diff -r 000000000000 -r 4f2f89ce4247 WebCore/xml/XPathStep.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/WebCore/xml/XPathStep.cpp Fri Sep 17 09:02:29 2010 +0300 @@ -0,0 +1,398 @@ +/* + * Copyright (C) 2005 Frerich Raabe + * Copyright (C) 2006, 2009 Apple Inc. All rights reserved. + * Copyright (C) 2007 Alexey Proskuryakov + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "config.h" +#include "XPathStep.h" + +#if ENABLE(XPATH) + +#include "Attr.h" +#include "Document.h" +#include "Element.h" +#include "NamedNodeMap.h" +#include "XMLNSNames.h" +#include "XPathParser.h" +#include "XPathUtil.h" + +namespace WebCore { +namespace XPath { + +Step::Step(Axis axis, const NodeTest& nodeTest, const Vector& predicates) + : m_axis(axis) + , m_nodeTest(nodeTest) + , m_predicates(predicates) +{ +} + +Step::~Step() +{ + deleteAllValues(m_predicates); + deleteAllValues(m_nodeTest.mergedPredicates()); +} + +void Step::optimize() +{ + // Evaluate predicates as part of node test if possible to avoid building unnecessary NodeSets. + // 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. + // 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]. + Vector remainingPredicates; + for (size_t i = 0; i < m_predicates.size(); ++i) { + Predicate* predicate = m_predicates[i]; + if ((!predicate->isContextPositionSensitive() || m_nodeTest.mergedPredicates().isEmpty()) && !predicate->isContextSizeSensitive() && remainingPredicates.isEmpty()) { + m_nodeTest.mergedPredicates().append(predicate); + } else + remainingPredicates.append(predicate); + } + swap(remainingPredicates, m_predicates); +} + +void optimizeStepPair(Step* first, Step* second, bool& dropSecondStep) +{ + dropSecondStep = false; + + if (first->m_axis == Step::DescendantOrSelfAxis + && first->m_nodeTest.kind() == Step::NodeTest::AnyNodeTest + && !first->m_predicates.size() + && !first->m_nodeTest.mergedPredicates().size()) { + + ASSERT(first->m_nodeTest.data().isEmpty()); + ASSERT(first->m_nodeTest.namespaceURI().isEmpty()); + + // Optimize the common case of "//" AKA /descendant-or-self::node()/child::NodeTest to /descendant::NodeTest. + if (second->m_axis == Step::ChildAxis && second->predicatesAreContextListInsensitive()) { + first->m_axis = Step::DescendantAxis; + first->m_nodeTest = Step::NodeTest(second->m_nodeTest.kind(), second->m_nodeTest.data(), second->m_nodeTest.namespaceURI()); + swap(second->m_nodeTest.mergedPredicates(), first->m_nodeTest.mergedPredicates()); + swap(second->m_predicates, first->m_predicates); + first->optimize(); + dropSecondStep = true; + } + } +} + +bool Step::predicatesAreContextListInsensitive() const +{ + for (size_t i = 0; i < m_predicates.size(); ++i) { + Predicate* predicate = m_predicates[i]; + if (predicate->isContextPositionSensitive() || predicate->isContextSizeSensitive()) + return false; + } + + for (size_t i = 0; i < m_nodeTest.mergedPredicates().size(); ++i) { + Predicate* predicate = m_nodeTest.mergedPredicates()[i]; + if (predicate->isContextPositionSensitive() || predicate->isContextSizeSensitive()) + return false; + } + + return true; +} + +void Step::evaluate(Node* context, NodeSet& nodes) const +{ + EvaluationContext& evaluationContext = Expression::evaluationContext(); + evaluationContext.position = 0; + + nodesInAxis(context, nodes); + + // Check predicates that couldn't be merged into node test. + for (unsigned i = 0; i < m_predicates.size(); i++) { + Predicate* predicate = m_predicates[i]; + + NodeSet newNodes; + if (!nodes.isSorted()) + newNodes.markSorted(false); + + for (unsigned j = 0; j < nodes.size(); j++) { + Node* node = nodes[j]; + + evaluationContext.node = node; + evaluationContext.size = nodes.size(); + evaluationContext.position = j + 1; + if (predicate->evaluate()) + newNodes.append(node); + } + + nodes.swap(newNodes); + } +} + +static inline Node::NodeType primaryNodeType(Step::Axis axis) +{ + switch (axis) { + case Step::AttributeAxis: + return Node::ATTRIBUTE_NODE; + case Step::NamespaceAxis: + return Node::XPATH_NAMESPACE_NODE; + default: + return Node::ELEMENT_NODE; + } +} + +// Evaluate