Source/WebCore/css/SelectorChecker.cpp

   1 /*
   2  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
   3  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
   4  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
   5  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
   6  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
   7  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
   8  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
   9  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  10  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
  11  *
  12  * This library is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU Library General Public
  14  * License as published by the Free Software Foundation; either
  15  * version 2 of the License, or (at your option) any later version.
  16  *
  17  * This library is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20  * Library General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Library General Public License
  23  * along with this library; see the file COPYING.LIB.  If not, write to
  24  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  25  * Boston, MA 02110-1301, USA.
  26  */
  27
  28 #include "config.h"
  29 #include "SelectorChecker.h"
  30
  31 #include "CSSSelector.h"
  32 #include "CSSSelectorList.h"
  33 #include "Document.h"
  34 #include "FocusController.h"
  35 #include "Frame.h"
  36 #include "FrameSelection.h"
  37 #include "HTMLAnchorElement.h"
  38 #include "HTMLFrameElementBase.h"
  39 #include "HTMLInputElement.h"
  40 #include "HTMLNames.h"
  41 #include "HTMLOptionElement.h"
  42 #include "HTMLProgressElement.h"
  43 #include "HTMLStyleElement.h"
  44 #include "InspectorInstrumentation.h"
  45 #include "NodeRenderStyle.h"
  46 #include "Page.h"
  47 #include "PageGroup.h"
  48 #include "RenderObject.h"
  49 #include "RenderScrollbar.h"
  50 #include "RenderStyle.h"
  51 #include "ScrollableArea.h"
  52 #include "ScrollbarTheme.h"
  53 #include "StyledElement.h"
  54 #include "Text.h"
  55 #include "XLinkNames.h"
  56
  57 #if USE(PLATFORM_STRATEGIES)
  58 #include "PlatformStrategies.h"
  59 #include "VisitedLinkStrategy.h"
  60 #endif
  61
  62 namespace WebCore {
  63
  64 using namespace HTMLNames;
  65
  66 static bool htmlAttributeHasCaseInsensitiveValue(const QualifiedName& attr);
  67
  68 SelectorChecker::SelectorChecker(Document* document, bool strictParsing)
  69     : m_document(document)
  70     , m_strictParsing(strictParsing)
  71     , m_documentIsHTML(document->isHTMLDocument())
  72     , m_mode(ResolvingStyle)
  73     , m_pseudoStyle(NOPSEUDO)
  74     , m_hasUnknownPseudoElements(false)
  75 {
  76 }
  77
  78 // Salt to separate otherwise identical string hashes so a class-selector like .article won't match <article> elements.
  79 enum { TagNameSalt = 13, IdAttributeSalt = 17, ClassAttributeSalt = 19 };
  80
  81 static inline void collectElementIdentifierHashes(const Element* element, Vector<unsigned, 4>& identifierHashes)
  82 {
  83     identifierHashes.append(element->localName().impl()->existingHash() * TagNameSalt);
  84     if (element->hasID())
  85         identifierHashes.append(element->idForStyleResolution().impl()->existingHash() * IdAttributeSalt);
  86     const StyledElement* styledElement = element->isStyledElement() ? static_cast<const StyledElement*>(element) : 0;
  87     if (styledElement && styledElement->hasClass()) {
  88         const SpaceSplitString& classNames = styledElement->classNames();
  89         size_t count = classNames.size();
  90         for (size_t i = 0; i < count; ++i)
  91             identifierHashes.append(classNames[i].impl()->existingHash() * ClassAttributeSalt);
  92     }
  93 }
  94
  95 void SelectorChecker::pushParentStackFrame(Element* parent)
  96 {
  97     ASSERT(m_ancestorIdentifierFilter);
  98     ASSERT(m_parentStack.isEmpty() || m_parentStack.last().element == parent->parentOrHostElement());
  99     ASSERT(!m_parentStack.isEmpty() || !parent->parentOrHostElement());
 100     m_parentStack.append(ParentStackFrame(parent));
 101     ParentStackFrame& parentFrame = m_parentStack.last();
 102     // Mix tags, class names and ids into some sort of weird bouillabaisse.
 103     // The filter is used for fast rejection of child and descendant selectors.
 104     collectElementIdentifierHashes(parent, parentFrame.identifierHashes);
 105     size_t count = parentFrame.identifierHashes.size();
 106     for (size_t i = 0; i < count; ++i)
 107         m_ancestorIdentifierFilter->add(parentFrame.identifierHashes[i]);
 108 }
 109
 110 void SelectorChecker::popParentStackFrame()
 111 {
 112     ASSERT(!m_parentStack.isEmpty());
 113     ASSERT(m_ancestorIdentifierFilter);
 114     const ParentStackFrame& parentFrame = m_parentStack.last();
 115     size_t count = parentFrame.identifierHashes.size();
 116     for (size_t i = 0; i < count; ++i)
 117         m_ancestorIdentifierFilter->remove(parentFrame.identifierHashes[i]);
 118     m_parentStack.removeLast();
 119     if (m_parentStack.isEmpty()) {
 120         ASSERT(m_ancestorIdentifierFilter->likelyEmpty());
 121         m_ancestorIdentifierFilter.clear();
 122     }
 123 }
 124
 125 void SelectorChecker::setupParentStack(Element* parent)
 126 {
 127     ASSERT(m_parentStack.isEmpty() == !m_ancestorIdentifierFilter);
 128     // Kill whatever we stored before.
 129     m_parentStack.shrink(0);
 130     m_ancestorIdentifierFilter = adoptPtr(new BloomFilter<bloomFilterKeyBits>);
 131     // Fast version if parent is a root element:
 132     if (!parent->parentOrHostNode()) {
 133         pushParentStackFrame(parent);
 134         return;
 135     }
 136     // Otherwise climb up the tree.
 137     Vector<Element*, 30> ancestors;
 138     for (Element* ancestor = parent; ancestor; ancestor = ancestor->parentOrHostElement())
 139         ancestors.append(ancestor);
 140     for (size_t n = ancestors.size(); n; --n)
 141         pushParentStackFrame(ancestors[n - 1]);
 142 }
 143
 144 void SelectorChecker::pushParent(Element* parent)
 145 {
 146     ASSERT(m_ancestorIdentifierFilter);
 147     // We may get invoked for some random elements in some wacky cases during style resolve.
 148     // Pause maintaining the stack in this case.
 149     if (m_parentStack.last().element != parent->parentOrHostElement())
 150         return;
 151     pushParentStackFrame(parent);
 152 }
 153
 154 static inline void collectDescendantSelectorIdentifierHashes(const CSSSelector* selector, unsigned*& hash, const unsigned* end)
 155 {
 156     switch (selector->m_match) {
 157     case CSSSelector::Id:
 158         if (!selector->value().isEmpty())
 159             (*hash++) = selector->value().impl()->existingHash() * IdAttributeSalt;
 160         break;
 161     case CSSSelector::Class:
 162         if (!selector->value().isEmpty())
 163             (*hash++) = selector->value().impl()->existingHash() * ClassAttributeSalt;
 164         break;
 165     default:
 166         break;
 167     }
 168     if (hash == end)
 169         return;
 170     const AtomicString& localName = selector->tag().localName();
 171     if (localName != starAtom)
 172         (*hash++) = localName.impl()->existingHash() * TagNameSalt;
 173 }
 174
 175 void SelectorChecker::collectIdentifierHashes(const CSSSelector* selector, unsigned* identifierHashes, unsigned maximumIdentifierCount)
 176 {
 177     unsigned* hash = identifierHashes;
 178     unsigned* end = identifierHashes + maximumIdentifierCount;
 179     CSSSelector::Relation relation = selector->relation();
 180
 181     // Skip the topmost selector. It is handled quickly by the rule hashes.
 182     bool skipOverSubselectors = true;
 183     for (selector = selector->tagHistory(); selector; selector = selector->tagHistory()) {
 184         // Only collect identifiers that match ancestors.
