/*
* 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()) {
Element* n = static_cast<Attr*>(context)->ownerElement();
if (nodeMatches(n, ParentAxis, m_nodeTest))
nodes.append(n);
} else {
ContainerNode* 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 (ContainerNode* parent = n->parentNode()) {
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)