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/****************************************************************************
**
** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/
**
** This file is part of the QtDeclarative module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** GNU Lesser General Public License Usage
** 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 package.
**
** 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.
**
** Other Usage
** Alternatively, this file may be used in accordance with the terms and
** conditions contained in a signed written agreement between you and Nokia.
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef QPOINTERVALUEPAIR_P_H
#define QPOINTERVALUEPAIR_P_H
//
// W A R N I N G
// -------------
//
// This file is not part of the Qt API. It exists purely as an
// implementation detail. This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
#include <QtCore/qglobal.h>
#include <private/qflagpointer_p.h>
QT_BEGIN_NAMESPACE
// QPointerValuePair is intended to help reduce the memory consumption of a class.
// In the common case, QPointerValuePair behaves like a pointer. In this mode, it
// consumes the same memory as a regular pointer.
// Additionally, QPointerValuePair can store an arbitrary value type in *addition*
// to the pointer. In this case, it uses slightly more memory than the pointer and
// value type combined.
// Consequently, this class is most useful in cases where a pointer is always stored
// and a value type is rarely stored.
template<typename P, typename V>
class QPointerValuePair {
public:
inline QPointerValuePair();
inline QPointerValuePair(P *);
inline ~QPointerValuePair();
inline bool isNull() const;
inline bool flag() const;
inline void setFlag();
inline void clearFlag();
inline void setFlagValue(bool);
inline QPointerValuePair<P, V> &operator=(P *);
inline P *operator->() const;
inline P *operator*() const;
inline bool hasValue() const;
inline V &value();
inline const V *constValue() const;
private:
struct Value { P *pointer; V value; };
QBiPointer<P, Value> d;
};
template<typename P, typename V>
QPointerValuePair<P, V>::QPointerValuePair()
{
}
template<typename P, typename V>
QPointerValuePair<P, V>::QPointerValuePair(P *p)
: d(p)
{
}
template<typename P, typename V>
QPointerValuePair<P, V>::~QPointerValuePair()
{
if (d.isT2()) delete d.asT2();
}
template<typename P, typename V>
bool QPointerValuePair<P, V>::isNull() const
{
if (d.isT1()) return 0 == d.asT1();
else return d.asT2()->pointer == 0;
}
template<typename P, typename V>
bool QPointerValuePair<P, V>::flag() const
{
return d.flag();
}
template<typename P, typename V>
void QPointerValuePair<P, V>::setFlag()
{
d.setFlag();
}
template<typename P, typename V>
void QPointerValuePair<P, V>::clearFlag()
{
d.clearFlag();
}
template<typename P, typename V>
void QPointerValuePair<P, V>::setFlagValue(bool v)
{
d.setFlagValue(v);
}
template<typename P, typename V>
QPointerValuePair<P, V> &QPointerValuePair<P, V>::operator=(P *o)
{
if (d.isT1()) d = o;
else d.asT2()->pointer = o;
return *this;
}
template<typename P, typename V>
P *QPointerValuePair<P, V>::operator->() const
{
if (d.isT1()) return d.asT1();
else return d.asT2()->pointer;
}
template<typename P, typename V>
P *QPointerValuePair<P, V>::operator*() const
{
if (d.isT1()) return d.asT1();
else return d.asT2()->pointer;
}
template<typename P, typename V>
bool QPointerValuePair<P, V>::hasValue() const
{
return d.isT2();
}
template<typename P, typename V>
V &QPointerValuePair<P, V>::value()
{
if (d.isT1()) {
P *p = d.asT1();
Value *value = new Value;
value->pointer = p;
d = value;
}
return d.asT2()->value;
}
// Will return null if hasValue() == false
template<typename P, typename V>
const V *QPointerValuePair<P, V>::constValue() const
{
if (d.isT2()) return &d.asT2()->value;
else return 0;
}
QT_END_NAMESPACE
#endif // QPOINTERVALUEPAIR_P_H
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