Source/WebCore/style/StyleInvalidator.cpp

/*
 * Copyright (C) 2012, 2014, 2017 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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#include "config.h"
#include "StyleInvalidator.h"

#include "CSSSelectorList.h"
#include "Document.h"
#include "ElementIterator.h"
#include "ElementRuleCollector.h"
#include "HTMLSlotElement.h"
#include "SelectorFilter.h"
#include "ShadowRoot.h"
#include "StyleRuleImport.h"
#include "StyleSheetContents.h"

namespace WebCore {
namespace Style {

static bool shouldDirtyAllStyle(const Vector<RefPtr<StyleRuleBase>>& rules)
{
    for (auto& rule : rules) {
        if (is<StyleRuleMedia>(*rule)) {
            const auto* childRules = downcast<StyleRuleMedia>(*rule).childRulesWithoutDeferredParsing();
            if (childRules && shouldDirtyAllStyle(*childRules))
                return true;
            continue;
        }
        // FIXME: At least font faces don't need full recalc in all cases.
        if (!is<StyleRule>(*rule))
            return true;
    }
    return false;
}

static bool shouldDirtyAllStyle(const StyleSheetContents& sheet)
{
    for (auto& import : sheet.importRules()) {
        if (!import->styleSheet())
            continue;
        if (shouldDirtyAllStyle(*import->styleSheet()))
            return true;
    }
    if (shouldDirtyAllStyle(sheet.childRules()))
        return true;
    return false;
}

static bool shouldDirtyAllStyle(const Vector<StyleSheetContents*>& sheets)
{
    for (auto& sheet : sheets) {
        if (shouldDirtyAllStyle(*sheet))
            return true;
    }
    return false;
}

Invalidator::Invalidator(const Vector<StyleSheetContents*>& sheets, const MediaQueryEvaluator& mediaQueryEvaluator)
    : m_ownedRuleSet(std::make_unique<RuleSet>())
    , m_ruleSet(*m_ownedRuleSet)
    , m_dirtiesAllStyle(shouldDirtyAllStyle(sheets))
{
    if (m_dirtiesAllStyle)
        return;

    m_ownedRuleSet->disableAutoShrinkToFit();
    for (auto& sheet : sheets)
        m_ownedRuleSet->addRulesFromSheet(*sheet, mediaQueryEvaluator);

    m_hasShadowPseudoElementRulesInAuthorSheet = m_ruleSet.hasShadowPseudoElementRules();
}

Invalidator::Invalidator(const RuleSet& ruleSet)
    : m_ruleSet(ruleSet)
    , m_hasShadowPseudoElementRulesInAuthorSheet(ruleSet.hasShadowPseudoElementRules())
{
}

Invalidator::CheckDescendants Invalidator::invalidateIfNeeded(Element& element, const SelectorFilter* filter)
{
    if (m_hasShadowPseudoElementRulesInAuthorSheet) {
        // FIXME: This could do actual rule matching too.
        if (element.shadowRoot())
            element.invalidateStyleForSubtreeInternal();
    }

    bool shouldCheckForSlots = !m_ruleSet.slottedPseudoElementRules().isEmpty() && !m_didInvalidateHostChildren;
    if (shouldCheckForSlots && is<HTMLSlotElement>(element)) {
        auto* containingShadowRoot = element.containingShadowRoot();
        if (containingShadowRoot && containingShadowRoot->host()) {
            for (auto& possiblySlotted : childrenOfType<Element>(*containingShadowRoot->host()))
                possiblySlotted.invalidateStyleInternal();
        }
        // No need to do this again.
        m_didInvalidateHostChildren = true;
    }

    switch (element.styleValidity()) {
    case Style::Validity::Valid: {
        ElementRuleCollector ruleCollector(element, m_ruleSet, filter);
        ruleCollector.setMode(SelectorChecker::Mode::CollectingRulesIgnoringVirtualPseudoElements);
        ruleCollector.matchAuthorRules(false);

        if (ruleCollector.hasMatchedRules())
            element.invalidateStyleInternal();
        return CheckDescendants::Yes;
    }
    case Style::Validity::ElementInvalid:
        return CheckDescendants::Yes;
    case Style::Validity::SubtreeInvalid:
    case Style::Validity::SubtreeAndRenderersInvalid:
        if (shouldCheckForSlots)
            return CheckDescendants::Yes;
        return CheckDescendants::No;
    }
    ASSERT_NOT_REACHED();
    return CheckDescendants::Yes;
}

