| /* |
| * Copyright (C) 1999 Lars Knoll (knoll@kde.org) |
| * (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com) |
| * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com) |
| * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved. |
| * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org> |
| * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org> |
| * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/) |
| * Copyright (c) 2011, Code Aurora Forum. All rights reserved. |
| * Copyright (C) Research In Motion Limited 2011. All rights reserved. |
| * Copyright (C) 2012 Google Inc. All rights reserved. |
| * |
| * This library is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Library General Public |
| * License as published by the Free Software Foundation; either |
| * version 2 of the License, or (at your option) any later version. |
| * |
| * This library is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Library General Public License for more details. |
| * |
| * You should have received a copy of the GNU Library General Public License |
| * along with this library; see the file COPYING.LIB. If not, write to |
| * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, |
| * Boston, MA 02110-1301, USA. |
| */ |
| |
| #include "config.h" |
| #include "SelectorFilter.h" |
| |
| #include "CSSSelector.h" |
| #include "ShadowRoot.h" |
| #include "StyledElement.h" |
| |
| namespace WebCore { |
| |
| // Salt to separate otherwise identical string hashes so a class-selector like .article won't match <article> elements. |
| enum { TagNameSalt = 13, IdSalt = 17, ClassSalt = 19, AttributeSalt = 23 }; |
| |
| static bool isExcludedAttribute(const AtomString& name) |
| { |
| return name == HTMLNames::classAttr->localName() || name == HTMLNames::idAttr->localName() || name == HTMLNames::styleAttr->localName(); |
| } |
| |
| static inline void collectElementIdentifierHashes(const Element& element, Vector<unsigned, 4>& identifierHashes) |
| { |
| AtomString tagLowercaseLocalName = element.localName().convertToASCIILowercase(); |
| identifierHashes.append(tagLowercaseLocalName.impl()->existingHash() * TagNameSalt); |
| |
| auto& id = element.idForStyleResolution(); |
| if (!id.isNull()) |
| identifierHashes.append(id.impl()->existingHash() * IdSalt); |
| |
| if (element.hasClass()) { |
| const SpaceSplitString& classNames = element.classNames(); |
| size_t count = classNames.size(); |
| for (size_t i = 0; i < count; ++i) |
| identifierHashes.append(classNames[i].impl()->existingHash() * ClassSalt); |
| } |
| |
| if (element.hasAttributesWithoutUpdate()) { |
| for (auto& attribute : element.attributesIterator()) { |
| auto attributeName = element.isHTMLElement() ? attribute.localName() : attribute.localName().convertToASCIILowercase(); |
| if (isExcludedAttribute(attributeName)) |
| continue; |
| identifierHashes.append(attributeName.impl()->existingHash() * AttributeSalt); |
| } |
| } |
| } |
| |
| bool SelectorFilter::parentStackIsConsistent(const ContainerNode* parentNode) const |
| { |
| if (!parentNode || is<Document>(parentNode) || is<ShadowRoot>(parentNode)) |
| return m_parentStack.isEmpty(); |
| |
| return !m_parentStack.isEmpty() && m_parentStack.last().element == parentNode; |
| } |
| |
| void SelectorFilter::initializeParentStack(Element& parent) |
| { |
| Vector<Element*, 20> ancestors; |
| for (auto* ancestor = &parent; ancestor; ancestor = ancestor->parentElement()) |
| ancestors.append(ancestor); |
| for (unsigned i = ancestors.size(); i--;) |
| pushParent(ancestors[i]); |
| } |
| |
| void SelectorFilter::pushParent(Element* parent) |
| { |
| ASSERT(m_parentStack.isEmpty() || m_parentStack.last().element == parent->parentElement()); |
| ASSERT(!m_parentStack.isEmpty() || !parent->parentElement()); |
| m_parentStack.append(ParentStackFrame(parent)); |
| ParentStackFrame& parentFrame = m_parentStack.last(); |
| // Mix tags, class names and ids into some sort of weird bouillabaisse. |
| // The filter is used for fast rejection of child and descendant selectors. |
| collectElementIdentifierHashes(*parent, parentFrame.identifierHashes); |
| size_t count = parentFrame.identifierHashes.size(); |
| for (size_t i = 0; i < count; ++i) |
| m_ancestorIdentifierFilter.add(parentFrame.identifierHashes[i]); |
| } |
| |
| void SelectorFilter::pushParentInitializingIfNeeded(Element& parent) |
| { |
| if (UNLIKELY(m_parentStack.isEmpty())) { |
| initializeParentStack(parent); |
| return; |
