Add fast-path for propagated variable changes (WIP)

third_party/WebKit/Source/core/style/ComputedStyle.cpp

 /*
  * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2011 Adobe Systems Incorporated. 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.
@@ skipping 194 matching lines @@
 
   if (oldStyle->display() != newStyle->display() ||
       oldStyle->hasPseudoStyle(PseudoIdFirstLetter) !=
           newStyle->hasPseudoStyle(PseudoIdFirstLetter) ||
       !oldStyle->contentDataEquivalent(newStyle) ||
       oldStyle->hasTextCombine() != newStyle->hasTextCombine())
     return Reattach;
 
   bool independentEqual = oldStyle->independentInheritedEqual(*newStyle);
   bool nonIndependentEqual = oldStyle->nonIndependentInheritedEqual(*newStyle);
-  if (!independentEqual || !nonIndependentEqual) {
+  bool variablesEqual = oldStyle->variablesEqual(*newStyle);
+  if (!independentEqual || !nonIndependentEqual || !variablesEqual) {
+    // Check if only independent inherited properties changed.
     if (nonIndependentEqual && !oldStyle->hasExplicitlyInheritedProperties())
-      return IndependentInherit;
+      if (variablesEqual)
+        return IndependentInherit;
+    // Variables and possibly independent inherited properties changed.
+    return IndependentInheritWithVariables;
     return Inherit;
   }
 
   if (!oldStyle->loadingCustomFontsEqual(*newStyle) ||
       oldStyle->alignItems() != newStyle->alignItems() ||
       oldStyle->justifyItems() != newStyle->justifyItems())
     return Inherit;
 
   if (*oldStyle == *newStyle)
     return diffPseudoStyles(*oldStyle, *newStyle);
 
   if (oldStyle->hasExplicitlyInheritedProperties())
     return Inherit;
 
   return NoInherit;
 }
 
 // TODO(sashab): Generate this function.
 void ComputedStyle::propagateIndependentInheritedProperties(
     const ComputedStyle& parentStyle) {
   if (m_nonInheritedData.m_isPointerEventsInherited)
     setPointerEvents(parentStyle.pointerEvents());
   if (m_nonInheritedData.m_isVisibilityInherited)
     setVisibility(parentStyle.visibility());
+
+  // Variables.
+  if (parentStyle.variables() != variables()) {
+    for (const auto& variable : *parentStyle.variables()) {
+      if (inheritsVariableDefinitionFromParent(variable.key) &&
+          *variable.value != *variables()->getVariable(variable.key)) {
+        setVariable(variable.key, variable.value);
+      }
+    }
+  }
 }
 
 StyleSelfAlignmentData resolvedSelfAlignment(
     const StyleSelfAlignmentData& value,
     ItemPosition normalValueBehavior) {
   // To avoid needing to copy the RareNonInheritedData, we repurpose the 'auto'
   // flag to not just mean 'auto' prior to running the StyleAdjuster but also
   // mean 'normal' after running it.
   if (value.position() == ItemPositionNormal ||
       value.position() == ItemPositionAuto)
@@ skipping 259 matching lines @@
 
 bool ComputedStyle::nonIndependentInheritedEqual(
     const ComputedStyle& other) const {
   return ComputedStyleBase::nonIndependentInheritedEqual(other) &&
          m_inheritedData.compareEqualNonIndependent(other.m_inheritedData) &&
          m_styleInheritedData == other.m_styleInheritedData &&
          m_svgStyle->inheritedEqual(*other.m_svgStyle) &&
          m_rareInheritedData == other.m_rareInheritedData;
 }
 
+bool ComputedStyle::variablesEqual(const ComputedStyle& other) const {
+  return m_rareInheritedData->compareEqualVariables(*other.m_rareInheritedData);
+}
+
 bool ComputedStyle::loadingCustomFontsEqual(const ComputedStyle& other) const {
   return font().loadingCustomFonts() == other.font().loadingCustomFonts();
 }
 
 bool ComputedStyle::nonInheritedEqual(const ComputedStyle& other) const {
   // compare everything except the pseudoStyle pointer
   return ComputedStyleBase::nonInheritedEqual(other) &&
          m_nonInheritedData == other.m_nonInheritedData &&
          m_box == other.m_box && m_visual == other.m_visual &&
          m_background == other.m_background && m_surround == other.m_surround &&
@@ skipping 1886 matching lines @@
     if (value < 0)
       fvalue -= 0.5f;
     else
       fvalue += 0.5f;
   }
 
   return roundForImpreciseConversion<int>(fvalue / zoomFactor);
 }
 
 }  // namespace blink