LibWeb: Add support for inline SVG element scripts

Author: https://github.com/shannonbooth
Commit: https://github.com/SerenityOS/serenity/commit/4821d284c6
Pull-request: https://github.com/SerenityOS/serenity/pull/21227
Reviewed-by: https://github.com/AtkinsSJ ✅
Reviewed-by: https://github.com/kemzeb

Tests/LibWeb/Text/expected/SVG/svg-script-element.txt

@@ -1 +1 @@
-  Name = SVGScriptElement
+   Hello from SVGScriptElement!

Tests/LibWeb/Text/input/SVG/svg-script-element.html

@@ -1,7 +1,8 @@
 <script src="../include.js"></script>
-<svg xmlns="http://www.w3.org/2000/svg"><script id="svg-script-element"></script></svg>
-<script>
-    test(() => {
-        println(`Name = ${document.getElementById('svg-script-element').constructor.name}`);
-    });
-</script>
+<svg xmlns="http://www.w3.org/2000/svg">
+    <script id="svg-script-element">
+        test(() => {
+            println(`Hello from ${document.getElementById('svg-script-element').constructor.name}!`);
+        });
+    </script>
+</svg>

Userland/Libraries/LibWeb/Forward.h

@@ -618,6 +618,7 @@ class SVGPathElement;
 class SVGPolygonElement;
 class SVGPolylineElement;
 class SVGRectElement;
+class SVGScriptElement;
 class SVGSVGElement;
 class SVGTitleElement;
 }

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

@@ -39,6 +39,7 @@
 #include <LibWeb/Infra/Strings.h>
 #include <LibWeb/MathML/TagNames.h>
 #include <LibWeb/Namespace.h>
+#include <LibWeb/SVG/SVGScriptElement.h>
 #include <LibWeb/SVG/TagNames.h>
 
 namespace Web::HTML {
@@ -3525,6 +3526,9 @@ void HTMLParser::process_using_the_rules_for_foreign_content(HTMLToken& token)
 
             // -> If the token's tag name is "script", and the new current node is in the SVG namespace
             if (token.tag_name() == SVG::TagNames::script && current_node().namespace_uri() == Namespace::SVG) {
+                auto& script_element = verify_cast<SVG::SVGScriptElement>(current_node());
+                script_element.set_source_line_number({}, token.start_position().line + 1); // FIXME: This +1 is incorrect for script tags whose script does not start on a new line
+
                 // Acknowledge the token's self-closing flag, and then act as described in the steps for a "script" end tag below.
                 token.acknowledge_self_closing_flag_if_set();
                 goto ScriptEndTag;
@@ -3544,7 +3548,7 @@ void HTMLParser::process_using_the_rules_for_foreign_content(HTMLToken& token)
     if (token.is_end_tag() && current_node().namespace_uri() == Namespace::SVG && current_node().tag_name() == SVG::TagNames::script) {
     ScriptEndTag:
         // Pop the current node off the stack of open elements.
-        (void)m_stack_of_open_elements.pop();
+        auto& script_element = verify_cast<SVG::SVGScriptElement>(*m_stack_of_open_elements.pop());
         // Let the old insertion point have the same value as the current insertion point.
         m_tokenizer.store_insertion_point();
         // Let the insertion point be just before the next input character.
@@ -3554,8 +3558,12 @@ void HTMLParser::process_using_the_rules_for_foreign_content(HTMLToken& token)
         // Set the parser pause flag to true.
         m_parser_pause_flag = true;
 
-        // FIXME: If the active speculative HTML parser is null and the user agent supports SVG, then Process the SVG script element according to the SVG rules. [SVG]
-        dbgln("FIXME: Missing 'Process the SVG script element according to the SVG rules.");
+        // Non-standard: Make sure the <script> element has up-to-date text content before processing the script.
+        flush_character_insertions();
+
+        // If the active speculative HTML parser is null and the user agent supports SVG, then Process the SVG script element according to the SVG rules. [SVG]
+        // FIXME: If the active speculative HTML parser is null
+        script_element.process_the_script_element();
 
         // Decrement the parser's script nesting level by one.
         decrement_script_nesting_level();

Userland/Libraries/LibWeb/SVG/SVGScriptElement.cpp

@@ -4,6 +4,9 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <LibWeb/HTML/Scripting/ClassicScript.h>
+#include <LibWeb/Namespace.h>
+#include <LibWeb/SVG/AttributeNames.h>
 #include <LibWeb/SVG/SVGScriptElement.h>
 
 namespace Web::SVG {
@@ -19,4 +22,43 @@ void SVGScriptElement::initialize(JS::Realm& realm)
     set_prototype(&Bindings::ensure_web_prototype<Bindings::SVGScriptElementPrototype>(realm, "SVGScriptElement"));
 }
 
+void SVGScriptElement::visit_edges(Cell::Visitor& visitor)
+{
+    Base::visit_edges(visitor);
+    visitor.visit(m_script);
+}
+
+// https://www.w3.org/TR/SVGMobile12/script.html#ScriptContentProcessing
+void SVGScriptElement::process_the_script_element()
+{
+    // 1. If the 'script' element's "already processed" flag is true or if the element is not in the
+    //    document tree, then no action is performed and these steps are ended.
+    if (m_already_processed || !in_a_document_tree())
+        return;
+
+    auto inline_script = child_text_content();
+
+    // FIXME: 2. If the 'script' element references external script content, then the external script content
+    //           using the current value of the 'xlink:href' attribute is fetched. Further processing of the
+    //           'script' element is dependent on the external script content, and will block here until the
+    //           resource has been fetched or is determined to be an invalid IRI reference.
+    if (has_attribute(SVG::AttributeNames::href) || has_attribute_ns(Namespace::XLink.to_string(), SVG::AttributeNames::href)) {
+        dbgln("FIXME: Unsupported external fetch of SVGScriptElement!");
+        return;
+    }
+
+    // 3. The 'script' element's "already processed" flag is set to true.
+    m_already_processed = true;
+
+    // 4. If the script content is inline, or if it is external and was fetched successfully, then the
+    //    script is executed. Note that at this point, these steps may be re-entrant if the execution
+    //    of the script results in further 'script' elements being inserted into the document.
+    // FIXME: Support non-inline scripts.
+    auto& settings_object = document().relevant_settings_object();
+    auto base_url = document().base_url();
+
+    m_script = HTML::ClassicScript::create(m_document->url().to_deprecated_string(), inline_script, settings_object, base_url, m_source_line_number);
+    (void)m_script->run();
+}
+
 }

Userland/Libraries/LibWeb/SVG/SVGScriptElement.h

@@ -15,6 +15,10 @@ class SVGScriptElement : public SVGElement {
     WEB_PLATFORM_OBJECT(SVGScriptElement, SVGElement);
 
 public:
+    void process_the_script_element();
+
+    void set_source_line_number(Badge<HTML::HTMLParser>, size_t source_line_number) { m_source_line_number = source_line_number; }
+
 protected:
     SVGScriptElement(DOM::Document&, DOM::QualifiedName);
 
@@ -22,6 +26,14 @@ protected:
 
 private:
     virtual bool is_svg_script_element() const final { return true; }
+
+    virtual void visit_edges(Cell::Visitor&) override;
+
+    bool m_already_processed { false };
+
+    JS::GCPtr<HTML::ClassicScript> m_script;
+
+    size_t m_source_line_number { 1 };
 };
 
 }