1 files changed, 560 insertions, 0 deletions
diff --git a/Source/WebCore/style/StyleTreeResolver.cpp b/Source/WebCore/style/StyleTreeResolver.cpp
new file mode 100644
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+++ b/Source/WebCore/style/StyleTreeResolver.cpp
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+/*
+ * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
+ *           (C) 1999 Antti Koivisto (koivisto@kde.org)
+ *           (C) 2001 Peter Kelly (pmk@post.com)
+ *           (C) 2001 Dirk Mueller (mueller@kde.org)
+ *           (C) 2007 David Smith (catfish.man@gmail.com)
+ * Copyright (C) 2004-2010, 2012-2016 Apple Inc. All rights reserved.
+ *           (C) 2007 Eric Seidel (eric@webkit.org)
+ *
+ * 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 "StyleTreeResolver.h"
+
+#include "CSSFontSelector.h"
+#include "ComposedTreeAncestorIterator.h"
+#include "ComposedTreeIterator.h"
+#include "ElementIterator.h"
+#include "HTMLBodyElement.h"
+#include "HTMLMeterElement.h"
+#include "HTMLNames.h"
+#include "HTMLProgressElement.h"
+#include "HTMLSlotElement.h"
+#include "LoaderStrategy.h"
+#include "MainFrame.h"
+#include "NodeRenderStyle.h"
+#include "Page.h"
+#include "PlatformStrategies.h"
+#include "Settings.h"
+#include "ShadowRoot.h"
+#include "StyleFontSizeFunctions.h"
+#include "StyleResolver.h"
+#include "StyleScope.h"
+#include "Text.h"
+
+namespace WebCore {
+
+namespace Style {
+
+static std::unique_ptr<RenderStyle> makePlaceholderStyle(Document& document)
+{
+    auto placeholderStyle = RenderStyle::createPtr();
+    placeholderStyle->setDisplay(NONE);
+    placeholderStyle->setIsPlaceholderStyle();
+
+    FontCascadeDescription fontDescription;
+    fontDescription.setOneFamily(standardFamily);
+    fontDescription.setKeywordSizeFromIdentifier(CSSValueMedium);
+    float size = Style::fontSizeForKeyword(CSSValueMedium, false, document);
+    fontDescription.setSpecifiedSize(size);
+    fontDescription.setComputedSize(size);
+    placeholderStyle->setFontDescription(fontDescription);
+
+    placeholderStyle->fontCascade().update(&document.fontSelector());
+    return placeholderStyle;
+}
+
+TreeResolver::TreeResolver(Document& document)
+    : m_document(document)
+{
+}
+
+TreeResolver::~TreeResolver()
+{
+}
+
+TreeResolver::Scope::Scope(Document& document)
+    : styleResolver(document.styleScope().resolver())
+    , sharingResolver(document, styleResolver.ruleSets(), selectorFilter)
+{
+}
+
+TreeResolver::Scope::Scope(ShadowRoot& shadowRoot, Scope& enclosingScope)
+    : styleResolver(shadowRoot.styleScope().resolver())
+    , sharingResolver(shadowRoot.documentScope(), styleResolver.ruleSets(), selectorFilter)
+    , shadowRoot(&shadowRoot)
+    , enclosingScope(&enclosingScope)
+{
+}
+
+TreeResolver::Parent::Parent(Document& document, Change change)
+    : element(nullptr)
+    , style(*document.renderStyle())
+    , change(change)
+{
+}
+
+TreeResolver::Parent::Parent(Element& element, const RenderStyle& style, Change change)
+    : element(&element)
+    , style(style)
+    , change(change)
+{
+}
+
+void TreeResolver::pushScope(ShadowRoot& shadowRoot)
+{
+    m_scopeStack.append(adoptRef(*new Scope(shadowRoot, scope())));
+    scope().styleResolver.setOverrideDocumentElementStyle(m_documentElementStyle.get());
+}
+
+void TreeResolver::pushEnclosingScope()
+{
+    ASSERT(scope().enclosingScope);
+    m_scopeStack.append(*scope().enclosingScope);
+    scope().styleResolver.setOverrideDocumentElementStyle(m_documentElementStyle.get());
+}
+
+void TreeResolver::popScope()
+{
+    scope().styleResolver.setOverrideDocumentElementStyle(nullptr);
+    return m_scopeStack.removeLast();
+}
+
