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/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the QtXmlPatterns module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL21$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see http://www.qt.io/terms-conditions. For further
** information use the contact form at http://www.qt.io/contact-us.
**
** 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 or version 3 as published by the Free
** Software Foundation and appearing in the file LICENSE.LGPLv21 and
** LICENSE.LGPLv3 included in the packaging of this file. Please review the
** following information to ensure the GNU Lesser General Public License
** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** As a special exception, The Qt Company gives you certain additional
** rights. These rights are described in The Qt Company LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** $QT_END_LICENSE$
**
****************************************************************************/
//
// 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 <private/qunlimitedcontainer_p.h>
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
#endif
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