flutter_flutter/engine/core/css/RuleFeature.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 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/RuleFeature.h"

#include "core/css/CSSSelector.h"
#include "core/css/CSSSelectorList.h"
#include "core/css/RuleSet.h"
#include "core/css/StyleRule.h"
#include "core/css/invalidation/DescendantInvalidationSet.h"
#include "core/dom/Element.h"
#include "core/dom/Node.h"
#include "platform/RuntimeEnabledFeatures.h"
#include "wtf/BitVector.h"

namespace blink {

static bool isSkippableComponentForInvalidation(const CSSSelector& selector)
{
    if (selector.match() == CSSSelector::Tag) {
        ASSERT(selector.tagQName().localName() == starAtom);
        return true;
    }
    if (selector.match() == CSSSelector::PseudoElement)
        return false;
    if (selector.match() != CSSSelector::PseudoClass)
        return false;
    switch (selector.pseudoType()) {
    case CSSSelector::PseudoHover:
    case CSSSelector::PseudoFocus:
    case CSSSelector::PseudoActive:
    case CSSSelector::PseudoLang:
    case CSSSelector::PseudoUnresolved:
        return true;
    default:
        return false;
    }
}

RuleFeature::RuleFeature(StyleRule* rule, unsigned selectorIndex)
    : rule(rule)
    , selectorIndex(selectorIndex)
{
}

void RuleFeature::trace(Visitor* visitor)
{
    visitor->trace(rule);
}

// This method is somewhat conservative in what it accepts.
RuleFeatureSet::InvalidationSetMode RuleFeatureSet::invalidationSetModeForSelector(const CSSSelector& selector)
{
    bool foundCombinator = false;
    bool foundIdent = false;
    for (const CSSSelector* component = &selector; component; component = component->tagHistory()) {

        if (component->match() == CSSSelector::Class || component->match() == CSSSelector::Id
            || (component->match() == CSSSelector::Tag && component->tagQName().localName() != starAtom)
            || component->isAttributeSelector() || component->isCustomPseudoElement()) {
            if (!foundCombinator) {
                // We have found an invalidation set feature in the rightmost compound selector.
                foundIdent = true;
            }
        } else if (component->pseudoType() == CSSSelector::PseudoHost) {
            if (const CSSSelectorList* selectorList = component->selectorList()) {
                // Features inside :not() are not added to the feature set, so consider it a universal selector.
                bool foundUniversal = false;
                for (const CSSSelector* selector = selectorList->first(); selector; selector = CSSSelectorList::next(*selector)) {
                    // Find the invalidation set mode for each of the selectors in the selector list
                    // of a :not(), :host(), etc. For instance, ".x :-webkit-any(.a, .b)" yields an
                    // AddFeatures mode for both ".a" and ".b". ":-webkit-any(.a, *)" yields AddFeatures
                    // for ".a", but UseSubtreeStyleChange for "*". One sub-selector without invalidation
                    // set features is sufficient to cause the selector to be a universal selector as far
                    // the invalidation set is concerned.
                    InvalidationSetMode subSelectorMode = invalidationSetModeForSelector(*selector);

                    // The sub-selector contained something unskippable, fall back to whole subtree
                    // recalcs in collectFeaturesFromSelector. subSelectorMode will return
                    // UseSubtreeStyleChange since there are no combinators inside the selector list,
                    // so translate it to UseLocalStyleChange if a combinator has been seen in the
                    // outer context.
                    //
                    // FIXME: Is UseSubtreeStyleChange ever needed as input to collectFeaturesFromSelector?
                    // That is, are there any selectors for which we need to use SubtreeStyleChange for
                    // changing features when present in the rightmost compound selector?
                    if (subSelectorMode == UseSubtreeStyleChange)
                        return foundCombinator ? UseLocalStyleChange : UseSubtreeStyleChange;

                    // We found no features in the sub-selector, only skippable ones (foundIdent was
                    // false at the end of this method). That is a universal selector as far as the
                    // invalidation set is concerned.
                    if (subSelectorMode == UseLocalStyleChange)
                        foundUniversal = true;
                }
                if (!foundUniversal && !foundCombinator) {
                    // All sub-selectors contained invalidation set features and
                    // we are in the rightmost compound selector.
                    foundIdent = true;
                }
            }
        } else if (!isSkippableComponentForInvalidation(*component)) {
            return foundCombinator ? UseLocalStyleChange : UseSubtreeStyleChange;
        }
        foundCombinator = true;
    }
    return foundIdent ? AddFeatures : UseLocalStyleChange;
}

void RuleFeatureSet::extractInvalidationSetFeature(const CSSSelector& selector, InvalidationSetFeatures& features)
{
    if (selector.match() == CSSSelector::Tag)
        features.tagName = selector.tagQName().localName();
    else if (selector.match() == CSSSelector::Id)
        features.id = selector.value();
    else if (selector.match() == CSSSelector::Class)
        features.classes.append(selector.value());
    else if (selector.isAttributeSelector())
        features.attributes.append(selector.attribute().localName());
    else if (selector.isCustomPseudoElement())
        features.customPseudoElement = true;
}

