LibWeb: Ensure Noah's Ark clause is called in the Parser

Libraries/LibWeb/HTML/Parser/ListOfActiveFormattingElements.cpp

@@ -9,6 +9,7 @@
 
 namespace Web::HTML {
 
+static constexpr size_t NoahsArkCapacity = 3;
 ListOfActiveFormattingElements::~ListOfActiveFormattingElements() = default;
 
 void ListOfActiveFormattingElements::visit_edges(JS::Cell::Visitor& visitor)
@@ -17,9 +18,46 @@ void ListOfActiveFormattingElements::visit_edges(JS::Cell::Visitor& visitor)
         visitor.visit(entry.element);
 }
 
+void ListOfActiveFormattingElements::ensure_noahs_ark_clause(DOM::Element& element)
+{
+    Vector<Entry> possible_matches;
+    for (size_t i = m_entries.size(); i > 0;) {
+        i--;
+        auto& entry = m_entries[i];
+        if (entry.is_marker())
+            break;
+        if (entry.element->local_name() == element.local_name()
+            && entry.element->namespace_uri() == element.namespace_uri()
+            && entry.element->attribute_list_size() == element.attribute_list_size())
+            possible_matches.append(entry);
+    }
+
+    if (possible_matches.size() < NoahsArkCapacity)
+        return;
+
+    // FIXME: the attributes should be compared as they where created by the parser
+    element.for_each_attribute([&](auto& name, auto& value) {
+        possible_matches.remove_all_matching([&](auto& entry) {
+            auto attr = entry.element->get_attribute(name);
+            return !attr.has_value() || attr != value;
+        });
+    });
+
+    if (possible_matches.size() < NoahsArkCapacity)
+        return;
+
+    remove(*possible_matches.last().element);
+}
+
+// https://html.spec.whatwg.org/multipage/parsing.html#push-onto-the-list-of-active-formatting-elements
 void ListOfActiveFormattingElements::add(DOM::Element& element)
 {
-    // FIXME: Implement the Noah's Ark clause https://html.spec.whatwg.org/multipage/parsing.html#push-onto-the-list-of-active-formatting-elements
+    // 1. If there are already three elements in the list of active formatting elements after the last marker, if any, or anywhere in the list if there are no markers,
+    //    that have the same tag name, namespace, and attributes as element, then remove the earliest such element from the list of active formatting elements.
+    //    For these purposes, the attributes must be compared as they were when the elements were created by the parser; two elements have the same attributes if all their parsed attributes
+    //    can be paired such that the two attributes in each pair have identical names, namespaces, and values (the order of the attributes does not matter).
+    ensure_noahs_ark_clause(element);
+    // 2. Add element to the list of active formatting elements.
     m_entries.append({ element });
 }
 

Libraries/LibWeb/HTML/Parser/ListOfActiveFormattingElements.h

@@ -46,6 +46,7 @@ public:
 
 private:
     Vector<Entry> m_entries;
+    void ensure_noahs_ark_clause(DOM::Element& element);
 };
 
 }

Tests/LibWeb/Text/expected/wpt-import/html/syntax/parsing/html5lib_adoption01.txt

@@ -2,8 +2,7 @@ Harness status: OK
 
 Found 17 tests
 
-16 Pass
-1 Fail
+17 Pass
 Pass	html5lib_adoption01.html dab5eca760a630bc57719d678d789dd1ca74f492
 Pass	html5lib_adoption01.html a3a46907dc73b7be1e1171f797a9f696b7fb185b
 Pass	html5lib_adoption01.html b720cd1d95283d6288e7ca17142540b10ef8f847
@@ -20,4 +19,4 @@ Pass	html5lib_adoption01.html 52b62611a847a3f5fc3dc607a6b0174f1697247c
 Pass	html5lib_adoption01.html 88d0d3403d2a7b4058fcfb4e62835acb1c207e0f
 Pass	html5lib_adoption01.html d7338f457789f65d47b240e203b9e40a3925f2ca
 Pass	html5lib_adoption01.html bf8088acd8bd48d8487bae49a613c248c488c041
-Fail	html5lib_adoption01.html 39edaa2e298c60ad4a1b0b9fdb4481d4aea98f36
+Pass	html5lib_adoption01.html 39edaa2e298c60ad4a1b0b9fdb4481d4aea98f36

Tests/LibWeb/Text/expected/wpt-import/html/syntax/parsing/html5lib_tests23.txt

@@ -2,10 +2,9 @@ Harness status: OK
 
 Found 5 tests
 
-2 Pass
-3 Fail
-Fail	html5lib_tests23.html 79c0dc8da653d983d07795852b5f38d1533ff404
-Fail	html5lib_tests23.html 403404388390abddf3fb44db8dd7d643652f5df9
-Fail	html5lib_tests23.html b9a81ae44ab81719fc6a4e3b6460fc6efc684e65
+5 Pass
+Pass	html5lib_tests23.html 79c0dc8da653d983d07795852b5f38d1533ff404
+Pass	html5lib_tests23.html 403404388390abddf3fb44db8dd7d643652f5df9
+Pass	html5lib_tests23.html b9a81ae44ab81719fc6a4e3b6460fc6efc684e65
 Pass	html5lib_tests23.html d271d3662baafff4893d32b250cadcf4c2ff3352
 Pass	html5lib_tests23.html f8e296b2f362a64c1c464bedd6248e314f41c701