Get rid of TreeBoundaryCrossingRules.

Source/core/css/resolver/StyleResolver.cpp

Index: Source/core/css/resolver/StyleResolver.cpp
diff --git a/Source/core/css/resolver/StyleResolver.cpp b/Source/core/css/resolver/StyleResolver.cpp
index 6126f704eb577fe785d9340ae24832bb01b0149d..d66178a0cb26805dd6e80ccc2fa75a5359bb1007 100644
--- a/Source/core/css/resolver/StyleResolver.cpp
+++ b/Source/core/css/resolver/StyleResolver.cpp
@@ -124,21 +124,6 @@ static StylePropertySet* rightToLeftDeclaration()
     return rightToLeftDecl;
 }
 
-static void collectScopedResolversForHostedShadowTrees(const Element* element, WillBeHeapVector<RawPtrWillBeMember<ScopedStyleResolver>, 8>& resolvers)
-{
-    ElementShadow* shadow = element->shadow();
-    if (!shadow)
-        return;
-
-    // Adding scoped resolver for active shadow roots for shadow host styling.
-    for (ShadowRoot* shadowRoot = shadow->youngestShadowRoot(); shadowRoot; shadowRoot = shadowRoot->olderShadowRoot()) {
-        if (shadowRoot->numberOfStyles() > 0) {
-            if (ScopedStyleResolver* resolver = shadowRoot->scopedStyleResolver())
-                resolvers.append(resolver);
-        }
-    }
-}
-
 StyleResolver::StyleResolver(Document& document)
     : m_document(document)
     , m_viewportStyleResolver(ViewportStyleResolver::create(&document))
@@ -232,14 +217,8 @@ void StyleResolver::resetRuleFeatures()
     m_needCollectFeatures = true;
 }
 
-void StyleResolver::addTreeBoundaryCrossingScope(ContainerNode& scope)
-{
-    m_treeBoundaryCrossingRules.addScope(scope);
-}
-
 void StyleResolver::resetAuthorStyle(TreeScope& treeScope)
 {
-    m_treeBoundaryCrossingRules.removeScope(treeScope.rootNode());
     resetRuleFeatures();
 
     ScopedStyleResolver* resolver = treeScope.scopedStyleResolver();
@@ -339,11 +318,11 @@ StyleResolver::~StyleResolver()
 {
 }
 
-static inline ScopedStyleResolver* scopedResolverFor(const Element* element)
+static inline ScopedStyleResolver* scopedResolverFor(const Element& element)
 {
     // Ideally, returning element->treeScope().scopedStyleResolver() should be
     // enough, but ::cue and custom pseudo elements like ::-webkit-meter-bar pierce
-    // through a shadow dom boundary, yet they are not part of m_treeBoundaryCrossingRules.
+    // through a shadow dom boundary, yet they are not part of treeBoundaryCrossingRules.
     // The assumption here is that these rules only pierce through one boundary and
     // that the scope of these elements do not have a style resolver due to the fact
     // that VTT scopes and UA shadow trees don't have <style> elements. This is
@@ -352,40 +331,76 @@ static inline ScopedStyleResolver* scopedResolverFor(const Element* element)
     // FIXME: Make ::cue and custom pseudo elements part of boundary crossing rules
     // when moving those rules to ScopedStyleResolver as part of issue 401359.
 
-    TreeScope* treeScope = &element->treeScope();
+    TreeScope* treeScope = &element.treeScope();
     if (ScopedStyleResolver* resolver = treeScope->scopedStyleResolver()) {
-        ASSERT(element->shadowPseudoId().isEmpty());
-        ASSERT(!element->isVTTElement());
+        ASSERT(element.shadowPseudoId().isEmpty());
+        ASSERT(!element.isVTTElement());
         return resolver;
     }
 
     treeScope = treeScope->parentTreeScope();
     if (!treeScope)
         return nullptr;
-    if (element->shadowPseudoId().isEmpty() && !element->isVTTElement())
+    if (element.shadowPseudoId().isEmpty() && !element.isVTTElement())
         return nullptr;
     return treeScope->scopedStyleResolver();
 }
 
