400 lines
16 KiB
C++
400 lines
16 KiB
C++
/*
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* Copyright (C) 2005 Frerich Raabe <raabe@kde.org>
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* Copyright (C) 2006, 2009 Apple Inc. All rights reserved.
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* Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "config.h"
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#include "XPathStep.h"
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#include "Attr.h"
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#include "Document.h"
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#include "HTMLElement.h"
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#include "NodeTraversal.h"
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#include "XMLNSNames.h"
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#include "XPathParser.h"
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#include "XPathUtil.h"
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namespace WebCore {
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namespace XPath {
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Step::Step(Axis axis, NodeTest nodeTest)
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: m_axis(axis)
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, m_nodeTest(WTFMove(nodeTest))
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{
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}
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Step::Step(Axis axis, NodeTest nodeTest, Vector<std::unique_ptr<Expression>> predicates)
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: m_axis(axis)
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, m_nodeTest(WTFMove(nodeTest))
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, m_predicates(WTFMove(predicates))
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{
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}
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Step::~Step() = default;
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void Step::optimize()
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{
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// Evaluate predicates as part of node test if possible to avoid building unnecessary NodeSets.
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// E.g., there is no need to build a set of all "foo" nodes to evaluate "foo[@bar]", we can check the predicate while enumerating.
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// This optimization can be applied to predicates that are not context node list sensitive, or to first predicate that is only context position sensitive, e.g. foo[position() mod 2 = 0].
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Vector<std::unique_ptr<Expression>> remainingPredicates;
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for (auto& predicate : m_predicates) {
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if ((!predicateIsContextPositionSensitive(*predicate) || m_nodeTest.m_mergedPredicates.isEmpty()) && !predicate->isContextSizeSensitive() && remainingPredicates.isEmpty())
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m_nodeTest.m_mergedPredicates.append(WTFMove(predicate));
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else
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remainingPredicates.append(WTFMove(predicate));
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}
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m_predicates = WTFMove(remainingPredicates);
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}
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void optimizeStepPair(Step& first, Step& second, bool& dropSecondStep)
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{
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dropSecondStep = false;
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if (first.m_axis != Step::DescendantOrSelfAxis)
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return;
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if (first.m_nodeTest.m_kind != Step::NodeTest::AnyNodeTest)
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return;
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if (!first.m_predicates.isEmpty())
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return;
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if (!first.m_nodeTest.m_mergedPredicates.isEmpty())
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return;
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ASSERT(first.m_nodeTest.m_data.isEmpty());
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ASSERT(first.m_nodeTest.m_namespaceURI.isEmpty());
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// Optimize the common case of "//" AKA /descendant-or-self::node()/child::NodeTest to /descendant::NodeTest.
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if (second.m_axis != Step::ChildAxis)
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return;
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if (!second.predicatesAreContextListInsensitive())
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return;
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first.m_axis = Step::DescendantAxis;
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first.m_nodeTest = WTFMove(second.m_nodeTest);
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first.m_predicates = WTFMove(second.m_predicates);
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first.optimize();
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dropSecondStep = true;
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}
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bool Step::predicatesAreContextListInsensitive() const
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{
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for (auto& predicate : m_predicates) {
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if (predicateIsContextPositionSensitive(*predicate) || predicate->isContextSizeSensitive())
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return false;
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}
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for (auto& predicate : m_nodeTest.m_mergedPredicates) {
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if (predicateIsContextPositionSensitive(*predicate) || predicate->isContextSizeSensitive())
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return false;
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}
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return true;
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}
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void Step::evaluate(Node& context, NodeSet& nodes) const
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{
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EvaluationContext& evaluationContext = Expression::evaluationContext();
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evaluationContext.position = 0;
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nodesInAxis(context, nodes);
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// Check predicates that couldn't be merged into node test.
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for (auto& predicate : m_predicates) {
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NodeSet newNodes;
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if (!nodes.isSorted())
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newNodes.markSorted(false);
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for (unsigned j = 0; j < nodes.size(); j++) {
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Node* node = nodes[j];
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evaluationContext.node = node;
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evaluationContext.size = nodes.size();
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evaluationContext.position = j + 1;
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if (evaluatePredicate(*predicate))
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newNodes.append(node);
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}
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nodes = WTFMove(newNodes);
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}
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}
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#if ASSERT_ENABLED
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static inline Node::NodeType primaryNodeType(Step::Axis axis)
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{
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switch (axis) {
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case Step::AttributeAxis:
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return Node::ATTRIBUTE_NODE;
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default:
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return Node::ELEMENT_NODE;
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}
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}
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#endif // ASSERT_ENABLED
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// Evaluate NodeTest without considering merged predicates.
