| /* |
| * Copyright (C) 2005 Frerich Raabe <raabe@kde.org> |
| * Copyright (C) 2006, 2009 Apple Inc. All rights reserved. |
| * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org> |
| * |
| * 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" |
| |
| #include "Attr.h" |
| #include "Document.h" |
| #include "ElementInlines.h" |
| #include "HTMLElement.h" |
| #include "NodeTraversal.h" |
| #include "XMLNSNames.h" |
| #include "XPathParser.h" |
| #include "XPathUtil.h" |
| |
| namespace WebCore { |
| namespace XPath { |
| |
| Step::Step(Axis axis, NodeTest nodeTest) |
| : m_axis(axis) |
| , m_nodeTest(WTFMove(nodeTest)) |
| { |
| } |
| |
| Step::Step(Axis axis, NodeTest nodeTest, Vector<std::unique_ptr<Expression>> predicates) |
| : m_axis(axis) |
| , m_nodeTest(WTFMove(nodeTest)) |
| , m_predicates(WTFMove(predicates)) |
| { |
| } |
| |
| Step::~Step() = default; |
| |
| 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<std::unique_ptr<Expression>> remainingPredicates; |
| for (auto& predicate : m_predicates) { |
| if ((!predicateIsContextPositionSensitive(*predicate) || m_nodeTest.m_mergedPredicates.isEmpty()) && !predicate->isContextSizeSensitive() && remainingPredicates.isEmpty()) |
| m_nodeTest.m_mergedPredicates.append(WTFMove(predicate)); |
| else |
| remainingPredicates.append(WTFMove(predicate)); |
| } |
| m_predicates = WTFMove(remainingPredicates); |
| } |
| |
| void optimizeStepPair(Step& first, Step& second, bool& dropSecondStep) |
| { |
| dropSecondStep = false; |
| |
| if (first.m_axis != Step::DescendantOrSelfAxis) |
| return; |
| |
| if (first.m_nodeTest.m_kind != Step::NodeTest::AnyNodeTest) |
| return; |
| |
| if (!first.m_predicates.isEmpty()) |
| return; |
| |
| if (!first.m_nodeTest.m_mergedPredicates.isEmpty()) |
| return; |
| |
| ASSERT(first.m_nodeTest.m_data.isEmpty()); |
| ASSERT(first.m_nodeTest.m_namespaceURI.isEmpty()); |
| |
| // Optimize the common case of "//" AKA /descendant-or-self::node()/child::NodeTest to /descendant::NodeTest. |
| if (second.m_axis != Step::ChildAxis) |
| return; |
| |
| if (!second.predicatesAreContextListInsensitive()) |
| return; |
| |
| first.m_axis = Step::DescendantAxis; |
| first.m_nodeTest = WTFMove(second.m_nodeTest); |
| first.m_predicates = WTFMove(second.m_predicates); |
| first.optimize(); |
| dropSecondStep = true; |
| } |
| |
| bool Step::predicatesAreContextListInsensitive() const |
| { |
| for (auto& predicate : m_predicates) { |
| if (predicateIsContextPositionSensitive(*predicate) || predicate->isContextSizeSensitive()) |
| return false; |
| } |
| |
| for (auto& predicate : m_nodeTest.m_mergedPredicates) { |
| if (predicateIsContextPositionSensitive(*predicate) || 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 (auto& predicate : m_predicates) { |
| 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 (evaluatePredicate(*predicate)) |
| newNodes.append(node); |
| } |
| |
| nodes = WTFMove(newNodes); |
| } |
| } |
| |
| #if ASSERT_ENABLED |
| static inline Node::NodeType primaryNodeType(Step::Axis axis) |
| { |
| switch (axis) { |
| case Step::AttributeAxis: |
| return Node::ATTRIBUTE_NODE; |
| default: |
| return Node::ELEMENT_NODE; |
| } |
| } |
| #endif // ASSERT_ENABLED |
| |
| // Evaluate NodeTest without considering merged predicates. |
| inline bool nodeMatchesBasicTest(Node& node, Step::Axis axis, const Step::NodeTest& nodeTest) |
