--- /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 <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 "XMLNSNames.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() == 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<Element*>(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<Element*>(node)->hasLocalName(name) && namespaceURI == node->namespaceURI() && !namespaceURI.isNull();
+ }
+ 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() != 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> 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)