| /* |
| * 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 "core/xml/XPathStep.h" |
| |
| #include "core/XMLNSNames.h" |
| #include "core/dom/Attr.h" |
| #include "core/dom/Document.h" |
| #include "core/dom/Element.h" |
| #include "core/dom/NodeTraversal.h" |
| #include "core/xml/XPathParser.h" |
| #include "core/xml/XPathUtil.h" |
| |
| namespace blink { |
| namespace XPath { |
| |
| Step::Step(Axis axis, const NodeTest& nodeTest) |
| : m_axis(axis), m_nodeTest(new NodeTest(nodeTest)) {} |
| |
| Step::Step(Axis axis, |
| const NodeTest& nodeTest, |
| HeapVector<Member<Predicate>>& predicates) |
| : m_axis(axis), m_nodeTest(new NodeTest(nodeTest)) { |
| m_predicates.swap(predicates); |
| } |
| |
| Step::~Step() {} |
| |
| DEFINE_TRACE(Step) { |
| visitor->trace(m_nodeTest); |
| visitor->trace(m_predicates); |
| ParseNode::trace(visitor); |
| } |
| |
| 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]. |
| HeapVector<Member<Predicate>> remainingPredicates; |
| for (size_t i = 0; i < m_predicates.size(); ++i) { |
| Predicate* predicate = m_predicates[i]; |
| if ((!predicate->isContextPositionSensitive() || |
| nodeTest().mergedPredicates().isEmpty()) && |
| !predicate->isContextSizeSensitive() && remainingPredicates.isEmpty()) { |
| nodeTest().mergedPredicates().append(predicate); |
| } else { |
| remainingPredicates.append(predicate); |
| } |
| } |
| swap(remainingPredicates, m_predicates); |
| } |
| |
| bool optimizeStepPair(Step* first, Step* second) { |
| if (first->m_axis == Step::DescendantOrSelfAxis && |
| first->nodeTest().getKind() == Step::NodeTest::AnyNodeTest && |
| !first->m_predicates.size() && |
| !first->nodeTest().mergedPredicates().size()) { |
| DCHECK(first->nodeTest().data().isEmpty()); |
| DCHECK(first->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->nodeTest() = Step::NodeTest(second->nodeTest().getKind(), |
| second->nodeTest().data(), |
| second->nodeTest().namespaceURI()); |
| swap(second->nodeTest().mergedPredicates(), |
| first->nodeTest().mergedPredicates()); |
| swap(second->m_predicates, first->m_predicates); |
| first->optimize(); |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| bool Step::predicatesAreContextListInsensitive() const { |
| for (size_t i = 0; i < m_predicates.size(); ++i) { |
| Predicate* predicate = m_predicates[i].get(); |
| if (predicate->isContextPositionSensitive() || |
| predicate->isContextSizeSensitive()) |
| return false; |
| } |
| |
| for (size_t i = 0; i < nodeTest().mergedPredicates().size(); ++i) { |
| Predicate* predicate = nodeTest().mergedPredicates()[i].get(); |
| if (predicate->isContextPositionSensitive() || |
| predicate->isContextSizeSensitive()) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| void Step::evaluate(EvaluationContext& evaluationContext, |
| Node* context, |
| NodeSet& nodes) const { |
| evaluationContext.position = 0; |
| |
| nodesInAxis(evaluationContext, 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].get(); |
| |
| NodeSet* newNodes = NodeSet::create(); |
| 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(evaluationContext)) |
| newNodes->append(node); |
| } |
| |
| nodes.swap(*newNodes); |
| } |
| } |
| |
| #if DCHECK_IS_ON() |
| static inline Node::NodeType primaryNodeType(Step::Axis axis) { |
| switch (axis) { |
| case Step::AttributeAxis: |
| return Node::kAttributeNode; |
| default: |
| return Node::kElementNode; |
| } |
| } |
| #endif |
| |
| // Evaluate NodeTest without considering merged predicates. |
| static inline bool nodeMatchesBasicTest(Node* node, |
| Step::Axis axis, |
| const Step::NodeTest& nodeTest) { |
| switch (nodeTest.getKind()) { |
| case Step::NodeTest::TextNodeTest: { |
| Node::NodeType type = node->getNodeType(); |
| return type == Node::kTextNode || type == Node::kCdataSectionNode; |
| } |
| case Step::NodeTest::CommentNodeTest: |
| return node->getNodeType() == Node::kCommentNode; |
| case Step::NodeTest::ProcessingInstructionNodeTest: { |
| const AtomicString& name = nodeTest.data(); |
