Resolve URL/target reference at a single point in SVGUseElement

third_party/WebKit/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 41 matching lines @@
     return sharedLoadEventSender;
 }
 
 inline SVGUseElement::SVGUseElement(Document& document)
     : SVGGraphicsElement(SVGNames::useTag, document)
     , SVGURIReference(this)
     , m_x(SVGAnimatedLength::create(this, SVGNames::xAttr, SVGLength::create(SVGLengthMode::Width)))
     , m_y(SVGAnimatedLength::create(this, SVGNames::yAttr, SVGLength::create(SVGLengthMode::Height)))
     , m_width(SVGAnimatedLength::create(this, SVGNames::widthAttr, SVGLength::create(SVGLengthMode::Width)))
     , m_height(SVGAnimatedLength::create(this, SVGNames::heightAttr, SVGLength::create(SVGLengthMode::Height)))
+    , m_elementIdentifierIsLocal(true)
     , m_haveFiredLoadEvent(false)
     , m_needsShadowTreeRecreation(false)
 {
     ASSERT(hasCustomStyleCallbacks());
     ThreadState::current()->registerPreFinalizer(this);
 
     addToPropertyMap(m_x);
     addToPropertyMap(m_y);
     addToPropertyMap(m_width);
     addToPropertyMap(m_height);
@@ skipping 52 matching lines @@
 
 void SVGUseElement::removedFrom(ContainerNode* rootParent)
 {
     SVGGraphicsElement::removedFrom(rootParent);
     if (rootParent->isConnected()) {
         clearShadowTree();
         cancelShadowTreeRecreation();
     }
 }
 
-Document* SVGUseElement::externalDocument() const
-{
-    // Gracefully handle error condition.
-    if (!resourceIsValid())
-        return nullptr;
-    ASSERT(m_resource->document());
-    return m_resource->document();
-}
-
 static void transferUseWidthAndHeightIfNeeded(const SVGUseElement& use, SVGElement& shadowElement, const SVGElement& originalElement)
 {
     DEFINE_STATIC_LOCAL(const AtomicString, hundredPercentString, ("100%"));
     // Use |originalElement| for checking the element type, because we will
     // have replaced a <symbol> with an <svg> in the instance tree.
     if (isSVGSymbolElement(originalElement)) {
         // Spec (<use> on <symbol>): This generated 'svg' will always have
         // explicit values for attributes width and height.  If attributes
         // width and/or height are provided on the 'use' element, then these
         // attributes will be transferred to the generated 'svg'. If attributes
@@ skipping 32 matching lines @@
 {
     SVGAnimatedPropertyBase* property = propertyFromAttribute(name);
     if (property == m_x)
         addPropertyToPresentationAttributeStyle(style, CSSPropertyX, m_x->currentValue()->asCSSPrimitiveValue());
     else if (property == m_y)
         addPropertyToPresentationAttributeStyle(style, CSSPropertyY, m_y->currentValue()->asCSSPrimitiveValue());
     else
         SVGGraphicsElement::collectStyleForPresentationAttribute(name, value, style);
 }
 
+void SVGUseElement::updateTargetReference()
+{
+    KURL resolvedUrl = document().completeURL(hrefString());
+    m_elementIdentifier = AtomicString(resolvedUrl.fragmentIdentifier());
+    m_elementIdentifierIsLocal = resolvedUrl.isNull()
+        || equalIgnoringFragmentIdentifier(resolvedUrl, document().url());
+    if (m_elementIdentifierIsLocal) {
+        setDocumentResource(nullptr);
+        return;
+    }
+    if (m_elementIdentifier.isEmpty()
+        || (m_resource && equalIgnoringFragmentIdentifier(resolvedUrl, m_resource->url())))
+        return;
+    FetchRequest request(ResourceRequest(resolvedUrl), localName());
+    setDocumentResource(DocumentResource::fetchSVGDocument(request, document().fetcher()));
+}
+
 void SVGUseElement::svgAttributeChanged(const QualifiedName& attrName)
 {
     if (attrName == SVGNames::xAttr
         || attrName == SVGNames::yAttr
         || attrName == SVGNames::widthAttr
         || attrName == SVGNames::heightAttr) {
         SVGElement::InvalidationGuard invalidationGuard(this);
 
         if (attrName == SVGNames::xAttr
             || attrName == SVGNames::yAttr) {
             invalidateSVGPresentationAttributeStyle();
             setNeedsStyleRecalc(LocalStyleChange,
                 StyleChangeReasonForTracing::fromAttribute(attrName));
         }
 
         updateRelativeLengthsInformation();
         if (m_targetElementInstance) {
             ASSERT(m_targetElementInstance->correspondingElement());
             transferUseWidthAndHeightIfNeeded(*this, *m_targetElementInstance, *m_targetElementInstance->correspondingElement());
         }
 
