| /* |
| * 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/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" |
| #include "core/xmlns_names.h" |
| |
| namespace blink { |
| namespace XPath { |
| |
| Step::Step(Axis axis, const NodeTest& node_test) |
| : axis_(axis), node_test_(new NodeTest(node_test)) {} |
| |
| Step::Step(Axis axis, |
| const NodeTest& node_test, |
| HeapVector<Member<Predicate>>& predicates) |
| : axis_(axis), node_test_(new NodeTest(node_test)) { |
| predicates_.swap(predicates); |
| } |
| |
| Step::~Step() = default; |
| |
| void Step::Trace(blink::Visitor* visitor) { |
| visitor->Trace(node_test_); |
| visitor->Trace(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>> remaining_predicates; |
| for (const auto& predicate : predicates_) { |
| if ((!predicate->IsContextPositionSensitive() || |
| GetNodeTest().MergedPredicates().IsEmpty()) && |
| !predicate->IsContextSizeSensitive() && |
| remaining_predicates.IsEmpty()) { |
| GetNodeTest().MergedPredicates().push_back(predicate); |
| } else { |
| remaining_predicates.push_back(predicate); |
| } |
| } |
| swap(remaining_predicates, predicates_); |
| } |
| |
| bool OptimizeStepPair(Step* first, Step* second) { |
| if (first->axis_ == Step::kDescendantOrSelfAxis && |
| first->GetNodeTest().GetKind() == Step::NodeTest::kAnyNodeTest && |
| !first->predicates_.size() && |
| !first->GetNodeTest().MergedPredicates().size()) { |
| DCHECK(first->GetNodeTest().Data().IsEmpty()); |
| DCHECK(first->GetNodeTest().NamespaceURI().IsEmpty()); |
| |
| // Optimize the common case of "//" AKA |
| // /descendant-or-self::node()/child::NodeTest to /descendant::NodeTest. |
| if (second->axis_ == Step::kChildAxis && |
| second->PredicatesAreContextListInsensitive()) { |
| first->axis_ = Step::kDescendantAxis; |
| first->GetNodeTest() = Step::NodeTest( |
| second->GetNodeTest().GetKind(), second->GetNodeTest().Data(), |
| second->GetNodeTest().NamespaceURI()); |
| swap(second->GetNodeTest().MergedPredicates(), |
| first->GetNodeTest().MergedPredicates()); |
| swap(second->predicates_, first->predicates_); |
| first->Optimize(); |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| bool Step::PredicatesAreContextListInsensitive() const { |
| for (const auto& predicate : predicates_) { |
| if (predicate->IsContextPositionSensitive() || |
| predicate->IsContextSizeSensitive()) |
| return false; |
| } |
| |
| for (const auto& predicate : GetNodeTest().MergedPredicates()) { |
| if (predicate->IsContextPositionSensitive() || |
| predicate->IsContextSizeSensitive()) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| void Step::Evaluate(EvaluationContext& evaluation_context, |
| Node* context, |
| NodeSet& nodes) const { |
| evaluation_context.position = 0; |
| |
| NodesInAxis(evaluation_context, context, nodes); |
| |
| // Check predicates that couldn't be merged into node test. |
| for (const auto& predicate : predicates_) { |
| NodeSet* new_nodes = NodeSet::Create(); |
| if (!nodes.IsSorted()) |
| new_nodes->MarkSorted(false); |
| |
| for (unsigned j = 0; j < nodes.size(); j++) { |
| Node* node = nodes[j]; |
| |
| evaluation_context.node = node; |
| evaluation_context.size = nodes.size(); |
| evaluation_context.position = j + 1; |
| if (predicate->Evaluate(evaluation_context)) |
| new_nodes->Append(node); |
| } |
| |
| nodes.Swap(*new_nodes); |
| } |
| } |
| |
| #if DCHECK_IS_ON() |
| static inline Node::NodeType PrimaryNodeType(Step::Axis axis) { |
| switch (axis) { |
| case Step::kAttributeAxis: |
| 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& node_test) { |
| switch (node_test.GetKind()) { |
| case Step::NodeTest::kTextNodeTest: { |
| Node::NodeType type = node->getNodeType(); |
| return type == Node::kTextNode || type == Node::kCdataSectionNode; |
| } |
| case Step::NodeTest::kCommentNodeTest: |
| return node->getNodeType() == Node::kCommentNode; |
