qsingletoniterator_p.h

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** This file is part of the QtXmlPatterns module of the Qt Toolkit.
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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
{
    template<typename T>
    class SingletonIterator : public QAbstractXmlForwardIterator<T>
    {
    public:
        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;
        }

        virtual typename QAbstractXmlForwardIterator<T>::Ptr toReversed()
        {
            return typename QAbstractXmlForwardIterator<T>::Ptr(new SingletonIterator<T>(m_item));
        }

        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;
    };

    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