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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_AxisStep_H

#define Patternist_AxisStep_H

#include "qemptycontainer_p.h"

#include "qitem_p.h"

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

namespace QPatternist

{

    /**

     * @short A step in a path expression that with an axis and a node test evaluates

     * to a sequence of nodes from the context item.

     *

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

     * @ingroup Patternist_expressions

     */

    class Q_AUTOTEST_EXPORT AxisStep : public EmptyContainer

    {

    public:

        AxisStep(const QXmlNodeModelIndex::Axis axis,

                 const ItemType::Ptr &nodeTest);

        virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &) const;

        virtual Item evaluateSingleton(const DynamicContext::Ptr &) const;

        /**

         * Returns @p node if it matches the node test this step is using, otherwise @c null.

         */

        inline Item mapToItem(const QXmlNodeModelIndex &node,

                              const DynamicContext::Ptr &context) const;

        virtual SequenceType::List expectedOperandTypes() const;

        virtual SequenceType::Ptr staticType() const;

        /**

         * Rewrites to ParentNodeAxis, if possible.

         */

        virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,

                                          const SequenceType::Ptr &reqType);

        /**

         * @returns always BuiltinTypes::node;

         */

        virtual ItemType::Ptr expectedContextItemType() const;

        virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const;

        virtual Properties properties() const;

        /**

         * @returns the axis this step is using.

         */

        QXmlNodeModelIndex::Axis axis() const;

        /**

         * @returns the node test this step is using.

         */

        inline ItemType::Ptr nodeTest() const

        {

            return m_nodeTest;

        }

        void setNodeTest(const ItemType::Ptr &nev)

        {

            m_nodeTest = nev;

        }

        /**

         * @short Prints the EBNF name corresponding to @p axis.

         *

         * For instance, for QXmlNodeModelIndex::Child, "child" is returned.

         *

         * Apart from being used in this class, it is used in the SDK.

         */

        static QString axisName(const QXmlNodeModelIndex::Axis axis);

        virtual ID id() const;

        virtual PatternPriority patternPriority() const;

        inline void setAxis(const QXmlNodeModelIndex::Axis newAxis);

    private:

        typedef QExplicitlySharedDataPointer<const AxisStep> ConstPtr;

        static const QXmlNodeModelIndex::NodeKind s_whenAxisNodeKindEmpty[];

        /**

         * @returns @c true when the axis @p axis and a node test testing node of

         * type @p nodeKind always produces an empty sequence. One such example

         * is <tt>attribute::comment()</tt>.

         */

        static bool isAlwaysEmpty(const QXmlNodeModelIndex::Axis axis,

                                  const QXmlNodeModelIndex::NodeKind nodeKind);

        /**

         * The reason this variable is mutable, is that in the case of XSL-T patterns,

         * we do quite some reordering.

         */

        QXmlNodeModelIndex::Axis    m_axis;

        ItemType::Ptr               m_nodeTest;

    };

    void AxisStep::setAxis(const QXmlNodeModelIndex::Axis newAxis)

    {

        m_axis = newAxis;

    }

}

QT_END_NAMESPACE

QT_END_HEADER

#endif