-void StyleResolver::matchAuthorRules(Element* element, ElementRuleCollector& collector, bool includeEmptyRules)
+void StyleResolver::matchHostRules(const Element& element, ElementRuleCollector& collector, bool includeEmptyRules)
 {
-    collector.clearMatchedRules();
+    ElementShadow* shadow = element.shadow();
+    if (!shadow)
+        return;
 
-    CascadeOrder cascadeOrder = 0;
-    WillBeHeapVector<RawPtrWillBeMember<ScopedStyleResolver>, 8> resolversInShadowTree;
-    collectScopedResolversForHostedShadowTrees(element, resolversInShadowTree);
+    // Adding scoped resolvers for active shadow roots for shadow host styling.
+    for (ShadowRoot* shadowRoot = shadow->oldestShadowRoot(); shadowRoot; shadowRoot = shadowRoot->youngerShadowRoot()) {
+        if (!shadowRoot->numberOfStyles())
+            continue;
+        if (ScopedStyleResolver* resolver = shadowRoot->scopedStyleResolver()) {
+            collector.clearMatchedRules();
+            resolver->collectMatchingShadowHostRules(collector, includeEmptyRules);
+            collector.sortAndTransferMatchedRules();
+        }
+    }
+}
 
-    // Apply :host and :host-context rules from inner scopes.
-    for (int j = resolversInShadowTree.size() - 1; j >= 0; --j)
-        resolversInShadowTree.at(j)->collectMatchingShadowHostRules(collector, includeEmptyRules, ++cascadeOrder);
+void StyleResolver::matchScopedRules(const Element& element, ElementRuleCollector& collector, bool includeEmptyRules)
+{
+    // TODO(rune@opera.com): TreeScope::treeScopeInComposedTree can potentially be expensive as its doing
+    // composed tree traversal to find the closest tree-scope for the element in the composed tree. Getting the
+    // ancestor tree-scopes are much cheaper as we do the composed tree traversal for each TreeScope once and then cache
+    // its composed tree parent scope as a member.
 
-    // Apply normal rules from element scope.
-    if (ScopedStyleResolver* resolver = scopedResolverFor(element))
-        resolver->collectMatchingAuthorRules(collector, includeEmptyRules, ++cascadeOrder);
+    // TODO(rune@opera.com): The current implementation does not handle cascading order as
+    // spec'ed for !important rules.
 
-    // Apply /deep/ and ::shadow rules from outer scopes, and ::content from inner.
-    m_treeBoundaryCrossingRules.collectTreeBoundaryCrossingRules(element, collector, includeEmptyRules);
-    collector.sortAndTransferMatchedRules();
+    ScopedStyleResolver* resolverForElementScope = scopedResolverFor(element);
+
+    if (!document().styleEngine().hasTreeBoundaryCrossingRules()) {
+        if (!resolverForElementScope)
+            return;
+        collector.clearMatchedRules();
+        resolverForElementScope->collectMatchingAuthorRules(collector, includeEmptyRules);
+        collector.sortAndTransferMatchedRules();
+        return;
+    }
+
+    for (TreeScope* scope = TreeScope::treeScopeInComposedTree(element); scope; scope = scope->composedParent()) {
+        if (ScopedStyleResolver* resolver = scope->scopedStyleResolver()) {
+            collector.clearMatchedRules();
+            if (resolver == resolverForElementScope)
+                resolver->collectMatchingAuthorRules(collector, includeEmptyRules);
+            if (resolver->hasTreeBoundaryCrossingRules())
+                resolver->collectMatchingTreeBoundaryCrossingRules(collector, includeEmptyRules);
+            collector.sortAndTransferMatchedRules();
+        }
+    }
+}
+
+void StyleResolver::matchAuthorRules(const Element& element, ElementRuleCollector& collector, bool includeEmptyRules)
+{
+    matchHostRules(element, collector, includeEmptyRules);
+    matchScopedRules(element, collector, includeEmptyRules);
 }
 
 void StyleResolver::matchUARules(ElementRuleCollector& collector)
@@ -437,7 +452,7 @@ void StyleResolver::matchAllRules(StyleResolverState& state, ElementRuleCollecto
         }
     }
 