+std::unique_ptr<RenderStyle> TreeResolver::styleForElement(Element& element, const RenderStyle& inheritedStyle)
+{
+    if (!m_document.haveStylesheetsLoaded() && !element.renderer()) {
+        m_document.setHasNodesWithPlaceholderStyle();
+        return makePlaceholderStyle(m_document);
+    }
+
+    if (element.hasCustomStyleResolveCallbacks()) {
+        RenderStyle* shadowHostStyle = scope().shadowRoot ? m_update->elementStyle(*scope().shadowRoot->host()) : nullptr;
+        if (auto customStyle = element.resolveCustomStyle(inheritedStyle, shadowHostStyle)) {
+            if (customStyle->relations)
+                commitRelations(WTFMove(customStyle->relations), *m_update);
+
+            return WTFMove(customStyle->renderStyle);
+        }
+    }
+
+    if (auto style = scope().sharingResolver.resolve(element, *m_update))
+        return style;
+
+    auto elementStyle = scope().styleResolver.styleForElement(element, &inheritedStyle, parentBoxStyle(), MatchAllRules, nullptr, &scope().selectorFilter);
+
+    if (elementStyle.relations)
+        commitRelations(WTFMove(elementStyle.relations), *m_update);
+
+    return WTFMove(elementStyle.renderStyle);
+}
+
+static void resetStyleForNonRenderedDescendants(Element& current)
+{
+    // FIXME: This is not correct with shadow trees. This should be done with ComposedTreeIterator.
+    bool elementNeedingStyleRecalcAffectsNextSiblingElementStyle = false;
+    for (auto& child : childrenOfType<Element>(current)) {
+        bool affectedByPreviousSibling = child.styleIsAffectedByPreviousSibling() && elementNeedingStyleRecalcAffectsNextSiblingElementStyle;
+        if (child.needsStyleRecalc() || elementNeedingStyleRecalcAffectsNextSiblingElementStyle)
+            elementNeedingStyleRecalcAffectsNextSiblingElementStyle = child.affectsNextSiblingElementStyle();
+
+        if (child.needsStyleRecalc() || affectedByPreviousSibling) {
+            child.resetComputedStyle();
+            child.resetStyleRelations();
+            child.setHasValidStyle();
+        }
+
+        if (child.childNeedsStyleRecalc()) {
+            resetStyleForNonRenderedDescendants(child);
+            child.clearChildNeedsStyleRecalc();
+        }
+    }
+}
+
+static bool affectsRenderedSubtree(Element& element, const RenderStyle& newStyle)
+{
+    if (element.renderer())
+        return true;
+    if (newStyle.display() != NONE)
+        return true;
+    if (element.rendererIsNeeded(newStyle))
+        return true;
+#if ENABLE(CSS_REGIONS)
+    if (element.shouldMoveToFlowThread(newStyle))
+        return true;
+#endif
+    return false;
+}
+
+ElementUpdate TreeResolver::resolveElement(Element& element)
+{
+    auto newStyle = styleForElement(element, parent().style);
+
+    if (!affectsRenderedSubtree(element, *newStyle))
+        return { };
+
+    auto update = createAnimatedElementUpdate(WTFMove(newStyle), element, parent().change);
+
+    auto* existingStyle = element.renderStyle();
+
+    if (&element == m_document.documentElement()) {
+        m_documentElementStyle = RenderStyle::clonePtr(*update.style);
+        scope().styleResolver.setOverrideDocumentElementStyle(m_documentElementStyle.get());
+
+        if (update.change != NoChange && existingStyle && existingStyle->fontSize() != update.style->fontSize()) {
+            // "rem" units are relative to the document element's font size so we need to recompute everything.
+            // In practice this is rare.
+            scope().styleResolver.invalidateMatchedPropertiesCache();
+            update.change = std::max(update.change, Force);
+        }
+    }
+
+    // This is needed for resolving color:-webkit-text for subsequent elements.
+    // FIXME: We shouldn't mutate document when resolving style.
