*** DO NOT LAND *** Attempt to understand Regions complexity

Source/core/css/resolver/StyleResolver.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, 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.
@@ skipping 488 matching lines @@
 {
     if (!m_watchedSelectorsRules)
         return;
 
     collector.clearMatchedRules();
     collector.matchedResult().ranges.lastUserRule = collector.matchedResult().matchedProperties.size() - 1;
 
     MatchRequest matchRequest(m_watchedSelectorsRules.get());
     RuleRange ruleRange = collector.matchedResult().ranges.userRuleRange();
     collector.collectMatchingRules(matchRequest, ruleRange);
-    collector.collectMatchingRulesForRegion(matchRequest, ruleRange);
 
     collector.sortAndTransferMatchedRules();
 }
 
 void StyleResolver::matchUARules(ElementRuleCollector& collector)
 {
     collector.setMatchingUARules(true);
 
     RuleSet* userAgentStyleSheet = m_medium->mediaTypeMatchSpecific("print")
         ? CSSDefaultStyleSheets::defaultPrintStyle : CSSDefaultStyleSheets::defaultStyle;
@@ skipping 105 matching lines @@
     document.setWritingModeSetOnDocumentElement(false);
 }
 
 static void addContentAttrValuesToFeatures(const Vector<AtomicString>& contentAttrValues, RuleFeatureSet& features)
 {
     for (size_t i = 0; i < contentAttrValues.size(); ++i)
         features.attrsInRules.add(contentAttrValues[i]);
 }
 
 PassRefPtr<RenderStyle> StyleResolver::styleForElement(Element* element, RenderStyle* defaultParent, StyleSharingBehavior sharingBehavior,
-    RuleMatchingBehavior matchingBehavior, RenderRegion* regionForStyling)
+    RuleMatchingBehavior matchingBehavior)
 {
     ASSERT(document().frame());
     ASSERT(documentSettings());
     ASSERT(!hasPendingAuthorStyleSheets());
     ASSERT(!m_needCollectFeatures);
 
     // Once an element has a renderer, we don't try to destroy it, since otherwise the renderer
     // will vanish if a style recalc happens during loading.
     if (sharingBehavior == AllowStyleSharing && !element->document().haveStylesheetsLoaded() && !element->renderer()) {
         if (!s_styleNotYetAvailable) {
             s_styleNotYetAvailable = RenderStyle::create().leakRef();
             s_styleNotYetAvailable->setDisplay(NONE);
             s_styleNotYetAvailable->font().update(document().styleEngine()->fontSelector());
         }
         element->document().setHasNodesWithPlaceholderStyle();
         return s_styleNotYetAvailable;
     }
 
     didAccess();
 
     if (element == document().documentElement())
         resetDirectionAndWritingModeOnDocument(document());
-    StyleResolverState state(document(), element, defaultParent, regionForStyling);
+    StyleResolverState state(document(), element, defaultParent);
 
     if (sharingBehavior == AllowStyleSharing && !state.distributedToInsertionPoint() && state.parentStyle()) {
         SharedStyleFinder styleFinder(state.elementContext(), m_features, m_siblingRuleSet.get(), m_uncommonAttributeRuleSet.get(), *this);
         if (RefPtr<RenderStyle> sharedStyle = styleFinder.findSharedStyle())
             return sharedStyle.release();
     }
 
     if (state.parentStyle()) {
         state.setStyle(RenderStyle::create());
         state.style()->inheritFrom(state.parentStyle(), isAtShadowBoundary(element) ? RenderStyle::AtShadowBoundary : RenderStyle::NotAtShadowBoundary);
@@ skipping 23 matching lines @@
         state.style()->setInsideLink(linkState);
     }
 
     bool needsCollection = false;
     CSSDefaultStyleSheets::ensureDefaultStyleSheetsForElement(element, needsCollection);
     if (needsCollection)
         collectFeatures();
 
     {
         ElementRuleCollector collector(state.elementContext(), m_selectorFilter, state.style());
-        collector.setRegionForStyling(regionForStyling);
 
         if (matchingBehavior == MatchOnlyUserAgentRules)
             matchUARules(collector);
         else
             matchAllRules(state, collector, matchingBehavior != MatchAllRulesExcludingSMIL);
 
         applyMatchedProperties(state, collector.matchedResult());
 
         addContentAttrValuesToFeatures(state.contentAttrValues(), m_features);
     }
@@ skipping 349 matching lines @@
 {
     ASSERT(textNode);
 
     NodeRenderingTraversal::ParentDetails parentDetails;
     Node* parentNode = NodeRenderingTraversal::parent(textNode, &parentDetails);
     if (!parentNode || !parentNode->renderStyle() || parentDetails.resetStyleInheritance())
         return defaultStyleForElement();
     return parentNode->renderStyle();
 }
 