| case Step::NodeTest::kProcessingInstructionNodeTest: { |
| const AtomicString& name = node_test.Data(); |
| return node->getNodeType() == Node::kProcessingInstructionNode && |
| (name.IsEmpty() || node->nodeName() == name); |
| } |
| case Step::NodeTest::kAnyNodeTest: |
| return true; |
| case Step::NodeTest::kNameTest: { |
| const AtomicString& name = node_test.Data(); |
| const AtomicString& namespace_uri = node_test.NamespaceURI(); |
| |
| if (axis == Step::kAttributeAxis) { |
| 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 == g_star_atom) |
| return namespace_uri.IsEmpty() || |
| attr->namespaceURI() == namespace_uri; |
| |
| return attr->localName() == name && |
| attr->namespaceURI() == namespace_uri; |
| } |
| |
| // Node test on the namespace axis is not implemented yet, the caller |
| // has a check for it. |
| DCHECK_NE(Step::kNamespaceAxis, 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 == g_star_atom) |
| return namespace_uri.IsEmpty() || |
| namespace_uri == element.namespaceURI(); |
| |
| if (element.GetDocument().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 DeprecatedEqualIgnoringCase(element.localName(), name) && |
| (namespace_uri.IsNull() || |
| namespace_uri == element.namespaceURI()); |
| } |
| // An expression without any prefix shouldn't match no-namespace |
| // nodes (because HTML5 says so). |
| return element.HasLocalName(name) && |
| namespace_uri == element.namespaceURI() && |
| !namespace_uri.IsNull(); |
| } |
| return element.HasLocalName(name) && |
| namespace_uri == element.namespaceURI(); |
| } |
| } |
| NOTREACHED(); |
| return false; |
| } |
| |
| static inline bool NodeMatches(EvaluationContext& evaluation_context, |
| Node* node, |
| Step::Axis axis, |
| const Step::NodeTest& node_test) { |
| if (!NodeMatchesBasicTest(node, axis, node_test)) |
| return false; |
| |
| // Only the first merged predicate may depend on position. |
| ++evaluation_context.position; |
| |
| for (const auto& predicate : node_test.MergedPredicates()) { |
| evaluation_context.node = node; |
| // No need to set context size - we only get here when evaluating |
| // predicates that do not depend on it. |
| if (!predicate->Evaluate(evaluation_context)) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| // Result nodes are ordered in axis order. Node test (including merged |
| // predicates) is applied. |
| void Step::NodesInAxis(EvaluationContext& evaluation_context, |
| Node* context, |
| NodeSet& nodes) const { |
| DCHECK(nodes.IsEmpty()); |
| switch (axis_) { |
| case kChildAxis: |
| // In XPath model, attribute nodes do not have children. |
| if (context->IsAttributeNode()) |
| return; |
| |
| for (Node* n = context->firstChild(); n; n = n->nextSibling()) { |
| if (NodeMatches(evaluation_context, n, kChildAxis, GetNodeTest())) |
| nodes.Append(n); |
| } |
| return; |
| |
| case kDescendantAxis: |
| // In XPath model, attribute nodes do not have children. |
| if (context->IsAttributeNode()) |
| return; |
| |
| for (Node& n : NodeTraversal::DescendantsOf(*context)) { |
| if (NodeMatches(evaluation_context, &n, kDescendantAxis, GetNodeTest())) |
| nodes.Append(&n); |
| } |
| return; |
| |
| case kParentAxis: |
| if (context->IsAttributeNode()) { |
| Element* n = ToAttr(context)->ownerElement(); |
| if (NodeMatches(evaluation_context, n, kParentAxis, GetNodeTest())) |
| nodes.Append(n); |
| } else { |
| ContainerNode* n = context->parentNode(); |
| if (n && NodeMatches(evaluation_context, n, kParentAxis, GetNodeTest())) |
| nodes.Append(n); |
| } |
| return; |
| |
| case kAncestorAxis: { |
| Node* n = context; |
| if (context->IsAttributeNode()) { |
| n = ToAttr(context)->ownerElement(); |
| if (NodeMatches(evaluation_context, n, kAncestorAxis, GetNodeTest())) |
| nodes.Append(n); |
| } |
| for (n = n->parentNode(); n; n = n->parentNode()) { |
| if (NodeMatches(evaluation_context, n, kAncestorAxis, GetNodeTest())) |
