/**************************************************************************** | |
** | |
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies). | |
** All rights reserved. | |
** Contact: Nokia Corporation (qt-info@nokia.com) | |
** | |
** This file is part of the QtXmlPatterns 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: | |
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** Other Usage | |
** Alternatively, this file may be used in accordance with the terms and | |
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** $QT_END_LICENSE$ | |
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// | |
// 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. | |
#ifndef Patternist_SingletonIterator_H | |
#define Patternist_SingletonIterator_H | |
#include <QtXmlPatterns/private/qabstractxmlforwarditerator_p.h> | |
#include <QtXmlPatterns/private/qprimitives_p.h> | |
QT_BEGIN_HEADER | |
QT_BEGIN_NAMESPACE | |
namespace QPatternist | |
{ | |
/** | |
* @short An QAbstractXmlForwardIterator over exactly one item. | |
* | |
* SingletonIterator's constructor takes one value which is | |
* the item it forms an QAbstractXmlForwardIterator over. Other QAbstractXmlForwardIterator instances can | |
* also form an QAbstractXmlForwardIterator with one in length, but by that SingletonIterator | |
* has this as it only task, it means it is efficient at it. | |
* | |
* Having to represent single items in Iterators is relatively common. | |
* | |
* @author Frans Englich <frans.englich@nokia.com> | |
* @ingroup Patternist_iterators | |
*/ | |
template<typename T> | |
class SingletonIterator : public QAbstractXmlForwardIterator<T> | |
{ | |
public: | |
/** | |
* Creates an iterator over @p item. | |
* | |
* @note item may not be @c null. Use the EmptyIterator for | |
* the empty sequence | |
*/ | |
SingletonIterator(const T &item) : m_item(item), | |
m_position(0) | |
{ | |
Q_ASSERT(!qIsForwardIteratorEnd(item)); | |
} | |
virtual T next() | |
{ | |
switch(m_position) | |
{ | |
case 0: | |
{ | |
++m_position; | |
return m_item; | |
} | |
case 1: | |
{ | |
m_position = -1; | |
return T(); | |
} | |
default: | |
{ | |
Q_ASSERT(m_position == -1); | |
return T(); | |
} | |
} | |
} | |
virtual T current() const | |
{ | |
if(m_position == 1) | |
return m_item; | |
else | |
return T(); | |
} | |
virtual xsInteger position() const | |
{ | |
return m_position; | |
} | |
/** | |
* @returns a copy of this instance, rewinded to the beginning. | |
*/ | |
virtual typename QAbstractXmlForwardIterator<T>::Ptr toReversed() | |
{ | |
return typename QAbstractXmlForwardIterator<T>::Ptr(new SingletonIterator<T>(m_item)); | |
} | |
/** | |
* @returns always 1 | |
*/ | |
virtual xsInteger count() | |
{ | |
return 1; | |
} | |
virtual typename QAbstractXmlForwardIterator<T>::Ptr copy() const | |
{ | |
return typename QAbstractXmlForwardIterator<T>::Ptr(new SingletonIterator(m_item)); | |
} | |
private: | |
const T m_item; | |
qint8 m_position; | |
}; | |
/** | |
* @short An object generator for SingletonIterator. | |
* | |
* makeSingletonIterator() is a convenience function for avoiding specifying | |
* the full template instantiation for SingletonIterator. Conceptually, it | |
* is identical to Qt's qMakePair(). | |
* | |
* @relates SingletonIterator | |
*/ | |
template<typename T> | |
inline | |
typename SingletonIterator<T>::Ptr | |
makeSingletonIterator(const T &item) | |
{ | |
return typename SingletonIterator<T>::Ptr(new SingletonIterator<T>(item)); | |
} | |
} | |
QT_END_NAMESPACE | |
QT_END_HEADER | |
#endif |