/****************************************************************************

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** This file is part of the QtXmlPatterns module of the Qt Toolkit.

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****************************************************************************/

#include "qxpathhelper_p.h"

#include "qsubsequenceiterator_p.h"

QT_BEGIN_NAMESPACE

using namespace QPatternist;

SubsequenceIterator::SubsequenceIterator(const Item::Iterator::Ptr &iterator,

                                         const xsInteger start,

                                         const xsInteger len)

                                         : m_position(0),

                                           m_it(iterator),

                                           m_counter(start),

                                           m_start(start),

                                           m_len(len),

                                           m_stop(m_start + m_len)

{

    Q_ASSERT(iterator);

    Q_ASSERT(start >= 1);

    Q_ASSERT(len == -1 || len >= 1);

    /* Note, "The first item of a sequence is located at position 1, not position 0." */

    for(xsInteger i = 1; i != m_start; ++i)

        m_it->next();

}

Item SubsequenceIterator::next()

{

    if(m_position == -1)

        return Item();

    m_current = m_it->next();

    ++m_position;

    if(m_len == -1)

    {

        if(!m_current)

            m_position = -1;

        return m_current;

    }

    ++m_counter;

    if(!(m_counter > m_stop) && m_current)

        return m_current;

    m_position = -1;

    m_current.reset();

    return Item();

}

Item SubsequenceIterator::current() const

{

    return m_current;

}

xsInteger SubsequenceIterator::position() const

{

    return m_position;

}

Item::Iterator::Ptr SubsequenceIterator::copy() const

{

    return Item::Iterator::Ptr(new SubsequenceIterator(m_it->copy(), m_start, m_len));

}

QT_END_NAMESPACE