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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.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "qcommonsequencetypes_p.h"
#include "qdeduplicateiterator_p.h"
#include "qnodesort_p.h"
QT_BEGIN_NAMESPACE
using namespace QPatternist;
NodeSortExpression::NodeSortExpression(const Expression::Ptr &op) : SingleContainer(op)
{
}
bool NodeSortExpression::lessThanUsingNodeModel(const Item &n1,
const Item &n2)
{
Q_ASSERT(n1.isNode());
Q_ASSERT(n2.isNode());
if(n1.asNode().model() == n2.asNode().model())
return n1.asNode().compareOrder(n2.asNode()) == QXmlNodeModelIndex::Precedes;
else
{
/* The two nodes are from different trees. The sort order is implementation
* defined, but it must be stable.
*
* We do this by looking at the pointer difference. The value means nothing,
* but it is stable, and that's what we're looking for. */
return n1.asNode().model() - n2.asNode().model() < 0;
}
}
Item::Iterator::Ptr NodeSortExpression::evaluateSequence(const DynamicContext::Ptr &context) const
{
Q_ASSERT_X(m_operand->staticType()->cardinality().allowsMany(), Q_FUNC_INFO,
"It makes no sense to sort a single node.");
Item::List nodes(m_operand->evaluateSequence(context)->toList());
if(nodes.isEmpty())
return CommonValues::emptyIterator;
else if(nodes.first().isAtomicValue())
return makeListIterator(nodes);
else
{
qSort(nodes.begin(), nodes.end(), lessThanUsingNodeModel);
return Item::Iterator::Ptr(new DeduplicateIterator(nodes));
}
}
Expression::Ptr NodeSortExpression::wrapAround(const Expression::Ptr &operand,
const StaticContext::Ptr &context)
{
Q_ASSERT(operand);
Q_ASSERT(context);
const Expression::Ptr sort(new NodeSortExpression(operand));
context->wrapExpressionWith(operand.data(), sort);
return sort;
}
Expression::Ptr NodeSortExpression::compress(const StaticContext::Ptr &context)
{
const Expression::Ptr me(SingleContainer::compress(context));
/* It make no sense to sort & deduplicate a single node. */
if(m_operand->staticType()->cardinality().allowsMany())
return me;
else
return m_operand;
}
SequenceType::Ptr NodeSortExpression::staticType() const
{
return m_operand->staticType();
}
SequenceType::List NodeSortExpression::expectedOperandTypes() const
{
SequenceType::List result;
result.append(CommonSequenceTypes::ZeroOrMoreItems);
return result;
}
ExpressionVisitorResult::Ptr
NodeSortExpression::accept(const ExpressionVisitor::Ptr &visitor) const
{
return visitor->visit(this);
}
Expression::Properties NodeSortExpression::properties() const
{
/* The reason we disable elimination is that the assert for sorting a
* single node in evaluateSequence() triggers unless our compress() routine
* has been run. Anyhow, it's not that we would manage to write away anyway,
* since the node source in most(all?) cases prevents it.
*/
return AffectsOrderOnly | DisableElimination;
}
QT_END_NAMESPACE
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