+    if (&element == m_document.body())
+        m_document.setTextColor(update.style->visitedDependentColor(CSSPropertyColor));
+
+    // FIXME: These elements should not change renderer based on appearance property.
+    if (element.hasTagName(HTMLNames::meterTag) || is<HTMLProgressElement>(element)) {
+        if (existingStyle && update.style->appearance() != existingStyle->appearance())
+            update.change = Detach;
+    }
+
+    return update;
+}
+
+const RenderStyle* TreeResolver::parentBoxStyle() const
+{
+    // 'display: contents' doesn't generate boxes.
+    for (unsigned i = m_parentStack.size(); i; --i) {
+        auto& parent = m_parentStack[i - 1];
+        if (parent.style.display() == NONE)
+            return nullptr;
+        if (parent.style.display() != CONTENTS)
+            return &parent.style;
+    }
+    ASSERT_NOT_REACHED();
+    return nullptr;
+}
+
+ElementUpdate TreeResolver::createAnimatedElementUpdate(std::unique_ptr<RenderStyle> newStyle, Element& element, Change parentChange)
+{
+    auto validity = element.styleValidity();
+    bool recompositeLayer = element.styleResolutionShouldRecompositeLayer();
+
+    auto makeUpdate = [&] (std::unique_ptr<RenderStyle> style, Change change) {
+        if (validity >= Validity::SubtreeInvalid)
+            change = std::max(change, validity == Validity::SubtreeAndRenderersInvalid ? Detach : Force);
+        if (parentChange >= Force)
+            change = std::max(change, parentChange);
+        return ElementUpdate { WTFMove(style), change, recompositeLayer };
+    };
+
+    auto* renderer = element.renderer();
+
+    bool shouldReconstruct = validity >= Validity::SubtreeAndRenderersInvalid || parentChange == Detach;
+    if (shouldReconstruct)
+        return makeUpdate(WTFMove(newStyle), Detach);
+
+    if (!renderer) {
+        auto keepsDisplayContents = newStyle->display() == CONTENTS && element.hasDisplayContents();
+        // Some inherited property might have changed.
+        return makeUpdate(WTFMove(newStyle), keepsDisplayContents ? Inherit : Detach);
+    }
+
+    std::unique_ptr<RenderStyle> animatedStyle;
+    if (element.document().frame()->animation().updateAnimations(*renderer, *newStyle, animatedStyle))
+        recompositeLayer = true;
+
+    if (animatedStyle) {
+        auto change = determineChange(renderer->style(), *animatedStyle);
+        if (renderer->hasInitialAnimatedStyle()) {
+            renderer->setHasInitialAnimatedStyle(false);
+            // When we initialize a newly created renderer with initial animated style we don't inherit it to descendants.
+            // The first animation frame needs to correct this.
+            // FIXME: We should compute animated style correctly during initial style resolution when we don't have renderers yet.
+            //        https://bugs.webkit.org/show_bug.cgi?id=171926
+            change = std::max(change, Inherit);
+        }
+        // If animation forces render tree reconstruction pass the original style. The animation will be applied on renderer construction.
+        // FIXME: We should always use the animated style here.
