)

{

    if (o) q_guard_addGuard(reinterpret_cast<QGuard<QObject> *>(this));

}

template<class T>

QGuard<T>::QGuard(const QGuard<T> &g)

: o(g.o), next(0), prev(0)

{

    if (o) q_guard_addGuard(reinterpret_cast<QGuard<QObject> *>(this));

}

template<class T>

QGuard<T>::~QGuard()

{

    if (prev) q_guard_removeGuard(reinterpret_cast<QGuard<QObject> *>(this));

    o = 0;

}

template<class T>

QGuard<T> &QGuard<T>::operator=(const QGuard<T> &g)

{

    if (g.o != o) {

        if (prev) 

            q_guard_removeGuard(reinterpret_cast<QGuard<QObject> *>(this));

        o = g.o;

        if (o) q_guard_addGuard(reinterpret_cast<QGuard<QObject> *>(this));

    }

    return *this;

}

template<class T>

inline QGuard<T> &QGuard<T>::operator=(T *g)

{

    if (g != o) {

        if (prev) 

            q_guard_removeGuard(reinterpret_cast<QGuard<QObject> *>(this));

        o = g;

        if (o) q_guard_addGuard(reinterpret_cast<QGuard<QObject> *>(this));

    }

    return *this;

}

QT_END_NAMESPACE

#endif // QGUARD_P_H