RuleFeatureSet::RuleFeatureSet()
    : m_targetedStyleRecalcEnabled(RuntimeEnabledFeatures::targetedStyleRecalcEnabled())
{
}

RuleFeatureSet::~RuleFeatureSet()
{
}

DescendantInvalidationSet* RuleFeatureSet::invalidationSetForSelector(const CSSSelector& selector)
{
    if (selector.match() == CSSSelector::Class)
        return &ensureClassInvalidationSet(selector.value());
    if (selector.isAttributeSelector())
        return &ensureAttributeInvalidationSet(selector.attribute().localName());
    if (selector.match() == CSSSelector::Id)
        return &ensureIdInvalidationSet(selector.value());
    if (selector.match() == CSSSelector::PseudoClass) {
        CSSSelector::PseudoType pseudo = selector.pseudoType();
        if (pseudo == CSSSelector::PseudoHover || pseudo == CSSSelector::PseudoActive || pseudo == CSSSelector::PseudoFocus)
            return &ensurePseudoInvalidationSet(pseudo);
    }
    return 0;
}

// Given a selector, update the descendant invalidation sets for the features found
// in the selector. The first step is to extract the features from the rightmost
// compound selector (extractInvalidationSetFeatures). Secondly, those features will be
// added to the invalidation sets for the features found in the other compound selectors
// (addFeaturesToInvalidationSets).

RuleFeatureSet::InvalidationSetMode RuleFeatureSet::updateInvalidationSets(const CSSSelector& selector)
{
    InvalidationSetMode mode = invalidationSetModeForSelector(selector);
    if (mode != AddFeatures)
        return mode;

    InvalidationSetFeatures features;
    if (const CSSSelector* current = extractInvalidationSetFeatures(selector, features, false))
        addFeaturesToInvalidationSets(*current, features);
    return AddFeatures;
}

const CSSSelector* RuleFeatureSet::extractInvalidationSetFeatures(const CSSSelector& selector, InvalidationSetFeatures& features, bool negated)
{
    for (const CSSSelector* current = &selector; current; current = current->tagHistory()) {
        if (!negated)
            extractInvalidationSetFeature(*current, features);
        // Initialize the entry in the invalidation set map, if supported.
        invalidationSetForSelector(*current);
        if (current->pseudoType() == CSSSelector::PseudoHost) {
            if (const CSSSelectorList* selectorList = current->selectorList()) {
                for (const CSSSelector* selector = selectorList->first(); selector; selector = CSSSelectorList::next(*selector))
                    extractInvalidationSetFeatures(*selector, features, false);
            }
        }
    }
    return 0;
}

// Add features extracted from the rightmost compound selector to descendant invalidation
// sets for features found in other compound selectors.
//
// As we encounter a descendant type of combinator, the features only need to be checked
// against descendants in the same subtree only. Hence wholeSubtree is reset to false.

void RuleFeatureSet::addFeaturesToInvalidationSets(const CSSSelector& selector, InvalidationSetFeatures& features)
{
    for (const CSSSelector* current = &selector; current; current = current->tagHistory()) {
        if (DescendantInvalidationSet* invalidationSet = invalidationSetForSelector(*current)) {
            if (features.treeBoundaryCrossing)
                invalidationSet->setTreeBoundaryCrossing();
            if (features.wholeSubtree) {
                invalidationSet->setWholeSubtreeInvalid();
            } else {
                if (!features.id.isEmpty())
                    invalidationSet->addId(features.id);
                if (!features.tagName.isEmpty())
                    invalidationSet->addTagName(features.tagName);
                for (Vector<AtomicString>::const_iterator it = features.classes.begin(); it != features.classes.end(); ++it)
                    invalidationSet->addClass(*it);
                for (Vector<AtomicString>::const_iterator it = features.attributes.begin(); it != features.attributes.end(); ++it)
                    invalidationSet->addAttribute(*it);
                if (features.customPseudoElement)
                    invalidationSet->setCustomPseudoInvalid();
            }
        } else {
            if (current->pseudoType() == CSSSelector::PseudoHost)
                features.treeBoundaryCrossing = true;
            if (const CSSSelectorList* selectorList = current->selectorList()) {
                ASSERT(current->pseudoType() == CSSSelector::PseudoHost);
                for (const CSSSelector* selector = selectorList->first(); selector; selector = CSSSelectorList::next(*selector))
                    addFeaturesToInvalidationSets(*selector, features);
            }
        }
    }
}

