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Diffstat (limited to 'src/xmlpatterns/expr/qnodesort.cpp')
| -rw-r--r-- | src/xmlpatterns/expr/qnodesort.cpp | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/src/xmlpatterns/expr/qnodesort.cpp b/src/xmlpatterns/expr/qnodesort.cpp new file mode 100644 index 0000000..0f0d9a2 --- /dev/null +++ b/src/xmlpatterns/expr/qnodesort.cpp @@ -0,0 +1,142 @@ +/**************************************************************************** +** +** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). +** Contact: Qt Software Information (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 either Technology Preview License Agreement or the +** Beta Release License Agreement. +** +** 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 1.0, 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. +** +** If you are unsure which license is appropriate for your use, please +** contact the sales department at qt-sales@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 |