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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 Technology Preview License Agreement accompanying
** this package.
**
** 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 1.1, included in the file LGPL_EXCEPTION.txt in this
** package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
//
// 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_ExpressionSequence_H
#define Patternist_ExpressionSequence_H
#include "qunlimitedcontainer_p.h"
QT_BEGIN_HEADER
QT_BEGIN_NAMESPACE
namespace QPatternist
{
/**
* @short Implements the comma(",") operator, the sequence constructor.
*
* For example, the expression <tt>alpha, beta</tt> evaluates to a sequence
* containing the items the nodetest @c alpha evaluates to, concatenated
* with the items the nodetest @c beta evaluates to.
*
* @see <a href="http://www.w3.org/TR/xpath20/#construct_seq">XML Path Language
* (XPath) 2.0, 3.3.1 Constructing Sequences</a>
* @author Frans Englich <frans.englich@nokia.com>
* @ingroup Patternist_expressions
*/
class ExpressionSequence : public UnlimitedContainer
{
public:
/**
* Creates an ExpressionSequence with the operands @p operands. @p operands
* must contain two or more Expression instances.
*/
ExpressionSequence(const Expression::List &operands);
virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &) const;
/**
* Forwards the call to its children.
*/
virtual void evaluateToSequenceReceiver(const DynamicContext::Ptr &context) const;
virtual SequenceType::List expectedOperandTypes() const;
virtual SequenceType::Ptr staticType() const;
/**
* Removes any empty sequences, typically "()", from its list of children. If
* after that rewrite has no children, it rewrites itself to the CommonValues::empty;
* if it has only one, it rewrites to the child.
*
* This optimization is not very usable by itself, but potentially becomes effective after other
* optimizations have rewritten themselves into empty sequences. Thus,
* saving memory consumption and runtime overhead.
*/
virtual Expression::Ptr compress(const StaticContext::Ptr &context);
inline Item::Iterator::Ptr mapToSequence(const Expression::Ptr &,
const DynamicContext::Ptr &) const;
virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
const SequenceType::Ptr &reqType);
/**
* @returns Expression::DisableElimination, plus the union
* of all this ExpressionSequence's children's properties. If any child
* does not have IsEvaluated, it is removed from the result.
*/
virtual Expression::Properties properties() const;
virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const;
virtual ID id() const;
private:
typedef QExplicitlySharedDataPointer<const ExpressionSequence> ConstPtr;
};
}
QT_END_NAMESPACE
QT_END_HEADER
#endif
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