NodeTest without considering merged predicates. +static inline bool nodeMatchesBasicTest(Node* node, Step::Axis axis, const Step::NodeTest& nodeTest) +{ + switch (nodeTest.kind()) { + case Step::NodeTest::TextNodeTest: + return node->nodeType() == Node::TEXT_NODE || node->nodeType() == Node::CDATA_SECTION_NODE; + case Step::NodeTest::CommentNodeTest: + return node->nodeType() == Node::COMMENT_NODE; + case Step::NodeTest::ProcessingInstructionNodeTest: { + const AtomicString& name = nodeTest.data(); + return node->nodeType() == Node::PROCESSING_INSTRUCTION_NODE && (name.isEmpty() || node->nodeName() == name); + } + case Step::NodeTest::AnyNodeTest: + return true; + case Step::NodeTest::NameTest: { + const AtomicString& name = nodeTest.data(); + const AtomicString& namespaceURI = nodeTest.namespaceURI(); + + if (axis == Step::AttributeAxis) { + ASSERT(node->isAttributeNode()); + + // In XPath land, namespace nodes are not accessible on the attribute axis. + if (node->namespaceURI() == XMLNSNames::xmlnsNamespaceURI) + return false; + + if (name == starAtom) + return namespaceURI.isEmpty() || node->namespaceURI() == namespaceURI; + + return node->localName() == name && node->namespaceURI() == namespaceURI; + } + + // Node test on the namespace axis is not implemented yet, the caller has a check for it. + ASSERT(axis != Step::NamespaceAxis); + + // For other axes, the principal node type is element. + ASSERT(primaryNodeType(axis) == Node::ELEMENT_NODE); + if (node->nodeType() != Node::ELEMENT_NODE) + return false; + + if (name == starAtom) + return namespaceURI.isEmpty() || namespaceURI == node->namespaceURI(); + + if (node->document()->isHTMLDocument()) { + if (node->isHTMLElement()) { + // Paths without namespaces should match HTML elements in HTML documents despite those having an XHTML namespace. Names are compared case-insensitively. + return equalIgnoringCase(static_cast(node)->localName(), name) && (namespaceURI.isNull() || namespaceURI == node->namespaceURI()); + } + // An expression without any prefix shouldn't match no-namespace nodes (because HTML5 says so). + return static_cast(node)->hasLocalName(name) && namespaceURI == node->namespaceURI() && !namespaceURI.isNull(); + } + return static_cast(node)->hasLocalName(name) && namespaceURI == node->namespaceURI(); + } + } + ASSERT_NOT_REACHED(); + return false; +} + +static inline bool nodeMatches(Node* node, Step::Axis axis, const Step::NodeTest& nodeTest) +{ + if (!nodeMatchesBasicTest(node, axis, nodeTest)) + return false; + + EvaluationContext& evaluationContext = Expression::evaluationContext(); + + // Only the first merged predicate may depend on position. + ++evaluationContext.position; + + const Vector& mergedPredicates = nodeTest.mergedPredicates(); + for (unsigned i = 0; i < mergedPredicates.size(); i++) { + Predicate* predicate = mergedPredicates[i]; + + evaluationContext.node = node; + // No need to set context size - we only get here when evaluating predicates that do not depend on it. + if (!predicate->evaluate()) + return false; + } + + return true; +} + +// Result nodes are ordered in axis order. Node test (including merged predicates) is applied. +void Step::nodesInAxis(Node* context, NodeSet& nodes) const +{ + ASSERT(nodes.isEmpty()); + switch (m_axis) { + case ChildAxis: + if (context->isAttributeNode()) // In XPath model, attribute nodes do not have children. + return; + + for (Node* n = context->firstChild(); n; n = n->nextSibling()) + if (nodeMatches(n, ChildAxis, m_nodeTest)) + nodes.append(n); + return; + case DescendantAxis: + if (context->isAttributeNode()) // In XPath model, attribute nodes do not have children. + return; + + for (Node* n = context->firstChild(); n; n = n->traverseNextNode(context)) + if (nodeMatches(n, DescendantAxis, m_nodeTest)) + nodes.append(n); + return; + case ParentAxis: + if (context->isAttributeNode()) { + Node* n = static_cast(context)->ownerElement(); + if (nodeMatches(n, ParentAxis, m_nodeTest)) + nodes.append(n); + } else { + Node* n = context->parentNode(); + if (n && nodeMatches(n, ParentAxis, m_nodeTest)) + nodes.append(n); + } + return; + case AncestorAxis: { + Node* n = context; + if (context->isAttributeNode()) { + n = static_cast(context)->ownerElement(); + if (nodeMatches(n, AncestorAxis, m_nodeTest)) + nodes.append(n); + } + for (n = n->parentNode(); n; n = n->parentNode()) + if (nodeMatches(n, AncestorAxis, m_nodeTest)) + nodes.append(n); + nodes.markSorted(false); + return; + } + case FollowingSiblingAxis: + if (context->nodeType() == Node::ATTRIBUTE_NODE || + context->nodeType() == Node::XPATH_NAMESPACE_NODE) + return; + + for (Node* n = context->nextSibling(); n; n = n->nextSibling()) + if (nodeMatches(n, FollowingSiblingAxis, m_nodeTest)) + nodes.append(n); + return; + case PrecedingSiblingAxis: + if (context->nodeType() == Node::ATTRIBUTE_NODE || + context->nodeType() == Node::XPATH_NAMESPACE_NODE) + return; + + for (Node* n = context->previousSibling(); n; n = n->previousSibling()) + if (nodeMatches(n, PrecedingSiblingAxis, m_nodeTest)) + nodes.append(n); + + nodes.markSorted(false); + return; + case FollowingAxis: + if (context->isAttributeNode()) { + Node* p = static_cast(context)->ownerElement(); + while ((p = p->traverseNextNode())) + if (nodeMatches(p, FollowingAxis, m_nodeTest)) + nodes.append(p); + } else { + for (Node* p = context; !isRootDomNode(p); p = p->parentNode()) { + for (Node* n = p->nextSibling(); n; n = n->nextSibling()) { + if (nodeMatches(n, FollowingAxis, m_nodeTest)) + nodes.append(n); + for (Node* c = n->firstChild(); c; c = c->traverseNextNode(n)) + if (nodeMatches(c, FollowingAxis, m_nodeTest)) + nodes.append(c); + } + } + } + return; + case PrecedingAxis: { + if (context->isAttributeNode()) + context = static_cast(context)->ownerElement(); + + Node* n = context; + while (Node* parent = n->parent()) { + for (n = n->traversePreviousNode(); n != parent; n = n->traversePreviousNode()) + if (nodeMatches(n, PrecedingAxis, m_nodeTest)) + nodes.append(n); + n = parent; + } + nodes.markSorted(false); + return; + } + case AttributeAxis: { + if (context->nodeType() != Node::ELEMENT_NODE) + return; + + // Avoid lazily creating attribute nodes for attributes that we do not need anyway. + if (m_nodeTest.kind() == NodeTest::NameTest && m_nodeTest.data() != starAtom) { + RefPtr n = static_cast(context)->getAttributeNodeNS(m_nodeTest.namespaceURI(), m_nodeTest.data()); + if (n && n->namespaceURI() != XMLNSNames::xmlnsNamespaceURI) { // In XPath land, namespace nodes are not accessible on the attribute axis. + if (nodeMatches(n.get(), AttributeAxis, m_nodeTest)) // Still need to check merged predicates. + nodes.append(n.release()); + } + return; + } + + NamedNodeMap* attrs = context->attributes(); + if (!attrs) + return; + + for (unsigned i = 0; i < attrs->length(); ++i) { + RefPtr attr = attrs->attributeItem(i)->createAttrIfNeeded(static_cast(context)); + if (nodeMatches(attr.get(), AttributeAxis, m_nodeTest)) + nodes.append(attr.release()); + } + return; + } + case NamespaceAxis: + // XPath namespace nodes are not implemented yet. + return; + case SelfAxis: + if (nodeMatches(context, SelfAxis, m_nodeTest)) + nodes.append(context); + return; + case DescendantOrSelfAxis: + if (nodeMatches(context, DescendantOrSelfAxis, m_nodeTest)) + nodes.append(context); + if (context->isAttributeNode()) // In XPath model, attribute nodes do not have children. + return; + + for (Node* n = context->firstChild(); n; n = n->traverseNextNode(context)) + if (nodeMatches(n, DescendantOrSelfAxis, m_nodeTest)) + nodes.append(n); + return; + case AncestorOrSelfAxis: { + if (nodeMatches(context, AncestorOrSelfAxis, m_nodeTest)) + nodes.append(context); + Node* n = context; + if (context->isAttributeNode()) { + n = static_cast(context)->ownerElement(); + if (nodeMatches(n, AncestorOrSelfAxis, m_nodeTest)) + nodes.append(n); + } + for (n = n->parentNode(); n; n = n->parentNode()) + if (nodeMatches(n, AncestorOrSelfAxis, m_nodeTest)) + nodes.append(n); + + nodes.markSorted(false); + return; + } + } + ASSERT_NOT_REACHED(); +} + + +} +} + +#endif // ENABLE(XPATH)