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#include "qinsertioniterator_p.h"

QT_BEGIN_NAMESPACE

using namespace QPatternist;

InsertionIterator::InsertionIterator(const Item::Iterator::Ptr &target,
                                     const xsInteger pos,
                                     const Item::Iterator::Ptr &inserts)
                                    : m_target(target),
                                      m_insertPos(pos),
                                      m_inserts(inserts),
                                      m_position(0),
                                      m_isInserting(pos == 1)
{
    Q_ASSERT(target);
    Q_ASSERT(inserts);
    Q_ASSERT(m_insertPos >= 1);
}

Item InsertionIterator::next()
{
    if(m_isInserting)
    {
        m_current = m_inserts->next();

        if(m_current)
        {
            ++m_position;
            return m_current;
        }
    }
    else if(m_position == (m_insertPos - 1) && !m_isInserting)
    { /* Entered only the first time insertion starts. */
        m_isInserting = true;
        return next();
    }

    ++m_position;
    m_current = m_target->next();

    if(m_current)
        return m_current;
    else if(m_inserts->position() == -1) /* We're at the end of the both iterators. */
    {
        m_position = -1;
        m_current.reset();
        return Item();
    }

    /* Insert the insertion iterator, since it's still left. */
    Q_ASSERT(m_target->position() < m_insertPos);
    m_isInserting = true;
    m_current = m_inserts->next();

    if(m_current)
        return m_current;
    else
    {
        /* m_current is already null, so no need to reset it. */
        m_position = -1;
        return Item();
    }
}

xsInteger InsertionIterator::count()
{
    return m_target->count() + m_inserts->count();
}

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

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

Item::Iterator::Ptr InsertionIterator::copy() const
{
    return Item::Iterator::Ptr(new InsertionIterator(m_target->copy(), m_insertPos, m_inserts->copy()));
}

QT_END_NAMESPACE