| { |
| switch (nodeTest.m_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 AtomString& name = nodeTest.m_data; |
| return node.nodeType() == Node::PROCESSING_INSTRUCTION_NODE && (name.isEmpty() || node.nodeName() == name); |
| } |
| case Step::NodeTest::AnyNodeTest: |
| return true; |
| case Step::NodeTest::NameTest: { |
| const AtomString& name = nodeTest.m_data; |
| const AtomString& namespaceURI = nodeTest.m_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 (!is<Element>(node)) |
| return false; |
| |
| if (name == starAtom()) |
| return namespaceURI.isEmpty() || namespaceURI == node.namespaceURI(); |
| |
| if (node.document().isHTMLDocument()) { |
| if (is<HTMLElement>(node)) { |
| // Paths without namespaces should match HTML elements in HTML documents despite those having an XHTML namespace. Names are compared case-insensitively. |
| return equalIgnoringASCIICase(downcast<HTMLElement>(node).localName(), name) && (namespaceURI.isNull() || namespaceURI == node.namespaceURI()); |
| } |
| // An expression without any prefix shouldn't match no-namespace nodes (because HTML5 says so). |
| return downcast<Element>(node).hasLocalName(name) && namespaceURI == node.namespaceURI() && !namespaceURI.isNull(); |
| } |
| return downcast<Element>(node).hasLocalName(name) && namespaceURI == node.namespaceURI(); |
| } |
| } |
| ASSERT_NOT_REACHED(); |
| return false; |
| } |
| |
| 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; |
| |
| for (auto& predicate : nodeTest.m_mergedPredicates) { |
| // No need to set context size - we only get here when evaluating predicates that do not depend on it. |
| evaluationContext.node = &node; |
| if (!evaluatePredicate(*predicate)) |
| 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* node = context.firstChild(); node; node = node->nextSibling()) { |
| if (nodeMatches(*node, ChildAxis, m_nodeTest)) |
| nodes.append(node); |
| } |
| return; |
| case DescendantAxis: |
| if (context.isAttributeNode()) // In XPath model, attribute nodes do not have children. |
| return; |
| for (Node* node = context.firstChild(); node; node = NodeTraversal::next(*node, &context)) { |
| if (nodeMatches(*node, DescendantAxis, m_nodeTest)) |
| nodes.append(node); |
| } |
| return; |
| case ParentAxis: |
| if (context.isAttributeNode()) { |
| Element* node = static_cast<Attr&>(context).ownerElement(); |
| if (node && nodeMatches(*node, ParentAxis, m_nodeTest)) |
| nodes.append(node); |
| } else { |
| ContainerNode* node = context.parentNode(); |
| if (node && nodeMatches(*node, ParentAxis, m_nodeTest)) |
| nodes.append(node); |
| } |
| return; |
| case AncestorAxis: { |
| Node* node = &context; |
| if (context.isAttributeNode()) { |
| node = static_cast<Attr&>(context).ownerElement(); |
| if (!node) |
| return; |
| if (nodeMatches(*node, AncestorAxis, m_nodeTest)) |
| nodes.append(node); |
| } |
| for (node = node->parentNode(); node; node = node->parentNode()) { |
| if (nodeMatches(*node, AncestorAxis, m_nodeTest)) |
| nodes.append(node); |
| } |
| nodes.markSorted(false); |
| return; |
| } |
| case FollowingSiblingAxis: |
| if (context.isAttributeNode()) |
| return; |
| for (Node* node = context.nextSibling(); node; node = node->nextSibling()) { |
| if (nodeMatches(*node, FollowingSiblingAxis, m_nodeTest)) |
| nodes.append(node); |
| } |
| return; |
| case PrecedingSiblingAxis: |
| if (context.isAttributeNode()) |