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inline bool nodeMatchesBasicTest(Node& node, Step::Axis axis, const Step::NodeTest& nodeTest)
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{
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switch (nodeTest.m_kind) {
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case Step::NodeTest::TextNodeTest:
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return node.nodeType() == Node::TEXT_NODE || node.nodeType() == Node::CDATA_SECTION_NODE;
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case Step::NodeTest::CommentNodeTest:
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return node.nodeType() == Node::COMMENT_NODE;
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case Step::NodeTest::ProcessingInstructionNodeTest: {
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const AtomString& name = nodeTest.m_data;
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return node.nodeType() == Node::PROCESSING_INSTRUCTION_NODE && (name.isEmpty() || node.nodeName() == name);
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}
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case Step::NodeTest::AnyNodeTest:
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return true;
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case Step::NodeTest::NameTest: {
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const AtomString& name = nodeTest.m_data;
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const AtomString& namespaceURI = nodeTest.m_namespaceURI;
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if (axis == Step::AttributeAxis) {
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ASSERT(node.isAttributeNode());
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// In XPath land, namespace nodes are not accessible on the attribute axis.
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if (node.namespaceURI() == XMLNSNames::xmlnsNamespaceURI)
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return false;
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if (name == starAtom())
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return namespaceURI.isEmpty() || node.namespaceURI() == namespaceURI;
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return node.localName() == name && node.namespaceURI() == namespaceURI;
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}
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// Node test on the namespace axis is not implemented yet, the caller has a check for it.
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ASSERT(axis != Step::NamespaceAxis);
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// For other axes, the principal node type is element.
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ASSERT(primaryNodeType(axis) == Node::ELEMENT_NODE);
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if (!is<Element>(node))
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return false;
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if (name == starAtom())
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return namespaceURI.isEmpty() || namespaceURI == node.namespaceURI();
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if (node.document().isHTMLDocument()) {
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if (is<HTMLElement>(node)) {
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// Paths without namespaces should match HTML elements in HTML documents despite those having an XHTML namespace. Names are compared case-insensitively.
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return equalIgnoringASCIICase(downcast<HTMLElement>(node).localName(), name) && (namespaceURI.isNull() || namespaceURI == node.namespaceURI());
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}
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// An expression without any prefix shouldn't match no-namespace nodes (because HTML5 says so).
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return downcast<Element>(node).hasLocalName(name) && namespaceURI == node.namespaceURI() && !namespaceURI.isNull();
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}
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return downcast<Element>(node).hasLocalName(name) && namespaceURI == node.namespaceURI();
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}
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}
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ASSERT_NOT_REACHED();
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return false;
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}
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inline bool nodeMatches(Node& node, Step::Axis axis, const Step::NodeTest& nodeTest)
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{
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if (!nodeMatchesBasicTest(node, axis, nodeTest))
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return false;
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EvaluationContext& evaluationContext = Expression::evaluationContext();
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// Only the first merged predicate may depend on position.
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++evaluationContext.position;
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for (auto& predicate : nodeTest.m_mergedPredicates) {
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// No need to set context size - we only get here when evaluating predicates that do not depend on it.
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evaluationContext.node = &node;
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if (!evaluatePredicate(*predicate))
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return false;
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}
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return true;
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}
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// Result nodes are ordered in axis order. Node test (including merged predicates) is applied.
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void Step::nodesInAxis(Node& context, NodeSet& nodes) const
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{
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ASSERT(nodes.isEmpty());
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switch (m_axis) {
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case ChildAxis:
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if (context.isAttributeNode()) // In XPath model, attribute nodes do not have children.
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return;
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for (Node* node = context.firstChild(); node; node = node->nextSibling()) {
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if (nodeMatches(*node, ChildAxis, m_nodeTest))
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nodes.append(node);
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}
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return;
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case DescendantAxis:
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if (context.isAttributeNode()) // In XPath model, attribute nodes do not have children.