+        auto style = change == Detach ? WTFMove(newStyle) : WTFMove(animatedStyle);
+        return makeUpdate(WTFMove(style), change);
+    }
+
+    auto change = determineChange(renderer->style(), *newStyle);
+    return makeUpdate(WTFMove(newStyle), change);
+}
+
+void TreeResolver::pushParent(Element& element, const RenderStyle& style, Change change)
+{
+    scope().selectorFilter.pushParent(&element);
+
+    Parent parent(element, style, change);
+
+    if (auto* shadowRoot = element.shadowRoot()) {
+        pushScope(*shadowRoot);
+        parent.didPushScope = true;
+    }
+    else if (is<HTMLSlotElement>(element) && downcast<HTMLSlotElement>(element).assignedNodes()) {
+        pushEnclosingScope();
+        parent.didPushScope = true;
+    }
+
+    m_parentStack.append(WTFMove(parent));
+}
+
+void TreeResolver::popParent()
+{
+    auto& parentElement = *parent().element;
+
+    parentElement.setHasValidStyle();
+    parentElement.clearChildNeedsStyleRecalc();
+
+    if (parent().didPushScope)
+        popScope();
+
+    scope().selectorFilter.popParent();
+
+    m_parentStack.removeLast();
+}
+
+void TreeResolver::popParentsToDepth(unsigned depth)
+{
+    ASSERT(depth);
+    ASSERT(m_parentStack.size() >= depth);
+
+    while (m_parentStack.size() > depth)
+        popParent();
+}
+
+static bool shouldResolvePseudoElement(const PseudoElement* pseudoElement)
+{
+    if (!pseudoElement)
+        return false;
+    return pseudoElement->needsStyleRecalc();
+}
+
+static bool shouldResolveElement(const Element& element, Style::Change parentChange)
+{
+    if (parentChange >= Inherit)
+        return true;
+    if (parentChange == NoInherit) {
+        auto* existingStyle = element.renderStyle();
+        if (existingStyle && existingStyle->hasExplicitlyInheritedProperties())
+            return true;
+    }
+    if (element.needsStyleRecalc())
+        return true;
+    if (element.hasDisplayContents())
+        return true;
+    if (shouldResolvePseudoElement(element.beforePseudoElement()))
+        return true;
+    if (shouldResolvePseudoElement(element.afterPseudoElement()))
+        return true;
+
+    return false;
+}
+
+static void clearNeedsStyleResolution(Element& element)
+{
+    element.setHasValidStyle();
+    if (auto* before = element.beforePseudoElement())
+        before->setHasValidStyle();
+    if (auto* after = element.afterPseudoElement())
+        after->setHasValidStyle();
+}
+
+void TreeResolver::resolveComposedTree()
+{
+    ASSERT(m_parentStack.size() == 1);
+    ASSERT(m_scopeStack.size() == 1);
+
+    auto descendants = composedTreeDescendants(m_document);
+    auto it = descendants.begin();
+    auto end = descendants.end();
+
+    // FIXME: SVG <use> element may cause tree mutations during style recalc.
+    it.dropAssertions();
+
+    while (it != end) {
+        popParentsToDepth(it.depth());
+
+        auto& node = *it;
+        auto& parent = this->parent();
+
+        ASSERT(node.isConnected());
+        ASSERT(node.containingShadowRoot() == scope().shadowRoot);
+        ASSERT(node.parentElement() == parent.element || is<ShadowRoot>(node.parentNode()) || node.parentElement()->shadowRoot());
+
+        if (is<Text>(node)) {
+            auto& text = downcast<Text>(node);
+            if (text.styleValidity() >= Validity::SubtreeAndRenderersInvalid && parent.change != Detach)
+                m_update->addText(text, parent.element);
+
+            text.setHasValidStyle();
+            it.traverseNextSkippingChildren();
+            continue;
+        }
+
+        auto& element = downcast<Element>(node);
+
+        if (it.depth() > Settings::defaultMaximumRenderTreeDepth) {
+            resetStyleForNonRenderedDescendants(element);
+            element.clearChildNeedsStyleRecalc();
+            it.traverseNextSkippingChildren();
+            continue;
+        }
+
+        // FIXME: We should deal with this during style invalidation.
