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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.
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "qcommonsequencetypes_p.h"
#include "qgenericsequencetype_p.h"
#include "qfirstitempredicate_p.h"
QT_BEGIN_NAMESPACE
using namespace QPatternist;
FirstItemPredicate::FirstItemPredicate(const Expression::Ptr &source) : SingleContainer(source)
{
}
Item FirstItemPredicate::evaluateSingleton(const DynamicContext::Ptr &context) const
{
/* If our operand allows the empty sequence, this function can return Item(), otherwise
* it returns the first item. As simple as that. */
return m_operand->evaluateSequence(context)->next();
}
SequenceType::Ptr FirstItemPredicate::staticType() const
{
const SequenceType::Ptr t(m_operand->staticType());
return makeGenericSequenceType(t->itemType(), t->cardinality().toWithoutMany());
}
Expression::Ptr FirstItemPredicate::compress(const StaticContext::Ptr &context)
{
const Expression::Ptr me(SingleContainer::compress(context));
if(me != this)
return me;
if(m_operand->is(IDFirstItemPredicate))
m_operand = m_operand->operands().first();
return me;
}
SequenceType::List FirstItemPredicate::expectedOperandTypes() const
{
SequenceType::List result;
result.append(CommonSequenceTypes::ZeroOrMoreItems);
return result;
}
ExpressionVisitorResult::Ptr FirstItemPredicate::accept(const ExpressionVisitor::Ptr &visitor) const
{
return visitor->visit(this);
}
Expression::ID FirstItemPredicate::id() const
{
return IDFirstItemPredicate;
}
QT_END_NAMESPACE
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