-bool StyleResolver::checkRegionStyle(Element* regionElement)
-{
-    // FIXME (BUG 72472): We don't add @-webkit-region rules of scoped style sheets for the moment,
-    // so all region rules are global by default. Verify whether that can stand or needs changing.
-    if (ScopedStyleResolver* scopedResolver = m_styleTree.scopedStyleResolverForDocument()) {
-        if (scopedResolver->checkRegionStyle(regionElement))
-            return true;
-    }
-    return false;
-}
-
 void StyleResolver::updateFont(StyleResolverState& state)
 {
     state.fontBuilder().createFont(document().styleEngine()->fontSelector(), state.parentStyle(), state.style());
     if (state.fontBuilder().fontSizeHasViewportUnits())
         state.style()->setHasViewportUnits();
 }
 
 PassRefPtr<StyleRuleList> StyleResolver::styleRulesForElement(Element* element, unsigned rulesToInclude)
 {
     ASSERT(element);
@@ skipping 82 matching lines @@
     for (AnimationEffect::CompositableValueMap::const_iterator iter = compositableValues.begin(); iter != compositableValues.end(); ++iter) {
         CSSPropertyID property = iter->key;
         if (!isPropertyForPass<pass>(property))
             continue;
         ASSERT_WITH_MESSAGE(!iter->value->dependsOnUnderlyingValue(), "Web Animations not yet implemented: An interface for compositing onto the underlying value.");
         RefPtr<AnimatableValue> animatableValue = iter->value->compositeOnto(0);
         AnimatedStyleBuilder::applyProperty(property, state, animatableValue.get());
     }
 }
 
-// http://dev.w3.org/csswg/css3-regions/#the-at-region-style-rule
-// FIXME: add incremental support for other region styling properties.
-static inline bool isValidRegionStyleProperty(CSSPropertyID id)
-{
-    switch (id) {
-    case CSSPropertyBackgroundColor:
-    case CSSPropertyColor:
-        return true;
-    default:
-        break;
-    }
-
-    return false;
-}
-
 static inline bool isValidCueStyleProperty(CSSPropertyID id)
 {
     switch (id) {
     case CSSPropertyBackground:
     case CSSPropertyBackgroundAttachment:
     case CSSPropertyBackgroundClip:
     case CSSPropertyBackgroundColor:
     case CSSPropertyBackgroundImage:
     case CSSPropertyBackgroundOrigin:
     case CSSPropertyBackgroundPosition:
@@ skipping 57 matching lines @@
     case LowPriorityProperties:
         return property > lastHighPriorityProperty;
     }
     ASSERT_NOT_REACHED();
     return false;
 }
 
 template <StyleResolver::StyleApplicationPass pass>
 void StyleResolver::applyProperties(StyleResolverState& state, const StylePropertySet* properties, StyleRule* rule, bool isImportant, bool inheritedOnly, PropertyWhitelistType propertyWhitelistType)
 {
-    ASSERT((propertyWhitelistType != PropertyWhitelistRegion) || state.regionForStyling());
     state.setCurrentRule(rule);
 
     unsigned propertyCount = properties->propertyCount();
     for (unsigned i = 0; i < propertyCount; ++i) {
         StylePropertySet::PropertyReference current = properties->propertyAt(i);
         if (isImportant != current.isImportant())
             continue;
         if (inheritedOnly && !current.isInherited()) {
             // If the property value is explicitly inherited, we need to apply further non-inherited properties
             // as they might override the value inherited here. For this reason we don't allow declarations with
             // explicitly inherited properties to be cached.
             ASSERT(!current.value()->isInheritedValue());
             continue;
         }
         CSSPropertyID property = current.id();
 
-        if (propertyWhitelistType == PropertyWhitelistRegion && !isValidRegionStyleProperty(property))
-            continue;
         if (propertyWhitelistType == PropertyWhitelistCue && !isValidCueStyleProperty(property))
             continue;
         if (!isPropertyForPass<pass>(property))
             continue;
         if (pass == HighPriorityProperties && property == CSSPropertyLineHeight)
             state.setLineHeightValue(current.value());
         else
             StyleBuilder::applyProperty(current.id(), state, current.value());
     }
 }
@@ skipping 208 matching lines @@
 bool StyleResolver::mediaQueryAffectedByViewportChange() const
 {
     for (unsigned i = 0; i < m_viewportDependentMediaQueryResults.size(); ++i) {
         if (m_medium->eval(&m_viewportDependentMediaQueryResults[i]->m_expression) != m_viewportDependentMediaQueryResults[i]->m_result)
             return true;
     }
     return false;
 }
 
 } // namespace WebCore