+        bool affectedByPreviousSibling = element.styleIsAffectedByPreviousSibling() && parent.elementNeedingStyleRecalcAffectsNextSiblingElementStyle;
+        if (element.needsStyleRecalc() || parent.elementNeedingStyleRecalcAffectsNextSiblingElementStyle)
+            parent.elementNeedingStyleRecalcAffectsNextSiblingElementStyle = element.affectsNextSiblingElementStyle();
+
+        auto* style = element.renderStyle();
+        auto change = NoChange;
+
+        bool shouldResolve = shouldResolveElement(element, parent.change) || affectedByPreviousSibling;
+        if (shouldResolve) {
+            element.resetComputedStyle();
+            element.resetStyleRelations();
+
+            if (element.hasCustomStyleResolveCallbacks())
+                element.willRecalcStyle(parent.change);
+
+            auto elementUpdate = resolveElement(element);
+
+            if (element.hasCustomStyleResolveCallbacks())
+                element.didRecalcStyle(elementUpdate.change);
+
+            style = elementUpdate.style.get();
+            change = elementUpdate.change;
+
+            if (affectedByPreviousSibling && change != Detach)
+                change = Force;
+
+            if (elementUpdate.style)
+                m_update->addElement(element, parent.element, WTFMove(elementUpdate));
+
+            clearNeedsStyleResolution(element);
+        }
+
+        if (!style) {
+            resetStyleForNonRenderedDescendants(element);
+            element.clearChildNeedsStyleRecalc();
+        }
+
+        bool shouldIterateChildren = style && (element.childNeedsStyleRecalc() || change != NoChange);
+        if (!shouldIterateChildren) {
+            it.traverseNextSkippingChildren();
+            continue;
+        }
+
+        pushParent(element, *style, change);
+
+        it.traverseNext();
+    }
+
+    popParentsToDepth(1);
+}
+
+std::unique_ptr<Update> TreeResolver::resolve(Change change)
+{
+    auto& renderView = *m_document.renderView();
+
+    Element* documentElement = m_document.documentElement();
+    if (!documentElement) {
+        m_document.styleScope().resolver();
+        return nullptr;
+    }
+    if (change != Force && !documentElement->childNeedsStyleRecalc() && !documentElement->needsStyleRecalc())
+        return nullptr;
+
+    m_update = std::make_unique<Update>(m_document);
+    m_scopeStack.append(adoptRef(*new Scope(m_document)));
+    m_parentStack.append(Parent(m_document, change));
+
+    // Pseudo element removal and similar may only work with these flags still set. Reset them after the style recalc.
+    renderView.setUsesFirstLineRules(renderView.usesFirstLineRules() || scope().styleResolver.usesFirstLineRules());
+    renderView.setUsesFirstLetterRules(renderView.usesFirstLetterRules() || scope().styleResolver.usesFirstLetterRules());
+
+    resolveComposedTree();
+
+    renderView.setUsesFirstLineRules(scope().styleResolver.usesFirstLineRules());
+    renderView.setUsesFirstLetterRules(scope().styleResolver.usesFirstLetterRules());
+
+    ASSERT(m_scopeStack.size() == 1);
+    ASSERT(m_parentStack.size() == 1);
+    m_parentStack.clear();
+    popScope();
+
+    if (m_update->roots().isEmpty())
+        return { };
+
+    return WTFMove(m_update);
+}
+
+static Vector<Function<void ()>>& postResolutionCallbackQueue()
+{
+    static NeverDestroyed<Vector<Function<void ()>>> vector;
+    return vector;
+}
+
+void queuePostResolutionCallback(Function<void ()>&& callback)
+{
+    postResolutionCallbackQueue().append(WTFMove(callback));
+}
+
+static void suspendMemoryCacheClientCalls(Document& document)
+{
+    Page* page = document.page();
+    if (!page || !page->areMemoryCacheClientCallsEnabled())
+        return;
+
+    page->setMemoryCacheClientCallsEnabled(false);
+
+    postResolutionCallbackQueue().append([protectedMainFrame = Ref<MainFrame>(page->mainFrame())] {
+        if (Page* page = protectedMainFrame->page())
+            page->setMemoryCacheClientCallsEnabled(true);
+    });
+}
+
+static unsigned resolutionNestingDepth;
+
+PostResolutionCallbackDisabler::PostResolutionCallbackDisabler(Document& document)
+{
+    ++resolutionNestingDepth;
+
+    if (resolutionNestingDepth == 1)
+        platformStrategies()->loaderStrategy()->suspendPendingRequests();
+
+    // FIXME: It's strange to build this into the disabler.
+    suspendMemoryCacheClientCalls(document);
+}
+
+PostResolutionCallbackDisabler::~PostResolutionCallbackDisabler()
+{
+    if (resolutionNestingDepth == 1) {
+        // Get size each time through the loop because a callback can add more callbacks to the end of the queue.
+        auto& queue = postResolutionCallbackQueue();
+        for (size_t i = 0; i < queue.size(); ++i)
+            queue[i]();
+        queue.clear();
+
+        platformStrategies()->loaderStrategy()->resumePendingRequests();
+    }
+
+    --resolutionNestingDepth;
+}
+
+bool postResolutionCallbacksAreSuspended()
+{
+    return resolutionNestingDepth;
+}
+
+}
+}