void Invalidator::invalidateStyleForTree(Element& root, SelectorFilter* filter)
{
    if (invalidateIfNeeded(root, filter) == CheckDescendants::No)
        return;
    invalidateStyleForDescendants(root, filter);
}

void Invalidator::invalidateStyleForDescendants(Element& root, SelectorFilter* filter)
{
    Vector<Element*, 20> parentStack;
    Element* previousElement = &root;
    auto descendants = descendantsOfType<Element>(root);
    for (auto it = descendants.begin(), end = descendants.end(); it != end;) {
        auto& descendant = *it;
        auto* parent = descendant.parentElement();
        if (parentStack.isEmpty() || parentStack.last() != parent) {
            if (parent == previousElement) {
                parentStack.append(parent);
                if (filter)
                    filter->pushParentInitializingIfNeeded(*parent);
            } else {
                while (parentStack.last() != parent) {
                    parentStack.removeLast();
                    if (filter)
                        filter->popParent();
                }
            }
        }
        previousElement = &descendant;

        if (invalidateIfNeeded(descendant, filter) == CheckDescendants::Yes)
            it.traverseNext();
        else
            it.traverseNextSkippingChildren();
    }
}

void Invalidator::invalidateStyle(Document& document)
{
    ASSERT(!m_dirtiesAllStyle);

    Element* documentElement = document.documentElement();
    if (!documentElement)
        return;

    SelectorFilter filter;
    invalidateStyleForTree(*documentElement, &filter);
}

void Invalidator::invalidateStyle(ShadowRoot& shadowRoot)
{
    ASSERT(!m_dirtiesAllStyle);

    if (!m_ruleSet.hostPseudoClassRules().isEmpty() && shadowRoot.host())
        shadowRoot.host()->invalidateStyleInternal();

    for (auto& child : childrenOfType<Element>(shadowRoot)) {
        SelectorFilter filter;
        invalidateStyleForTree(child, &filter);
    }
}

void Invalidator::invalidateStyle(Element& element)
{
    ASSERT(!m_dirtiesAllStyle);

    // Don't use SelectorFilter as the rule sets here tend to be small and the filter would have setup cost deep in the tree.
    invalidateStyleForTree(element, nullptr);
}

void Invalidator::invalidateStyleWithMatchElement(Element& element, MatchElement matchElement)
{
    switch (matchElement) {
    case MatchElement::Subject: {
        invalidateIfNeeded(element, nullptr);
        break;
    }
    case MatchElement::Parent: {
        auto children = childrenOfType<Element>(element);
        for (auto& child : children)
            invalidateIfNeeded(child, nullptr);
        break;
    }
    case MatchElement::Ancestor: {
        SelectorFilter filter;
        invalidateStyleForDescendants(element, &filter);
        break;
    }
    case MatchElement::DirectSibling:
        if (auto* sibling = element.nextElementSibling())
            invalidateIfNeeded(*sibling, nullptr);
        break;
    case MatchElement::IndirectSibling:
        for (auto* sibling = element.nextElementSibling(); sibling; sibling = sibling->nextElementSibling())
            invalidateIfNeeded(*sibling, nullptr);
        break;
    case MatchElement::AnySibling: {
        auto parentChildren = childrenOfType<Element>(*element.parentNode());
        for (auto& parentChild : parentChildren)
            invalidateIfNeeded(parentChild, nullptr);
        break;
    }
    case MatchElement::ParentSibling:
        for (auto* sibling = element.nextElementSibling(); sibling; sibling = sibling->nextElementSibling()) {
            auto siblingChildren = childrenOfType<Element>(*sibling);
            for (auto& siblingChild : siblingChildren)
                invalidateIfNeeded(siblingChild, nullptr);
        }
        break;
    case MatchElement::AncestorSibling: {
        SelectorFilter filter;
        for (auto* sibling = element.nextElementSibling(); sibling; sibling = sibling->nextElementSibling()) {
            filter.popParentsUntil(element.parentElement());
            invalidateStyleForDescendants(*sibling, &filter);
        }
        break;
    }
    case MatchElement::Host:
        // FIXME: Handle this here as well.
        break;
    }
}

}
}