-    matchAuthorRules(state.element(), collector, false);
+    matchAuthorRules(*state.element(), collector, false);
 
     if (state.element()->isStyledElement()) {
         if (state.element()->inlineStyle()) {
@@ -449,6 +464,8 @@ void StyleResolver::matchAllRules(StyleResolverState& state, ElementRuleCollecto
         // Now check SMIL animation override style.
         if (includeSMILProperties && state.element()->isSVGElement())
             collector.addElementStyleProperties(toSVGElement(state.element())->animatedSMILStyleProperties(), false /* isCacheable */);
+
+        collector.finishAddInlineStyle();
     }
 }
 
@@ -654,13 +671,13 @@ PassRefPtr<ComputedStyle> StyleResolver::styleForKeyframe(Element& element, cons
     // relevant one is animation-timing-function and we special-case that in
     // CSSAnimations.cpp
     bool inheritedOnly = false;
-    applyMatchedProperties<HighPropertyPriority>(state, result, false, result.begin(), result.end(), inheritedOnly);
+    applyMatchedProperties<HighPropertyPriority>(state, result.allRules(), false, inheritedOnly);
 
     // If our font got dirtied, go ahead and update it now.
     updateFont(state);
 
     // Now do rest of the properties.
-    applyMatchedProperties<LowPropertyPriority>(state, result, false, result.begin(), result.end(), inheritedOnly);
+    applyMatchedProperties<LowPropertyPriority>(state, result.allRules(), false, inheritedOnly);
 
     loadPendingResources(state);
 
@@ -775,9 +792,9 @@ bool StyleResolver::pseudoStyleForElementInternal(Element& element, const Pseudo
         collector.setPseudoStyleRequest(pseudoStyleRequest);
 
         matchUARules(collector);
-        matchAuthorRules(state.element(), collector, false);
+        matchAuthorRules(*state.element(), collector, false);
 
-        if (collector.matchedResult().matchedProperties.isEmpty())
+        if (!collector.matchedResult().hasMatchedProperties())
             return false;
 
         applyMatchedProperties(state, collector.matchedResult());
@@ -849,12 +866,12 @@ PassRefPtr<ComputedStyle> StyleResolver::styleForPage(int pageIndex)
     bool inheritedOnly = false;
 
     const MatchResult& result = collector.matchedResult();
-    applyMatchedProperties<HighPropertyPriority>(state, result, false, result.begin(), result.end(), inheritedOnly);
+    applyMatchedProperties<HighPropertyPriority>(state, result.allRules(), false, inheritedOnly);
 
     // If our font got dirtied, go ahead and update it now.
     updateFont(state);
 
-    applyMatchedProperties<LowPropertyPriority>(state, result, false, result.begin(), result.end(), inheritedOnly);
+    applyMatchedProperties<LowPropertyPriority>(state, result.allRules(), false, inheritedOnly);
 
     loadPendingResources(state);
 
@@ -924,7 +941,7 @@ void StyleResolver::collectPseudoRulesForElement(Element* element, ElementRuleCo
 
     if (rulesToInclude & AuthorCSSRules) {
         collector.setSameOriginOnly(!(rulesToInclude & CrossOriginCSSRules));
-        matchAuthorRules(element, collector, rulesToInclude & EmptyCSSRules);
+        matchAuthorRules(*element, collector, rulesToInclude & EmptyCSSRules);
     }
 }
 
@@ -967,10 +984,25 @@ bool StyleResolver::applyAnimatedProperties(StyleResolverState& state, const Ele
     return true;
 }
 
