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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_CacheCells_H

#define Patternist_CacheCells_H

#include <QList>

#include <QVector>

#include "qitem_p.h"

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

namespace QPatternist

{

    /**

     * @short Represents a cache entry for a single Item,

     * as opposed to for a sequence of items.

     *

     * A characteristic of the ItemCacheCell is that it has two states:

     * either its full or it's not, since it only deals with a single

     * item.

     *

     * Remember that cachedItem doesn't tell the state of the ItemCacheCell.

     * For instance, it can have a null pointer, the empty sequence, and that

     * can be the value of its cache.

     *

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

     */

    class ItemCacheCell

    {

    public:

        typedef QList<ItemCacheCell> List;

        typedef QVector<ItemCacheCell> Vector;

        enum CacheState

        {

            Full,

            Empty

        };

        inline ItemCacheCell() : cacheState(Empty)

        {

        }

        Item        cachedItem;

        CacheState  cacheState;

    };

    /**

     * @short Represents a cache entry for a sequence of items.

     *

     * As opposed to ItemCacheCell, ItemSequenceCacheCell can be partially

     * populated: e.g, four items is in the cache while three remains in the

     * source. For that reason ItemSequenceCacheCell in addition to the source

     * also carried an QAbstractXmlForwardIterator which is the source, such

     * that it can continue to populate the cache when it runs out.

     *

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

     */

    class ItemSequenceCacheCell

    {

    public:

        typedef QList<ItemSequenceCacheCell> List;

        typedef QVector<ItemSequenceCacheCell> Vector;

        enum CacheState

        {

            Full,

            Empty,

            PartiallyPopulated

        };

        inline ItemSequenceCacheCell() : cacheState(Empty)

                                       , inUse(false)

        {

        }

        Item::List          cachedItems;

        Item::Iterator::Ptr sourceIterator;

        CacheState          cacheState;

        /**

         * In XSL-T, we can have circularity which we cannot detect statically.

         * For instance, a global variable invokes a template, and the template

         * uses the variable. We can't detect that, because we can't figure out

         * what template will be invoked.

         *

         * For solution we have this toggle, which is set temporarily on the

         * cell such that EvaluationCache can detect whether it's trashing

         * itself.

         *

         * One might think that it would be sufficient to flag usage of the

         * variable in an arbitrary template, but that would also flag valid

         * cases.

         */

        bool                inUse;

    };

}

Q_DECLARE_TYPEINFO(QPatternist::ItemCacheCell, Q_MOVABLE_TYPE);

Q_DECLARE_TYPEINFO(QPatternist::ItemSequenceCacheCell, Q_MOVABLE_TYPE);

QT_END_NAMESPACE

QT_END_HEADER

#endif