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/****************************************************************************
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtXmlPatterns module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** GNU Lesser General Public License Usage
** This file may be used under the terms of the GNU Lesser 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 will be met:
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU General
** Public License version 3.0 as published by the Free Software Foundation
** and appearing in the file LICENSE.GPL included in the packaging of this
** file. Please review the following information to ensure the GNU General
** Public License version 3.0 requirements will be met:
** http://www.gnu.org/copyleft/gpl.html.
**
** Other Usage
** Alternatively, this file may be used in accordance with the terms and
** conditions contained in a signed written agreement between you and Nokia.
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/

//
//  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_DistinctIterator_H
#define Patternist_DistinctIterator_H

#include <QList>

#include "qexpression_p.h"
#include "qitem_p.h"
#include "qatomiccomparator_p.h"
#include "qcomparisonplatform_p.h"
#include "qsourcelocationreflection_p.h"

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

namespace QPatternist
{

    /**
     * @short Filters another sequence by removing duplicates such that the items are unique.
     *
     * DistinctIterator takes an input sequence, and returns a sequence where each
     * item is unique. Thus, DistinctIterator removes the duplicates of items
     * in a sequence. DistinctIterator is central in the implementation of the
     * <tt>fn:distinct-values()</tt> function.
     *
     * @see <a href="http://www.w3.org/TR/xpath-functions/#func-distinct-values">XQuery 1.0
     * and XPath 2.0 Functions and Operators, 15.1.6 fn:distinct-values</a>
     * @author Frans Englich <frans.englich@nokia.com>
     * @ingroup Patternist_iterators
     */
    class DistinctIterator : public Item::Iterator
                           , public ComparisonPlatform<DistinctIterator, false>
                           , public SourceLocationReflection
    {
    public:
        /**
         * Creates a DistinctIterator.
         * @param comp the AtomicComparator to be used for comparing values. This may be @c null,
         * meaning the IndexOfIterator iterator will dynamically determine what comparator to use
         * @param seq the sequence whose duplicates should be filtered out
         * @param context the usual context, used for error reporting and by AtomicComparators.
         * @param expression the Expression that this DistinctIterator is
         * evaluating for. It is used for error reporting, via
         * actualReflection().
         */
        DistinctIterator(const Item::Iterator::Ptr &seq,
                         const AtomicComparator::Ptr &comp,
                         const Expression::ConstPtr &expression,
                         const DynamicContext::Ptr &context);

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

        inline AtomicComparator::Operator operatorID() const
        {
            return AtomicComparator::OperatorEqual;
        }

    private:
        const Item::Iterator::Ptr   m_seq;
        const DynamicContext::Ptr   m_context;
        const Expression::ConstPtr  m_expr;
        Item                        m_current;
        xsInteger                   m_position;
        Item::List                  m_processed;
    };
}

QT_END_NAMESPACE

QT_END_HEADER

#endif