+static void collectScopedResolversForHostedShadowTrees(const Element& element, WillBeHeapVector<RawPtrWillBeMember<ScopedStyleResolver>, 8>& resolvers)
+{
+    ElementShadow* shadow = element.shadow();
+    if (!shadow)
+        return;
+
+    // Adding scoped resolver for active shadow roots for shadow host styling.
+    for (ShadowRoot* shadowRoot = shadow->youngestShadowRoot(); shadowRoot; shadowRoot = shadowRoot->olderShadowRoot()) {
+        if (shadowRoot->numberOfStyles() > 0) {
+            if (ScopedStyleResolver* resolver = shadowRoot->scopedStyleResolver())
+                resolvers.append(resolver);
+        }
+    }
+}
+
 StyleRuleKeyframes* StyleResolver::findKeyframesRule(const Element* element, const AtomicString& animationName)
 {
     WillBeHeapVector<RawPtrWillBeMember<ScopedStyleResolver>, 8> resolvers;
-    collectScopedResolversForHostedShadowTrees(element, resolvers);
+    collectScopedResolversForHostedShadowTrees(*element, resolvers);
     if (ScopedStyleResolver* scopedResolver = element->treeScope().scopedStyleResolver())
         resolvers.append(scopedResolver);
 
@@ -1252,16 +1284,13 @@ void StyleResolver::applyProperties(StyleResolverState& state, const StyleProper
 }
 
 template <CSSPropertyPriority priority>
-void StyleResolver::applyMatchedProperties(StyleResolverState& state, const MatchResult& matchResult, bool isImportant, unsigned startIndex, unsigned endIndex, bool inheritedOnly)
+void StyleResolver::applyMatchedProperties(StyleResolverState& state, const MatchedPropertiesRange& range, bool isImportant, bool inheritedOnly)
 {
-    if (startIndex == endIndex)
+    if (range.begin() == range.end())
         return;
 
-    ASSERT_WITH_SECURITY_IMPLICATION(endIndex <= matchResult.matchedProperties.size());
-
     if (state.style()->insideLink() != NotInsideLink) {
-        for (unsigned i = startIndex; i < endIndex; ++i) {
-            const MatchedProperties& matchedProperties = matchResult.matchedProperties[i];
+        for (const auto& matchedProperties : range) {
             unsigned linkMatchType = matchedProperties.m_types.linkMatchType;
             // FIXME: It would be nicer to pass these as arguments but that requires changes in many places.
             state.setApplyPropertyToRegularStyle(linkMatchType & CSSSelector::MatchLink);
@@ -1273,10 +1302,8 @@ void StyleResolver::applyMatchedProperties(StyleResolverState& state, const Matc
         state.setApplyPropertyToVisitedLinkStyle(false);
         return;
     }
-    for (unsigned i = startIndex; i < endIndex; ++i) {
-        const MatchedProperties& matchedProperties = matchResult.matchedProperties[i];
+    for (const auto& matchedProperties : range)
         applyProperties<priority>(state, matchedProperties.properties.get(), isImportant, inheritedOnly, static_cast<PropertyWhitelistType>(matchedProperties.m_types.whitelistType));
-    }
 }
 
 static unsigned computeMatchedPropertiesHash(const MatchedProperties* properties, unsigned size)
@@ -1302,9 +1329,9 @@ void StyleResolver::applyMatchedProperties(StyleResolverState& state, const Matc
 
     INCREMENT_STYLE_STATS_COUNTER(*this, matchedPropertyApply, 1);
 
-    unsigned cacheHash = matchResult.isCacheable ? computeMatchedPropertiesHash(matchResult.matchedProperties.data(), matchResult.matchedProperties.size()) : 0;
+    unsigned cacheHash = matchResult.isCacheable() ? computeMatchedPropertiesHash(matchResult.matchedProperties().data(), matchResult.matchedProperties().size()) : 0;
     bool applyInheritedOnly = false;
-    const CachedMatchedProperties* cachedMatchedProperties = cacheHash ? m_matchedPropertiesCache.find(cacheHash, state, matchResult) : 0;
+    const CachedMatchedProperties* cachedMatchedProperties = cacheHash ? m_matchedPropertiesCache.find(cacheHash, state, matchResult.matchedProperties()) : 0;
 
