LibWeb: Replace is<T>() with as_if<T>() where possible

Author: https://github.com/tcl3
Commit: cb1a1a5cb5
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/5985
Reviewed-by: https://github.com/gmta ✅

Libraries/LibWeb/DOM/Document.cpp

@@ -904,9 +904,7 @@ HTML::HTMLHtmlElement* Document::html_element()
 {
     // The html element of a document is its document element, if it's an html element, and null otherwise.
     auto* html = document_element();
-    if (is<HTML::HTMLHtmlElement>(html))
-        return as<HTML::HTMLHtmlElement>(html);
-    return nullptr;
+    return as_if<HTML::HTMLHtmlElement>(html);
 }
 
 // https://html.spec.whatwg.org/multipage/dom.html#the-head-element-2

Libraries/LibWeb/DOM/Element.cpp

@@ -1049,14 +1049,15 @@ WebIDL::ExceptionOr<void> Element::set_inner_html(StringView value)
     auto fragment = TRY(as<Element>(*context).parse_fragment(value));
 
     // 4. If context is a template element, then set context to the template element's template contents (a DocumentFragment).
-    if (is<HTML::HTMLTemplateElement>(*context))
-        context = as<HTML::HTMLTemplateElement>(*context).content();
+    auto* template_element = as_if<HTML::HTMLTemplateElement>(*context);
+    if (template_element)
+        context = template_element->content();
 
     // 5. Replace all with fragment within context.
     context->replace_all(fragment);
 
     // NOTE: We don't invalidate style & layout for <template> elements since they don't affect rendering.
-    if (!is<HTML::HTMLTemplateElement>(*context)) {
+    if (!template_element) {
         context->set_needs_style_update(true);
 
         if (context->is_connected()) {

Libraries/LibWeb/DOM/Element.h

@@ -491,10 +491,11 @@ public:
     void for_each_numbered_item_owned_by_list_owner(Callback callback)
     {
         for (auto* node = this->first_child(); node != nullptr; node = node->next_in_pre_order(this)) {
-            if (!is<Element>(*node))
+            auto* element = as_if<Element>(node);
+            if (!element)
                 continue;
 
-            static_cast<Element*>(node)->m_is_contained_in_list_subtree = true;
+            element->m_is_contained_in_list_subtree = true;
 
             if (node->is_html_ol_ul_menu_element()) {
                 // Skip list nodes and their descendents. They have their own, unrelated ordinals.
@@ -507,8 +508,6 @@ public:
             if (!node->layout_node())
                 continue; // Skip nodes that do not participate in the layout.
 
-            auto* element = static_cast<Element*>(node);
-
             if (!element->computed_properties()->display().is_list_item())
                 continue; // Skip nodes that are not list items.
 

Libraries/LibWeb/DOM/EventTarget.cpp

@@ -164,8 +164,7 @@ static bool default_passive_value(FlyString const& type, EventTarget* event_targ
         if (is<HTML::Window>(event_target))
             return true;
 
-        if (is<Node>(event_target)) {
-            auto* node = as<Node>(event_target);
+        if (auto* node = as_if<Node>(event_target)) {
             if (&node->document() == event_target || node->document().document_element() == event_target || node->document().body() == event_target)
                 return true;
         }
@@ -400,8 +399,7 @@ WebIDL::CallbackType* EventTarget::get_current_value_of_event_handler(FlyString
         GC::Ptr<Element> element;
         GC::Ptr<Document> document;
 
-        if (is<Element>(this)) {
-            auto* element_event_target = as<Element>(this);
+        if (auto* element_event_target = as_if<Element>(this)) {
             element = element_event_target;
             document = &element_event_target->document();
         } else {

Libraries/LibWeb/DOM/Node.cpp

@@ -136,11 +136,11 @@ String Node::base_uri() const
 const HTML::HTMLAnchorElement* Node::enclosing_link_element() const
 {
     for (auto* node = this; node; node = node->parent()) {
-        if (!is<HTML::HTMLAnchorElement>(*node))
+        auto const* anchor_element = as_if<HTML::HTMLAnchorElement>(*node);
+        if (!anchor_element)
             continue;
-        auto const& anchor_element = static_cast<HTML::HTMLAnchorElement const&>(*node);
-        if (anchor_element.has_attribute(HTML::AttributeNames::href))
-            return &anchor_element;
+        if (anchor_element->has_attribute(HTML::AttributeNames::href))
+            return anchor_element;
     }
     return nullptr;
 }
@@ -153,8 +153,8 @@ const HTML::HTMLElement* Node::enclosing_html_element() const
 const HTML::HTMLElement* Node::enclosing_html_element_with_attribute(FlyString const& attribute) const
 {
     for (auto* node = this; node; node = node->parent()) {
-        if (is<HTML::HTMLElement>(*node) && as<HTML::HTMLElement>(*node).has_attribute(attribute))
-            return as<HTML::HTMLElement>(node);
+        if (auto* html_element = as_if<HTML::HTMLElement>(*node); html_element && html_element->has_attribute(attribute))
+            return html_element;
     }
     return nullptr;
 }
@@ -354,13 +354,13 @@ Optional<String> Node::node_value() const
     // The nodeValue getter steps are to return the following, switching on the interface this implements:
 
     // If Attr, return this’s value.
-    if (is<Attr>(this)) {
-        return as<Attr>(this)->value();
+    if (auto* attr = as_if<Attr>(this)) {
+        return attr->value();
     }
 
     // If CharacterData, return this’s data.
-    if (is<CharacterData>(this)) {
-        return as<CharacterData>(this)->data().to_utf8_but_should_be_ported_to_utf16();
+    if (auto* character_data = as_if<CharacterData>(this)) {
+        return character_data->data().to_utf8_but_should_be_ported_to_utf16();
     }
 
     // Otherwise, return null.
@@ -375,11 +375,11 @@ void Node::set_node_value(Optional<String> const& maybe_value)
     auto value = maybe_value.value_or(String {});
 
     // If Attr, set an existing attribute value with this and the given value.
-    if (is<Attr>(this)) {
-        as<Attr>(this)->set_value(move(value));
-    } else if (is<CharacterData>(this)) {
+    if (auto* attr = as_if<Attr>(this)) {
+        attr->set_value(move(value));
+    } else if (auto* character_data = as_if<CharacterData>(this)) {
         // If CharacterData, replace data with node this, offset 0, count this’s length, and data the given value.
-        as<CharacterData>(this)->set_data(Utf16String::from_utf8(value));
+        character_data->set_data(Utf16String::from_utf8(value));
     }
 
     // Otherwise, do nothing.
@@ -545,8 +545,8 @@ Node& Node::shadow_including_root()
     // The shadow-including root of an object is its root’s host’s shadow-including root,
     // if the object’s root is a shadow root; otherwise its root.
     auto& node_root = root();
-    if (is<ShadowRoot>(node_root)) {
-        if (auto* host = static_cast<ShadowRoot&>(node_root).host(); host)
+    if (auto* shadow_root = as_if<ShadowRoot>(node_root)) {
+        if (auto* host = shadow_root->host(); host)
             return host->shadow_including_root();
     }
     return node_root;