/****************************************************************************
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** This file is part of the QtXmlPatterns module of the Qt Toolkit.
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** GNU Lesser General Public License Usage
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** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
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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_EmptySequence_H
#define Patternist_EmptySequence_H

#include "qemptycontainer_p.h"

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

namespace QPatternist
{
    /**
     * @short Implements the value instance of empty sequence: <tt>()</tt>.
     *
     * @author Frans Englich <fenglich@trolltech.com>
     * @ingroup Patternist_xdm
     */
    class EmptySequence : public EmptyContainer
    {
    public:
        /**
         * @short Creates an EmptySequence that is a replacement for @p
         * replacementFor.
         *
         * @see EmptySequence()
         */
        static Expression::Ptr create(const Expression *const replacementFor,
                                      const StaticContext::Ptr &context);


        /**
         * @short Creates an instance of EmptySequence.
         *
         * @note In most cases create() should be used, since it takes care of
         * adjusting source location annotations.
         *
         * @see create()
         */
        inline EmptySequence()
        {
        }

        virtual QString stringValue() const;

        /**
         * @returns always an empty iterator, an instance of EmptyIterator.
         */
        virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &) const;

        /**
         * @returns always @c null.
         */
        virtual Item evaluateSingleton(const DynamicContext::Ptr &) const;

        /**
         * Does nothing.
         */
        virtual void evaluateToSequenceReceiver(const DynamicContext::Ptr &) const;

        /**
         * @returns always @c false.
         */
        virtual bool evaluateEBV(const DynamicContext::Ptr &context) const;

        /**
         * @returns always CommonSequenceTypes::Empty
         */
        virtual ItemType::Ptr type() const;

        /**
         * @returns always CommonSequenceTypes::Empty
         */
        virtual SequenceType::Ptr staticType() const;

        virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const;
        virtual ID id() const;
        virtual Properties properties() const;
    };
}

QT_END_NAMESPACE

QT_END_HEADER

#endif