     if (cachedMatchedProperties && MatchedPropertiesCache::isCacheable(element, *state.style(), *state.parentStyle())) {
         INCREMENT_STYLE_STATS_COUNTER(*this, matchedPropertyCacheHit, 1);
@@ -1335,9 +1362,10 @@ void StyleResolver::applyMatchedProperties(StyleResolverState& state, const Matc
     // high-priority properties first, i.e., those properties that other properties depend on.
     // The order is (1) high-priority not important, (2) high-priority important, (3) normal not important
     // and (4) normal important.
-    applyMatchedProperties<HighPropertyPriority>(state, matchResult, false, matchResult.begin(), matchResult.end(), applyInheritedOnly);
-    applyMatchedProperties<HighPropertyPriority>(state, matchResult, true, matchResult.beginAuthor(), matchResult.endAuthor(), applyInheritedOnly);
-    applyMatchedProperties<HighPropertyPriority>(state, matchResult, true, matchResult.beginUA(), matchResult.endUA(), applyInheritedOnly);
+    applyMatchedProperties<HighPropertyPriority>(state, matchResult.allRules(), false, applyInheritedOnly);
+    for (auto range : ImportantAuthorRanges(matchResult))
+        applyMatchedProperties<HighPropertyPriority>(state, range, true, applyInheritedOnly);
+    applyMatchedProperties<HighPropertyPriority>(state, matchResult.uaRules(), true, applyInheritedOnly);
 
     if (UNLIKELY(isSVGForeignObjectElement(element))) {
         // LayoutSVGRoot handles zooming for the whole SVG subtree, so foreignObject content should not be scaled again.
@@ -1363,21 +1391,22 @@ void StyleResolver::applyMatchedProperties(StyleResolverState& state, const Matc
         applyInheritedOnly = false;
 
     // Now do the normal priority UA properties.
-    applyMatchedProperties<LowPropertyPriority>(state, matchResult, false, matchResult.beginUA(), matchResult.endUA(), applyInheritedOnly);
+    applyMatchedProperties<LowPropertyPriority>(state, matchResult.uaRules(), false, applyInheritedOnly);
 
     // Cache the UA properties to pass them to LayoutTheme in adjustComputedStyle.
     state.cacheUserAgentBorderAndBackground();
 
     // Now do the author and user normal priority properties and all the !important properties.
-    applyMatchedProperties<LowPropertyPriority>(state, matchResult, false, matchResult.beginAuthor(), matchResult.endAuthor(), applyInheritedOnly);
-    applyMatchedProperties<LowPropertyPriority>(state, matchResult, true, matchResult.beginAuthor(), matchResult.endAuthor(), applyInheritedOnly);
-    applyMatchedProperties<LowPropertyPriority>(state, matchResult, true, matchResult.beginUA(), matchResult.endUA(), applyInheritedOnly);
+    applyMatchedProperties<LowPropertyPriority>(state, matchResult.authorRules(), false, applyInheritedOnly);
+    for (auto range : ImportantAuthorRanges(matchResult))
+        applyMatchedProperties<LowPropertyPriority>(state, range, true, applyInheritedOnly);
+    applyMatchedProperties<LowPropertyPriority>(state, matchResult.uaRules(), true, applyInheritedOnly);
 
     loadPendingResources(state);
 
     if (!cachedMatchedProperties && cacheHash && MatchedPropertiesCache::isCacheable(element, *state.style(), *state.parentStyle())) {
         INCREMENT_STYLE_STATS_COUNTER(*this, matchedPropertyCacheAdded, 1);
-        m_matchedPropertiesCache.add(*state.style(), *state.parentStyle(), cacheHash, matchResult);
+        m_matchedPropertiesCache.add(*state.style(), *state.parentStyle(), cacheHash, matchResult.matchedProperties());
     }
 
     ASSERT(!state.fontBuilder().fontDirty());
@@ -1464,7 +1493,6 @@ DEFINE_TRACE(StyleResolver)
     visitor->trace(m_siblingRuleSet);
     visitor->trace(m_uncommonAttributeRuleSet);
     visitor->trace(m_watchedSelectorsRules);
-    visitor->trace(m_treeBoundaryCrossingRules);
     visitor->trace(m_styleResourceLoader);
     visitor->trace(m_styleSharingLists);
     visitor->trace(m_pendingStyleSheets);