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/****************************************************************************
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtXmlPatterns module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** GNU Lesser General Public License Usage
** This file may be used under the terms of the GNU Lesser General Public
** License version 2.1 as published by the Free Software Foundation and
** appearing in the file LICENSE.LGPL included in the packaging of this
** file. Please review the following information to ensure the GNU Lesser
** General Public License version 2.1 requirements will be met:
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU General
** Public License version 3.0 as published by the Free Software Foundation
** and appearing in the file LICENSE.GPL included in the packaging of this
** file. Please review the following information to ensure the GNU General
** Public License version 3.0 requirements will be met:
** http://www.gnu.org/copyleft/gpl.html.
**
** Other Usage
** Alternatively, this file may be used in accordance with the terms and
** conditions contained in a signed written agreement between you and Nokia.
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/

//
//  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_TreatAs_H
#define Patternist_TreatAs_H

#include "qsinglecontainer_p.h"

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

namespace QPatternist
{
    /**
     * @short Implements XPath 2.0's <tt>treat as</tt> expression.
     *
     * TreatAs is always a compile-time class only, and is always deallocated
     * by re-writing to CardinalityVerifier or ItemVerifier or both, by calling
     * TypeChecker::applyFunctionConversion().
     *
     *
     * One approach could be to skip instantiating TreatAs and simply let the
     * return value of TypeChecker::applyFunctionConversion() be inserted into
     * the AST, but that wouldn't handle type checking the context item
     * properly, which depends on that the StaticContext have been set by the
     * parent Expression.
     *
     * @see <a href="http://www.w3.org/TR/xpath20/#id-treat">XML Path Language
     * (XPath) 2.0, 3.10.5 Treat</a>
     * @author Frans Englich <frans.englich@nokia.com>
     * @ingroup Patternist_expressions
     */
    class TreatAs : public SingleContainer
    {
    public:
        /**
         * Creats a TreatAs where it is checked that the expression @p operand conforms
         * to the type @p reqType.
         */
        TreatAs(const Expression::Ptr &operand,
                const SequenceType::Ptr &reqType);

        /**
         * This function rewrites always. First the type that this TreatAs expression tests for
         * is verified. Then, the type the <tt>treat as</tt> expression itself must match, @p reqType,
         * is verified.
         */
        virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
                                          const SequenceType::Ptr &reqType);

        /**
         * @returns always the SequenceType passed in the constructor to this class. That is, the
         * SequenceType that the operand must conform to.
         */
        virtual SequenceType::Ptr staticType() const;

        /**
         * @returns a list containing one CommonSequenceTypes::ZeroOrMoreItems
         */
        virtual SequenceType::List expectedOperandTypes() const;

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

    private:
        const SequenceType::Ptr m_reqType;
    };
}

QT_END_NAMESPACE

QT_END_HEADER

#endif