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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_OrderBy_H

#define Patternist_OrderBy_H

#include "qatomiccomparator_p.h"

#include "qcomparisonplatform_p.h"

#include "qsinglecontainer_p.h"

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

namespace QPatternist

{

    class ReturnOrderBy;

    /**

     * @short Performs the sorting by being a parent to ForClause.

     *

     * The child of the ForClause is a ReturnOrderBy expression, which collects

     * the sort keys and values.

     *

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

     * @ingroup Patternist_expressions

     */

    class OrderBy : public SingleContainer

    {

    public:

        enum Stability

        {

            StableOrder,

            UnstableOrder

        };

        /**

         * This class is value based.

         */

        class OrderSpec : public ComparisonPlatform<OrderBy::OrderSpec,

                                                    true, /* Yes, issue errors. */

                                                    AtomicComparator::AsValueComparison>

        {

        public:

            /**

             * We want this guy to be public.

             */

            using ComparisonPlatform<OrderBy::OrderSpec, true, AtomicComparator::AsValueComparison>::detailedFlexibleCompare;

            typedef QVector<OrderSpec> Vector;

            enum Direction

            {

                Ascending,

                Descending

            };

            /**

             * @short Default constructor, which is needed by QVector.

             */

            inline OrderSpec()

            {

            }

            inline OrderSpec(const Direction dir,

                             const StaticContext::OrderingEmptySequence orderingEmpty) : direction(dir),

                                                                                         orderingEmptySequence(orderingEmpty)

            {

            }

            void prepare(const Expression::Ptr &source,

                         const StaticContext::Ptr &context);

            const SourceLocationReflection *actualReflection() const

            {

                return m_expr.data();

            }

        private:

            Expression::Ptr m_expr;

        public:

            /**

             * We place these afterwards, such that m_expr gets aligned at the

             * start of the address.

             */

            Direction direction;

            StaticContext::OrderingEmptySequence orderingEmptySequence;

            inline AtomicComparator::Operator operatorID() const

            {

                return orderingEmptySequence == StaticContext::Least ? AtomicComparator::OperatorLessThanNaNLeast

                                                                     : AtomicComparator::OperatorLessThanNaNGreatest;

            }

        };

        OrderBy(const Stability stability,

                const OrderSpec::Vector &orderSpecs,

                const Expression::Ptr &operand,

                ReturnOrderBy *const returnOrderBy);

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

        virtual SequenceType::Ptr staticType() const;

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

                                          const SequenceType::Ptr &reqType);

        virtual Expression::Ptr compress(const StaticContext::Ptr &context);

        virtual SequenceType::List expectedOperandTypes() const;

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

        inline Item::Iterator::Ptr mapToSequence(const Item &i,

                                                 const DynamicContext::Ptr &context) const;

        virtual Properties properties() const;

    private:

        /**

         * Needed when calling makeSequenceMappingIterator().

         */

        typedef QExplicitlySharedDataPointer<const OrderBy> ConstPtr;

        const Stability             m_stability;

        OrderSpec::Vector           m_orderSpecs;

        ReturnOrderBy *const        m_returnOrderBy;

    };

    /* TODO Q_DECLARE_TYPEINFO(OrderBy::OrderSpec, Q_MOVABLE_TYPE); Breaks,

     * probably because it's nested. */

}

QT_END_NAMESPACE

QT_END_HEADER

#endif