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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_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