Adopt more dynamicDowncast<> in XML code

https://bugs.webkit.org/show_bug.cgi?id=268460

Reviewed by Chris Dumez.

* Source/WebCore/xml/XPathFunctions.cpp:
(WebCore::XPath::expandedNameLocalPart):
(WebCore::XPath::expandedName):
(WebCore::XPath::FunLocalName::evaluate const):
(WebCore::XPath::FunName::evaluate const):
(WebCore::XPath::FunLang::evaluate const):
* Source/WebCore/xml/XPathStep.cpp:
(WebCore::XPath::nodeMatchesBasicTest):
(WebCore::XPath::Step::nodesInAxis const):
* Source/WebCore/xml/parser/XMLDocumentParserLibxml2.cpp:
(WebCore::XMLDocumentParser::startElementNs):

Canonical link: https://commits.webkit.org/273878@main

Source/WebCore/xml/XPathFunctions.cpp

@@ -353,16 +353,16 @@ Value FunId::evaluate() const
     return Value(WTFMove(result));
 }
 
-static inline String expandedNameLocalPart(Node* node)
+static inline String expandedNameLocalPart(Node& node)
 {
-    if (is<ProcessingInstruction>(*node))
-        return downcast<ProcessingInstruction>(*node).target();
-    return node->localName().string();
+    if (auto* pi = dynamicDowncast<ProcessingInstruction>(node))
+        return pi->target();
+    return node.localName().string();
 }
 
-static inline String expandedName(Node* node)
+static inline String expandedName(Node& node)
 {
-    const AtomString& prefix = node->prefix();
+    auto& prefix = node.prefix();
     return prefix.isEmpty() ? expandedNameLocalPart(node) : prefix + ":" + expandedNameLocalPart(node);
 }
 
@@ -373,11 +373,11 @@ Value FunLocalName::evaluate() const
         if (!a.isNodeSet())
             return emptyString();
 
-        Node* node = a.toNodeSet().firstNode();
-        return node ? expandedNameLocalPart(node) : emptyString();
+        auto* node = a.toNodeSet().firstNode();
+        return node ? expandedNameLocalPart(*node) : emptyString();
     }
 
-    return expandedNameLocalPart(evaluationContext().node.get());
+    return expandedNameLocalPart(*evaluationContext().node);
 }
 
 Value FunNamespaceURI::evaluate() const
@@ -401,11 +401,11 @@ Value FunName::evaluate() const
         if (!a.isNodeSet())
             return emptyString();
 
-        Node* node = a.toNodeSet().firstNode();
-        return node ? expandedName(node) : emptyString();
+        auto* node = a.toNodeSet().firstNode();
+        return node ? expandedName(*node) : emptyString();
     }
 
-    return expandedName(evaluationContext().node.get());
+    return expandedName(*evaluationContext().node);
 }
 
 Value FunCount::evaluate() const
@@ -627,10 +627,9 @@ Value FunLang::evaluate() const
     const Attribute* languageAttribute = nullptr;
     Node* node = evaluationContext().node.get();
     while (node) {
-        if (is<Element>(*node)) {
-            Element& element = downcast<Element>(*node);
-            if (element.hasAttributes())
-                languageAttribute = element.findAttributeByName(XMLNames::langAttr);
+        if (RefPtr element = dynamicDowncast<Element>(*node)) {
+            if (element->hasAttributes())
+                languageAttribute = element->findAttributeByName(XMLNames::langAttr);
         }
         if (languageAttribute)
             break;

Source/WebCore/xml/XPathStep.cpp

@@ -200,21 +200,22 @@ inline bool nodeMatchesBasicTest(Node& node, Step::Axis axis, const Step::NodeTe
 