 185         switch (relation) {
 186         case CSSSelector::SubSelector:
 187             if (!skipOverSubselectors)
 188                 collectDescendantSelectorIdentifierHashes(selector, hash, end);
 189             break;
 190         case CSSSelector::DirectAdjacent:
 191         case CSSSelector::IndirectAdjacent:
 192         case CSSSelector::ShadowDescendant:
 193             skipOverSubselectors = true;
 194             break;
 195         case CSSSelector::Descendant:
 196         case CSSSelector::Child:
 197             skipOverSubselectors = false;
 198             collectDescendantSelectorIdentifierHashes(selector, hash, end);
 199             break;
 200         }
 201         if (hash == end)
 202             return;
 203         relation = selector->relation();
 204     }
 205     *hash = 0;
 206 }
 207
 208 static inline const AtomicString* linkAttribute(Node* node)
 209 {
 210     if (!node->isLink())
 211         return 0;
 212
 213     ASSERT(node->isElementNode());
 214     Element* element = static_cast<Element*>(node);
 215     if (element->isHTMLElement())
 216         return &element->fastGetAttribute(hrefAttr);
 217     if (element->isSVGElement())
 218         return &element->getAttribute(XLinkNames::hrefAttr);
 219
 220     return 0;
 221 }
 222
 223 EInsideLink SelectorChecker::determineLinkStateSlowCase(Element* element) const
 224 {
 225     ASSERT(element->isLink());
 226
 227     const AtomicString* attribute = linkAttribute(element);
 228     if (!attribute || attribute->isNull())
 229         return NotInsideLink;
 230
 231     // An empty href refers to the document itself which is always visited. It is useful to check this explicitly so
 232     // that visited links can be tested in platform independent manner, without explicit support in the test harness.
 233     if (attribute->isEmpty())
 234         return InsideVisitedLink;
 235
 236     LinkHash hash;
 237     if (element->hasTagName(aTag))
 238         hash = static_cast<HTMLAnchorElement*>(element)->visitedLinkHash();
 239     else
 240         hash = visitedLinkHash(m_document->baseURL(), *attribute);
 241
 242     if (!hash)
 243         return InsideUnvisitedLink;
 244
 245     Frame* frame = m_document->frame();
 246     if (!frame)
 247         return InsideUnvisitedLink;
 248
 249     Page* page = frame->page();
 250     if (!page)
 251         return InsideUnvisitedLink;
 252
 253     m_linksCheckedForVisitedState.add(hash);
 254
 255 #if USE(PLATFORM_STRATEGIES)
 256     return platformStrategies()->visitedLinkStrategy()->isLinkVisited(page, hash, m_document->baseURL(), *attribute) ? InsideVisitedLink : InsideUnvisitedLink;
 257 #else
 258     return page->group().isLinkVisited(hash) ? InsideVisitedLink : InsideUnvisitedLink;
 259 #endif
 260 }
 261
 262 bool SelectorChecker::checkSelector(CSSSelector* sel, Element* element, bool isFastCheckableSelector) const
 263 {
 264     if (isFastCheckableSelector && !element->isSVGElement()) {
 265         if (!fastCheckRightmostSelector(sel, element, VisitedMatchDisabled))
 266             return false;
 267         return fastCheckSelector(sel, element);
 268     }
 269
 270     PseudoId dynamicPseudo = NOPSEUDO;
 271     return checkSelector(SelectorCheckingContext(sel, element, SelectorChecker::VisitedMatchDisabled), dynamicPseudo) == SelectorMatches;
 272 }
 273
 274 namespace {
 275
 276 template <bool checkValue(const Element*, AtomicStringImpl*, const QualifiedName&), bool initAttributeName>
 277 inline bool fastCheckSingleSelector(const CSSSelector*& selector, const Element*& element, const CSSSelector*& topChildOrSubselector, const Element*& topChildOrSubselectorMatchElement)
 278 {
 279     AtomicStringImpl* value = selector->value().impl();
 280     const QualifiedName& attribute = initAttributeName ? selector->attribute() : anyQName();
 281     for (; element; element = element->parentElement()) {
 282         if (checkValue(element, value, attribute) && SelectorChecker::tagMatches(element, selector)) {
 283             if (selector->relation() == CSSSelector::Descendant)
 284                 topChildOrSubselector = 0;
 285             else if (!topChildOrSubselector) {
 286                 ASSERT(selector->relation() == CSSSelector::Child || selector->relation() == CSSSelector::SubSelector);
 287                 topChildOrSubselector = selector;
 288                 topChildOrSubselectorMatchElement = element;
 289             }
 290             if (selector->relation() != CSSSelector::SubSelector)
 291                 element = element->parentElement();
 292             selector = selector->tagHistory();
 293             return true;
 294         }
 295         if (topChildOrSubselector) {
 296             // Child or subselector check failed.
 297             // If the match element is null, topChildOrSubselector was also the very topmost selector and had to match
 298             // the original element we were checking.
 299             if (!topChildOrSubselectorMatchElement)
 300                 return false;
 301             // There may be other matches down the ancestor chain.
 302             // Rewind to the topmost child or subselector and the element it matched, continue checking ancestors.
 303             selector = topChildOrSubselector;
 304             element = topChildOrSubselectorMatchElement->parentElement();
 305             topChildOrSubselector = 0;
 306             return true;
 307         }
 308     }
 309     return false;
 310 }
 311
 312 inline bool checkClassValue(const Element* element, AtomicStringImpl* value, const QualifiedName&)
 313 {
 314     return element->hasClass() && static_cast<const StyledElement*>(element)->classNames().contains(value);
 315 }
 316
 317 inline bool checkIDValue(const Element* element, AtomicStringImpl* value, const QualifiedName&)
 318 {
 319     return element->hasID() && element->idForStyleResolution().impl() == value;
 320 }
 321
 322 inline bool checkExactAttributeValue(const Element* element, AtomicStringImpl* value, const QualifiedName& attributeName)
 323 {
 324     return SelectorChecker::checkExactAttribute(element, attributeName, value);
 325 }
 326
 327 inline bool checkTagValue(const Element*, AtomicStringImpl*, const QualifiedName&)
 328 {
 329     return true;
 330 }
 331
 332 }
 333
 334 inline bool SelectorChecker::fastCheckRightmostSelector(const CSSSelector* selector, const Element* element, VisitedMatchType visitedMatchType) const
 335 {
 336     ASSERT(isFastCheckableSelector(selector));
 337
 338     if (!SelectorChecker::tagMatches(element, selector))
 339         return false;
 340     switch (selector->m_match) {
 341     case CSSSelector::None:
 342         return true;
 343     case CSSSelector::Class:
 344         return checkClassValue(element, selector->value().impl(), anyQName());
 345     case CSSSelector::Id:
 346         return checkIDValue(element, selector->value().impl(), anyQName());
 347     case CSSSelector::Exact:
 348     case CSSSelector::Set:
 349         return checkExactAttributeValue(element, selector->value().impl(), selector->attribute());
 350     case CSSSelector::PseudoClass:
 351         return commonPseudoClassSelectorMatches(element, selector, visitedMatchType);
 352     default:
 353         ASSERT_NOT_REACHED();
 354     }
 355     return false;
 356 }
 357
 358 bool SelectorChecker::fastCheckSelector(const CSSSelector* selector, const Element* element) const
 359 {
 360     ASSERT(fastCheckRightmostSelector(selector, element, VisitedMatchEnabled));
 361
 362     const CSSSelector* topChildOrSubselector = 0;
 363     const Element* topChildOrSubselectorMatchElement = 0;
 364     if (selector->relation() == CSSSelector::Child || selector->relation() == CSSSelector::SubSelector)
 365         topChildOrSubselector = selector;
 366
 367     if (selector->relation() != CSSSelector::SubSelector)
 368         element = element->parentElement();
 369
 370     selector = selector->tagHistory();
 371
 372     // We know this compound selector has descendant, child and subselector combinators only and all components are simple.
