blob: 386c1f466d18c7b99ce678aacc183ff21ab499e2 [file] [log] [blame]
/*
* 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 "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().kind() == Step::NodeTest::AnyNodeTest
&& !first->m_predicates.size()
&& !first->nodeTest().mergedPredicates().size()) {
ASSERT(first->nodeTest().data().isEmpty());
ASSERT(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().kind(), 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 ENABLE(ASSERT)
static inline Node::NodeType primaryNodeType(Step::Axis axis)
{
switch (axis) {
case Step::AttributeAxis:
return Node::ATTRIBUTE_NODE;
default:
return Node::ELEMENT_NODE;
}
}
#endif
// 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: {
Node::NodeType type = node->nodeType();
return type == Node::TEXT_NODE || type == 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->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();
}
}
ASSERT_NOT_REACHED();
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
{
ASSERT(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->nodeType() == Node::ATTRIBUTE_NODE)
return;
for (Node* n = context->nextSibling(); n; n = n->nextSibling()) {
if (nodeMatches(evaluationContext, n, FollowingSiblingAxis, nodeTest()))
nodes.append(n);
}
return;
case PrecedingSiblingAxis:
if (context->nodeType() == Node::ATTRIBUTE_NODE)
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().kind() == NodeTest::NameTest && nodeTest().data() != starAtom) {
RefPtrWillBeRawPtr<Node> n = contextElement->getAttributeNodeNS(nodeTest().namespaceURI(), nodeTest().data());
// In XPath land, namespace nodes are not accessible on the attribute axis.
if (n && n->namespaceURI() != XMLNSNames::xmlnsNamespaceURI) {
// Still need to check merged predicates.
if (nodeMatches(evaluationContext, n.get(), AttributeAxis, nodeTest()))
nodes.append(n.release());
}
return;
}
AttributeCollection attributes = contextElement->attributes();
for (auto& attribute : attributes) {
RefPtrWillBeRawPtr<Attr> attr = contextElement->ensureAttr(attribute.name());
if (nodeMatches(evaluationContext, attr.get(), AttributeAxis, nodeTest()))
nodes.append(attr.release());
}
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;
}
}
ASSERT_NOT_REACHED();
}
}
}