void RuleFeatureSet::addContentAttr(const AtomicString& attributeName)
{
    DescendantInvalidationSet& invalidationSet = ensureAttributeInvalidationSet(attributeName);
    invalidationSet.setWholeSubtreeInvalid();
}

void RuleFeatureSet::collectFeaturesFromRuleData(const RuleData& ruleData)
{
    InvalidationSetMode mode = UseSubtreeStyleChange;
    if (m_targetedStyleRecalcEnabled)
        mode = updateInvalidationSets(ruleData.selector());

    collectFeaturesFromSelector(ruleData.selector(), mode);

    if (ruleData.containsAttributeSelector())
        attributeRules.append(RuleFeature(ruleData.rule(), ruleData.selectorIndex()));
}

DescendantInvalidationSet& RuleFeatureSet::ensureClassInvalidationSet(const AtomicString& className)
{
    InvalidationSetMap::AddResult addResult = m_classInvalidationSets.add(className, nullptr);
    if (addResult.isNewEntry)
        addResult.storedValue->value = DescendantInvalidationSet::create();
    return *addResult.storedValue->value;
}

DescendantInvalidationSet& RuleFeatureSet::ensureAttributeInvalidationSet(const AtomicString& attributeName)
{
    InvalidationSetMap::AddResult addResult = m_attributeInvalidationSets.add(attributeName, nullptr);
    if (addResult.isNewEntry)
        addResult.storedValue->value = DescendantInvalidationSet::create();
    return *addResult.storedValue->value;
}

DescendantInvalidationSet& RuleFeatureSet::ensureIdInvalidationSet(const AtomicString& id)
{
    InvalidationSetMap::AddResult addResult = m_idInvalidationSets.add(id, nullptr);
    if (addResult.isNewEntry)
        addResult.storedValue->value = DescendantInvalidationSet::create();
    return *addResult.storedValue->value;
}

DescendantInvalidationSet& RuleFeatureSet::ensurePseudoInvalidationSet(CSSSelector::PseudoType pseudoType)
{
    PseudoTypeInvalidationSetMap::AddResult addResult = m_pseudoInvalidationSets.add(pseudoType, nullptr);
    if (addResult.isNewEntry)
        addResult.storedValue->value = DescendantInvalidationSet::create();
    return *addResult.storedValue->value;
}

void RuleFeatureSet::collectFeaturesFromSelector(const CSSSelector& selector)
{
    collectFeaturesFromSelector(selector, UseSubtreeStyleChange);
}

void RuleFeatureSet::collectFeaturesFromSelector(const CSSSelector& selector, InvalidationSetMode mode)
{
    for (const CSSSelector* current = &selector; current; current = current->tagHistory()) {
        if (mode != AddFeatures) {
            if (DescendantInvalidationSet* invalidationSet = invalidationSetForSelector(*current)) {
                if (mode == UseSubtreeStyleChange)
                    invalidationSet->setWholeSubtreeInvalid();
            }
        }

        collectFeaturesFromSelectorList(current->selectorList(), mode);
    }
}

void RuleFeatureSet::collectFeaturesFromSelectorList(const CSSSelectorList* selectorList, InvalidationSetMode mode)
{
    if (!selectorList)
        return;

    for (const CSSSelector* selector = selectorList->first(); selector; selector = CSSSelectorList::next(*selector))
        collectFeaturesFromSelector(*selector, mode);
}

void RuleFeatureSet::add(const RuleFeatureSet& other)
{
    for (InvalidationSetMap::const_iterator it = other.m_classInvalidationSets.begin(); it != other.m_classInvalidationSets.end(); ++it)
        ensureClassInvalidationSet(it->key).combine(*it->value);
    for (InvalidationSetMap::const_iterator it = other.m_attributeInvalidationSets.begin(); it != other.m_attributeInvalidationSets.end(); ++it)
        ensureAttributeInvalidationSet(it->key).combine(*it->value);
    for (InvalidationSetMap::const_iterator it = other.m_idInvalidationSets.begin(); it != other.m_idInvalidationSets.end(); ++it)
        ensureIdInvalidationSet(it->key).combine(*it->value);
    for (PseudoTypeInvalidationSetMap::const_iterator it = other.m_pseudoInvalidationSets.begin(); it != other.m_pseudoInvalidationSets.end(); ++it)
        ensurePseudoInvalidationSet(static_cast<CSSSelector::PseudoType>(it->key)).combine(*it->value);

