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

**

** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).

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** Contact: Nokia Corporation (qt-info@nokia.com)

**

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

**

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** No Commercial Usage

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** contained in the Technology Preview License Agreement accompanying

** this package.

**

** GNU Lesser General Public License Usage

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** General Public License version 2.1 as published by the Free Software

** Foundation and appearing in the file LICENSE.LGPL included in the

** packaging of this file.  Please review the following information to

** ensure the GNU Lesser General Public License version 2.1 requirements

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**

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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