| /* |
| * 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" |
| |
| #if ENABLE(XPATH) |
| |
| #include "Attr.h" |
| #include "Document.h" |
| #include "Element.h" |
| #include "NamedNodeMap.h" |
| #include "XPathParser.h" |
| #include "XPathUtil.h" |
| |
| namespace WebCore { |
| namespace XPath { |
| |
| Step::Step(Axis axis, const NodeTest& nodeTest, const Vector<Predicate*>& 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<Predicate*> 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() == "http://www.w3.org/2000/xmlns/") |
| 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->isHTMLElement() && node->document()->isHTMLDocument()) { |
| // 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<Element*>(node)->localName(), name) && (namespaceURI.isNull() || namespaceURI == node->namespaceURI()); |
| } |
| return static_cast<Element*>(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<Predicate*>& 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<Attr*>(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<Attr*>(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<Attr*>(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<Attr*>(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<Node> n = static_cast<Element*>(context)->getAttributeNodeNS(m_nodeTest.namespaceURI(), m_nodeTest.data()); |
| if (n && n->namespaceURI() != "http://www.w3.org/2000/xmlns/") { // 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> attr = attrs->attributeItem(i)->createAttrIfNeeded(static_cast<Element*>(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<Attr*>(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) |