 373     while (selector) {
 374         switch (selector->m_match) {
 375         case CSSSelector::Class:
 376             if (!fastCheckSingleSelector<checkClassValue, false>(selector, element, topChildOrSubselector, topChildOrSubselectorMatchElement))
 377                 return false;
 378             break;
 379         case CSSSelector::Id:
 380             if (!fastCheckSingleSelector<checkIDValue, false>(selector, element, topChildOrSubselector, topChildOrSubselectorMatchElement))
 381                 return false;
 382             break;
 383         case CSSSelector::None:
 384             if (!fastCheckSingleSelector<checkTagValue, false>(selector, element, topChildOrSubselector, topChildOrSubselectorMatchElement))
 385                 return false;
 386             break;
 387         case CSSSelector::Set:
 388         case CSSSelector::Exact:
 389             if (!fastCheckSingleSelector<checkExactAttributeValue, true>(selector, element, topChildOrSubselector, topChildOrSubselectorMatchElement))
 390                 return false;
 391             break;
 392         default:
 393             ASSERT_NOT_REACHED();
 394         }
 395     }
 396     return true;
 397 }
 398
 399 static inline bool isFastCheckableRelation(CSSSelector::Relation relation)
 400 {
 401     return relation == CSSSelector::Descendant || relation == CSSSelector::Child || relation == CSSSelector::SubSelector;
 402 }
 403
 404 static inline bool isFastCheckableMatch(const CSSSelector* selector)
 405 {
 406     if (selector->m_match == CSSSelector::Set) {
 407         // Style attribute is generated lazily but the fast path doesn't trigger it.
 408         // Disallow them here rather than making the fast path more branchy.
 409         return selector->attribute() != styleAttr;
 410     }
 411     if (selector->m_match == CSSSelector::Exact)
 412         return selector->attribute() != styleAttr && !htmlAttributeHasCaseInsensitiveValue(selector->attribute());
 413     return selector->m_match == CSSSelector::None || selector->m_match == CSSSelector::Id || selector->m_match == CSSSelector::Class;
 414 }
 415
 416 static inline bool isFastCheckableRightmostSelector(const CSSSelector* selector)
 417 {
 418     if (!isFastCheckableRelation(selector->relation()))
 419         return false;
 420     return isFastCheckableMatch(selector) || SelectorChecker::isCommonPseudoClassSelector(selector);
 421 }
 422
 423 bool SelectorChecker::isFastCheckableSelector(const CSSSelector* selector)
 424 {
 425     if (!isFastCheckableRightmostSelector(selector))
 426         return false;
 427     for (selector = selector->tagHistory(); selector; selector = selector->tagHistory()) {
 428         if (!isFastCheckableRelation(selector->relation()))
 429             return false;
 430         if (!isFastCheckableMatch(selector))
 431             return false;
 432     }
 433     return true;
 434 }
 435
 436 // Recursive check of selectors and combinators
 437 // It can return 4 different values:
 438 // * SelectorMatches          - the selector matches the element e
 439 // * SelectorFailsLocally     - the selector fails for the element e
 440 // * SelectorFailsAllSiblings - the selector fails for e and any sibling of e
 441 // * SelectorFailsCompletely  - the selector fails for e and any sibling or ancestor of e
 442 SelectorChecker::SelectorMatch SelectorChecker::checkSelector(const SelectorCheckingContext& context, PseudoId& dynamicPseudo) const
 443 {
 444     // first selector has to match
 445     if (!checkOneSelector(context, dynamicPseudo))
 446         return SelectorFailsLocally;
 447
 448     // The rest of the selectors has to match
 449     CSSSelector::Relation relation = context.selector->relation();
 450
 451     // Prepare next selector
 452     CSSSelector* historySelector = context.selector->tagHistory();
 453     if (!historySelector)
 454         return SelectorMatches;
 455
 456     SelectorCheckingContext nextContext(context);
 457     nextContext.selector = historySelector;
 458
 459     if (relation != CSSSelector::SubSelector) {
 460         // Abort if the next selector would exceed the scope.
 461         if (context.element == context.scope)
 462             return SelectorFailsCompletely;
 463
 464         // Bail-out if this selector is irrelevant for the pseudoStyle
 465         if (m_pseudoStyle != NOPSEUDO && m_pseudoStyle != dynamicPseudo)
 466             return SelectorFailsCompletely;
 467
 468         // Disable :visited matching when we see the first link or try to match anything else than an ancestors.
 469         if (!context.isSubSelector && (context.element->isLink() || (relation != CSSSelector::Descendant && relation != CSSSelector::Child)))
 470             nextContext.visitedMatchType = VisitedMatchDisabled;
 471     }
 472
 473     switch (relation) {
 474     case CSSSelector::Descendant:
 475         nextContext.element = context.element->parentElement();
 476         nextContext.isSubSelector = false;
 477         nextContext.elementStyle = 0;
 478         nextContext.elementParentStyle = 0;
 479         for (; nextContext.element; nextContext.element = nextContext.element->parentElement()) {
 480             SelectorMatch match = checkSelector(nextContext, dynamicPseudo);
 481             if (match == SelectorMatches || match == SelectorFailsCompletely)
 482                 return match;
 483             if (nextContext.element == nextContext.scope)
 484                 return SelectorFailsCompletely;
 485         }
 486         return SelectorFailsCompletely;
 487
 488     case CSSSelector::Child:
 489         nextContext.element = context.element->parentElement();
 490         if (!nextContext.element)
 491             return SelectorFailsCompletely;
 492         nextContext.isSubSelector = false;
 493         nextContext.elementStyle = 0;
 494         nextContext.elementParentStyle = 0;
 495         return checkSelector(nextContext, dynamicPseudo);
 496
 497     case CSSSelector::DirectAdjacent:
 498         if (m_mode == ResolvingStyle && context.element->parentElement()) {
 499             RenderStyle* parentStyle = context.elementStyle ? context.elementParentStyle : context.element->parentNode()->renderStyle();
 500             if (parentStyle)
 501                 parentStyle->setChildrenAffectedByDirectAdjacentRules();
 502         }
 503         nextContext.element = context.element->previousElementSibling();
 504         if (!nextContext.element)
 505             return SelectorFailsAllSiblings;
 506         nextContext.isSubSelector = false;
 507         nextContext.elementStyle = 0;
 508         nextContext.elementParentStyle = 0;
 509         return checkSelector(nextContext, dynamicPseudo);
 510
 511     case CSSSelector::IndirectAdjacent:
 512         if (m_mode == ResolvingStyle && context.element->parentElement()) {
 513             RenderStyle* parentStyle = context.elementStyle ? context.elementParentStyle : context.element->parentNode()->renderStyle();
 514             if (parentStyle)
 515                 parentStyle->setChildrenAffectedByForwardPositionalRules();
 516         }
 517         nextContext.element = context.element->previousElementSibling();
 518         nextContext.isSubSelector = false;
 519         nextContext.elementStyle = 0;
 520         nextContext.elementParentStyle = 0;
 521         for (; nextContext.element; nextContext.element = nextContext.element->previousElementSibling()) {
 522             SelectorMatch match = checkSelector(nextContext, dynamicPseudo);
 523             if (match == SelectorMatches || match == SelectorFailsAllSiblings || match == SelectorFailsCompletely)
 524                 return match;
 525         };
 526         return SelectorFailsAllSiblings;
 527
 528     case CSSSelector::SubSelector:
 529         // a selector is invalid if something follows a pseudo-element
 530         // We make an exception for scrollbar pseudo elements and allow a set of pseudo classes (but nothing else)
 531         // to follow the pseudo elements.
 532         if ((context.elementStyle || m_mode == CollectingRules || m_mode == QueryingRules) && dynamicPseudo != NOPSEUDO && dynamicPseudo != SELECTION
 533              && !((RenderScrollbar::scrollbarForStyleResolve() || dynamicPseudo == SCROLLBAR_CORNER || dynamicPseudo == RESIZER) && nextContext.selector->m_match == CSSSelector::PseudoClass))
 534             return SelectorFailsCompletely;
 535         nextContext.isSubSelector = true;
 536         return checkSelector(nextContext, dynamicPseudo);
 537
 538     case CSSSelector::ShadowDescendant:
 539         {
 540             // If we're in the same tree-scope as the scoping element, then following a shadow descendant combinator would escape that and thus the scope.
