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/HTML/EventLoop/EventLoop.cpp

@@ -526,10 +526,8 @@ TaskID queue_global_task(HTML::Task::Source source, JS::Object& global_object, G
 
     // 2. Let document be global's associated Document, if global is a Window object; otherwise null.
     DOM::Document* document { nullptr };
-    if (is<HTML::Window>(global_object)) {
-        auto& window_object = as<HTML::Window>(global_object);
-        document = &window_object.associated_document();
-    }
+    if (auto* window_object = as_if<HTML::Window>(global_object))
+        document = &window_object->associated_document();
 
     // 3. Queue a task given source, event loop, document, and steps.
     return queue_a_task(source, *event_loop, document, steps);

Libraries/LibWeb/HTML/HTMLElement.cpp

@@ -215,11 +215,12 @@ static void merge_with_the_next_text_node(DOM::Text& node)
     auto next = node.next_sibling();
 
     // 2. If next is not a Text node, then return.
-    if (!is<DOM::Text>(next))
+    auto* text = as_if<DOM::Text>(next);
+    if (!text)
         return;
 
     // 3. Replace data with node, node's data's length, 0, and next's data.
-    MUST(node.replace_data(node.length_in_utf16_code_units(), 0, static_cast<DOM::Text const&>(*next).data()));
+    MUST(node.replace_data(node.length_in_utf16_code_units(), 0, text->data()));
 
     // 4. Remove next.
     next->remove();
@@ -253,8 +254,8 @@ WebIDL::ExceptionOr<void> HTMLElement::set_outer_text(Utf16View const& value)
         merge_with_the_next_text_node(static_cast<DOM::Text&>(*next->previous_sibling()));
 
     // 8. If previous is a Text node, then merge with the next text node given previous.
-    if (is<DOM::Text>(previous))
-        merge_with_the_next_text_node(static_cast<DOM::Text&>(*previous));
+    if (auto* previous_text = as_if<DOM::Text>(previous))
+        merge_with_the_next_text_node(*previous_text);
 
     set_needs_style_update(true);
     return {};
@@ -842,7 +843,8 @@ GC::Ptr<DOM::NodeList> HTMLElement::labels()
 
     if (!m_labels) {
         m_labels = DOM::LiveNodeList::create(realm(), root(), DOM::LiveNodeList::Scope::Descendants, [&](auto& node) {
-            return is<HTMLLabelElement>(node) && as<HTMLLabelElement>(node).control() == this;
+            auto* label_element = as_if<HTMLLabelElement>(node);
+            return label_element && label_element->control() == this;
         });
     }
 

Libraries/LibWeb/HTML/HTMLImageElement.cpp

@@ -1087,8 +1087,8 @@ static void update_the_source_set(DOM::Element& element)
     VERIFY(is<HTMLImageElement>(element) || is<HTMLLinkElement>(element));
 
     // 1. Set el's source set to an empty source set.
-    if (is<HTMLImageElement>(element))
-        static_cast<HTMLImageElement&>(element).set_source_set(SourceSet {});
+    if (auto* image_element = as_if<HTMLImageElement>(element))
+        image_element->set_source_set(SourceSet {});
     else if (is<HTMLLinkElement>(element))
         TODO();
 

Libraries/LibWeb/HTML/HTMLInputElement.cpp

@@ -494,11 +494,9 @@ WebIDL::ExceptionOr<void> HTMLInputElement::run_input_activation_behavior(DOM::E
 
         // 3. If the user activated the control while explicitly selecting a coordinate, then set the element's selected
         //    coordinate to that coordinate.
-        if (event.is_trusted() && is<UIEvents::MouseEvent>(event)) {
-            auto const& mouse_event = static_cast<UIEvents::MouseEvent const&>(event);
-
-            CSSPixels x { mouse_event.offset_x() };
-            CSSPixels y { mouse_event.offset_y() };
+        if (auto* mouse_event = as_if<UIEvents::MouseEvent>(event); mouse_event && event.is_trusted()) {
+            CSSPixels x { mouse_event->offset_x() };
+            CSSPixels y { mouse_event->offset_y() };
 
             m_selected_coordinate = { x.to_int(), y.to_int() };
         }

Libraries/LibWeb/HTML/HTMLMediaElement.cpp

@@ -715,8 +715,8 @@ private:
         }
 
         // 14. ⌛ If the node after pointer is a source element, let candidate be that element.
-        if (is<HTMLSourceElement>(next_sibling))
-            candidate = static_cast<HTMLSourceElement*>(next_sibling);
+        if (auto* source_element = as_if<HTMLSourceElement>(next_sibling))
+            candidate = source_element;
 
         // 15. ⌛ Advance pointer so that the node before pointer is now the node that was after pointer, and the node
         //     after pointer is the node after the node that used to be after pointer, if any.

