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| ** Copyright (C) 2016 The Qt Company Ltd. |
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| ** This file is part of the QtXmlPatterns module of the Qt Toolkit. |
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| |
| #include "qcommonsequencetypes_p.h" |
| #include "qdeduplicateiterator_p.h" |
| #include "qnodesort_p.h" |
| |
| #include <algorithm> |
| |
| 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 |
| { |
| std::sort(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 |