 541             if (context.scope && context.scope->treeScope() == context.element->treeScope())
 542                 return SelectorFailsCompletely;
 543             Element* shadowHostNode = context.element->shadowHost();
 544             if (!shadowHostNode)
 545                 return SelectorFailsCompletely;
 546             nextContext.element = shadowHostNode;
 547             nextContext.isSubSelector = false;
 548             nextContext.elementStyle = 0;
 549             nextContext.elementParentStyle = 0;
 550             return checkSelector(nextContext, dynamicPseudo);
 551         }
 552     }
 553
 554     ASSERT_NOT_REACHED();
 555     return SelectorFailsCompletely;
 556 }
 557
 558 static void addLocalNameToSet(HashSet<AtomicStringImpl*>* set, const QualifiedName& qName)
 559 {
 560     set->add(qName.localName().impl());
 561 }
 562
 563 static HashSet<AtomicStringImpl*>* createHtmlCaseInsensitiveAttributesSet()
 564 {
 565     // This is the list of attributes in HTML 4.01 with values marked as "[CI]" or case-insensitive
 566     // Mozilla treats all other values as case-sensitive, thus so do we.
 567     HashSet<AtomicStringImpl*>* attrSet = new HashSet<AtomicStringImpl*>;
 568
 569     addLocalNameToSet(attrSet, accept_charsetAttr);
 570     addLocalNameToSet(attrSet, acceptAttr);
 571     addLocalNameToSet(attrSet, alignAttr);
 572     addLocalNameToSet(attrSet, alinkAttr);
 573     addLocalNameToSet(attrSet, axisAttr);
 574     addLocalNameToSet(attrSet, bgcolorAttr);
 575     addLocalNameToSet(attrSet, charsetAttr);
 576     addLocalNameToSet(attrSet, checkedAttr);
 577     addLocalNameToSet(attrSet, clearAttr);
 578     addLocalNameToSet(attrSet, codetypeAttr);
 579     addLocalNameToSet(attrSet, colorAttr);
 580     addLocalNameToSet(attrSet, compactAttr);
 581     addLocalNameToSet(attrSet, declareAttr);
 582     addLocalNameToSet(attrSet, deferAttr);
 583     addLocalNameToSet(attrSet, dirAttr);
 584     addLocalNameToSet(attrSet, disabledAttr);
 585     addLocalNameToSet(attrSet, enctypeAttr);
 586     addLocalNameToSet(attrSet, faceAttr);
 587     addLocalNameToSet(attrSet, frameAttr);
 588     addLocalNameToSet(attrSet, hreflangAttr);
 589     addLocalNameToSet(attrSet, http_equivAttr);
 590     addLocalNameToSet(attrSet, langAttr);
 591     addLocalNameToSet(attrSet, languageAttr);
 592     addLocalNameToSet(attrSet, linkAttr);
 593     addLocalNameToSet(attrSet, mediaAttr);
 594     addLocalNameToSet(attrSet, methodAttr);
 595     addLocalNameToSet(attrSet, multipleAttr);
 596     addLocalNameToSet(attrSet, nohrefAttr);
 597     addLocalNameToSet(attrSet, noresizeAttr);
 598     addLocalNameToSet(attrSet, noshadeAttr);
 599     addLocalNameToSet(attrSet, nowrapAttr);
 600     addLocalNameToSet(attrSet, readonlyAttr);
 601     addLocalNameToSet(attrSet, relAttr);
 602     addLocalNameToSet(attrSet, revAttr);
 603     addLocalNameToSet(attrSet, rulesAttr);
 604     addLocalNameToSet(attrSet, scopeAttr);
 605     addLocalNameToSet(attrSet, scrollingAttr);
 606     addLocalNameToSet(attrSet, selectedAttr);
 607     addLocalNameToSet(attrSet, shapeAttr);
 608     addLocalNameToSet(attrSet, targetAttr);
 609     addLocalNameToSet(attrSet, textAttr);
 610     addLocalNameToSet(attrSet, typeAttr);
 611     addLocalNameToSet(attrSet, valignAttr);
 612     addLocalNameToSet(attrSet, valuetypeAttr);
 613     addLocalNameToSet(attrSet, vlinkAttr);
 614
 615     return attrSet;
 616 }
 617
 618 bool htmlAttributeHasCaseInsensitiveValue(const QualifiedName& attr)
 619 {
 620     static HashSet<AtomicStringImpl*>* htmlCaseInsensitiveAttributesSet = createHtmlCaseInsensitiveAttributesSet();
 621     bool isPossibleHTMLAttr = !attr.hasPrefix() && (attr.namespaceURI() == nullAtom);
 622     return isPossibleHTMLAttr && htmlCaseInsensitiveAttributesSet->contains(attr.localName().impl());
 623 }
 624
 625 static bool attributeValueMatches(const Attribute* attributeItem, CSSSelector::Match match, const AtomicString& selectorValue, bool caseSensitive)
 626 {
 627     const AtomicString& value = attributeItem->value();
 628     if (value.isNull())
 629         return false;
 630
 631     switch (match) {
 632     case CSSSelector::Exact:
 633         if (caseSensitive ? selectorValue != value : !equalIgnoringCase(selectorValue, value))
 634             return false;
 635         break;
 636     case CSSSelector::List:
 637         {
 638             // Ignore empty selectors or selectors containing spaces
 639             if (selectorValue.contains(' ') || selectorValue.isEmpty())
 640                 return false;
 641
 642             unsigned startSearchAt = 0;
 643             while (true) {
 644                 size_t foundPos = value.find(selectorValue, startSearchAt, caseSensitive);
 645                 if (foundPos == notFound)
 646                     return false;
 647                 if (!foundPos || value[foundPos - 1] == ' ') {
 648                     unsigned endStr = foundPos + selectorValue.length();
 649                     if (endStr == value.length() || value[endStr] == ' ')
 650                         break; // We found a match.
 651                 }
 652
 653                 // No match. Keep looking.
 654                 startSearchAt = foundPos + 1;
 655             }
 656             break;
 657         }
 658     case CSSSelector::Contain:
 659         if (!value.contains(selectorValue, caseSensitive) || selectorValue.isEmpty())
 660             return false;
 661         break;
 662     case CSSSelector::Begin:
 663         if (!value.startsWith(selectorValue, caseSensitive) || selectorValue.isEmpty())
 664             return false;
 665         break;
 666     case CSSSelector::End:
 667         if (!value.endsWith(selectorValue, caseSensitive) || selectorValue.isEmpty())
 668             return false;
 669         break;
 670     case CSSSelector::Hyphen:
 671         if (value.length() < selectorValue.length())
 672             return false;
 673         if (!value.startsWith(selectorValue, caseSensitive))
 674             return false;
 675         // It they start the same, check for exact match or following '-':
 676         if (value.length() != selectorValue.length() && value[selectorValue.length()] != '-')
 677             return false;
 678         break;
 679     case CSSSelector::PseudoClass:
 680     case CSSSelector::PseudoElement:
 681     default:
 682         break;
 683     }
 684
 685     return true;
 686 }
 687
 688 static bool anyAttributeMatches(Element* element, CSSSelector::Match match, const QualifiedName& selectorAttr, const AtomicString& selectorValue, bool caseSensitive)
 689 {
 690     ASSERT(element->hasAttributesWithoutUpdate());
 691     for (size_t i = 0; i < element->attributeCount(); ++i) {
 692         const Attribute* attributeItem = element->attributeItem(i);
 693
 694         if (!SelectorChecker::attributeNameMatches(attributeItem, selectorAttr))
 695             continue;
 696
 697         if (attributeValueMatches(attributeItem, match, selectorValue, caseSensitive))
 698             return true;
 699     }
 700
 701     return false;
 702 }
 703
 704 bool SelectorChecker::checkOneSelector(const SelectorCheckingContext& context, PseudoId& dynamicPseudo) const
 705 {
 706     Element* const & element = context.element;
 707     CSSSelector* const & selector = context.selector;
 708     ASSERT(element);
 709     ASSERT(selector);
 710
 711     if (!SelectorChecker::tagMatches(element, selector))
 712         return false;
 713
 714     if (selector->m_match == CSSSelector::Class)
 715         return element->hasClass() && static_cast<StyledElement*>(element)->classNames().contains(selector->value());
 716
 717     if (selector->m_match == CSSSelector::Id)
 718         return element->hasID() && element->idForStyleResolution() == selector->value();
 719
 720     if (selector->isAttributeSelector()) {
 721         const QualifiedName& attr = selector->attribute();
 722
 723         if (!element->hasAttributes())
 724             return false;
 725
 726         bool caseSensitive = !m_documentIsHTML || !htmlAttributeHasCaseInsensitiveValue(attr);
 727
 728         if (!anyAttributeMatches(element, static_cast<CSSSelector::Match>(selector->m_match), attr, selector->value(), caseSensitive))
 729             return false;
 730     }
 731
 732     if (selector->m_match == CSSSelector::PseudoClass) {
 733         // Handle :not up front.