| return; |
| for (Node* node = context.previousSibling(); node; node = node->previousSibling()) { |
| if (nodeMatches(*node, PrecedingSiblingAxis, m_nodeTest)) |
| nodes.append(node); |
| } |
| nodes.markSorted(false); |
| return; |
| case FollowingAxis: |
| if (context.isAttributeNode()) { |
| Node* node = static_cast<Attr&>(context).ownerElement(); |
| if (!node) |
| return; |
| while ((node = NodeTraversal::next(*node))) { |
| if (nodeMatches(*node, FollowingAxis, m_nodeTest)) |
| nodes.append(node); |
| } |
| } else { |
| for (Node* parent = &context; !isRootDomNode(parent); parent = parent->parentNode()) { |
| for (Node* node = parent->nextSibling(); node; node = node->nextSibling()) { |
| if (nodeMatches(*node, FollowingAxis, m_nodeTest)) |
| nodes.append(node); |
| for (Node* child = node->firstChild(); child; child = NodeTraversal::next(*child, node)) { |
| if (nodeMatches(*child, FollowingAxis, m_nodeTest)) |
| nodes.append(child); |
| } |
| } |
| } |
| } |
| return; |
| case PrecedingAxis: { |
| Node* node; |
| if (context.isAttributeNode()) { |
| node = static_cast<Attr&>(context).ownerElement(); |
| if (!node) |
| return; |
| } else |
| node = &context; |
| while (ContainerNode* parent = node->parentNode()) { |
| for (node = NodeTraversal::previous(*node); node != parent; node = NodeTraversal::previous(*node)) { |
| if (nodeMatches(*node, PrecedingAxis, m_nodeTest)) |
| nodes.append(node); |
| } |
| node = parent; |
| } |
| nodes.markSorted(false); |
| return; |
| } |
| case AttributeAxis: { |
| if (!is<Element>(context)) |
| return; |
| |
| Element& contextElement = downcast<Element>(context); |
| |
| // Avoid lazily creating attribute nodes for attributes that we do not need anyway. |
| if (m_nodeTest.m_kind == NodeTest::NameTest && m_nodeTest.m_data != starAtom()) { |
| auto attr = contextElement.getAttributeNodeNS(m_nodeTest.m_namespaceURI, m_nodeTest.m_data); |
| if (attr && attr->namespaceURI() != XMLNSNames::xmlnsNamespaceURI) { // In XPath land, namespace nodes are not accessible on the attribute axis. |
| if (nodeMatches(*attr, AttributeAxis, m_nodeTest)) // Still need to check merged predicates. |
| nodes.append(WTFMove(attr)); |
| } |
| return; |
| } |
| |
| if (!contextElement.hasAttributes()) |
| return; |
| |
| for (const Attribute& attribute : contextElement.attributesIterator()) { |
| auto attr = contextElement.ensureAttr(attribute.name()); |
| if (nodeMatches(attr.get(), AttributeAxis, m_nodeTest)) |
| nodes.append(WTFMove(attr)); |
| } |
| 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* node = context.firstChild(); node; node = NodeTraversal::next(*node, &context)) { |
| if (nodeMatches(*node, DescendantOrSelfAxis, m_nodeTest)) |
| nodes.append(node); |
| } |
| return; |
| case AncestorOrSelfAxis: { |
| if (nodeMatches(context, AncestorOrSelfAxis, m_nodeTest)) |
| nodes.append(&context); |
| Node* node = &context; |
| if (context.isAttributeNode()) { |
| node = static_cast<Attr&>(context).ownerElement(); |
| if (!node) |
| return; |
| if (nodeMatches(*node, AncestorOrSelfAxis, m_nodeTest)) |
| nodes.append(node); |
| } |
| for (node = node->parentNode(); node; node = node->parentNode()) { |
| if (nodeMatches(*node, AncestorOrSelfAxis, m_nodeTest)) |
| nodes.append(node); |
| } |
| nodes.markSorted(false); |
| return; |
| } |
| } |
| ASSERT_NOT_REACHED(); |
| } |
| |
| } |
| } |
