115 lines
3.0 KiB
C
115 lines
3.0 KiB
C
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/****************************************************************************
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**
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** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
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** All rights reserved.
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** Contact: Nokia Corporation (qt-info@nokia.com)
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**
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** This file is part of the test suite of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:LGPL$
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** No Commercial Usage
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** This file contains pre-release code and may not be distributed.
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** You may use this file in accordance with the terms and conditions
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** contained in the Technology Preview License Agreement accompanying
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** this package.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 2.1 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU Lesser General Public License version 2.1 requirements
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** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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**
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** In addition, as a special exception, Nokia gives you certain additional
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** rights. These rights are described in the Nokia Qt LGPL Exception
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** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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**
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** If you have questions regarding the use of this file, please contact
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** Nokia at qt-info@nokia.com.
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**
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**
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**
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**
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**
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**
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**
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#ifndef QTHREADONCE_H
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#define QTHREADONCE_H
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#include <QtCore/qglobal.h>
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#include <QtCore/qatomic.h>
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QT_BEGIN_HEADER
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QT_MODULE(Core)
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#ifndef QT_NO_THREAD
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class QOnceControl
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{
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public:
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QOnceControl(QBasicAtomicInt *);
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~QOnceControl();
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bool mustRunCode();
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void done();
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private:
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QBasicAtomicInt *gv;
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union {
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qint32 extra;
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void *d;
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};
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};
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#define Q_ONCE_GV_NAME2(prefix, line) prefix ## line
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#define Q_ONCE_GV_NAME(prefix, line) Q_ONCE_GV_NAME2(prefix, line)
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#define Q_ONCE_GV Q_ONCE_GV_NAME(_q_once_, __LINE__)
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#define Q_ONCE \
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static QBasicAtomicInt Q_ONCE_GV = Q_BASIC_ATOMIC_INITIALIZER(0); \
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if (0){} else \
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for (QOnceControl _control_(&Q_ONCE_GV); _control_.mustRunCode(); _control_.done())
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template<typename T>
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class QSingleton
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{
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// this is a POD-like class
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struct Destructor
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{
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T *&pointer;
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Destructor(T *&ptr) : pointer(ptr) {}
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~Destructor() { delete pointer; }
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};
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public:
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T *_q_value;
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QBasicAtomicInt _q_guard;
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inline T *value()
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{
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for (QOnceControl control(&_q_guard); control.mustRunCode(); control.done()) {
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_q_value = new T();
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static Destructor cleanup(_q_value);
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}
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return _q_value;
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}
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inline T& operator*() { return *value(); }
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inline T* operator->() { return value(); }
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inline operator T*() { return value(); }
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};
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#endif // QT_NO_THREAD
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QT_END_HEADER
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#endif
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