Use m_targetElementInstance in fewer places

Source/core/svg/SVGUseElement.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007 Rob Buis <buis@kde.org>
  * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
  * Copyright (C) 2011 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  * Copyright (C) 2012 University of Szeged
  * Copyright (C) 2012 Renata Hodovan <reni@webkit.org>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 463 matching lines @@
     ASSERT(!m_targetElementInstance->shadowTreeElement());
     ASSERT(m_targetElementInstance->correspondingUseElement() == this);
     ASSERT(m_targetElementInstance->directUseElement() == this);
     ASSERT(m_targetElementInstance->correspondingElement() == target);
 
     ShadowRoot* shadowTreeRootElement = userAgentShadowRoot();
     ASSERT(shadowTreeRootElement);
 
     // Build shadow tree from instance tree
     // This also handles the special cases: <use> on <symbol>, <use> on <svg>.
     buildShadowTree(target, m_targetElementInstance.get());

[pdr., 2014/05/03 21:02:08]

Could you pass in shadowTreeRootElement here to avoid calling
userAgentShadowRoot in buildShadowTree?

 
     // Expand all <use> elements in the shadow tree.
     // Expand means: replace the actual <use> element by what it references.
     expandUseElementsInShadowTree(shadowTreeRootElement);
 
     // Expand all <symbol> elements in the shadow tree.
     // Expand means: replace the actual <symbol> element by the <svg> element.
     expandSymbolElementsInShadowTree(shadowTreeRootElement);
 
+    Node* shadowTreeTargetNode = shadowTreeRootElement->firstChild();
     // Now that the shadow tree is completly expanded, we can associate
     // shadow tree elements <-> instances in the instance tree.
-    associateInstancesWithShadowTreeElements(shadowTreeRootElement->firstChild(), m_targetElementInstance.get());
-
-    ASSERT(m_targetElementInstance->correspondingElement());
-    transferUseWidthAndHeightIfNeeded(*this, m_targetElementInstance->shadowTreeElement(), *m_targetElementInstance->correspondingElement());
+    associateInstancesWithShadowTreeElements(shadowTreeTargetNode, m_targetElementInstance.get());

[pdr., 2014/05/03 21:02:08]

Can this be moved below the !shadowTreeTargetNode check?

 
     // If no shadow tree element is present, this means that the reference root
     // element was removed, as it is disallowed (ie. <use> on <foreignObject>)
     // Do NOT leave an inconsistent instance tree around, instead destruct it.
-    if (!m_targetElementInstance->shadowTreeElement()) {
+    if (!shadowTreeTargetNode) {
         clearResourceReferences();
         return;
     }
 
-    ASSERT(m_targetElementInstance->shadowTreeElement()->parentNode() == shadowTreeRootElement);
+    SVGElement* shadowTreeTargetElement = toSVGElement(shadowTreeTargetNode);
+    ASSERT(shadowTreeTargetElement->correspondingElement());
+    transferUseWidthAndHeightIfNeeded(*this, shadowTreeTargetElement, *shadowTreeTargetElement->correspondingElement());
+
+    ASSERT(shadowTreeTargetNode()->parentNode() == shadowTreeRootElement);
 
     // Transfer event listeners assigned to the referenced element to our shadow tree elements.
-    transferEventListenersToShadowTree(m_targetElementInstance.get());
+    transferEventListenersToShadowTree(shadowTreeTargetElement);
 
     // Update relative length information.
     updateRelativeLengthsInformation();
 
     // Eventually dump instance tree
 #ifdef DUMP_INSTANCE_TREE
     String text;
     unsigned depth = 0;
 
     dumpInstanceTree(depth, text, m_targetElementInstance.get());
@@ skipping 21 matching lines @@
         || isSVGEllipseElement(node)
         || isSVGPolygonElement(node)
         || isSVGPolylineElement(node)
         || isSVGTextElement(node);
 }
 
 void SVGUseElement::toClipPath(Path& path)
 {
     ASSERT(path.isEmpty());
 
