qpointer.h

Go to the documentation of this file.

/****************************************************************************
**
** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this module.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/

#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