| } |
| pushParent(&parent); |
| } |
| |
| void SelectorFilter::popParent() |
| { |
| ASSERT(!m_parentStack.isEmpty()); |
| const ParentStackFrame& parentFrame = m_parentStack.last(); |
| size_t count = parentFrame.identifierHashes.size(); |
| for (size_t i = 0; i < count; ++i) |
| m_ancestorIdentifierFilter.remove(parentFrame.identifierHashes[i]); |
| m_parentStack.removeLast(); |
| if (m_parentStack.isEmpty()) { |
| ASSERT(m_ancestorIdentifierFilter.likelyEmpty()); |
| m_ancestorIdentifierFilter.clear(); |
| } |
| } |
| |
| void SelectorFilter::popParentsUntil(Element* parent) |
| { |
| while (!m_parentStack.isEmpty()) { |
| if (parent && m_parentStack.last().element == parent) |
| return; |
| popParent(); |
| } |
| } |
| |
| struct CollectedSelectorHashes { |
| using HashVector = Vector<unsigned, 8>; |
| HashVector ids; |
| HashVector classes; |
| HashVector tags; |
| HashVector attributes; |
| }; |
| |
| static inline void collectSimpleSelectorHash(CollectedSelectorHashes& collectedHashes, const CSSSelector& selector) |
| { |
| switch (selector.match()) { |
| case CSSSelector::Id: |
| if (!selector.value().isEmpty()) |
| collectedHashes.ids.append(selector.value().impl()->existingHash() * IdSalt); |
| break; |
| case CSSSelector::Class: |
| if (!selector.value().isEmpty()) |
| collectedHashes.classes.append(selector.value().impl()->existingHash() * ClassSalt); |
| break; |
| case CSSSelector::Tag: { |
| auto& tagLowercaseLocalName = selector.tagLowercaseLocalName(); |
| if (tagLowercaseLocalName != starAtom()) |
| collectedHashes.tags.append(tagLowercaseLocalName.impl()->existingHash() * TagNameSalt); |
| break; |
| } |
| case CSSSelector::Exact: |
| case CSSSelector::Set: |
| case CSSSelector::List: |
| case CSSSelector::Hyphen: |
| case CSSSelector::Contain: |
| case CSSSelector::Begin: |
| case CSSSelector::End: { |
| auto attributeName = selector.attributeCanonicalLocalName().convertToASCIILowercase(); |
| if (!isExcludedAttribute(attributeName)) |
| collectedHashes.attributes.append(attributeName.impl()->existingHash() * AttributeSalt); |
| break; |
| } |
| default: |
| break; |
| } |
| } |
| |
| static CollectedSelectorHashes collectSelectorHashes(const CSSSelector& rightmostSelector) |
| { |
| CollectedSelectorHashes collectedHashes; |
| |
| auto* selector = &rightmostSelector; |
| auto relation = selector->relation(); |
| |
| // Skip the topmost selector. It is handled quickly by the rule hashes. |
| bool skipOverSubselectors = true; |
| for (selector = selector->tagHistory(); selector; selector = selector->tagHistory()) { |
| // Only collect identifiers that match ancestors. |
| switch (relation) { |
| case CSSSelector::Subselector: |
| if (!skipOverSubselectors) |
| collectSimpleSelectorHash(collectedHashes, *selector); |
| break; |
| case CSSSelector::DirectAdjacent: |
| case CSSSelector::IndirectAdjacent: |
| case CSSSelector::ShadowDescendant: |
| skipOverSubselectors = true; |
| break; |
| case CSSSelector::DescendantSpace: |
| case CSSSelector::Child: |
| skipOverSubselectors = false; |
| collectSimpleSelectorHash(collectedHashes, *selector); |
| break; |
| } |
| relation = selector->relation(); |
| } |
| return collectedHashes; |
| } |
| |
| static SelectorFilter::Hashes chooseSelectorHashesForFilter(const CollectedSelectorHashes& collectedSelectorHashes) |
| { |
| SelectorFilter::Hashes resultHashes; |
| unsigned index = 0; |
| |
| auto addIfNew = [&] (unsigned hash) { |
| for (unsigned i = 0; i < index; ++i) { |
| if (resultHashes[i] == hash) |
| return; |
| } |
| resultHashes[index++] = hash; |
| }; |
| |
| auto copyHashes = [&] (auto& hashes) { |
| for (auto& hash : hashes) { |
| addIfNew(hash); |
| if (index == resultHashes.size()) |
| return true; |
| } |
| return false; |
| }; |
| |
| // There is a limited number of slots. Prefer more specific selector types. |
| if (copyHashes(collectedSelectorHashes.ids)) |
| return resultHashes; |
| if (copyHashes(collectedSelectorHashes.attributes)) |
| return resultHashes; |
| if (copyHashes(collectedSelectorHashes.classes)) |
| return resultHashes; |
| if (copyHashes(collectedSelectorHashes.tags)) |
| return resultHashes; |
| |
| // Null-terminate if not full. |
| resultHashes[index] = 0; |
| return resultHashes; |
| } |
| |
| SelectorFilter::Hashes SelectorFilter::collectHashes(const CSSSelector& selector) |
| { |
| auto hashes = collectSelectorHashes(selector); |
| return chooseSelectorHashesForFilter(hashes); |
| } |
| |
| } |
| |