         LayoutObject* object = this->layoutObject();
         if (object)
             markForLayoutAndParentResourceInvalidation(object);
         return;
     }
 
     if (SVGURIReference::isKnownAttribute(attrName)) {
         SVGElement::InvalidationGuard invalidationGuard(this);
-        if (isStructurallyExternal()) {
-            KURL url = document().completeURL(hrefString());
-            const KURL& existingURL = m_resource ? m_resource->url() : KURL();
-            if (url.hasFragmentIdentifier() && !equalIgnoringFragmentIdentifier(url, existingURL)) {
-                FetchRequest request(ResourceRequest(url), localName());
-                setDocumentResource(DocumentResource::fetchSVGDocument(request, document().fetcher()));
-            }
-        } else {
-            setDocumentResource(nullptr);
-        }
-
+        updateTargetReference();
         invalidateShadowTree();
-
         return;
     }
 
     SVGGraphicsElement::svgAttributeChanged(attrName);
 }
 
 static bool isDisallowedElement(const Element& element)
 {
     // Spec: "Any 'svg', 'symbol', 'g', graphics element or other 'use' is potentially a template object that can be re-used
     // (i.e., "instanced") in the SVG document via a 'use' element."
@@ skipping 51 matching lines @@
 {
     clearInstanceRoot();
 
     // FIXME: We should try to optimize this, to at least allow partial reclones.
     if (ShadowRoot* shadowTreeRootElement = userAgentShadowRoot())
         shadowTreeRootElement->removeChildren(OmitSubtreeModifiedEvent);
 
     removeAllOutgoingReferences();
 }
 
+Element* SVGUseElement::resolveTargetElement()
+{
+    if (m_elementIdentifier.isEmpty())
+        return nullptr;
+    const TreeScope* lookupScope = nullptr;
+    if (m_elementIdentifierIsLocal)
+        lookupScope = &treeScope();
+    else if (resourceIsValid())
+        lookupScope = m_resource->document();
+    else
+        return nullptr;
+    Element* target = lookupScope->getElementById(m_elementIdentifier);
+    // TODO(fs): Why would the Element not be "connected" at this point?
+    if (target && target->isConnected())
+        return target;
+    // Don't record any pending references for external resources.
+    if (!m_resource) {
+        document().accessSVGExtensions().addPendingResource(m_elementIdentifier, this);
+        DCHECK(hasPendingResources());
+    }
+    return nullptr;
+}
+
 void SVGUseElement::buildPendingResource()
 {
     if (inUseShadowTree())
         return;
     clearShadowTree();
     cancelShadowTreeRecreation();
     if (!isConnected())
         return;
-    Document* externalDocument = this->externalDocument();
-    if (isStructurallyExternal() && !externalDocument)
-        return;
-
-    AtomicString id;
-    Element* target = targetElementFromIRIString(hrefString(), treeScope(), &id, externalDocument);
-    if (!target || !target->isConnected()) {
-        // If we can't find the target of an external element, just give up.
-        // We can't observe if the target somewhen enters the external document, nor should we do it.
-        if (externalDocument)
-            return;
-        if (id.isEmpty())
-            return;
-
-        document().accessSVGExtensions().addPendingResource(id, this);
-        ASSERT(hasPendingResources());
-        return;
-    }
-
-    if (target->isSVGElement()) {
+    Element* target = resolveTargetElement();
+    if (target && target->isSVGElement()) {
         buildShadowAndInstanceTree(toSVGElement(*target));
         invalidateDependentShadowTrees();
     }
 
     ASSERT(!m_needsShadowTreeRecreation);
 }
 
 static void associateCorrespondingElements(SVGElement& targetRoot, SVGElement& instanceRoot)
 {
     auto targetRange = Traversal<SVGElement>::inclusiveDescendantsOf(targetRoot);
@@ skipping 402 matching lines @@
 
     if (m_resource)
         m_resource->removeClient(this);
 
     m_resource = resource;
     if (m_resource)
         m_resource->addClient(this);
 }
 
 } // namespace blink