Improve RAII of StyleResolverState.

Source/core/css/resolver/StyleResolverState.cpp

Index: Source/core/css/resolver/StyleResolverState.cpp
diff --git a/Source/core/css/resolver/StyleResolverState.cpp b/Source/core/css/resolver/StyleResolverState.cpp
index 52353a8e40428602adbedd755391eb4d912fe833..01d548416052e54189ac151e1d432bf7a893ce8e 100644
--- a/Source/core/css/resolver/StyleResolverState.cpp
+++ b/Source/core/css/resolver/StyleResolverState.cpp
@@ -23,27 +23,57 @@
 #include "core/css/resolver/StyleResolverState.h"
 
 #include "core/animation/css/CSSAnimations.h"
+#include "core/css/CSSFontSelector.h"
 #include "core/dom/Node.h"
 #include "core/dom/NodeRenderStyle.h"
+#include "core/dom/StyleEngine.h"
 #include "core/frame/FrameHost.h"
 
 namespace blink {
 
-StyleResolverState::StyleResolverState(Document& document, Element* element, RenderStyle* parentStyle)
-    : m_elementContext(element ? ElementResolveContext(*element) : ElementResolveContext(document))
-    , m_document(document)
-    , m_style(nullptr)
-    , m_cssToLengthConversionData(0, rootElementStyle(), document.renderView())
-    , m_parentStyle(parentStyle)
+static PassRefPtr<RenderStyle> createStyleFromContext(const ElementResolveContext& elementContext)
+{
+    if (elementContext.baseRenderStyle())
+        return RenderStyle::clone(elementContext.baseRenderStyle());
+    if (elementContext.parentStyle())
+        return RenderStyle::create();
+    return StyleResolverState::defaultStyleForElement(elementContext.document());
+}

[rune, 2014/10/29 13:02:14]

I'm unsure what to think about this. It feels too magical to have this
RenderStyle creation logic in the StyleResolverState constructor.

[andersr, 2014/10/29 13:29:47]

I agree. We can't do this anyway, because of the pseudoElement horribleness.

+
+static PassRefPtr<RenderStyle> parentStyleFromContext(const ElementResolveContext& elementContext, RenderStyle* style)
+{
+    ASSERT(style);
+    if (elementContext.parentStyle())
+        return elementContext.parentStyle();
+    if (elementContext.baseRenderStyle())
+        return StyleResolverState::defaultStyleForElement(elementContext.document());
+    return RenderStyle::clone(style);
+}
+
+StyleResolverState::StyleResolverState(const ElementResolveContext& elementContext)
+    : m_elementContext(elementContext)
+    , m_style(createStyleFromContext(elementContext))
+    , m_cssToLengthConversionData(style(), rootElementStyle(), document().renderView())
+    , m_parentStyle(parentStyleFromContext(elementContext, style()))
     , m_applyPropertyToRegularStyle(true)
     , m_applyPropertyToVisitedLinkStyle(false)
-    , m_lineHeightValue(nullptr)
-    , m_fontBuilder(document)
+    , m_fontBuilder(document(), style())
     , m_styleMap(*this, m_elementStyleResources)
 {
-    if (!parentStyle && m_elementContext.parentNode())
-        m_parentStyle = m_elementContext.parentNode()->renderStyle();
+    ASSERT(document().isActive());
+    m_elementStyleResources.setDeviceScaleFactor(document().frameHost()->deviceScaleFactor());
+}
 
+StyleResolverState::StyleResolverState(Document& document, Element* element, PassRefPtr<RenderStyle> style, RenderStyle* parentStyle)
+    : m_elementContext(document, element, parentStyle)
+    , m_style(style)
+    , m_cssToLengthConversionData(m_style.get(), rootElementStyle(), document.renderView())
+    , m_parentStyle(parentStyleFromContext(m_elementContext, m_style.get()))
+    , m_applyPropertyToRegularStyle(true)
+    , m_applyPropertyToVisitedLinkStyle(false)
+    , m_fontBuilder(document, m_style.get())
+    , m_styleMap(*this, m_elementStyleResources)
+{
     ASSERT(document.isActive());
     m_elementStyleResources.setDeviceScaleFactor(document.frameHost()->deviceScaleFactor());
 }
@@ -52,6 +82,15 @@ StyleResolverState::~StyleResolverState()
 {
 }
 
+PassRefPtr<RenderStyle> StyleResolverState::defaultStyleForElement(Document& document)
+{
+    RefPtr<RenderStyle> style = RenderStyle::create();
+    FontBuilder fontBuilder(document, style.get());
+    fontBuilder.setInitial(style->effectiveZoom());
+    style->font().update(document.styleEngine()->fontSelector());
+    return style;
+}
+
 void StyleResolverState::setAnimationUpdate(PassOwnPtrWillBeRawPtr<CSSAnimationUpdate> update)
 {
     m_animationUpdate = update;