| return node->getNodeType() == Node::kProcessingInstructionNode && |
| (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) { |
| Attr* attr = toAttr(node); |
| |
| // In XPath land, namespace nodes are not accessible on the |
| // attribute axis. |
| if (attr->namespaceURI() == XMLNSNames::xmlnsNamespaceURI) |
| return false; |
| |
| if (name == starAtom) |
| return namespaceURI.isEmpty() || attr->namespaceURI() == namespaceURI; |
| |
| return attr->localName() == name && |
| attr->namespaceURI() == namespaceURI; |
| } |
| |
| // Node test on the namespace axis is not implemented yet, the caller |
| // has a check for it. |
| DCHECK_NE(Step::NamespaceAxis, axis); |
| |
| // For other axes, the principal node type is element. |
| #if DCHECK_IS_ON() |
| DCHECK_EQ(Node::kElementNode, primaryNodeType(axis)); |
| #endif |
| if (!node->isElementNode()) |
| return false; |
| Element& element = toElement(*node); |
| |
| if (name == starAtom) |
| return namespaceURI.isEmpty() || namespaceURI == element.namespaceURI(); |
| |
| if (element.document().isHTMLDocument()) { |
| if (element.isHTMLElement()) { |
| // Paths without namespaces should match HTML elements in HTML |
| // documents despite those having an XHTML namespace. Names are |
| // compared case-insensitively. |
| return equalIgnoringCase(element.localName(), name) && |
| (namespaceURI.isNull() || |
| namespaceURI == element.namespaceURI()); |
| } |
| // An expression without any prefix shouldn't match no-namespace |
| // nodes (because HTML5 says so). |
| return element.hasLocalName(name) && |
| namespaceURI == element.namespaceURI() && !namespaceURI.isNull(); |
| } |
| return element.hasLocalName(name) && |
| namespaceURI == element.namespaceURI(); |
| } |
| } |
| NOTREACHED(); |
| return false; |
| } |
| |
| static inline bool nodeMatches(EvaluationContext& evaluationContext, |
| Node* node, |
| Step::Axis axis, |
| const Step::NodeTest& nodeTest) { |
| if (!nodeMatchesBasicTest(node, axis, nodeTest)) |
| return false; |
| |
| // Only the first merged predicate may depend on position. |
| ++evaluationContext.position; |
| |
| const HeapVector<Member<Predicate>>& mergedPredicates = |
| nodeTest.mergedPredicates(); |
| for (unsigned i = 0; i < mergedPredicates.size(); i++) { |
| Predicate* predicate = mergedPredicates[i].get(); |
| |
| 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(evaluationContext)) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| // Result nodes are ordered in axis order. Node test (including merged |
| // predicates) is applied. |
| void Step::nodesInAxis(EvaluationContext& evaluationContext, |
| Node* context, |
| NodeSet& nodes) const { |
| DCHECK(nodes.isEmpty()); |
| switch (m_axis) { |
| case ChildAxis: |
| // In XPath model, attribute nodes do not have children. |
| if (context->isAttributeNode()) |
| return; |
| |
| for (Node* n = context->firstChild(); n; n = n->nextSibling()) { |
| if (nodeMatches(evaluationContext, n, ChildAxis, nodeTest())) |
| nodes.append(n); |
| } |
| return; |
| |
| case DescendantAxis: |
| // In XPath model, attribute nodes do not have children. |
| if (context->isAttributeNode()) |
| return; |
| |
| for (Node& n : NodeTraversal::descendantsOf(*context)) { |
| if (nodeMatches(evaluationContext, &n, DescendantAxis, nodeTest())) |
| nodes.append(&n); |
| } |
| return; |
| |
| case ParentAxis: |
| if (context->isAttributeNode()) { |
| Element* n = toAttr(context)->ownerElement(); |
| if (nodeMatches(evaluationContext, n, ParentAxis, nodeTest())) |
| nodes.append(n); |
| } else { |
| ContainerNode* n = context->parentNode(); |
| if (n && nodeMatches(evaluationContext, n, ParentAxis, nodeTest())) |
| nodes.append(n); |
| } |
| return; |
| |
| case AncestorAxis: { |
| Node* n = context; |
| if (context->isAttributeNode()) { |
| n = toAttr(context)->ownerElement(); |
| if (nodeMatches(evaluationContext, n, AncestorAxis, nodeTest())) |
| nodes.append(n); |
| } |
| for (n = n->parentNode(); n; n = n->parentNode()) { |
| if (nodeMatches(evaluationContext, n, AncestorAxis, nodeTest())) |
