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/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the test suite of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** 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
** package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef QTHREADONCE_H
#define QTHREADONCE_H
#include <QtCore/qglobal.h>
#include <QtCore/qatomic.h>
QT_BEGIN_HEADER
QT_MODULE(Core)
#ifndef QT_NO_THREAD
class QOnceControl
{
public:
QOnceControl(QBasicAtomicInt *);
~QOnceControl();
bool mustRunCode();
void done();
private:
QBasicAtomicInt *gv;
union {
qint32 extra;
void *d;
};
};
#define Q_ONCE_GV_NAME2(prefix, line) prefix ## line
#define Q_ONCE_GV_NAME(prefix, line) Q_ONCE_GV_NAME2(prefix, line)
#define Q_ONCE_GV Q_ONCE_GV_NAME(_q_once_, __LINE__)
#define Q_ONCE \
static QBasicAtomicInt Q_ONCE_GV = Q_BASIC_ATOMIC_INITIALIZER(0); \
if (0){} else \
for (QOnceControl _control_(&Q_ONCE_GV); _control_.mustRunCode(); _control_.done())
template<typename T>
class QSingleton
{
// this is a POD-like class
struct Destructor
{
T *&pointer;
Destructor(T *&ptr) : pointer(ptr) {}
~Destructor() { delete pointer; }
};
public:
T *_q_value;
QBasicAtomicInt _q_guard;
inline T *value()
{
for (QOnceControl control(&_q_guard); control.mustRunCode(); control.done()) {
_q_value = new T();
static Destructor cleanup(_q_value);
}
return _q_value;
}
inline T& operator*() { return *value(); }
inline T* operator->() { return value(); }
inline operator T*() { return value(); }
};
#endif // QT_NO_THREAD
QT_END_HEADER
#endif
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