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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_RangeIterator_H

#define Patternist_RangeIterator_H

#include "qitem_p.h"

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

namespace QPatternist

{

    /**

     * @short RangeIterator represents a sequence of integers between a

     * start and end value.

     *

     * The RangeIterator contains the evaluation logic for the range expression, <tt>N to M</tt>,

     * and its behavior is therefore consistent with the definition of that XPath expression.

     * Hence, the detailed behavior of the RangeIterator can be found in the XPath 2.0

     * specification.

     *

     * @see <a href="http://www.w3.org/TR/xpath20/\#doc-xpath-RangeExpr">XML Path Language

     * (XPath) 2.0, 3.3 Sequence Expressions, RangeExpr</a>

     * @see RangeExpression

     * @author Frans Englich <frans.englich@nokia.com>

     * @ingroup Patternist_iterators

     * @todo Documentation is missing

     */

    class Q_AUTOTEST_EXPORT RangeIterator : public Item::Iterator

    {

    public:

        /**

         * RangeIterator can iterate in both directions.

         * This enumerator exist for identifying different directions.

         */

        enum Direction

        {

            /**

             * Signifies that the QAbstractXmlForwardIterator operates in a reverse direction, where the

             * first item returned by the next() function is from the beginning of the

             * source sequence.

             */

            Backward = 0,

            /**

             * Signifies the forward direction. Iterators do conceptually operate

             * in the forward direction by default.

             */

            Forward = 1

        };

        /**

         * Creates an QAbstractXmlForwardIterator that returns integer values from consecutive sequence

         * of integers between @p start and @p end, where the step taken

         * between each integer is 1 with polarity as specified in @p direction.

         *

         * @note @p start must be smaller than @p end, not larger

         * or equal. This is not checked.

         */

        RangeIterator(const xsInteger start,

                      const Direction direction,

                      const xsInteger end);

        virtual Item next();

        virtual Item current() const;

        virtual xsInteger position() const;

        virtual xsInteger count();

        virtual Item::Iterator::Ptr toReversed();

        virtual Item::Iterator::Ptr copy() const;

    private:

        xsInteger m_start;

        xsInteger m_end;

        Item m_current;

        xsInteger m_position;

        xsInteger m_count;

        const Direction m_direction;

        /**

         * We only need to store -1 or 1, so save memory with a bit field.

         */

        const qint8 m_increment : 2;

    };

}

QT_END_NAMESPACE

QT_END_HEADER

#endif