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

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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_Path_H

#define Patternist_Path_H

#include "qpaircontainer_p.h"

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

namespace QPatternist

{

    /**

     * @short Implements the path expression, containing two steps, such as in <tt>html/body</tt>.

     *

     * @see <a href="http://www.w3.org/TR/xquery/#id-path-expressions">XQuery 1.0: An

     * XML Query Language, 3.2 Path Expressions</a>

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

     * @ingroup Patternist_expressions

     */

    class Path : public PairContainer

    {

    public:

        enum Kind

        {

            /**

             * This Path is a plain old path expression as found in XPath.

             * Sorting is performed, and atomics are disallowed as left

             * operand.

             */

            RegularPath = 1,

            /**

             * This Path emulates an @c xsl:for-each instruction. This means no

             * sorting of result, and atomics are allowed as left operand.

             */

            XSLTForEach,

            /**

             * This Path performs the iteration in an @c xsl:apply-templates

             * instruction. This means sorting, and atomics are disallowed

             * as left operand.

             */

            ForApplyTemplate

        };

        Path(const Expression::Ptr &operand1,

             const Expression::Ptr &operand2,

             const Kind kind = RegularPath);

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

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

        virtual void evaluateToSequenceReceiver(const DynamicContext::Ptr &context) const;

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

                                                 const DynamicContext::Ptr &context) const;

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

                                          const SequenceType::Ptr &reqType);

        virtual SequenceType::List expectedOperandTypes() const;

        /**

         * @returns the static type of the last step where the cardinality is multiplied with

         * the cardinality of the first step's cardinality.

         */

        virtual SequenceType::Ptr staticType() const;

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

        virtual Properties properties() const;

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

        /**

         * @returns the item type of the last step's static type.

         */

        virtual ItemType::Ptr newFocusType() const;

        virtual ID id() const;

        inline void setLast();

        inline Kind kind() const

        {

            return m_kind;

        }

    private:

        typedef QExplicitlySharedDataPointer<const Path> ConstPtr;

        /**

         * One might think this block exists for preventing multiple

         * NodeSortExpressions to be created. However, that is not an issue,

         * since NodeSortExpression optimizes this away anyway.

         *

         * The real reason is to avoid infinite recursion. When our typeCheck()

         * forwards on the type check to the just created

         * NodeSortExpression, it in turn calls typeCheck() on its child, which

         * is this Path. Rince and repeat.

         *

         * We only create node sorts when we're a regular path expression, and

         * not when standing in as a generic map expression. */

        bool        m_hasCreatedSorter;

        /**

         * Whether this path is the step. For instance, in <tt>a/b/c</tt>, the

         * last path has @c c as the right operand.

         */

        bool        m_isLast;

        bool        m_checkXPTY0018;

        const Kind  m_kind;

    };

    void Path::setLast()

    {

        m_isLast = true;

    }

}

QT_END_NAMESPACE

QT_END_HEADER

#endif