-    Node* n = m_targetElementInstance ? m_targetElementInstance->shadowTreeElement() : 0;
+    Node* n = userAgentShadowRoot()->firstChild();
     if (!n)
         return;
 
     if (n->isSVGElement() && toSVGElement(n)->isSVGGraphicsElement()) {
         if (!isDirectReference(*n)) {
             // Spec: Indirect references are an error (14.3.5)
             document().accessSVGExtensions().reportError("Not allowed to use indirect reference in <clip-path>");
         } else {
             toSVGGraphicsElement(n)->toClipPath(path);
             // FIXME: Avoid manual resolution of x/y here. Its potentially harmful.
             SVGLengthContext lengthContext(this);
             path.translate(FloatSize(m_x->currentValue()->value(lengthContext), m_y->currentValue()->value(lengthContext)));
             path.transform(animatedLocalTransform());
         }
     }
 }
 
 RenderObject* SVGUseElement::rendererClipChild() const
 {
-    Node* n = m_targetElementInstance ? m_targetElementInstance->shadowTreeElement() : 0;
-    if (!n)
-        return 0;
-
-    if (n->isSVGElement() && isDirectReference(*n))
-        return toSVGElement(n)->renderer();
+    if (Node* n = userAgentShadowRoot()->firstChild()) {
+        if (n->isSVGElement() && isDirectReference(*n))
+            return toSVGElement(n)->renderer();
+    }
 
     return 0;
 }
 
 void SVGUseElement::buildInstanceTree(SVGElement* target, SVGElementInstance* targetInstance, bool& foundProblem, bool foundUse)
 {
     ASSERT(target);
     ASSERT(targetInstance);
 
     // Spec: If the referenced object is itself a 'use', or if there are 'use' subelements within the referenced
@@ skipping 211 matching lines @@
         // lose the sibling chain when we are back from recursion.
         element = replacingElement.get();
         for (RefPtr<Node> sibling = element->nextSibling(); sibling; sibling = sibling->nextSibling())
             expandSymbolElementsInShadowTree(sibling.get());
     }
 
     for (RefPtr<Node> child = element->firstChild(); child; child = child->nextSibling())
         expandSymbolElementsInShadowTree(child.get());
 }
 
-void SVGUseElement::transferEventListenersToShadowTree(SVGElementInstance* target)
+void SVGUseElement::transferEventListenersToShadowTree(SVGElement* shadowElement)

[pdr., 2014/05/03 21:02:08]

For consistency, can we call this the shadowTreeTargetElement (or similar)? The
shadow element is the shadowElement's parent.

 {
-    if (!target)
+    if (!shadowElement)
         return;
 
-    SVGElement* originalElement = target->correspondingElement();
+    SVGElement* originalElement = shadowElement->correspondingElement();
     ASSERT(originalElement);
+    if (EventTargetData* data = originalElement->eventTargetData())
+        data->eventListenerMap.copyEventListenersNotCreatedFromMarkupToTarget(shadowElement);
 
-    if (SVGElement* shadowTreeElement = target->shadowTreeElement()) {
-        if (EventTargetData* data = originalElement->eventTargetData())
-            data->eventListenerMap.copyEventListenersNotCreatedFromMarkupToTarget(shadowTreeElement);
-    }
-
-    for (SVGElementInstance* instance = target->firstChild(); instance; instance = instance->nextSibling())
-        transferEventListenersToShadowTree(instance);
+    for (SVGElement* child = Traversal<SVGElement>::firstChild(*shadowElement); child; child = Traversal<SVGElement>::nextSibling(*child))
+        transferEventListenersToShadowTree(child);
 }
 
 void SVGUseElement::associateInstancesWithShadowTreeElements(Node* target, SVGElementInstance* targetInstance)
 {
     if (!target || !targetInstance)
         return;
 
     SVGElement* originalElement = targetInstance->correspondingElement();
     ASSERT(originalElement);
     if (isSVGUseElement(*originalElement)) {
@@ skipping 161 matching lines @@
 
     if (m_resource)
         m_resource->removeClient(this);
 
     m_resource = resource;
     if (m_resource)
         m_resource->addClient(this);
 }
 
 }