root/Source/core/css/ElementRuleCollector.cpp

DEFINITIONS

1. m_matchingUARules
2. matchedResult
3. matchedStyleRuleList
4. matchedCSSRuleList
5. addMatchedRule
6. clearMatchedRules
7. ensureStyleRuleList
8. ensureRuleList
9. addElementStyleProperties
10. rulesApplicableInCurrentTreeScope
11. collectMatchingRules
12. nestedRuleList
13. findStyleRule
14. appendCSSOMWrapperForRule
15. sortAndTransferMatchedRules
16. ruleMatches
17. collectRuleIfMatches
18. compareRules
19. sortMatchedRules
20. hasAnyMatchingRules

/*
 * 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 "config.h"
#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/SiblingTraversalStrategies.h"
#include "core/css/StylePropertySet.h"
#include "core/css/resolver/StyleResolver.h"
#include "core/dom/shadow/ShadowRoot.h"

namespace WebCore {

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

ElementRuleCollector::~ElementRuleCollector()
{
}

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

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

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

inline void ElementRuleCollector::addMatchedRule(const RuleData* rule, unsigned specificity, CascadeScope cascadeScope, CascadeOrder cascadeOrder, unsigned styleSheetIndex, const CSSStyleSheet* parentStyleSheet)
{
    if (!m_matchedRules)
        m_matchedRules = adoptPtrWillBeNoop(new WillBeHeapVector<MatchedRule, 32>);
    m_matchedRules->append(MatchedRule(rule, specificity, cascadeScope, cascadeOrder, styleSheetIndex, parentStyleSheet));
}

void ElementRuleCollector::clearMatchedRules()
{
    if (!m_matchedRules)
        return;
    m_matchedRules->clear();
}

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

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.ranges.authorRuleRange().shiftLast(m_result.matchedProperties.size());
    m_result.addMatchedProperties(propertySet);
    if (!isCacheable)
        m_result.isCacheable = false;
}

static bool rulesApplicableInCurrentTreeScope(const Element* element, const ContainerNode* scopingNode, SelectorChecker::BehaviorAtBoundary behaviorAtBoundary, bool elementApplyAuthorStyles)
{
    TreeScope& treeScope = element->treeScope();

    // [skipped, because already checked] a) it's a UA rule
    // b) element is allowed to apply author rules
    if (elementApplyAuthorStyles)
        return true;
    // c) the rules comes from a scoped style sheet within the same tree scope
    if (!scopingNode || treeScope == scopingNode->treeScope())
        return true;
    // d) the rules comes from a scoped style sheet within an active shadow root whose host is the given element
    if (element->isInShadowTree() && (behaviorAtBoundary & SelectorChecker::ScopeIsShadowHost) && scopingNode == element->containingShadowRoot()->host())
        return true;
    return false;
}

void ElementRuleCollector::collectMatchingRules(const MatchRequest& matchRequest, RuleRange& ruleRange, SelectorChecker::BehaviorAtBoundary behaviorAtBoundary, CascadeScope cascadeScope, CascadeOrder cascadeOrder)
{
    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), behaviorAtBoundary, ignoreCascadeScope, cascadeOrder, matchRequest, ruleRange);
    }

    if (element.isVTTElement())
        collectMatchingRulesForList(matchRequest.ruleSet->cuePseudoRules(), behaviorAtBoundary, cascadeScope, cascadeOrder, matchRequest, ruleRange);
    // Check whether other types of rules are applicable in the current tree scope. Criteria for this:
    // a) it's a UA rule
    // b) the tree scope allows author rules
    // c) the rules comes from a scoped style sheet within the same tree scope
    // d) the rules comes from a scoped style sheet within an active shadow root whose host is the given element
    // e) the rules can cross boundaries
    // b)-e) is checked in rulesApplicableInCurrentTreeScope.
    if (!m_matchingUARules && !rulesApplicableInCurrentTreeScope(&element, matchRequest.scope, behaviorAtBoundary, matchRequest.elementApplyAuthorStyles))
        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()), behaviorAtBoundary, cascadeScope, cascadeOrder, matchRequest, ruleRange);
    if (element.isStyledElement() && element.hasClass()) {
        for (size_t i = 0; i < element.classNames().size(); ++i)
            collectMatchingRulesForList(matchRequest.ruleSet->classRules(element.classNames()[i]), behaviorAtBoundary, cascadeScope, cascadeOrder, matchRequest, ruleRange);
    }

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

CSSRuleList* ElementRuleCollector::nestedRuleList(CSSRule* rule)
{
    switch (rule->type()) {
    case CSSRule::MEDIA_RULE:
        return toCSSMediaRule(rule)->cssRules();
    case CSSRule::KEYFRAMES_RULE:
        return toCSSKeyframesRule(rule)->cssRules();
    case CSSRule::SUPPORTS_RULE:
        return toCSSSupportsRule(rule)->cssRules();
    default:
        return 0;
    }
}

template<class CSSRuleCollection>
CSSRule* ElementRuleCollector::findStyleRule(CSSRuleCollection* cssRules, StyleRule* styleRule)
{
    if (!cssRules)
        return 0;
    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::STYLE_RULE) {
            CSSStyleRule* cssStyleRule = toCSSStyleRule(cssRule);
            if (cssStyleRule->styleRule() == styleRule)
                result = cssRule;
        } else if (cssRuleType == CSSRule::IMPORT_RULE) {
            CSSImportRule* cssImportRule = toCSSImportRule(cssRule);
            result = findStyleRule(cssImportRule->styleSheet(), styleRule);
        } else {
            result = findStyleRule(nestedRuleList(cssRule), 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.
    RefPtrWillBeRawPtr<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 || m_matchedRules->isEmpty())
        return;

    sortMatchedRules();

