LibWeb: Add generic string_from_style_value method

Reduces duplication in line with `Time::from_style_value()`,
`Angle::from_style_value()` etc

Libraries/LibWeb/CSS/ComputedProperties.cpp

@@ -2100,16 +2100,7 @@ Vector<ComputedProperties::AnimationProperties> ComputedProperties::animations(D
         auto delay = Time::from_style_value(animation_delay_style_value, {}).to_milliseconds();
         auto fill_mode = keyword_to_animation_fill_mode(animation_fill_mode_style_value->to_keyword()).value();
         auto composition = keyword_to_animation_composition(animation_composition_style_value->to_keyword()).value();
-
-        auto name = [&] {
-            if (animation_name_style_value->is_custom_ident())
-                return animation_name_style_value->as_custom_ident().custom_ident();
-
-            if (animation_name_style_value->is_string())
-                return animation_name_style_value->as_string().string_value();
-
-            VERIFY_NOT_REACHED();
-        }();
+        auto name = string_from_style_value(animation_name_style_value);
 
         // https://drafts.csswg.org/css-animations-2/#animation-timeline
         auto const& timeline = [&]() -> GC::Ptr<Animations::AnimationTimeline> {

Libraries/LibWeb/CSS/FontComputer.cpp

@@ -73,12 +73,8 @@ struct Traits<Web::CSS::ComputedFontCacheKey> : public DefaultTraits<Web::CSS::C
         for (auto const& family_value : key.font_family->as_value_list().values()) {
             if (family_value->is_keyword())
                 hash = pair_int_hash(hash, to_underlying(family_value->as_keyword().keyword()));
-            else if (family_value->is_string())
-                hash = pair_int_hash(hash, family_value->as_string().string_value().hash());
-            else if (family_value->is_custom_ident())
-                hash = pair_int_hash(hash, family_value->as_custom_ident().custom_ident().hash());
             else
-                VERIFY_NOT_REACHED();
+                hash = string_from_style_value(family_value).hash();
         }
 
         hash = pair_int_hash(hash, to_underlying(key.font_optical_sizing));
@@ -492,10 +488,8 @@ NonnullRefPtr<Gfx::FontCascadeList const> FontComputer::compute_font_for_style_v
         RefPtr<Gfx::FontCascadeList const> other_font_list;
         if (family->is_keyword()) {
             other_font_list = find_generic_font(family->to_keyword());
-        } else if (family->is_string()) {
-            other_font_list = find_font(family->as_string().string_value());
-        } else if (family->is_custom_ident()) {
-            other_font_list = find_font(family->as_custom_ident().custom_ident());
+        } else {
+            other_font_list = find_font(string_from_style_value(family));
         }
 
         if (other_font_list)
@@ -547,13 +541,10 @@ static bool style_value_references_font_family(StyleValue const& font_family_val
         return false;
 
     for (auto const& item : font_family_value.as_value_list().values()) {
-        FlyString item_family_name;
-        if (item->is_string())
-            item_family_name = item->as_string().string_value();
-        else if (item->is_custom_ident())
-            item_family_name = item->as_custom_ident().custom_ident();
-        else
-            continue; // Skip generic keywords (sans-serif, serif, etc.)
+        if (item->is_keyword())
+            continue; // Skip generic keywords (monospace, serif, etc.)
+
+        FlyString item_family_name = string_from_style_value(*item);
 
         if (item_family_name.equals_ignoring_ascii_case(family_name))
             return true;

Libraries/LibWeb/CSS/FontFace.cpp

@@ -281,12 +281,7 @@ WebIDL::ExceptionOr<void> FontFace::set_family(String const& string)
 
 void FontFace::set_family_impl(NonnullRefPtr<StyleValue const> const& value)
 {
-    if (value->is_custom_ident())
-        m_family = value->as_custom_ident().custom_ident().to_string();
-    else if (value->is_string())
-        m_family = value->as_string().string_value().to_string();
-    else
-        VERIFY_NOT_REACHED();
+    m_family = string_from_style_value(value).to_string();
 }
 
