/****************************************************************************

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** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).

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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_SubsequenceIterator_H

#define Patternist_SubsequenceIterator_H

#include "qitem_p.h"

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

namespace QPatternist

{

    /**

     * @short Picks out a slice from another QAbstractXmlForwardIterator, specified by a start and end position.

     *

     * SubsequenceIterator allows a "slice", a subsequence, from an QAbstractXmlForwardIterator to

     * be extracted. The SubsequenceIterator's constructor takes a source QAbstractXmlForwardIterator,

     * a start position, and the length of the subsequence to be extracted.

     *

     * SubsequenceIterator contains the central business logic to implement

     * the <tt>fn:subsequence()</tt> function. The detailed behavior, such as how it behaves

     * if the source QAbstractXmlForwardIterator is empty or if the specified subsequence stretches

     * beyond the source QAbstractXmlForwardIterator, is therefore consistent with the definition of

     * the <tt>fn:subsequence()</tt> function.

     *

     * @see <a href="http://www.w3.org/TR/xpath-functions/#func-subsequence">XQuery 1.0

     * and XPath 2.0 Functions and Operators, 15.1.10 fn:subsequence</a>

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

     * @ingroup Patternist_iterators

     */

    class SubsequenceIterator : public Item::Iterator

    {

    public:

        /**

         * Creates a SubsequenceIterator that extracts a subsequence from the sequence

         * in @p iterator, as specified by the @p start position and @p length parameter.

         *

         * @param iterator the iterator which the subsequence should

         * be extracted from

         * @param start the start position of extraction. Must be 1 or larger.

         * @param length the length of the subsequence to extract. If it is

         * -1, to the end is returned. The value must be -1 or 1 or larger.

         */

        SubsequenceIterator(const Item::Iterator::Ptr &iterator,

                            const xsInteger start,

                            const xsInteger length);

        virtual Item next();

        virtual Item current() const;

        virtual xsInteger position() const;

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

    private:

        xsInteger m_position;

        Item m_current;

        const Item::Iterator::Ptr m_it;

        xsInteger m_counter;

        const xsInteger m_start;

        const xsInteger m_len;

        const xsInteger m_stop;

    };

}

QT_END_NAMESPACE

QT_END_HEADER

#endif