third_party/WebKit/Source/core/css/ElementRuleCollector.cpp

/*
 * 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, 2012, 2013 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 "core/css/ElementRuleCollector.h"

#include "core/css/CSSImportRule.h"
#include "core/css/CSSKeyframesRule.h"
#include "core/css/CSSMediaRule.h"
#include "core/css/CSSRuleList.h"
#include "core/css/CSSSelector.h"
#include "core/css/CSSStyleRule.h"
#include "core/css/CSSStyleSheet.h"
#include "core/css/CSSSupportsRule.h"
#include "core/css/StylePropertySet.h"
#include "core/css/resolver/StyleResolver.h"
#include "core/css/resolver/StyleResolverStats.h"
#include "core/css/resolver/StyleRuleUsageTracker.h"
#include "core/dom/StyleEngine.h"
#include "core/dom/shadow/ShadowRoot.h"
#include "core/style/StyleInheritedData.h"

namespace blink {

ElementRuleCollector::ElementRuleCollector(const ElementResolveContext& context,
                                           const SelectorFilter& filter,
                                           ComputedStyle* style)
    : m_context(context),
      m_selectorFilter(filter),
      m_style(style),
      m_pseudoStyleRequest(PseudoIdNone),
      m_mode(SelectorChecker::ResolvingStyle),
      m_canUseFastReject(
          m_selectorFilter.parentStackIsConsistent(context.parentNode())),
      m_sameOriginOnly(false),
      m_matchingUARules(false),
      m_includeEmptyRules(false) {}

ElementRuleCollector::~ElementRuleCollector() {}

const MatchResult& ElementRuleCollector::matchedResult() const {
  return m_result;
}

StyleRuleList* ElementRuleCollector::matchedStyleRuleList() {
  ASSERT(m_mode == SelectorChecker::CollectingStyleRules);
  return m_styleRuleList.release();
}

CSSRuleList* ElementRuleCollector::matchedCSSRuleList() {
  ASSERT(m_mode == SelectorChecker::CollectingCSSRules);
  return m_cssRuleList.release();
}

void ElementRuleCollector::clearMatchedRules() {
  m_matchedRules.clear();
}

inline StyleRuleList* ElementRuleCollector::ensureStyleRuleList() {
  if (!m_styleRuleList)
    m_styleRuleList = new StyleRuleList();
  return m_styleRuleList;
}

inline StaticCSSRuleList* ElementRuleCollector::ensureRuleList() {
  if (!m_cssRuleList)
    m_cssRuleList = StaticCSSRuleList::create();
  return m_cssRuleList.get();
}

void ElementRuleCollector::addElementStyleProperties(
    const StylePropertySet* propertySet,
    bool isCacheable) {
  if (!propertySet)
    return;
  m_result.addMatchedProperties(propertySet);
  if (!isCacheable)
    m_result.setIsCacheable(false);
}

static bool rulesApplicableInCurrentTreeScope(
    const Element* element,
    const ContainerNode* scopingNode) {
  // Check if the rules come from a shadow style sheet in the same tree scope.
  return !scopingNode ||
         element->containingTreeScope() == scopingNode->containingTreeScope();
}

template <typename RuleDataListType>
void ElementRuleCollector::collectMatchingRulesForList(
    const RuleDataListType* rules,
    CascadeOrder cascadeOrder,
    const MatchRequest& matchRequest) {
  if (!rules)
    return;

  SelectorChecker::Init init;
  init.mode = m_mode;
  init.isUARule = m_matchingUARules;
  init.elementStyle = m_style.get();
  init.scrollbar = m_pseudoStyleRequest.scrollbar;
  init.scrollbarPart = m_pseudoStyleRequest.scrollbarPart;
  SelectorChecker checker(init);
  SelectorChecker::SelectorCheckingContext context(
      m_context.element(), SelectorChecker::VisitedMatchEnabled);
  context.scope = matchRequest.scope;
  context.pseudoId = m_pseudoStyleRequest.pseudoId;

  unsigned rejected = 0;
  unsigned fastRejected = 0;
  unsigned matched = 0;

  for (const auto& ruleData : *rules) {
    if (m_canUseFastReject &&
        m_selectorFilter.fastRejectSelector<RuleData::maximumIdentifierCount>(
            ruleData.descendantSelectorIdentifierHashes())) {
      fastRejected++;
      continue;
    }

    // FIXME: Exposing the non-standard getMatchedCSSRules API to web is the
    // only reason this is needed.
    if (m_sameOriginOnly && !ruleData.hasDocumentSecurityOrigin())
      continue;

    StyleRule* rule = ruleData.rule();

    // If the rule has no properties to apply, then ignore it in the non-debug
    // mode.
    if (!rule->shouldConsiderForMatchingRules(m_includeEmptyRules))
      continue;