             // For other axes, the principal node type is element.
             ASSERT(primaryNodeType(axis) == Node::ELEMENT_NODE);
-            if (!is<Element>(node))
+            auto* element = dynamicDowncast<Element>(node);
+            if (!element)
                 return false;
 
             if (name == starAtom())
                 return namespaceURI.isEmpty() || namespaceURI == node.namespaceURI();
 
             if (node.document().isHTMLDocument()) {
-                if (is<HTMLElement>(node)) {
+                if (is<HTMLElement>(*element)) {
                     // Paths without namespaces should match HTML elements in HTML documents despite those having an XHTML namespace. Names are compared case-insensitively.
-                    return equalIgnoringASCIICase(downcast<HTMLElement>(node).localName(), name) && (namespaceURI.isNull() || namespaceURI == node.namespaceURI());
+                    return equalIgnoringASCIICase(element->localName(), name) && (namespaceURI.isNull() || namespaceURI == node.namespaceURI());
                 }
                 // An expression without any prefix shouldn't match no-namespace nodes (because HTML5 says so).
-                return downcast<Element>(node).hasLocalName(name) && namespaceURI == node.namespaceURI() && !namespaceURI.isNull();
+                return element->hasLocalName(name) && namespaceURI == node.namespaceURI() && !namespaceURI.isNull();
             }
-            return downcast<Element>(node).hasLocalName(name) && namespaceURI == node.namespaceURI();
+            return element->hasLocalName(name) && namespaceURI == node.namespaceURI();
         }
     }
     ASSERT_NOT_REACHED();
@@ -347,32 +348,31 @@ void Step::nodesInAxis(Node& context, NodeSet& nodes) const
             return;
         }
         case AttributeAxis: {
-            if (!is<Element>(context))
+            RefPtr contextElement = dynamicDowncast<Element>(context);
+            if (!contextElement)
                 return;
 
-            Element& contextElement = downcast<Element>(context);
-
             // Avoid lazily creating attribute nodes for attributes that we do not need anyway.
             if (m_nodeTest.m_kind == NodeTest::NameTest && m_nodeTest.m_data != starAtom()) {
                 RefPtr<Attr> attr;
                 // We need this branch because getAttributeNodeNS() doesn't do
                 // ignore-case matching even for an HTML element in an HTML document.
                 if (m_nodeTest.m_namespaceURI.isNull())
-                    attr = contextElement.getAttributeNode(m_nodeTest.m_data);
+                    attr = contextElement->getAttributeNode(m_nodeTest.m_data);
                 else
-                    attr = contextElement.getAttributeNodeNS(m_nodeTest.m_namespaceURI, m_nodeTest.m_data);
+                    attr = contextElement->getAttributeNodeNS(m_nodeTest.m_namespaceURI, m_nodeTest.m_data);
                 if (attr && attr->namespaceURI() != XMLNSNames::xmlnsNamespaceURI) { // In XPath land, namespace nodes are not accessible on the attribute axis.
                     if (nodeMatches(*attr, AttributeAxis, m_nodeTest)) // Still need to check merged predicates.
                         nodes.append(WTFMove(attr));
                 }
                 return;
             }
 
-            if (!contextElement.hasAttributes())
+            if (!contextElement->hasAttributes())
                 return;
 
-            for (const Attribute& attribute : contextElement.attributesIterator()) {
-                auto attr = contextElement.ensureAttr(attribute.name());
+            for (const Attribute& attribute : contextElement->attributesIterator()) {
+                auto attr = contextElement->ensureAttr(attribute.name());
                 if (nodeMatches(attr.get(), AttributeAxis, m_nodeTest))
                     nodes.append(WTFMove(attr));
             }

Source/WebCore/xml/parser/XMLDocumentParserLibxml2.cpp

@@ -837,8 +837,8 @@ void XMLDocumentParser::startElementNs(const xmlChar* xmlLocalName, const xmlCha
     if (!m_currentNode) // Synchronous DOM events may have removed the current node.
         return;
 
-    if (is<HTMLTemplateElement>(newElement))
-        pushCurrentNode(&downcast<HTMLTemplateElement>(newElement.get()).content());
+    if (RefPtr templateElement = dynamicDowncast<HTMLTemplateElement>(newElement))
+        pushCurrentNode(&templateElement->content());
     else
         pushCurrentNode(newElement.ptr());