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

**

** 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_CachingIterator_H

#define Patternist_CachingIterator_H

#include <QList>

#include <QVector>

#include "qdynamiccontext_p.h"

#include "qitem_p.h"

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

namespace QPatternist

{

    /**

     * @short An QAbstractXmlForwardIterator that gets its item from a cache unless its empty, in

     * which case it continues to populate the cache as well as deliver on its

     * own from a source QAbstractXmlForwardIterator.

     *

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

     * @ingroup Patternist_iterators

     */

    class CachingIterator : public Item::Iterator

    {

    public:

        /**

         * We always use the same cache cell so why don't we use it directly,

         * instead of passing the slot and ItemSequenceCacheCell::Vector to

         * this class? Because the GenericDynamicContext might decide to resize

         * the vector and that would invalidate the reference.

         *

         * We intentionally pass in a non-const reference here.

         */

        CachingIterator(ItemSequenceCacheCell::Vector &cacheCells,

                        const VariableSlotID slot,

                        const DynamicContext::Ptr &context);

        virtual Item next();

        virtual Item current() const;

        virtual xsInteger position() const;

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

    private:

        Item                        m_current;

        xsInteger                   m_position;

        /**

         * This variable cannot be called m_slot, because

         * /usr/include/sys/sysmacros.h on hpuxi-acc defines it.

         */

        const VariableSlotID        m_varSlot;

        /**

         * We don't use the context. We only keep a reference such that it

         * doesn't get deleted, and m_cacheCells starts to dangle.

         */

        const DynamicContext::Ptr   m_context;

        /**

         * We intentionally store a reference here such that we are able to

         * modify the item.

         */

        ItemSequenceCacheCell::Vector &m_cacheCells;

        /**

         * Whether this CachingIterator is delivering items from

         * m_cacheCell.cacheItems or from m_cacheCell.sourceIterator.

         */

        bool m_usingCache;

    };

}

QT_END_NAMESPACE

QT_END_HEADER

#endif