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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_CombineNodes_H

#define Patternist_CombineNodes_H

#include "qpaircontainer_p.h"

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

namespace QPatternist

{

    /**

     * @short Implements XPath 2.0's operators for combining node sequences: @c union,

     * @c intersect and @c except.

     *

     * @see <a href="http://www.w3.org/TR/xquery/#combining_seq">XQuery 1.0: An XML Query

     * Language, 3.3.3 Combining QXmlNodeModelIndex Sequences</a>

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

     * @ingroup Patternist_expressions

     */

    class Q_AUTOTEST_EXPORT CombineNodes : public PairContainer

    {

    public:

        enum Operator

        {

            Union       = 1,

            Intersect   = 2,

            Except      = 4

        };

        CombineNodes(const Expression::Ptr &operand1,

                     const Operator op,

                     const Expression::Ptr &operand2);

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

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

        virtual bool evaluateEBV(const DynamicContext::Ptr &context) const;

        virtual SequenceType::Ptr staticType() const;

        virtual SequenceType::List expectedOperandTypes() const;

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

                                          const SequenceType::Ptr &reqType);

        Operator operatorID() const;

        virtual ID id() const;

        /**

         * Determines the string representation for operator @p op.

         *

         * @return "union" if @p op is Union, "intersect" if @p op

         * is Intersect and "except" if @p op is Except.

         */

        static QString displayName(const Operator op);

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

    private:

        const Operator m_operator;

    };

}

QT_END_NAMESPACE

QT_END_HEADER

#endif