 734         if (selector->pseudoType() == CSSSelector::PseudoNot) {
 735             CSSSelectorList* selectorList = selector->selectorList();
 736
 737             // FIXME: We probably should fix the parser and make it never produce :not rules with missing selector list.
 738             if (!selectorList)
 739                 return false;
 740
 741             SelectorCheckingContext subContext(context);
 742             subContext.isSubSelector = true;
 743             for (subContext.selector = selectorList->first(); subContext.selector; subContext.selector = subContext.selector->tagHistory()) {
 744                 // :not cannot nest. I don't really know why this is a
 745                 // restriction in CSS3, but it is, so let's honor it.
 746                 // the parser enforces that this never occurs
 747                 ASSERT(subContext.selector->pseudoType() != CSSSelector::PseudoNot);
 748                 // We select between :visited and :link when applying. We don't know which one applied (or not) yet.
 749                 if (subContext.selector->pseudoType() == CSSSelector::PseudoVisited || (subContext.selector->pseudoType() == CSSSelector::PseudoLink && subContext.visitedMatchType == VisitedMatchEnabled))
 750                     return true;
 751                 if (!checkOneSelector(subContext, dynamicPseudo))
 752                     return true;
 753             }
 754         } else if (dynamicPseudo != NOPSEUDO && (RenderScrollbar::scrollbarForStyleResolve() || dynamicPseudo == SCROLLBAR_CORNER || dynamicPseudo == RESIZER)) {
 755             // CSS scrollbars match a specific subset of pseudo classes, and they have specialized rules for each
 756             // (since there are no elements involved).
 757             return checkScrollbarPseudoClass(selector, dynamicPseudo);
 758         } else if (dynamicPseudo == SELECTION) {
 759             if (selector->pseudoType() == CSSSelector::PseudoWindowInactive)
 760                 return !m_document->page()->focusController()->isActive();
 761         }
 762
 763         // Normal element pseudo class checking.
 764         switch (selector->pseudoType()) {
 765             // Pseudo classes:
 766         case CSSSelector::PseudoNot:
 767             break; // Already handled up above.
 768         case CSSSelector::PseudoEmpty:
 769             {
 770                 bool result = true;
 771                 for (Node* n = element->firstChild(); n; n = n->nextSibling()) {
 772                     if (n->isElementNode()) {
 773                         result = false;
 774                         break;
 775                     }
 776                     if (n->isTextNode()) {
 777                         Text* textNode = toText(n);
 778                         if (!textNode->data().isEmpty()) {
 779                             result = false;
 780                             break;
 781                         }
 782                     }
 783                 }
 784                 if (m_mode == ResolvingStyle) {
 785                     if (context.elementStyle)
 786                         context.elementStyle->setEmptyState(result);
 787                     else if (element->renderStyle() && (element->document()->usesSiblingRules() || element->renderStyle()->unique()))
 788                         element->renderStyle()->setEmptyState(result);
 789                 }
 790                 return result;
 791             }
 792         case CSSSelector::PseudoFirstChild:
 793             // first-child matches the first child that is an element
 794             if (element->parentElement()) {
 795                 bool result = false;
 796                 if (!element->previousElementSibling())
 797                     result = true;
 798                 if (m_mode == ResolvingStyle) {
 799                     RenderStyle* childStyle = context.elementStyle ? context.elementStyle : element->renderStyle();
 800                     RenderStyle* parentStyle = context.elementStyle ? context.elementParentStyle : element->parentNode()->renderStyle();
 801                     if (parentStyle)
 802                         parentStyle->setChildrenAffectedByFirstChildRules();
 803                     if (result && childStyle)
 804                         childStyle->setFirstChildState();
 805                 }
 806                 return result;
 807             }
 808             break;
 809         case CSSSelector::PseudoFirstOfType:
 810             // first-of-type matches the first element of its type
 811             if (element->parentElement()) {
 812                 bool result = true;
 813                 const QualifiedName& type = element->tagQName();
 814                 for (const Element* sibling = element->previousElementSibling(); sibling; sibling = sibling->previousElementSibling()) {
 815                     if (sibling->hasTagName(type)) {
 816                         result = false;
 817                         break;
 818                     }
 819                 }
 820                 if (m_mode == ResolvingStyle) {
 821                     RenderStyle* parentStyle = context.elementStyle ? context.elementParentStyle : element->parentNode()->renderStyle();
 822                     if (parentStyle)
 823                         parentStyle->setChildrenAffectedByForwardPositionalRules();
 824                 }
 825                 return result;
 826             }
 827             break;
 828         case CSSSelector::PseudoLastChild:
 829             // last-child matches the last child that is an element
 830             if (Element* parentElement = element->parentElement()) {
 831                 bool result = parentElement->isFinishedParsingChildren() && !element->nextElementSibling();
 832                 if (m_mode == ResolvingStyle) {
 833                     RenderStyle* childStyle = context.elementStyle ? context.elementStyle : element->renderStyle();
 834                     RenderStyle* parentStyle = context.elementStyle ? context.elementParentStyle : parentElement->renderStyle();
 835                     if (parentStyle)
 836                         parentStyle->setChildrenAffectedByLastChildRules();
 837                     if (result && childStyle)
 838                         childStyle->setLastChildState();
 839                 }
 840                 return result;
 841             }
 842             break;
 843         case CSSSelector::PseudoLastOfType:
 844             // last-of-type matches the last element of its type
 845             if (Element* parentElement = element->parentElement()) {
 846                 if (m_mode == ResolvingStyle) {
 847                     RenderStyle* parentStyle = context.elementStyle ? context.elementParentStyle : parentElement->renderStyle();
 848                     if (parentStyle)
 849                         parentStyle->setChildrenAffectedByBackwardPositionalRules();
 850                 }
 851                 if (!parentElement->isFinishedParsingChildren())
 852                     return false;
 853                 const QualifiedName& type = element->tagQName();
 854                 for (const Element* sibling = element->nextElementSibling(); sibling; sibling = sibling->nextElementSibling()) {
 855                     if (sibling->hasTagName(type))
 856                         return false;
 857                 }
 858                 return true;
 859             }
 860             break;
 861         case CSSSelector::PseudoOnlyChild:
 862             if (Element* parentElement = element->parentElement()) {
 863                 bool firstChild = !element->previousElementSibling();
 864                 bool onlyChild = firstChild && parentElement->isFinishedParsingChildren() && !element->nextElementSibling();
 865
 866                 if (m_mode == ResolvingStyle) {
 867                     RenderStyle* childStyle = context.elementStyle ? context.elementStyle : element->renderStyle();
 868                     RenderStyle* parentStyle = context.elementStyle ? context.elementParentStyle : parentElement->renderStyle();
 869                     if (parentStyle) {
 870                         parentStyle->setChildrenAffectedByFirstChildRules();
 871                         parentStyle->setChildrenAffectedByLastChildRules();
 872                     }
 873                     if (firstChild && childStyle)
 874                         childStyle->setFirstChildState();
 875                     if (onlyChild && childStyle)
 876                         childStyle->setLastChildState();
 877                 }
 878                 return onlyChild;
 879             }
 880             break;
 881         case CSSSelector::PseudoOnlyOfType:
 882             // FIXME: This selector is very slow.
