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#include "qinteger_p.h"

#include "qrangeiterator_p.h"

QT_BEGIN_NAMESPACE

using namespace QPatternist;

RangeIterator::RangeIterator(const xsInteger start,
                             const Direction direction,
                             const xsInteger end)
                             : m_start(start),
                               m_end(end),
                               m_position(0),
                               m_count(start),
                               m_direction(direction),
                               m_increment(m_direction == Forward ? 1 : -1)
{
    Q_ASSERT(m_start < m_end);
    Q_ASSERT(m_direction == Backward || m_direction == Forward);

    if(m_direction == Backward)
    {
        qSwap(m_start, m_end);
        m_count = m_start;
    }
}

Item RangeIterator::next()
{
    if(m_position == -1)
        return Item();
    else if((m_direction == Forward && m_count > m_end) ||
            (m_direction == Backward && m_count < m_end))
    {
        m_position = -1;
        m_current.reset();
        return Item();
    }
    else
    {
        m_current = Integer::fromValue(m_count);
        m_count += m_increment;
        ++m_position;
        return m_current;
    }
}

xsInteger RangeIterator::count()
{
    /* This complication is for handling that m_start & m_end may be reversed. */
    xsInteger ret;

    if(m_start < m_end)
        ret = m_end - m_start;
    else
        ret = m_start - m_end;

    return ret + 1;
}

Item::Iterator::Ptr RangeIterator::toReversed()
{
    return Item::Iterator::Ptr(new RangeIterator(m_start, Backward, m_end));
}

Item RangeIterator::current() const
{
    return m_current;
}

xsInteger RangeIterator::position() const
{
    return m_position;
}

Item::Iterator::Ptr RangeIterator::copy() const
{
    if(m_direction == Backward)
        return Item::Iterator::Ptr(new RangeIterator(m_end, Backward, m_start));
    else
        return Item::Iterator::Ptr(new RangeIterator(m_start, Forward, m_end));
}

QT_END_NAMESPACE