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/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Qt Software Information (qt-info@nokia.com)
**
** This file is part of the QtXmlPatterns module 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 either Technology Preview License Agreement or the
** Beta Release License Agreement.
**
** 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 1.0, 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.
**
** If you are unsure which license is appropriate for your use, please
** contact the sales department at qt-sales@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
//
// 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_EmptyIterator_H
#define Patternist_EmptyIterator_H
#include "qabstractxmlforwarditerator_p.h"
#include "qprimitives_p.h"
QT_BEGIN_HEADER
QT_BEGIN_NAMESPACE
namespace QPatternist
{
/**
* @short An QAbstractXmlForwardIterator which always is empty.
*
* EmptyIterator is an QAbstractXmlForwardIterator over the type @c T, which always is empty. Other
* iterators can also be empty(or, at least behave as they are empty), but this
* class is special designed for this purpose and is therefore fast.
*
* EmptyIterator's constructor is protected, instances is retrieved from CommonValues.
*
* @author Frans Englich <fenglich@trolltech.com>
* @ingroup Patternist_iterators
*/
template<typename T> class EmptyIterator : public QAbstractXmlForwardIterator<T>
{
public:
/**
* @returns always a default constructed value, T().
*/
virtual T next()
{
return T();
}
/**
* @returns always a default constructed value, T().
*/
virtual T current() const
{
return T();
}
/**
* @returns always 0.
*/
virtual xsInteger position() const
{
return 0;
}
/**
* @returns always @c this, the reverse of <tt>()</tt> is <tt>()</tt>.
*/
virtual typename QAbstractXmlForwardIterator<T>::Ptr toReversed()
{
return typename QAbstractXmlForwardIterator<T>::Ptr(const_cast<EmptyIterator<T> *>(this));
}
/**
* @returns always 0
*/
virtual xsInteger count()
{
return 0;
}
/**
* @returns @c this
*/
virtual typename QAbstractXmlForwardIterator<T>::Ptr copy() const
{
return typename QAbstractXmlForwardIterator<T>::Ptr(const_cast<EmptyIterator *>(this));
}
protected:
friend class CommonValues;
};
template<typename T>
static inline
typename QAbstractXmlForwardIterator<T>::Ptr
makeEmptyIterator()
{
return typename QAbstractXmlForwardIterator<T>::Ptr(new EmptyIterator<T>());
}
}
QT_END_NAMESPACE
QT_END_HEADER
#endif
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