 883             if (Element* parentElement = element->parentElement()) {
 884                 if (m_mode == ResolvingStyle) {
 885                     RenderStyle* parentStyle = context.elementStyle ? context.elementParentStyle : parentElement->renderStyle();
 886                     if (parentStyle) {
 887                         parentStyle->setChildrenAffectedByForwardPositionalRules();
 888                         parentStyle->setChildrenAffectedByBackwardPositionalRules();
 889                     }
 890                 }
 891                 if (!parentElement->isFinishedParsingChildren())
 892                     return false;
 893                 const QualifiedName& type = element->tagQName();
 894                 for (const Element* sibling = element->previousElementSibling(); sibling; sibling = sibling->previousElementSibling()) {
 895                     if (sibling->hasTagName(type))
 896                         return false;
 897                 }
 898                 for (const Element* sibling = element->nextElementSibling(); sibling; sibling = sibling->nextElementSibling()) {
 899                     if (sibling->hasTagName(type))
 900                         return false;
 901                 }
 902                 return true;
 903             }
 904             break;
 905         case CSSSelector::PseudoNthChild:
 906             if (!selector->parseNth())
 907                 break;
 908             if (Element* parentElement = element->parentElement()) {
 909                 int count = 1;
 910                 for (const Element* sibling = element->previousElementSibling(); sibling; sibling = sibling->previousElementSibling()) {
 911                     RenderStyle* s = sibling->renderStyle();
 912                     unsigned index = s ? s->childIndex() : 0;
 913                     if (index) {
 914                         count += index;
 915                         break;
 916                     }
 917                     count++;
 918                 }
 919
 920                 if (m_mode == ResolvingStyle) {
 921                     RenderStyle* childStyle = context.elementStyle ? context.elementStyle : element->renderStyle();
 922                     RenderStyle* parentStyle = context.elementStyle ? context.elementParentStyle : parentElement->renderStyle();
 923                     if (childStyle)
 924                         childStyle->setChildIndex(count);
 925                     if (parentStyle)
 926                         parentStyle->setChildrenAffectedByForwardPositionalRules();
 927                 }
 928
 929                 if (selector->matchNth(count))
 930                     return true;
 931             }
 932             break;
 933         case CSSSelector::PseudoNthOfType:
 934             if (!selector->parseNth())
 935                 break;
 936             if (Element* parentElement = element->parentElement()) {
 937                 int count = 1;
 938                 const QualifiedName& type = element->tagQName();
 939                 for (const Element* sibling = element->previousElementSibling(); sibling; sibling = sibling->previousElementSibling()) {
 940                     if (sibling->hasTagName(type))
 941                         ++count;
 942                 }
 943                 if (m_mode == ResolvingStyle) {
 944                     RenderStyle* parentStyle = context.elementStyle ? context.elementParentStyle : parentElement->renderStyle();
 945                     if (parentStyle)
 946                         parentStyle->setChildrenAffectedByForwardPositionalRules();
 947                 }
 948
 949                 if (selector->matchNth(count))
 950                     return true;
 951             }
 952             break;
 953         case CSSSelector::PseudoNthLastChild:
 954             if (!selector->parseNth())
 955                 break;
 956             if (Element* parentElement = element->parentElement()) {
 957                 if (m_mode == ResolvingStyle) {
 958                     RenderStyle* parentStyle = context.elementStyle ? context.elementParentStyle : parentElement->renderStyle();
 959                     if (parentStyle)
 960                         parentStyle->setChildrenAffectedByBackwardPositionalRules();
 961                 }
 962                 if (!parentElement->isFinishedParsingChildren())
 963                     return false;
 964                 int count = 1;
 965                 for (const Element* sibling = element->nextElementSibling(); sibling; sibling = sibling->nextElementSibling())
 966                     ++count;
 967                 if (selector->matchNth(count))
 968                     return true;
 969             }
 970             break;
 971         case CSSSelector::PseudoNthLastOfType:
 972             if (!selector->parseNth())
 973                 break;
 974             if (Element* parentElement = element->parentElement()) {
 975                 if (m_mode == ResolvingStyle) {
 976                     RenderStyle* parentStyle = context.elementStyle ? context.elementParentStyle : parentElement->renderStyle();
 977                     if (parentStyle)
 978                         parentStyle->setChildrenAffectedByBackwardPositionalRules();
 979                 }
 980                 if (!parentElement->isFinishedParsingChildren())
 981                     return false;
 982                 int count = 1;
 983                 const QualifiedName& type = element->tagQName();
 984                 for (const Element* sibling = element->nextElementSibling(); sibling; sibling = sibling->nextElementSibling()) {
 985                     if (sibling->hasTagName(type))
 986                         ++count;
 987                 }
 988                 if (selector->matchNth(count))
 989                     return true;
 990             }
 991             break;
 992         case CSSSelector::PseudoTarget:
 993             if (element == element->document()->cssTarget())
 994                 return true;
 995             break;
 996         case CSSSelector::PseudoAny:
 997             {
 998                 SelectorCheckingContext subContext(context);
 999                 subContext.isSubSelector = true;
1000                 for (subContext.selector = selector->selectorList()->first(); subContext.selector; subContext.selector = CSSSelectorList::next(subContext.selector)) {
1001                     if (checkSelector(subContext, dynamicPseudo) == SelectorMatches)
1002                         return true;
1003                 }
1004             }
1005             break;
1006         case CSSSelector::PseudoAutofill:
1007             if (!element || !element->isFormControlElement())
1008                 break;
1009             if (HTMLInputElement* inputElement = element->toInputElement())
1010                 return inputElement->isAutofilled();
1011             break;
1012         case CSSSelector::PseudoAnyLink:
1013         case CSSSelector::PseudoLink:
1014             // :visited and :link matches are separated later when applying the style. Here both classes match all links...
1015             return element->isLink();
1016         case CSSSelector::PseudoVisited:
1017             // ...except if :visited matching is disabled for ancestor/sibling matching.
1018             return element->isLink() && context.visitedMatchType == VisitedMatchEnabled;
1019         case CSSSelector::PseudoDrag:
1020             if (context.elementStyle)
1021                 context.elementStyle->setAffectedByDragRules(true);
1022             else if (element->renderStyle())
1023                 element->renderStyle()->setAffectedByDragRules(true);
1024             if (element->renderer() && element->renderer()->isDragging())
1025                 return true;
1026             break;
1027         case CSSSelector::PseudoFocus:
1028             return matchesFocusPseudoClass(element);
1029         case CSSSelector::PseudoHover:
1030             // If we're in quirks mode, then hover should never match anchors with no
1031             // href and *:hover should not match anything. This is important for sites like wsj.com.
1032             if (m_strictParsing || context.isSubSelector || (selector->hasTag() && !element->hasTagName(aTag)) || element->isLink()) {
1033                 if (context.elementStyle)
1034                     context.elementStyle->setAffectedByHoverRules(true);
1035                 else if (element->renderStyle())
1036                     element->renderStyle()->setAffectedByHoverRules(true);
1037                 if (element->hovered() || InspectorInstrumentation::forcePseudoState(element, CSSSelector::PseudoHover))
1038                     return true;
1039             }
1040             break;
1041         case CSSSelector::PseudoActive:
1042             // If we're in quirks mode, then :active should never match anchors with no
1043             // href and *:active should not match anything.