| nodes.Append(n); |
| } |
| nodes.MarkSorted(false); |
| return; |
| } |
| |
| case kFollowingSiblingAxis: |
| if (context->getNodeType() == Node::kAttributeNode) |
| return; |
| |
| for (Node* n = context->nextSibling(); n; n = n->nextSibling()) { |
| if (NodeMatches(evaluation_context, n, kFollowingSiblingAxis, |
| GetNodeTest())) |
| nodes.Append(n); |
| } |
| return; |
| |
| case kPrecedingSiblingAxis: |
| if (context->getNodeType() == Node::kAttributeNode) |
| return; |
| |
| for (Node* n = context->previousSibling(); n; n = n->previousSibling()) { |
| if (NodeMatches(evaluation_context, n, kPrecedingSiblingAxis, |
| GetNodeTest())) |
| nodes.Append(n); |
| } |
| nodes.MarkSorted(false); |
| return; |
| |
| case kFollowingAxis: |
| if (context->IsAttributeNode()) { |
| for (Node& p : |
| NodeTraversal::StartsAfter(*ToAttr(context)->ownerElement())) { |
| if (NodeMatches(evaluation_context, &p, kFollowingAxis, |
| GetNodeTest())) |
| nodes.Append(&p); |
| } |
| } else { |
| for (Node* p = context; !IsRootDomNode(p); p = p->parentNode()) { |
| for (Node* n = p->nextSibling(); n; n = n->nextSibling()) { |
| if (NodeMatches(evaluation_context, n, kFollowingAxis, |
| GetNodeTest())) |
| nodes.Append(n); |
| for (Node& c : NodeTraversal::DescendantsOf(*n)) { |
| if (NodeMatches(evaluation_context, &c, kFollowingAxis, |
| GetNodeTest())) |
| nodes.Append(&c); |
| } |
| } |
| } |
| } |
| return; |
| |
| case kPrecedingAxis: { |
| 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(evaluation_context, n, kPrecedingAxis, GetNodeTest())) |
| nodes.Append(n); |
| } |
| n = parent; |
| } |
| nodes.MarkSorted(false); |
| return; |
| } |
| |
| case kAttributeAxis: { |
| if (!context->IsElementNode()) |
| return; |
| |
| Element* context_element = ToElement(context); |
| // Avoid lazily creating attribute nodes for attributes that we do not |
| // need anyway. |
| if (GetNodeTest().GetKind() == NodeTest::kNameTest && |
| GetNodeTest().Data() != g_star_atom) { |
| Attr* attr = context_element->getAttributeNodeNS( |
| GetNodeTest().NamespaceURI(), GetNodeTest().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(evaluation_context, attr, kAttributeAxis, |
| GetNodeTest())) |
| nodes.Append(attr); |
| } |
| return; |
| } |
| |
| AttributeCollection attributes = context_element->Attributes(); |
| for (auto& attribute : attributes) { |
| Attr* attr = context_element->EnsureAttr(attribute.GetName()); |
| if (NodeMatches(evaluation_context, attr, kAttributeAxis, |
| GetNodeTest())) |
| nodes.Append(attr); |
| } |
| return; |
| } |
| |
| case kNamespaceAxis: |
| // XPath namespace nodes are not implemented. |
| return; |
| |
| case kSelfAxis: |
| if (NodeMatches(evaluation_context, context, kSelfAxis, GetNodeTest())) |
| nodes.Append(context); |
| return; |
| |
| case kDescendantOrSelfAxis: |
| if (NodeMatches(evaluation_context, context, kDescendantOrSelfAxis, |
| GetNodeTest())) |
| nodes.Append(context); |
| // In XPath model, attribute nodes do not have children. |
| if (context->IsAttributeNode()) |
| return; |
| |
| for (Node& n : NodeTraversal::DescendantsOf(*context)) { |
| if (NodeMatches(evaluation_context, &n, kDescendantOrSelfAxis, |
| GetNodeTest())) |
| nodes.Append(&n); |
| } |
| return; |
| |
| case kAncestorOrSelfAxis: { |
| if (NodeMatches(evaluation_context, context, kAncestorOrSelfAxis, |
| GetNodeTest())) |
| nodes.Append(context); |
| Node* n = context; |
| if (context->IsAttributeNode()) { |
| n = ToAttr(context)->ownerElement(); |
| if (NodeMatches(evaluation_context, n, kAncestorOrSelfAxis, |
| GetNodeTest())) |
| nodes.Append(n); |
| } |
| for (n = n->parentNode(); n; n = n->parentNode()) { |
| if (NodeMatches(evaluation_context, n, kAncestorOrSelfAxis, |
| GetNodeTest())) |
| nodes.Append(n); |
| } |
| nodes.MarkSorted(false); |
| return; |
| } |
| } |
| NOTREACHED(); |
| } |
| |
| } // namespace XPath |
| |
| } // namespace blink |
