/**************************************************************************** | |
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** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies). | |
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** This file is part of the QtXmlPatterns module of the Qt Toolkit. | |
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** $QT_BEGIN_LICENSE:LGPL$ | |
** GNU Lesser General Public License Usage | |
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** License version 2.1 as published by the Free Software Foundation and | |
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** 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: | |
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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_FirstItemPredicate_H | |
#define Patternist_FirstItemPredicate_H | |
#include "qsinglecontainer_p.h" | |
QT_BEGIN_HEADER | |
QT_BEGIN_NAMESPACE | |
namespace QPatternist | |
{ | |
/** | |
* @short A predicate that always selects the first item from its sequence. | |
* | |
* FirstItemPredicate corresponds exactly to the predicate | |
* in the expression <tt>input[1]</tt>. | |
* | |
* @author Frans Englich <frans.englich@nokia.com> | |
* @ingroup Patternist_expressions | |
*/ | |
class FirstItemPredicate : public SingleContainer | |
{ | |
public: | |
/** | |
* Creates a FirstItemPredicate that filters @p source. | |
*/ | |
FirstItemPredicate(const Expression::Ptr &source); | |
/** | |
* @returns the first item, if any, from evaluating the source expression. | |
*/ | |
virtual Item evaluateSingleton(const DynamicContext::Ptr &) const; | |
/** | |
* @returns a list containing one CommonSequenceTypes::ZeroOrMoreItems instance. | |
*/ | |
virtual SequenceType::List expectedOperandTypes() const; | |
/** | |
* @returns a SequenceType where the item type is the same as the source expression | |
* and where the cardinality is either Cardinality::zeroOrOne() or Cardinality::exactlyOne(), | |
* depending on the source expression. | |
*/ | |
virtual SequenceType::Ptr staticType() const; | |
virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const; | |
/** | |
* Rewrites <tt>expression[1][1]</tt> into <tt>expression[1]</tt>. | |
*/ | |
virtual Expression::Ptr compress(const StaticContext::Ptr &context); | |
/** | |
* @returns always IDFirstItemPredicate. | |
*/ | |
virtual ID id() const; | |
}; | |
} | |
QT_END_NAMESPACE | |
QT_END_HEADER | |
#endif |