qpointer.h

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#ifndef QPOINTER_H
#define QPOINTER_H

#include <QtCore/qobject.h>

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

QT_MODULE(Core)

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

    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)); }
};


#if (!defined(Q_CC_SUN) || (__SUNPRO_CC >= 0x580)) // ambiguity between const T * and T *

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

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

#else

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

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


#if (!defined(Q_CC_SUN) || (__SUNPRO_CC >= 0x580)) // ambiguity between const T * and T *

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

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

#else

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

template<class T>
inline bool operator!= (const QPointer<T> &p, const void *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_NAMESPACE

QT_END_HEADER

#endif // QPOINTER_H