LibWeb: Factor out attribute serialization into a separate function

Author: https://github.com/awesomekling
Commit: 0412e17bac
Pull-request: https://github.com/SerenityOS/serenity/pull/23905
Reviewed-by: https://github.com/trflynn89

Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.cpp

@@ -4244,33 +4244,13 @@ JS::NonnullGCPtr<HTMLParser> HTMLParser::create(DOM::Document& document, StringV
     return document.heap().allocate_without_realm<HTMLParser>(document, input, encoding);
 }
 
-// https://html.spec.whatwg.org/multipage/parsing.html#html-fragment-serialisation-algorithm
-String HTMLParser::serialize_html_fragment(DOM::Node const& node)
-{
-    // The algorithm takes as input a DOM Element, Document, or DocumentFragment referred to as the node.
-    VERIFY(node.is_element() || node.is_document() || node.is_document_fragment());
-    JS::NonnullGCPtr<DOM::Node const> actual_node = node;
-
-    if (is<DOM::Element>(node)) {
-        auto const& element = verify_cast<DOM::Element>(node);
-
-        // 1. If the node serializes as void, then return the empty string.
-        //    (NOTE: serializes as void is defined only on elements in the spec)
-        if (element.serializes_as_void())
-            return String {};
-
-        // 3. If the node is a template element, then let the node instead be the template element's template contents (a DocumentFragment node).
-        //    (NOTE: This is out of order of the spec to avoid another dynamic cast. The second step just creates a string builder, so it shouldn't matter)
-        if (is<HTML::HTMLTemplateElement>(element))
-            actual_node = verify_cast<HTML::HTMLTemplateElement>(element).content();
-    }
-
 enum class AttributeMode {
     No,
     Yes,
 };
 
-    auto escape_string = [](StringView string, AttributeMode attribute_mode) -> String {
+static String escape_string(StringView string, AttributeMode attribute_mode)
+{
     // https://html.spec.whatwg.org/multipage/parsing.html#escapingString
     StringBuilder builder;
     for (auto code_point : Utf8View { string }) {
@@ -4291,8 +4271,29 @@ String HTMLParser::serialize_html_fragment(DOM::Node const& node)
         else
             builder.append_code_point(code_point);
     }
-        return MUST(builder.to_string());
+    return builder.to_string_without_validation();
-    };
+}
+
+// https://html.spec.whatwg.org/multipage/parsing.html#html-fragment-serialisation-algorithm
+String HTMLParser::serialize_html_fragment(DOM::Node const& node)
+{
+    // The algorithm takes as input a DOM Element, Document, or DocumentFragment referred to as the node.
+    VERIFY(node.is_element() || node.is_document() || node.is_document_fragment());
+    JS::NonnullGCPtr<DOM::Node const> actual_node = node;
+
+    if (is<DOM::Element>(node)) {
+        auto const& element = verify_cast<DOM::Element>(node);
+
+        // 1. If the node serializes as void, then return the empty string.
+        //    (NOTE: serializes as void is defined only on elements in the spec)
+        if (element.serializes_as_void())
+            return String {};
+
+        // 3. If the node is a template element, then let the node instead be the template element's template contents (a DocumentFragment node).
+        //    (NOTE: This is out of order of the spec to avoid another dynamic cast. The second step just creates a string builder, so it shouldn't matter)
+        if (is<HTML::HTMLTemplateElement>(element))
+            actual_node = verify_cast<HTML::HTMLTemplateElement>(element).content();
+    }
 
     // 2. Let s be a string, and initialize it to the empty string.
     StringBuilder builder;