/****************************************************************************
**
** Copyright (C) 2010 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.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Lesser General Public License Usage
** Alternatively, 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.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/

//
//  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_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