 // https://drafts.csswg.org/css-font-loading/#dom-fontface-style

Libraries/LibWeb/CSS/FontFaceSet.cpp

@@ -230,22 +230,11 @@ static WebIDL::ExceptionOr<GC::Ref<JS::Set>> find_matching_font_faces(JS::Realm&
     //    that this may be more than just a single font face.
     for (auto const& font_family : font_family_list.values()) {
         // FIXME: The matching below is super basic. We currently just match font family names by their string value.
-        auto maybe_font_family_name = [&]() -> Optional<FlyString> {
-            if (font_family->is_string())
-                return font_family->as_string().string_value();
-
-            if (font_family->is_custom_ident())
-                return font_family->as_custom_ident().custom_ident();
-
-            return {};
-        }();
-
-        if (!maybe_font_family_name.has_value())
-            continue;
+        auto font_family_name = string_from_style_value(font_family);
 
         for (auto font_face_value : *available_font_faces) {
             auto& font_face = as<FontFace>(font_face_value.key.as_object());
-            if (font_face.family() != maybe_font_family_name.value())
+            if (font_face.family() != font_family_name)
                 continue;
 
             matched_font_faces->set_add(font_face_value.key);

Libraries/LibWeb/CSS/ParsedFontFace.cpp

@@ -26,22 +26,13 @@
 
 namespace Web::CSS {
 
-static FlyString extract_font_name(StyleValue const& value)
-{
-    if (value.is_string())
-        return value.as_string().string_value();
-    if (value.is_custom_ident())
-        return value.as_custom_ident().custom_ident();
-    return FlyString {};
-}
-
 Vector<ParsedFontFace::Source> ParsedFontFace::sources_from_style_value(StyleValue const& style_value)
 {
     Vector<Source> sources;
     auto add_source = [&sources](FontSourceStyleValue const& font_source) {
         font_source.source().visit(
             [&](FontSourceStyleValue::Local const& local) {
-                sources.empend(extract_font_name(local.name), OptionalNone {}, Vector<FontTech> {});
+                sources.empend(string_from_style_value(local.name), OptionalNone {}, Vector<FontTech> {});
             },
             [&](URL const& url) {
                 sources.empend(url, font_source.format(), font_source.tech());
@@ -74,7 +65,7 @@ ParsedFontFace ParsedFontFace::from_descriptors(CSSFontFaceDescriptors const& de
 
     FlyString font_family;
     if (auto value = descriptors.descriptor_or_initial_value(DescriptorID::FontFamily))
-        font_family = extract_font_name(*value);
+        font_family = string_from_style_value(*value);
 
     ComputationContext computation_context {
         .length_resolution_context = Length::ResolutionContext::for_document(*descriptors.parent_rule()->parent_style_sheet()->owning_document())

Libraries/LibWeb/CSS/StyleValues/StyleValue.cpp

@@ -213,4 +213,15 @@ double number_from_style_value(NonnullRefPtr<StyleValue const> const& style_valu
     VERIFY_NOT_REACHED();
 }
 
+FlyString const& string_from_style_value(NonnullRefPtr<StyleValue const> const& style_value)
+{
+    if (style_value->is_string())
+        return style_value->as_string().string_value();
+
+    if (style_value->is_custom_ident())
+        return style_value->as_custom_ident().custom_ident();
+
+    VERIFY_NOT_REACHED();
+}
+
 }

Libraries/LibWeb/CSS/StyleValues/StyleValue.h

@@ -203,6 +203,7 @@ struct StyleValueWithDefaultOperators : public StyleValue {
 };
 
 double number_from_style_value(NonnullRefPtr<StyleValue const> const& style_value, Optional<double> percentage_basis);
+FlyString const& string_from_style_value(NonnullRefPtr<StyleValue const> const& style_value);
 
 }