| nodes.append(n); |
| } |
| nodes.markSorted(false); |
| return; |
| } |
| |
| case FollowingSiblingAxis: |
| if (context->getNodeType() == Node::kAttributeNode) |
| return; |
| |
| for (Node* n = context->nextSibling(); n; n = n->nextSibling()) { |
| if (nodeMatches(evaluationContext, n, FollowingSiblingAxis, nodeTest())) |
| nodes.append(n); |
| } |
| return; |
| |
| case PrecedingSiblingAxis: |
| if (context->getNodeType() == Node::kAttributeNode) |
| return; |
| |
| for (Node* n = context->previousSibling(); n; n = n->previousSibling()) { |
| if (nodeMatches(evaluationContext, n, PrecedingSiblingAxis, nodeTest())) |
| nodes.append(n); |
| } |
| nodes.markSorted(false); |
| return; |
| |
| case FollowingAxis: |
| if (context->isAttributeNode()) { |
| for (Node& p : |
| NodeTraversal::startsAfter(*toAttr(context)->ownerElement())) { |
| if (nodeMatches(evaluationContext, &p, FollowingAxis, 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(evaluationContext, n, FollowingAxis, nodeTest())) |
| nodes.append(n); |
| for (Node& c : NodeTraversal::descendantsOf(*n)) { |
| if (nodeMatches(evaluationContext, &c, FollowingAxis, nodeTest())) |
| nodes.append(&c); |
| } |
| } |
| } |
| } |
| return; |
| |
| case PrecedingAxis: { |
| if (context->isAttributeNode()) |
| context = toAttr(context)->ownerElement(); |
| |
| Node* n = context; |
| while (ContainerNode* parent = n->parentNode()) { |
| for (n = NodeTraversal::previous(*n); n != parent; |
| n = NodeTraversal::previous(*n)) { |
| if (nodeMatches(evaluationContext, n, PrecedingAxis, nodeTest())) |
| nodes.append(n); |
| } |
| n = parent; |
| } |
| nodes.markSorted(false); |
| return; |
| } |
| |
| case AttributeAxis: { |
| if (!context->isElementNode()) |
| return; |
| |
| Element* contextElement = toElement(context); |
| // Avoid lazily creating attribute nodes for attributes that we do not |
| // need anyway. |
| if (nodeTest().getKind() == NodeTest::NameTest && |
| nodeTest().data() != starAtom) { |
| Attr* attr = contextElement->getAttributeNodeNS( |
| nodeTest().namespaceURI(), nodeTest().data()); |
| // In XPath land, namespace nodes are not accessible on the attribute |
| // axis. |
| if (attr && attr->namespaceURI() != XMLNSNames::xmlnsNamespaceURI) { |
| // Still need to check merged predicates. |
| if (nodeMatches(evaluationContext, attr, AttributeAxis, nodeTest())) |
| nodes.append(attr); |
| } |
| return; |
| } |
| |
| AttributeCollection attributes = contextElement->attributes(); |
| for (auto& attribute : attributes) { |
| Attr* attr = contextElement->ensureAttr(attribute.name()); |
| if (nodeMatches(evaluationContext, attr, AttributeAxis, nodeTest())) |
| nodes.append(attr); |
| } |
| return; |
| } |
| |
| case NamespaceAxis: |
| // XPath namespace nodes are not implemented. |
| return; |
| |
| case SelfAxis: |
| if (nodeMatches(evaluationContext, context, SelfAxis, nodeTest())) |
| nodes.append(context); |
| return; |
| |
| case DescendantOrSelfAxis: |
| if (nodeMatches(evaluationContext, context, DescendantOrSelfAxis, |
| nodeTest())) |
| nodes.append(context); |
| // In XPath model, attribute nodes do not have children. |
| if (context->isAttributeNode()) |
| return; |
| |
| for (Node& n : NodeTraversal::descendantsOf(*context)) { |
| if (nodeMatches(evaluationContext, &n, DescendantOrSelfAxis, |
| nodeTest())) |
| nodes.append(&n); |
| } |
| return; |
| |
| case AncestorOrSelfAxis: { |
| if (nodeMatches(evaluationContext, context, AncestorOrSelfAxis, |
| nodeTest())) |
| nodes.append(context); |
| Node* n = context; |
| if (context->isAttributeNode()) { |
| n = toAttr(context)->ownerElement(); |
| if (nodeMatches(evaluationContext, n, AncestorOrSelfAxis, nodeTest())) |
| nodes.append(n); |
| } |
| for (n = n->parentNode(); n; n = n->parentNode()) { |
| if (nodeMatches(evaluationContext, n, AncestorOrSelfAxis, nodeTest())) |
| nodes.append(n); |
| } |
| nodes.markSorted(false); |
| return; |
| } |
| } |
| NOTREACHED(); |
| } |
| |
| } // namespace XPath |
| |
| } // namespace blink |