1044             if (m_strictParsing || context.isSubSelector || (selector->hasTag() && !element->hasTagName(aTag)) || element->isLink()) {
1045                 if (context.elementStyle)
1046                     context.elementStyle->setAffectedByActiveRules(true);
1047                 else if (element->renderStyle())
1048                     element->renderStyle()->setAffectedByActiveRules(true);
1049                 if (element->active() || InspectorInstrumentation::forcePseudoState(element, CSSSelector::PseudoActive))
1050                     return true;
1051             }
1052             break;
1053         case CSSSelector::PseudoEnabled:
1054             if (element && (element->isFormControlElement() || element->hasTagName(optionTag) || element->hasTagName(optgroupTag)))
1055                 return element->isEnabledFormControl();
1056             break;
1057         case CSSSelector::PseudoFullPageMedia:
1058             return element && element->document() && element->document()->isMediaDocument();
1059             break;
1060         case CSSSelector::PseudoDefault:
1061             return element && element->isDefaultButtonForForm();
1062         case CSSSelector::PseudoDisabled:
1063             if (element && (element->isFormControlElement() || element->hasTagName(optionTag) || element->hasTagName(optgroupTag)))
1064                 return !element->isEnabledFormControl();
1065             break;
1066         case CSSSelector::PseudoReadOnly:
1067             if (!element || !element->isFormControlElement())
1068                 return false;
1069             return element->isTextFormControl() && element->isReadOnlyFormControl();
1070         case CSSSelector::PseudoReadWrite:
1071             if (!element || !element->isFormControlElement())
1072                 return false;
1073             return element->isTextFormControl() && !element->isReadOnlyFormControl();
1074         case CSSSelector::PseudoOptional:
1075             return element && element->isOptionalFormControl();
1076         case CSSSelector::PseudoRequired:
1077             return element && element->isRequiredFormControl();
1078         case CSSSelector::PseudoValid:
1079             if (!element)
1080                 return false;
1081             element->document()->setContainsValidityStyleRules();
1082             return element->willValidate() && element->isValidFormControlElement();
1083         case CSSSelector::PseudoInvalid:
1084             if (!element)
1085                 return false;
1086             element->document()->setContainsValidityStyleRules();
1087             return element->willValidate() && !element->isValidFormControlElement();
1088         case CSSSelector::PseudoChecked:
1089             {
1090                 if (!element)
1091                     break;
1092                 // Even though WinIE allows checked and indeterminate to co-exist, the CSS selector spec says that
1093                 // you can't be both checked and indeterminate. We will behave like WinIE behind the scenes and just
1094                 // obey the CSS spec here in the test for matching the pseudo.
1095                 HTMLInputElement* inputElement = element->toInputElement();
1096                 if (inputElement && inputElement->shouldAppearChecked() && !inputElement->isIndeterminate())
1097                     return true;
1098                 if (element->hasTagName(optionTag) && toHTMLOptionElement(element)->selected())
1099                     return true;
1100                 break;
1101             }
1102         case CSSSelector::PseudoIndeterminate:
1103             {
1104                 if (!element)
1105                     break;
1106 #if ENABLE(PROGRESS_ELEMENT)
1107                 if (element->hasTagName(progressTag)) {
1108                     HTMLProgressElement* progress = static_cast<HTMLProgressElement*>(element);
1109                     if (progress && !progress->isDeterminate())
1110                         return true;
1111                     break;
1112                 }
1113 #endif
1114                 HTMLInputElement* inputElement = element->toInputElement();
1115                 if (inputElement && inputElement->isIndeterminate())
1116                     return true;
1117                 break;
1118             }
1119         case CSSSelector::PseudoScope:
1120             if (context.scope)
1121                 return element == context.scope;
1122             // If there is no scope, :scope should behave as :root -> fall through
1123         case CSSSelector::PseudoRoot:
1124             if (element == element->document()->documentElement())
1125                 return true;
1126             break;
1127         case CSSSelector::PseudoLang:
1128             {
1129                 AtomicString value = element->computeInheritedLanguage();
1130                 const AtomicString& argument = selector->argument();
1131                 if (value.isEmpty() || !value.startsWith(argument, false))
1132                     break;
1133                 if (value.length() != argument.length() && value[argument.length()] != '-')
1134                     break;
1135                 return true;
1136             }
1137 #if ENABLE(FULLSCREEN_API)
1138         case CSSSelector::PseudoFullScreen:
1139             // While a Document is in the fullscreen state, and the document's current fullscreen
1140             // element is an element in the document, the 'full-screen' pseudoclass applies to
1141             // that element. Also, an <iframe>, <object> or <embed> element whose child browsing
1142             // context's Document is in the fullscreen state has the 'full-screen' pseudoclass applied.
1143             if (element->isFrameElementBase() && static_cast<HTMLFrameElementBase*>(element)->containsFullScreenElement())
1144                 return true;
1145             if (!element->document()->webkitIsFullScreen())
1146                 return false;
1147             return element == element->document()->webkitCurrentFullScreenElement();
1148         case CSSSelector::PseudoAnimatingFullScreenTransition:
1149             if (element != element->document()->webkitCurrentFullScreenElement())
1150                 return false;
1151             return element->document()->isAnimatingFullScreen();
1152         case CSSSelector::PseudoFullScreenAncestor:
1153             return element->containsFullScreenElement();
1154         case CSSSelector::PseudoFullScreenDocument:
1155             // While a Document is in the fullscreen state, the 'full-screen-document' pseudoclass applies
1156             // to all elements of that Document.
1157             if (!element->document()->webkitIsFullScreen())
1158                 return false;
1159             return true;
1160 #endif
1161         case CSSSelector::PseudoInRange:
1162             if (!element)
1163                 return false;
1164             element->document()->setContainsValidityStyleRules();
1165             return element->isInRange();
1166         case CSSSelector::PseudoOutOfRange:
1167             if (!element)
1168                 return false;
1169             element->document()->setContainsValidityStyleRules();
1170             return element->isOutOfRange();
1171         case CSSSelector::PseudoUnknown:
1172         case CSSSelector::PseudoNotParsed:
1173         default:
1174             ASSERT_NOT_REACHED();
1175             break;
1176         }
1177         return false;
1178     }
1179     if (selector->m_match == CSSSelector::PseudoElement) {
1180         if (selector->isUnknownPseudoElement()) {
1181             m_hasUnknownPseudoElements = true;
1182             return element->shadowPseudoId() == selector->value();
1183         }
1184
1185         if ((!context.elementStyle && m_mode == ResolvingStyle) || m_mode == QueryingRules)
1186             return false;
1187
1188         PseudoId pseudoId = CSSSelector::pseudoId(selector->pseudoType());
1189         if (pseudoId == FIRST_LETTER) {
1190             if (Document* document = element->document())
1191                 document->setUsesFirstLetterRules(true);
1192         }
1193         if (pseudoId != NOPSEUDO)
1194             dynamicPseudo = pseudoId;
1195     }
1196     // ### add the rest of the checks...
1197     return true;
1198 }
1199
1200 bool SelectorChecker::checkScrollbarPseudoClass(CSSSelector* sel, PseudoId&) const
1201 {
1202     RenderScrollbar* scrollbar = RenderScrollbar::scrollbarForStyleResolve();
1203     ScrollbarPart part = RenderScrollbar::partForStyleResolve();
1204
1205     // FIXME: This is a temporary hack for resizers and scrollbar corners. Eventually :window-inactive should become a real
1206     // pseudo class and just apply to everything.
