LibWeb: Add a way to test if a CSS::PropertyID is animatable

Author: https://github.com/mattco98
Commit: https://github.com/SerenityOS/serenity/commit/212a139292
Pull-request: https://github.com/SerenityOS/serenity/pull/23087
Reviewed-by: https://github.com/AtkinsSJ
Reviewed-by: https://github.com/awesomekling

Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSPropertyID.cpp

@@ -17,6 +17,7 @@ void replace_logical_aliases(JsonObject& properties);
 ErrorOr<void> generate_header_file(JsonObject& properties, Core::File& file);
 ErrorOr<void> generate_implementation_file(JsonObject& properties, Core::File& file);
 void generate_bounds_checking_function(JsonObject& properties, SourceGenerator& parent_generator, StringView css_type_name, StringView type_name, Optional<StringView> default_unit_name = {}, Optional<StringView> value_getter = {});
+bool is_animatable_property(JsonObject& properties, StringView property_name);
 
 static bool type_name_is_enum(StringView type_name)
 {
@@ -160,6 +161,16 @@ enum class PropertyID {
     generator.append(R"~~~(
 };
 
+enum class AnimationType {
+    Discrete,
+    ByComputedValue,
+    RepeatableList,
+    Custom,
+    None,
+};
+AnimationType animation_type_from_longhand_property(PropertyID);
+bool is_animatable_property(PropertyID);
+
 Optional<PropertyID> property_id_from_camel_case_string(StringView);
 Optional<PropertyID> property_id_from_string(StringView);
 StringView string_from_property_id(PropertyID);
@@ -412,6 +423,71 @@ StringView string_from_property_id(PropertyID property_id) {
     }
 }
 
+AnimationType animation_type_from_longhand_property(PropertyID property_id)
+{
+    switch (property_id) {
+)~~~");
+
+    properties.for_each_member([&](auto& name, auto& value) {
+        VERIFY(value.is_object());
+        auto member_generator = generator.fork();
+        member_generator.set("name:titlecase", title_casify(name));
+
+        // Shorthand properties should have already been expanded before calling into this function
+        if (value.as_object().has("longhands"sv)) {
+            if (value.as_object().has("animation-type"sv)) {
+                dbgln("Property '{}' with longhands cannot specify 'animation-type'", name);
+                VERIFY_NOT_REACHED();
+            }
+            member_generator.append(R"~~~(
+    case PropertyID::@name:titlecase@:
+        VERIFY_NOT_REACHED();
+)~~~");
+            return;
+        }
+
+        if (!value.as_object().has("animation-type"sv)) {
+            dbgln("No animation-type specified for property '{}'", name);
+            VERIFY_NOT_REACHED();
+        }
+
+        auto animation_type = value.as_object().get_byte_string("animation-type"sv).value();
+        member_generator.set("value", title_casify(animation_type));
+        member_generator.append(R"~~~(
+    case PropertyID::@name:titlecase@:
+        return AnimationType::@value@;
+)~~~");
+    });
+
+    generator.append(R"~~~(
+    default:
+        return AnimationType::None;
+    }
+}
+
+bool is_animatable_property(PropertyID property_id)
+{
+    switch (property_id) {
+)~~~");
+
+    properties.for_each_member([&](auto& name, auto& value) {
+        VERIFY(value.is_object());
+        if (is_animatable_property(properties, name)) {
+            auto member_generator = generator.fork();
+            member_generator.set("name:titlecase", title_casify(name));
+            member_generator.append(R"~~~(
+    case PropertyID::@name:titlecase@:
+)~~~");
+        }
+    });
+
+    generator.append(R"~~~(
+        return true;
+    default:
+        return false;
+    }
+}
+
 bool is_inherited_property(PropertyID property_id)
 {
     switch (property_id) {
@@ -860,3 +936,28 @@ Vector<PropertyID> longhands_for_shorthand(PropertyID property_id)
     TRY(file.write_until_depleted(generator.as_string_view().bytes()));
     return {};
 }
+
+bool is_animatable_property(JsonObject& properties, StringView property_name)
+{
+    auto property = properties.get_object(property_name);
+    VERIFY(property.has_value());
+
+    if (auto animation_type = property.value().get_byte_string("animation-type"sv); animation_type.has_value()) {
+        return animation_type != "none";
+    }
+
+    if (!property.value().has("longhands"sv)) {
+        dbgln("Property '{}' must specify either 'animation-type' or 'longhands'"sv, property_name);
+        VERIFY_NOT_REACHED();
+    }
+
+    auto longhands = property.value().get_array("longhands"sv);
+    VERIFY(longhands.has_value());
+    for (auto const& subproperty_name : longhands->values()) {
+        VERIFY(subproperty_name.is_string());
+        if (is_animatable_property(properties, subproperty_name.as_string()))
+            return true;
+    }
+
+    return false;
+}