/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtXmlPatterns module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
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** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
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** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
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** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
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****************************************************************************/

#include "qitem_p.h"

#include "qexceptiterator_p.h"

QT_BEGIN_NAMESPACE

using namespace QPatternist;

ExceptIterator::ExceptIterator(const Item::Iterator::Ptr &it1,
                               const Item::Iterator::Ptr &it2) : m_it1(it1)
                                                               , m_it2(it2)
                                                               , m_position(0)
                                                               , m_node1(m_it1->next())
                                                               , m_node2(m_it2->next())
{
    Q_ASSERT(m_it1);
    Q_ASSERT(m_it2);
}

Item ExceptIterator::fromFirstOperand()
{
    ++m_position;
    m_current = m_node1;
    m_node1 = m_it1->next();

    return m_current;
}

Item ExceptIterator::next()
{
    while(true)
    {
        if(!m_node1)
        {
            m_position = -1;
            m_current = Item();
            return Item();
        }
        else if(!m_node2)
            return fromFirstOperand();

        if(m_node1.asNode().model() != m_node2.asNode().model())
            return fromFirstOperand();

        switch(m_node1.asNode().compareOrder(m_node2.asNode()))
        {
            case QXmlNodeModelIndex::Precedes:
                return fromFirstOperand();
            case QXmlNodeModelIndex::Follows:
            {
                m_node2 = m_it2->next();
                if(m_node2)
                    continue;
                else
                    return fromFirstOperand();
            }
            default:
            {
                m_node1 = m_it1->next();
                m_node2 = m_it2->next();
            }
        }
    }
}

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

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

Item::Iterator::Ptr ExceptIterator::copy() const
{
    return Item::Iterator::Ptr(new ExceptIterator(m_it1->copy(), m_it2->copy()));
}

QT_END_NAMESPACE