/****************************************************************************
**
** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the QtXmlPatterns module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL21$
** 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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** use the contact form at http://qt.digia.com/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
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** Software Foundation and appearing in the file LICENSE.LGPLv21 and
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** following information to ensure the GNU Lesser General Public License
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** In addition, as a special exception, Digia gives you certain additional
** rights. These rights are described in the Digia Qt LGPL Exception
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****************************************************************************/

//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists purely as an
// implementation detail.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.

#ifndef Patternist_UnionIterator_H
#define Patternist_UnionIterator_H

#include <private/qitem_p.h>

QT_BEGIN_NAMESPACE

namespace QPatternist
{
    /**
     * @short Implements the @c except operator. That is, the computation
     * of the sequence of nodes from one sequence, that doesn't appear in the
     * other.
     *
     * @ingroup Patternist_iterators
     */
    class UnionIterator : public Item::Iterator
    {
    public:
        /**
         * It is assumed that @p it1 and @p it2 are in document order and
         * without duplicates.
         */
        UnionIterator(const Item::Iterator::Ptr &it1,
                      const Item::Iterator::Ptr &it2);

        virtual Item next();
        virtual Item current() const;
        virtual xsInteger position() const;
        virtual Item::Iterator::Ptr copy() const;

    private:
        inline Item nextFromFirstOperand()
        {
            ++m_position;
            m_current = m_node1;
            m_node1 = m_it1->next();
            return m_current;
        }

        const Item::Iterator::Ptr   m_it1;
        const Item::Iterator::Ptr   m_it2;
        Item                   m_current;
        xsInteger                   m_position;
        Item                   m_node1;
        Item                   m_node2;
    };
}

QT_END_NAMESPACE

#endif