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return;
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for (Node* node = context.firstChild(); node; node = NodeTraversal::next(*node, &context)) {
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if (nodeMatches(*node, DescendantAxis, m_nodeTest))
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nodes.append(node);
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}
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return;
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case ParentAxis:
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if (context.isAttributeNode()) {
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Element* node = static_cast<Attr&>(context).ownerElement();
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if (nodeMatches(*node, ParentAxis, m_nodeTest))
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nodes.append(node);
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} else {
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ContainerNode* node = context.parentNode();
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if (node && nodeMatches(*node, ParentAxis, m_nodeTest))
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nodes.append(node);
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}
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return;
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case AncestorAxis: {
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Node* node = &context;
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if (context.isAttributeNode()) {
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node = static_cast<Attr&>(context).ownerElement();
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if (nodeMatches(*node, AncestorAxis, m_nodeTest))
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nodes.append(node);
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}
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for (node = node->parentNode(); node; node = node->parentNode()) {
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if (nodeMatches(*node, AncestorAxis, m_nodeTest))
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nodes.append(node);
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}
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nodes.markSorted(false);
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return;
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}
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case FollowingSiblingAxis:
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if (context.isAttributeNode())
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return;
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for (Node* node = context.nextSibling(); node; node = node->nextSibling()) {
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if (nodeMatches(*node, FollowingSiblingAxis, m_nodeTest))
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nodes.append(node);
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}
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return;
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case PrecedingSiblingAxis:
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if (context.isAttributeNode())
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return;
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for (Node* node = context.previousSibling(); node; node = node->previousSibling()) {
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if (nodeMatches(*node, PrecedingSiblingAxis, m_nodeTest))
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nodes.append(node);
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}
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nodes.markSorted(false);
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return;
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case FollowingAxis:
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if (context.isAttributeNode()) {
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Node* node = static_cast<Attr&>(context).ownerElement();
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while ((node = NodeTraversal::next(*node))) {
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if (nodeMatches(*node, FollowingAxis, m_nodeTest))
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nodes.append(node);
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}
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} else {
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for (Node* parent = &context; !isRootDomNode(parent); parent = parent->parentNode()) {
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for (Node* node = parent->nextSibling(); node; node = node->nextSibling()) {
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if (nodeMatches(*node, FollowingAxis, m_nodeTest))
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nodes.append(node);
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for (Node* child = node->firstChild(); child; child = NodeTraversal::next(*child, node)) {
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if (nodeMatches(*child, FollowingAxis, m_nodeTest))
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nodes.append(child);
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}
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}
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}
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}
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return;
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case PrecedingAxis: {
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Node* node;
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if (context.isAttributeNode())
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node = static_cast<Attr&>(context).ownerElement();
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else
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node = &context;
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while (ContainerNode* parent = node->parentNode()) {
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for (node = NodeTraversal::previous(*node); node != parent; node = NodeTraversal::previous(*node)) {
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if (nodeMatches(*node, PrecedingAxis, m_nodeTest))
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nodes.append(node);
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}
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node = parent;
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}
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nodes.markSorted(false);
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return;
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}
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case AttributeAxis: {
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if (!is<Element>(context))
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return;
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Element& contextElement = downcast<Element>(context);
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// Avoid lazily creating attribute nodes for attributes that we do not need anyway.
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if (m_nodeTest.m_kind == NodeTest::NameTest && m_nodeTest.m_data != starAtom()) {
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auto attr = contextElement.getAttributeNodeNS(m_nodeTest.m_namespaceURI, m_nodeTest.m_data);
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if (attr && attr->namespaceURI() != XMLNSNames::xmlnsNamespaceURI) { // In XPath land, namespace nodes are not accessible on the attribute axis.
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if (nodeMatches(*attr, AttributeAxis, m_nodeTest)) // Still need to check merged predicates.
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nodes.append(WTFMove(attr));
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}
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return;
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}
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if (!contextElement.hasAttributes())
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return;
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for (const Attribute& attribute : contextElement.attributesIterator()) {
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auto attr = contextElement.ensureAttr(attribute.name());
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if (nodeMatches(attr.get(), AttributeAxis, m_nodeTest))
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nodes.append(WTFMove(attr));
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}
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return;
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}
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case NamespaceAxis:
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// XPath namespace nodes are not implemented yet.
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return;
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case SelfAxis:
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if (nodeMatches(context, SelfAxis, m_nodeTest))
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nodes.append(&context);
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return;
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case DescendantOrSelfAxis:
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if (nodeMatches(context, DescendantOrSelfAxis, m_nodeTest))
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nodes.append(&context);
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if (context.isAttributeNode()) // In XPath model, attribute nodes do not have children.
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return;
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for (Node* node = context.firstChild(); node; node = NodeTraversal::next(*node, &context)) {
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if (nodeMatches(*node, DescendantOrSelfAxis, m_nodeTest))
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nodes.append(node);
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}
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return;
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case AncestorOrSelfAxis: {
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if (nodeMatches(context, AncestorOrSelfAxis, m_nodeTest))
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nodes.append(&context);
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Node* node = &context;
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if (context.isAttributeNode()) {
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node = static_cast<Attr&>(context).ownerElement();
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if (nodeMatches(*node, AncestorOrSelfAxis, m_nodeTest))
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nodes.append(node);
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}
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for (node = node->parentNode(); node; node = node->parentNode()) {
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if (nodeMatches(*node, AncestorOrSelfAxis, m_nodeTest))
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nodes.append(node);
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}
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nodes.markSorted(false);
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return;
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}
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}
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ASSERT_NOT_REACHED();
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}
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}
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}
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