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qpointer.h

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** Foundation and appearing in the files LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file.  Alternatively you may (at
** your option) use any later version of the GNU General Public
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** (or its successors, if any) and the KDE Free Qt Foundation. In
** addition, as a special exception, Trolltech gives you certain
** additional rights. These rights are described in the Trolltech GPL
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#ifndef QPOINTER_H
#define QPOINTER_H

#include <QtCore/qobject.h>

QT_BEGIN_HEADER

QT_MODULE(Core)

template <class T>
00054 class QPointer
{
    QObject *o;
public:
00058     inline QPointer() : o(0) {}
00059     inline QPointer(T *p) : o(p)
        { QMetaObject::addGuard(&o); }
00061     inline QPointer(const QPointer<T> &p) : o(p.o)
        { QMetaObject::addGuard(&o); }
00063     inline ~QPointer()
        { QMetaObject::removeGuard(&o); }
00065     inline QPointer<T> &operator=(const QPointer<T> &p)
        { if (this != &p) QMetaObject::changeGuard(&o, p.o); return *this; }
00067     inline QPointer<T> &operator=(T* p)
        { if (o != p) QMetaObject::changeGuard(&o, p); return *this; }

00070     inline bool isNull() const
        { return !o; }

00073     inline T* operator->() const
        { return static_cast<T*>(const_cast<QObject*>(o)); }
00075     inline T& operator*() const
        { return *static_cast<T*>(const_cast<QObject*>(o)); }
00077     inline operator T*() const
        { return static_cast<T*>(const_cast<QObject*>(o)); }
};


template <class T>
inline bool operator==(const T *o, const QPointer<T> &p)
{ return o == p.operator->(); }

#ifndef Q_CC_SUN // ambiguity between const T * and T *
template<class T>
inline bool operator==(const QPointer<T> &p, const T *o)
{ return p.operator->() == o; }
#endif

template <class T>
inline bool operator==(T *o, const QPointer<T> &p)
{ return o == p.operator->(); }

template<class T>
inline bool operator==(const QPointer<T> &p, T *o)
{ return p.operator->() == o; }

template<class T>
inline bool operator==(const QPointer<T> &p1, const QPointer<T> &p2)
{ return p1.operator->() == p2.operator->(); }


template <class T>
inline bool operator!=(const T *o, const QPointer<T> &p)
{ return o != p.operator->(); }

#ifndef Q_CC_SUN // ambiguity between const T * and T *
template<class T>
inline bool operator!= (const QPointer<T> &p, const T *o)
{ return p.operator->() != o; }
#endif

template <class T>
inline bool operator!=(T *o, const QPointer<T> &p)
{ return o != p.operator->(); }

template<class T>
inline bool operator!= (const QPointer<T> &p, T *o)
{ return p.operator->() != o; }

template<class T>
inline bool operator!= (const QPointer<T> &p1, const QPointer<T> &p2)
{ return p1.operator->() != p2.operator->() ; }

// Make MSVC < 1400 (2005) handle "if (NULL == p)" syntax
#if defined(Q_CC_MSVC) && (_MSC_VER < 1400)
template<class T>
inline bool operator== (int i, const QPointer<T> &p)
{ Q_ASSERT(i == 0); return !i && p.isNull(); }

template<class T>
inline bool operator!= (int i, const QPointer<T> &p)
{ Q_ASSERT(i == 0); return !i && !p.isNull(); }
#endif

QT_END_HEADER

#endif // QPOINTER_H

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