    WillBeHeapVector<MatchedRule, 32>& matchedRules = *m_matchedRules;
    if (m_mode == SelectorChecker::CollectingStyleRules) {
        for (unsigned i = 0; i < matchedRules.size(); ++i)
            ensureStyleRuleList()->m_list.append(matchedRules[i].ruleData()->rule());
        return;
    }

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

    // Now transfer the set of matched rules over to our list of declarations.
    for (unsigned i = 0; i < matchedRules.size(); i++) {
        // FIXME: Matching should not modify the style directly.
        const RuleData* ruleData = matchedRules[i].ruleData();
        if (m_style && ruleData->containsUncommonAttributeSelector())
            m_style->setUnique();
        m_result.addMatchedProperties(&ruleData->rule()->properties(), ruleData->rule(), ruleData->linkMatchType(), ruleData->propertyWhitelistType(m_matchingUARules));
    }
}

inline bool ElementRuleCollector::ruleMatches(const RuleData& ruleData, const ContainerNode* scope, SelectorChecker::BehaviorAtBoundary behaviorAtBoundary, SelectorChecker::MatchResult* result)
{
    SelectorChecker selectorChecker(m_context.element()->document(), m_mode);
    SelectorChecker::SelectorCheckingContext context(ruleData.selector(), m_context.element(), SelectorChecker::VisitedMatchEnabled);
    context.elementStyle = m_style.get();
    context.scope = scope;
    context.pseudoId = m_pseudoStyleRequest.pseudoId;
    context.scrollbar = m_pseudoStyleRequest.scrollbar;
    context.scrollbarPart = m_pseudoStyleRequest.scrollbarPart;
    context.behaviorAtBoundary = behaviorAtBoundary;
    SelectorChecker::Match match = selectorChecker.match(context, DOMSiblingTraversalStrategy(), result);
    if (match != SelectorChecker::SelectorMatches)
        return false;
    if (m_pseudoStyleRequest.pseudoId != NOPSEUDO && m_pseudoStyleRequest.pseudoId != result->dynamicPseudo)
        return false;
    return true;
}

void ElementRuleCollector::collectRuleIfMatches(const RuleData& ruleData, SelectorChecker::BehaviorAtBoundary behaviorAtBoundary, CascadeScope cascadeScope, CascadeOrder cascadeOrder, const MatchRequest& matchRequest, RuleRange& ruleRange)
{
    if (m_canUseFastReject && m_selectorFilter.fastRejectSelector<RuleData::maximumIdentifierCount>(ruleData.descendantSelectorIdentifierHashes()))
        return;

    StyleRule* rule = ruleData.rule();
    SelectorChecker::MatchResult result;
    if (ruleMatches(ruleData, matchRequest.scope, behaviorAtBoundary, &result)) {
        // If the rule has no properties to apply, then ignore it in the non-debug mode.
        const StylePropertySet& properties = rule->properties();
        if (properties.isEmpty() && !matchRequest.includeEmptyRules)
            return;
        // FIXME: Exposing the non-standard getMatchedCSSRules API to web is the only reason this is needed.
        if (m_sameOriginOnly && !ruleData.hasDocumentSecurityOrigin())
            return;

        PseudoId dynamicPseudo = result.dynamicPseudo;
        // If we're matching normal rules, set a pseudo bit if
        // we really just matched a pseudo-element.
        if (dynamicPseudo != NOPSEUDO && m_pseudoStyleRequest.pseudoId == NOPSEUDO) {
            if (m_mode == SelectorChecker::CollectingCSSRules || m_mode == SelectorChecker::CollectingStyleRules)
                return;
            // FIXME: Matching should not modify the style directly.
            if (m_style && dynamicPseudo < FIRST_INTERNAL_PSEUDOID)
                m_style->setHasPseudoStyle(dynamicPseudo);
        } else {
            // Update our first/last rule indices in the matched rules array.
            ruleRange.shiftLastByOne();
            // Add this rule to our list of matched rules.
            addMatchedRule(&ruleData, result.specificity, cascadeScope, cascadeOrder, matchRequest.styleSheetIndex, matchRequest.styleSheet);
            return;
        }
    }
}

static inline bool compareRules(const MatchedRule& matchedRule1, const MatchedRule& matchedRule2)
{
    if (matchedRule1.cascadeScope() != matchedRule2.cascadeScope())
        return matchedRule1.cascadeScope() > matchedRule2.cascadeScope();

    unsigned specificity1 = matchedRule1.specificity();
    unsigned specificity2 = matchedRule2.specificity();
    if (specificity1 != specificity2)
        return specificity1 < specificity2;

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

void ElementRuleCollector::sortMatchedRules()
{
    ASSERT(m_matchedRules);
    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".
    // FIXME: Verify whether it's ok to ignore CascadeScope here.
    RuleRange ruleRange;
    collectMatchingRules(MatchRequest(ruleSet), ruleRange, SelectorChecker::StaysWithinTreeScope);

    return m_matchedRules && !m_matchedRules->isEmpty();
}

} // namespace WebCore