LibJS: Implement Intl.Locale.prototype.hourCycles property

Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h

@@ -258,6 +258,7 @@ namespace JS {
     P(hour)                                  \
     P(hour12)                                \
     P(hourCycle)                             \
+    P(hourCycles)                            \
     P(hours)                                 \
     P(hoursDisplay)                          \
     P(hoursInDay)                            \

Userland/Libraries/LibJS/Runtime/Intl/Locale.cpp

@@ -107,4 +107,23 @@ Array* collations_of_locale(GlobalObject& global_object, Locale const& locale_ob
     return create_array_from_list_or_restricted(global_object, move(list), move(restricted));
 }
 
+// 1.1.4 HourCyclesOfLocale ( loc ), https://tc39.es/proposal-intl-locale-info/#sec-hour-cycles-of-locale
+Array* hour_cycles_of_locale(GlobalObject& global_object, Locale const& locale_object)
+{
+    // 1. Let restricted be loc.[[HourCycle]].
+    Optional<String> restricted = locale_object.has_hour_cycle() ? locale_object.hour_cycle() : Optional<String> {};
+
+    // 2. Let locale be loc.[[Locale]].
+    auto const& locale = locale_object.locale();
+
+    // 3. Assert: locale matches the unicode_locale_id production.
+    VERIFY(Unicode::parse_unicode_locale_id(locale).has_value());
+
+    // 4. Let list be a List of 1 or more unique hour cycle identifiers, which must be lower case String values indicating either the 12-hour format ("h11", "h12") or the 24-hour format ("h23", "h24"), sorted in descending preference of those in common use for date and time formatting in locale.
+    auto list = Unicode::get_keywords_for_locale(locale, "hc"sv);
+
+    // 5. Return ! CreateArrayFromListOrRestricted( list, restricted ).
+    return create_array_from_list_or_restricted(global_object, move(list), move(restricted));
+}
+
 }

Userland/Libraries/LibJS/Runtime/Intl/Locale.h

@@ -76,5 +76,6 @@ private:
 
 Array* calendars_of_locale(GlobalObject& global_object, Locale const& locale);
 Array* collations_of_locale(GlobalObject& global_object, Locale const& locale);
+Array* hour_cycles_of_locale(GlobalObject& global_object, Locale const& locale);
 
 }

Userland/Libraries/LibJS/Runtime/Intl/LocalePrototype.cpp

@@ -40,6 +40,7 @@ void LocalePrototype::initialize(GlobalObject& global_object)
     define_native_accessor(vm.names.collation, collation, {}, Attribute::Configurable);
     define_native_accessor(vm.names.collations, collations, {}, Attribute::Configurable);
     define_native_accessor(vm.names.hourCycle, hour_cycle, {}, Attribute::Configurable);
+    define_native_accessor(vm.names.hourCycles, hour_cycles, {}, Attribute::Configurable);
     define_native_accessor(vm.names.numberingSystem, numbering_system, {}, Attribute::Configurable);
     define_native_accessor(vm.names.numeric, numeric, {}, Attribute::Configurable);
     define_native_accessor(vm.names.language, language, {}, Attribute::Configurable);
@@ -204,10 +205,12 @@ JS_DEFINE_NATIVE_FUNCTION(LocalePrototype::region)
 
 #define JS_ENUMERATE_LOCALE_INFO_PROPERTIES \
     __JS_ENUMERATE(calendars)               \
-    __JS_ENUMERATE(collations)
+    __JS_ENUMERATE(collations)              \
+    __JS_ENUMERATE(hour_cycles)
 
 // 1.4.16 get Intl.Locale.prototype.calendars, https://tc39.es/proposal-intl-locale-info/#sec-Intl.Locale.prototype.calendars
 // 1.4.17 get Intl.Locale.prototype.collations, https://tc39.es/proposal-intl-locale-info/#sec-Intl.Locale.prototype.collations
+// 1.4.18 get Intl.Locale.prototype.hourCycles, https://tc39.es/proposal-intl-locale-info/#sec-Intl.Locale.prototype.hourCycles
 #define __JS_ENUMERATE(keyword)                                      \
     JS_DEFINE_NATIVE_FUNCTION(LocalePrototype::keyword)              \
     {                                                                \

Userland/Libraries/LibJS/Runtime/Intl/LocalePrototype.h

@@ -31,6 +31,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(collation);
     JS_DECLARE_NATIVE_FUNCTION(collations);
     JS_DECLARE_NATIVE_FUNCTION(hour_cycle);
+    JS_DECLARE_NATIVE_FUNCTION(hour_cycles);
     JS_DECLARE_NATIVE_FUNCTION(numbering_system);
     JS_DECLARE_NATIVE_FUNCTION(numeric);
     JS_DECLARE_NATIVE_FUNCTION(language);

Userland/Libraries/LibJS/Tests/builtins/Intl/Locale/Locale.prototype.hourCycles.js

@@ -0,0 +1,29 @@
+describe("errors", () => {
+    test("called on non-Locale object", () => {
+        expect(() => {
+            Intl.Locale.prototype.hourCycles;
+        }).toThrowWithMessage(TypeError, "Not an object of type Intl.Locale");
+    });
+});
+
+describe("normal behavior", () => {
+    test("basic functionality", () => {
+        expect(Array.isArray(new Intl.Locale("en").hourCycles)).toBeTrue();
+        expect(new Intl.Locale("en").hourCycles).toContain("h12");
+
+        expect(Array.isArray(new Intl.Locale("ha").hourCycles)).toBeTrue();
+        expect(new Intl.Locale("ha").hourCycles).toContain("h23");
+    });
+
+    test("extension keyword overrides default data", () => {
+        expect(new Intl.Locale("en-u-hc-h24").hourCycles).toEqual(["h24"]);
+        expect(new Intl.Locale("en", { hourCycle: "h24" }).hourCycles).toEqual(["h24"]);
+
+        expect(new Intl.Locale("ar-u-hc-h24").hourCycles).toEqual(["h24"]);
+        expect(new Intl.Locale("ar", { hourCycle: "h24" }).hourCycles).toEqual(["h24"]);
+
+        // Invalid hourCycles also take precedence when specified in the locale string. Unlike other
+        // properties, Locale("en", { hourCycle: "ladybird" }) will explictly throw.
+        expect(new Intl.Locale("en-u-hc-ladybird").hourCycles).toEqual(["ladybird"]);
+    });
+});