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/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtXmlPatterns module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the either Technology Preview License Agreement or the
** Beta Release License Agreement.
**
** GNU Lesser General Public License Usage
** Alternatively, 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 1.0, 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.
**
** If you are unsure which license is appropriate for your use, please
** contact the sales department at http://qt.nokia.com/contact.
** $QT_END_LICENSE$
**
****************************************************************************/
//
// 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
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