    SelectorChecker::MatchResult result;
    context.selector = &ruleData.selector();
    if (!checker.match(context, result)) {
      rejected++;
      continue;
    }
    if (m_pseudoStyleRequest.pseudoId != PseudoIdNone &&
        m_pseudoStyleRequest.pseudoId != result.dynamicPseudo) {
      rejected++;
      continue;
    }

    matched++;
    didMatchRule(ruleData, result, cascadeOrder, matchRequest);
  }

  StyleEngine& styleEngine = m_context.element()->document().styleEngine();
  if (!styleEngine.stats())
    return;

  INCREMENT_STYLE_STATS_COUNTER(styleEngine, rulesRejected, rejected);
  INCREMENT_STYLE_STATS_COUNTER(styleEngine, rulesFastRejected, fastRejected);
  INCREMENT_STYLE_STATS_COUNTER(styleEngine, rulesMatched, matched);
}

DISABLE_CFI_PERF
void ElementRuleCollector::collectMatchingRules(
    const MatchRequest& matchRequest,
    CascadeOrder cascadeOrder,
    bool matchingTreeBoundaryRules) {
  ASSERT(matchRequest.ruleSet);
  ASSERT(m_context.element());

  Element& element = *m_context.element();
  const AtomicString& pseudoId = element.shadowPseudoId();
  if (!pseudoId.isEmpty()) {
    ASSERT(element.isStyledElement());
    collectMatchingRulesForList(
        matchRequest.ruleSet->shadowPseudoElementRules(pseudoId), cascadeOrder,
        matchRequest);
    if (pseudoId == "-webkit-input-placeholder") {
      collectMatchingRulesForList(
          matchRequest.ruleSet->placeholderPseudoRules(), cascadeOrder,
          matchRequest);
    }
  }

  if (element.isVTTElement())
    collectMatchingRulesForList(matchRequest.ruleSet->cuePseudoRules(),
                                cascadeOrder, matchRequest);
  // Check whether other types of rules are applicable in the current tree
  // scope. Criteria for this:
  // a) the rules are UA rules.
  // b) matching tree boundary crossing rules.
  // c) the rules come from a shadow style sheet in the same tree scope as the
  //    given element.
  // c) is checked in rulesApplicableInCurrentTreeScope.
  if (!m_matchingUARules && !matchingTreeBoundaryRules &&
      !rulesApplicableInCurrentTreeScope(&element, matchRequest.scope))
    return;

  // We need to collect the rules for id, class, tag, and everything else into a
  // buffer and then sort the buffer.
  if (element.hasID())
    collectMatchingRulesForList(
        matchRequest.ruleSet->idRules(element.idForStyleResolution()),
        cascadeOrder, matchRequest);
  if (element.isStyledElement() && element.hasClass()) {
    for (size_t i = 0; i < element.classNames().size(); ++i)
      collectMatchingRulesForList(
          matchRequest.ruleSet->classRules(element.classNames()[i]),
          cascadeOrder, matchRequest);
  }

  if (element.isLink())
    collectMatchingRulesForList(matchRequest.ruleSet->linkPseudoClassRules(),
                                cascadeOrder, matchRequest);
  if (SelectorChecker::matchesFocusPseudoClass(element))
    collectMatchingRulesForList(matchRequest.ruleSet->focusPseudoClassRules(),
                                cascadeOrder, matchRequest);
  collectMatchingRulesForList(
      matchRequest.ruleSet->tagRules(element.localNameForSelectorMatching()),
      cascadeOrder, matchRequest);
  collectMatchingRulesForList(matchRequest.ruleSet->universalRules(),
                              cascadeOrder, matchRequest);
}

void ElementRuleCollector::collectMatchingShadowHostRules(
    const MatchRequest& matchRequest,
    CascadeOrder cascadeOrder) {
  collectMatchingRulesForList(matchRequest.ruleSet->shadowHostRules(),
                              cascadeOrder, matchRequest);
}

template <class CSSRuleCollection>
CSSRule* ElementRuleCollector::findStyleRule(CSSRuleCollection* cssRules,
                                             StyleRule* styleRule) {
  if (!cssRules)
    return nullptr;
  CSSRule* result = 0;
  for (unsigned i = 0; i < cssRules->length() && !result; ++i) {
    CSSRule* cssRule = cssRules->item(i);
    CSSRule::Type cssRuleType = cssRule->type();
    if (cssRuleType == CSSRule::kStyleRule) {
      CSSStyleRule* cssStyleRule = toCSSStyleRule(cssRule);
      if (cssStyleRule->styleRule() == styleRule)
        result = cssRule;
    } else if (cssRuleType == CSSRule::kImportRule) {
      CSSImportRule* cssImportRule = toCSSImportRule(cssRule);
      result = findStyleRule(cssImportRule->styleSheet(), styleRule);
    } else {
      result = findStyleRule(cssRule->cssRules(), styleRule);
    }
  }
  return result;
}