Libraries/LibWeb/HTML/HTMLTableElement.cpp

@@ -213,8 +213,7 @@ GC::Ptr<HTMLTableSectionElement> HTMLTableElement::t_head()
     // The tHead IDL attribute must return, on getting, the first thead element child of the table element,
     // if any, or null otherwise.
     for (auto* child = first_child(); child; child = child->next_sibling()) {
-        if (is<HTMLTableSectionElement>(*child)) {
-            auto table_section_element = &as<HTMLTableSectionElement>(*child);
+        if (auto* table_section_element = as_if<HTMLTableSectionElement>(*child)) {
             if (table_section_element->local_name() == TagNames::thead)
                 return table_section_element;
         }
@@ -248,8 +247,7 @@ WebIDL::ExceptionOr<void> HTMLTableElement::set_t_head(HTMLTableSectionElement*
             continue;
         if (is<HTMLTableCaptionElement>(*child))
             continue;
-        if (is<HTMLTableColElement>(*child)) {
-            auto table_col_element = &as<HTMLTableColElement>(*child);
+        if (auto* table_col_element = as_if<HTMLTableColElement>(*child)) {
             if (table_col_element->local_name() == TagNames::colgroup)
                 continue;
         }
@@ -280,8 +278,7 @@ GC::Ref<HTMLTableSectionElement> HTMLTableElement::create_t_head()
             continue;
         if (is<HTMLTableCaptionElement>(*child))
             continue;
-        if (is<HTMLTableColElement>(*child)) {
-            auto table_col_element = &as<HTMLTableColElement>(*child);
+        if (auto* table_col_element = as_if<HTMLTableColElement>(*child)) {
             if (table_col_element->local_name() == TagNames::colgroup)
                 continue;
         }
@@ -311,8 +308,7 @@ GC::Ptr<HTMLTableSectionElement> HTMLTableElement::t_foot()
     // The tFoot IDL attribute must return, on getting, the first tfoot element child of the table element,
     // if any, or null otherwise.
     for (auto* child = first_child(); child; child = child->next_sibling()) {
-        if (is<HTMLTableSectionElement>(*child)) {
-            auto table_section_element = &as<HTMLTableSectionElement>(*child);
+        if (auto* table_section_element = as_if<HTMLTableSectionElement>(*child)) {
             if (table_section_element->local_name() == TagNames::tfoot)
                 return table_section_element;
         }
@@ -384,8 +380,7 @@ GC::Ref<HTMLTableSectionElement> HTMLTableElement::create_t_body()
     for (auto* child = last_child(); child; child = child->previous_sibling()) {
         if (!is<HTMLElement>(*child))
             continue;
-        if (is<HTMLTableSectionElement>(*child)) {
-            auto table_section_element = &as<HTMLTableSectionElement>(*child);
+        if (auto* table_section_element = as_if<HTMLTableSectionElement>(*child)) {
             if (table_section_element->local_name() == TagNames::tbody) {
                 // We have found an element which is a <tbody> we'll insert after this
                 child_to_insert_before = child->next_sibling();

Libraries/LibWeb/HTML/Navigable.cpp

@@ -1228,8 +1228,10 @@ static WebIDL::ExceptionOr<Navigable::NavigationParamsVariant> create_navigation
 
     // 26. If navigable's container is an iframe, and response's timing allow passed flag is set,
     //     then set navigable's container's pending resource-timing start time to null.
-    if (navigable->container() && is<HTML::HTMLIFrameElement>(*navigable->container()) && response_holder->response()->timing_allow_passed())
-        static_cast<HTML::HTMLIFrameElement&>(*navigable->container()).set_pending_resource_start_time({});
+    if (navigable->container() && response_holder->response()->timing_allow_passed()) {
+        if (auto* iframe_element = as_if<HTML::HTMLIFrameElement>(*navigable->container()))
+            iframe_element->set_pending_resource_start_time({});
+    }
 
     // 27. Return a new navigation params, with
     //     id: navigationId

Libraries/LibWeb/HTML/Parser/HTMLParser.cpp

@@ -766,8 +766,8 @@ HTMLParser::AdjustedInsertionLocation HTMLParser::find_appropriate_place_for_ins
 
     // 3. If the adjusted insertion location is inside a template element,
     //    let it instead be inside the template element's template contents, after its last child (if any).
-    if (is<HTMLTemplateElement>(*adjusted_insertion_location.parent))
-        adjusted_insertion_location = { static_cast<HTMLTemplateElement const&>(*adjusted_insertion_location.parent).content().ptr(), nullptr };
+    if (auto* template_element = as_if<HTMLTemplateElement>(*adjusted_insertion_location.parent))
+        adjusted_insertion_location = { template_element->content().ptr(), nullptr };
 
     // 4. Return the adjusted insertion location.
     return adjusted_insertion_location;

Libraries/LibWeb/HTML/Window.cpp

@@ -1238,8 +1238,8 @@ WebIDL::ExceptionOr<void> Window::window_post_message_steps(JS::Value message, W
         // FIXME: Use a FrozenArray
         Vector<GC::Root<MessagePort>> new_ports;
         for (auto const& object : deserialize_record.transferred_values) {
-            if (is<HTML::MessagePort>(*object)) {
-                new_ports.append(as<MessagePort>(*object));
+            if (auto* message_port = as_if<HTML::MessagePort>(*object)) {
+                new_ports.append(*message_port);
             }
         }