    attributeRules.appendVector(other.attributeRules);
}

void RuleFeatureSet::clear()
{
    attributeRules.clear();
    m_classInvalidationSets.clear();
    m_attributeInvalidationSets.clear();
    m_idInvalidationSets.clear();
    // We cannot clear m_styleInvalidator here, because the style invalidator might not
    // have been evaluated yet. If not yet, in StyleInvalidator, there exists some element
    // who has needsStyleInvlidation but does not have any invalidation list.
    // This makes Blink not to recalc style correctly. crbug.com/344729.
}

void RuleFeatureSet::scheduleStyleInvalidationForClassChange(const SpaceSplitString& changedClasses, Element& element)
{
    unsigned changedSize = changedClasses.size();
    for (unsigned i = 0; i < changedSize; ++i) {
        addClassToInvalidationSet(changedClasses[i], element);
    }
}

void RuleFeatureSet::scheduleStyleInvalidationForClassChange(const SpaceSplitString& oldClasses, const SpaceSplitString& newClasses, Element& element)
{
    if (!oldClasses.size()) {
        scheduleStyleInvalidationForClassChange(newClasses, element);
        return;
    }

    // Class vectors tend to be very short. This is faster than using a hash table.
    BitVector remainingClassBits;
    remainingClassBits.ensureSize(oldClasses.size());

    for (unsigned i = 0; i < newClasses.size(); ++i) {
        bool found = false;
        for (unsigned j = 0; j < oldClasses.size(); ++j) {
            if (newClasses[i] == oldClasses[j]) {
                // Mark each class that is still in the newClasses so we can skip doing
                // an n^2 search below when looking for removals. We can't break from
                // this loop early since a class can appear more than once.
                remainingClassBits.quickSet(j);
                found = true;
            }
        }
        // Class was added.
        if (!found)
            addClassToInvalidationSet(newClasses[i], element);
    }

    for (unsigned i = 0; i < oldClasses.size(); ++i) {
        if (remainingClassBits.quickGet(i))
            continue;
        // Class was removed.
        addClassToInvalidationSet(oldClasses[i], element);
    }
}

void RuleFeatureSet::scheduleStyleInvalidationForAttributeChange(const QualifiedName& attributeName, Element& element)
{

    if (RefPtrWillBeRawPtr<DescendantInvalidationSet> invalidationSet = m_attributeInvalidationSets.get(attributeName.localName()))
        m_styleInvalidator.scheduleInvalidation(invalidationSet, element);
}

void RuleFeatureSet::scheduleStyleInvalidationForIdChange(const AtomicString& oldId, const AtomicString& newId, Element& element)
{
    if (!oldId.isEmpty()) {
        if (RefPtrWillBeRawPtr<DescendantInvalidationSet> invalidationSet = m_idInvalidationSets.get(oldId))
            m_styleInvalidator.scheduleInvalidation(invalidationSet, element);
    }
    if (!newId.isEmpty()) {
        if (RefPtrWillBeRawPtr<DescendantInvalidationSet> invalidationSet = m_idInvalidationSets.get(newId))
            m_styleInvalidator.scheduleInvalidation(invalidationSet, element);
    }
}

void RuleFeatureSet::scheduleStyleInvalidationForPseudoChange(CSSSelector::PseudoType pseudo, Element& element)
{
    if (RefPtrWillBeRawPtr<DescendantInvalidationSet> invalidationSet = m_pseudoInvalidationSets.get(pseudo))
        m_styleInvalidator.scheduleInvalidation(invalidationSet, element);
}

void RuleFeatureSet::addClassToInvalidationSet(const AtomicString& className, Element& element)
{
    if (RefPtrWillBeRawPtr<DescendantInvalidationSet> invalidationSet = m_classInvalidationSets.get(className))
        m_styleInvalidator.scheduleInvalidation(invalidationSet, element);
}

StyleInvalidator& RuleFeatureSet::styleInvalidator()
{
    return m_styleInvalidator;
}

void RuleFeatureSet::trace(Visitor* visitor)
{
#if ENABLE(OILPAN)
    visitor->trace(attributeRules);
    visitor->trace(m_classInvalidationSets);
    visitor->trace(m_attributeInvalidationSets);
    visitor->trace(m_idInvalidationSets);
    visitor->trace(m_pseudoInvalidationSets);
    visitor->trace(m_styleInvalidator);
#endif
}

} // namespace blink