void ElementRuleCollector::appendCSSOMWrapperForRule(
    CSSStyleSheet* parentStyleSheet,
    StyleRule* rule) {
  // |parentStyleSheet| is 0 if and only if the |rule| is coming from User
  // Agent. In this case, it is safe to create CSSOM wrappers without
  // parentStyleSheets as they will be used only by inspector which will not try
  // to edit them.
  CSSRule* cssRule = nullptr;
  if (parentStyleSheet)
    cssRule = findStyleRule(parentStyleSheet, rule);
  else
    cssRule = rule->createCSSOMWrapper();
  ASSERT(!parentStyleSheet || cssRule);
  ensureRuleList()->rules().append(cssRule);
}

void ElementRuleCollector::sortAndTransferMatchedRules() {
  if (m_matchedRules.isEmpty())
    return;

  sortMatchedRules();

  if (m_mode == SelectorChecker::CollectingStyleRules) {
    for (unsigned i = 0; i < m_matchedRules.size(); ++i)
      ensureStyleRuleList()->append(m_matchedRules[i].ruleData()->rule());
    return;
  }

  if (m_mode == SelectorChecker::CollectingCSSRules) {
    for (unsigned i = 0; i < m_matchedRules.size(); ++i)
      appendCSSOMWrapperForRule(
          const_cast<CSSStyleSheet*>(m_matchedRules[i].parentStyleSheet()),
          m_matchedRules[i].ruleData()->rule());
    return;
  }

  // Now transfer the set of matched rules over to our list of declarations.
  for (unsigned i = 0; i < m_matchedRules.size(); i++) {
    const RuleData* ruleData = m_matchedRules[i].ruleData();
    m_result.addMatchedProperties(
        &ruleData->rule()->properties(), ruleData->linkMatchType(),
        ruleData->propertyWhitelist(m_matchingUARules));
  }
}

void ElementRuleCollector::didMatchRule(
    const RuleData& ruleData,
    const SelectorChecker::MatchResult& result,
    CascadeOrder cascadeOrder,
    const MatchRequest& matchRequest) {
  PseudoId dynamicPseudo = result.dynamicPseudo;
  // If we're matching normal rules, set a pseudo bit if we really just matched
  // a pseudo-element.
  if (dynamicPseudo != PseudoIdNone &&
      m_pseudoStyleRequest.pseudoId == PseudoIdNone) {
    if (m_mode == SelectorChecker::CollectingCSSRules ||
        m_mode == SelectorChecker::CollectingStyleRules)
      return;
    // FIXME: Matching should not modify the style directly.
    if (!m_style || dynamicPseudo >= FirstInternalPseudoId)
      return;
    if ((dynamicPseudo == PseudoIdBefore || dynamicPseudo == PseudoIdAfter) &&
        !ruleData.rule()->properties().hasProperty(CSSPropertyContent))
      return;
    m_style->setHasPseudoStyle(dynamicPseudo);
  } else {
    if (m_style && ruleData.containsUncommonAttributeSelector())
      m_style->setUnique();

    m_matchedRules.append(
        MatchedRule(&ruleData, result.specificity, cascadeOrder,
                    matchRequest.styleSheetIndex, matchRequest.styleSheet));
  }
}

static inline bool compareRules(const MatchedRule& matchedRule1,
                                const MatchedRule& matchedRule2) {
  unsigned specificity1 = matchedRule1.specificity();
  unsigned specificity2 = matchedRule2.specificity();
  if (specificity1 != specificity2)
    return specificity1 < specificity2;

  return matchedRule1.position() < matchedRule2.position();
}

void ElementRuleCollector::sortMatchedRules() {
  std::sort(m_matchedRules.begin(), m_matchedRules.end(), compareRules);
}

bool ElementRuleCollector::hasAnyMatchingRules(RuleSet* ruleSet) {
  clearMatchedRules();

  m_mode = SelectorChecker::SharingRules;
  // To check whether a given RuleSet has any rule matching a given element,
  // should not see the element's treescope. Because RuleSet has no information
  // about "scope".
  MatchRequest matchRequest(ruleSet);
  collectMatchingRules(matchRequest);
  collectMatchingShadowHostRules(matchRequest);

  return !m_matchedRules.isEmpty();
}

void ElementRuleCollector::addMatchedRulesToTracker(
    StyleRuleUsageTracker* tracker) const {
  for (auto matchedRule : m_matchedRules)
    tracker->track(matchedRule.ruleData()->rule());
}

}  // namespace blink