1207     if (sel->pseudoType() == CSSSelector::PseudoWindowInactive)
1208         return !m_document->page()->focusController()->isActive();
1209
1210     if (!scrollbar)
1211         return false;
1212
1213     ASSERT(sel->m_match == CSSSelector::PseudoClass);
1214     switch (sel->pseudoType()) {
1215     case CSSSelector::PseudoEnabled:
1216         return scrollbar->enabled();
1217     case CSSSelector::PseudoDisabled:
1218         return !scrollbar->enabled();
1219     case CSSSelector::PseudoHover:
1220         {
1221             ScrollbarPart hoveredPart = scrollbar->hoveredPart();
1222             if (part == ScrollbarBGPart)
1223                 return hoveredPart != NoPart;
1224             if (part == TrackBGPart)
1225                 return hoveredPart == BackTrackPart || hoveredPart == ForwardTrackPart || hoveredPart == ThumbPart;
1226             return part == hoveredPart;
1227         }
1228     case CSSSelector::PseudoActive:
1229         {
1230             ScrollbarPart pressedPart = scrollbar->pressedPart();
1231             if (part == ScrollbarBGPart)
1232                 return pressedPart != NoPart;
1233             if (part == TrackBGPart)
1234                 return pressedPart == BackTrackPart || pressedPart == ForwardTrackPart || pressedPart == ThumbPart;
1235             return part == pressedPart;
1236         }
1237     case CSSSelector::PseudoHorizontal:
1238         return scrollbar->orientation() == HorizontalScrollbar;
1239     case CSSSelector::PseudoVertical:
1240         return scrollbar->orientation() == VerticalScrollbar;
1241     case CSSSelector::PseudoDecrement:
1242         return part == BackButtonStartPart || part == BackButtonEndPart || part == BackTrackPart;
1243     case CSSSelector::PseudoIncrement:
1244         return part == ForwardButtonStartPart || part == ForwardButtonEndPart || part == ForwardTrackPart;
1245     case CSSSelector::PseudoStart:
1246         return part == BackButtonStartPart || part == ForwardButtonStartPart || part == BackTrackPart;
1247     case CSSSelector::PseudoEnd:
1248         return part == BackButtonEndPart || part == ForwardButtonEndPart || part == ForwardTrackPart;
1249     case CSSSelector::PseudoDoubleButton:
1250         {
1251             ScrollbarButtonsPlacement buttonsPlacement = scrollbar->theme()->buttonsPlacement();
1252             if (part == BackButtonStartPart || part == ForwardButtonStartPart || part == BackTrackPart)
1253                 return buttonsPlacement == ScrollbarButtonsDoubleStart || buttonsPlacement == ScrollbarButtonsDoubleBoth;
1254             if (part == BackButtonEndPart || part == ForwardButtonEndPart || part == ForwardTrackPart)
1255                 return buttonsPlacement == ScrollbarButtonsDoubleEnd || buttonsPlacement == ScrollbarButtonsDoubleBoth;
1256             return false;
1257         }
1258     case CSSSelector::PseudoSingleButton:
1259         {
1260             ScrollbarButtonsPlacement buttonsPlacement = scrollbar->theme()->buttonsPlacement();
1261             if (part == BackButtonStartPart || part == ForwardButtonEndPart || part == BackTrackPart || part == ForwardTrackPart)
1262                 return buttonsPlacement == ScrollbarButtonsSingle;
1263             return false;
1264         }
1265     case CSSSelector::PseudoNoButton:
1266         {
1267             ScrollbarButtonsPlacement buttonsPlacement = scrollbar->theme()->buttonsPlacement();
1268             if (part == BackTrackPart)
1269                 return buttonsPlacement == ScrollbarButtonsNone || buttonsPlacement == ScrollbarButtonsDoubleEnd;
1270             if (part == ForwardTrackPart)
1271                 return buttonsPlacement == ScrollbarButtonsNone || buttonsPlacement == ScrollbarButtonsDoubleStart;
1272             return false;
1273         }
1274     case CSSSelector::PseudoCornerPresent:
1275         return scrollbar->scrollableArea()->isScrollCornerVisible();
1276     default:
1277         return false;
1278     }
1279 }
1280
1281 void SelectorChecker::allVisitedStateChanged()
1282 {
1283     if (m_linksCheckedForVisitedState.isEmpty())
1284         return;
1285     for (Node* node = m_document; node; node = node->traverseNextNode()) {
1286         if (node->isLink())
1287             node->setNeedsStyleRecalc();
1288     }
1289 }
1290
1291 void SelectorChecker::visitedStateChanged(LinkHash visitedHash)
1292 {
1293     if (!m_linksCheckedForVisitedState.contains(visitedHash))
1294         return;
1295     for (Node* node = m_document; node; node = node->traverseNextNode()) {
1296         LinkHash hash = 0;
1297         if (node->hasTagName(aTag))
1298             hash = static_cast<HTMLAnchorElement*>(node)->visitedLinkHash();
1299         else if (const AtomicString* attr = linkAttribute(node))
1300             hash = visitedLinkHash(m_document->baseURL(), *attr);
1301         if (hash == visitedHash)
1302             node->setNeedsStyleRecalc();
1303     }
1304 }
1305
1306 bool SelectorChecker::commonPseudoClassSelectorMatches(const Element* element, const CSSSelector* selector, VisitedMatchType visitedMatchType) const
1307 {
1308     ASSERT(isCommonPseudoClassSelector(selector));
1309     switch (selector->pseudoType()) {
1310     case CSSSelector::PseudoLink:
1311     case CSSSelector::PseudoAnyLink:
1312         return element->isLink();
1313     case CSSSelector::PseudoVisited:
1314         return element->isLink() && visitedMatchType == VisitedMatchEnabled;
1315     case CSSSelector::PseudoFocus:
1316         return matchesFocusPseudoClass(element);
1317     default:
1318         ASSERT_NOT_REACHED();
1319     }
1320     return true;
1321 }
1322
1323 unsigned SelectorChecker::determineLinkMatchType(const CSSSelector* selector)
1324 {
1325     unsigned linkMatchType = MatchAll;
1326
1327     // Statically determine if this selector will match a link in visited, unvisited or any state, or never.
1328     // :visited never matches other elements than the innermost link element.
1329     for (; selector; selector = selector->tagHistory()) {
1330         switch (selector->pseudoType()) {
1331         case CSSSelector::PseudoNot:
1332             {
1333                 // :not(:visited) is equivalent to :link. Parser enforces that :not can't nest.
1334                 CSSSelectorList* selectorList = selector->selectorList();
1335                 if (!selectorList)
1336                     break;
1337
1338                 for (CSSSelector* subSelector = selectorList->first(); subSelector; subSelector = subSelector->tagHistory()) {
1339                     CSSSelector::PseudoType subType = subSelector->pseudoType();
1340                     if (subType == CSSSelector::PseudoVisited)
1341                         linkMatchType &= ~SelectorChecker::MatchVisited;
1342                     else if (subType == CSSSelector::PseudoLink)
1343                         linkMatchType &= ~SelectorChecker::MatchLink;
1344                 }
1345             }
1346             break;
1347         case CSSSelector::PseudoLink:
1348             linkMatchType &= ~SelectorChecker::MatchVisited;
1349             break;
1350         case CSSSelector::PseudoVisited:
1351             linkMatchType &= ~SelectorChecker::MatchLink;
1352             break;
1353         default:
1354             // We don't support :link and :visited inside :-webkit-any.
1355             break;
1356         }
1357         CSSSelector::Relation relation = selector->relation();
1358         if (relation == CSSSelector::SubSelector)
1359             continue;
1360         if (relation != CSSSelector::Descendant && relation != CSSSelector::Child)
1361             return linkMatchType;
1362         if (linkMatchType != MatchAll)
1363             return linkMatchType;
1364     }
1365     return linkMatchType;
1366 }
1367
1368 bool SelectorChecker::isFrameFocused(const Element* element)
1369 {
1370     return element->document()->frame() && element->document()->frame()->selection()->isFocusedAndActive();
1371 }
1372
1373 bool SelectorChecker::determineSelectorScopes(const CSSSelectorList& selectorList, HashSet<AtomicStringImpl*>& idScopes, HashSet<AtomicStringImpl*>& classScopes)
1374 {
1375     for (CSSSelector* selector = selectorList.first(); selector; selector = CSSSelectorList::next(selector)) {
1376         CSSSelector* scopeSelector = 0;
1377         // This picks the widest scope, not the narrowest, to minimize the number of found scopes.
1378         for (CSSSelector* current = selector; current; current = current->tagHistory()) {
1379             // Prefer ids over classes.
1380             if (current->m_match == CSSSelector::Id)
1381                 scopeSelector = current;
1382             else if (current->m_match == CSSSelector::Class && (!scopeSelector || scopeSelector->m_match != CSSSelector::Id))
1383                 scopeSelector = current;
1384             CSSSelector::Relation relation = current->relation();
1385             if (relation != CSSSelector::Descendant && relation != CSSSelector::Child && relation != CSSSelector::SubSelector)
1386                 break;
1387         }
1388         if (!scopeSelector)
1389             return false;
1390         ASSERT(scopeSelector->m_match == CSSSelector::Class || scopeSelector->m_match == CSSSelector::Id);
1391         if (scopeSelector->m_match == CSSSelector::Id)
1392             idScopes.add(scopeSelector->value().impl());
1393         else
1394             classScopes.add(scopeSelector->value().impl());
1395     }
1396     return true;
1397 }
1398
1399 }