LibJS: Implement Intl.Locale.prototype.weekInfo property

Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h

@@ -174,6 +174,7 @@ namespace JS {
     P(findLast)                              \
     P(findLastIndex)                         \
     P(findIndex)                             \
+    P(firstDay)                              \
     P(fixed)                                 \
     P(flags)                                 \
     P(flat)                                  \
@@ -330,6 +331,7 @@ namespace JS {
     P(milliseconds)                          \
     P(millisecondsDisplay)                   \
     P(min)                                   \
+    P(minimalDays)                           \
     P(minimize)                              \
     P(maximumFractionDigits)                 \
     P(maximumSignificantDigits)              \
@@ -531,8 +533,10 @@ namespace JS {
     P(valueOf)                               \
     P(values)                                \
     P(warn)                                  \
+    P(weekInfo)                              \
     P(weekOfYear)                            \
     P(weekday)                               \
+    P(weekend)                               \
     P(weeks)                                 \
     P(weeksDisplay)                          \
     P(with)                                  \

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

@@ -9,6 +9,7 @@
 #include <LibJS/Runtime/GlobalObject.h>
 #include <LibJS/Runtime/Intl/Locale.h>
 #include <LibTimeZone/TimeZone.h>
+#include <LibUnicode/DateTimeFormat.h>
 #include <LibUnicode/Locale.h>
 
 namespace JS::Intl {
@@ -186,4 +187,64 @@ StringView character_direction_of_locale(Locale const& locale_object)
     return "ltr"sv;
 }
 
+static u8 weekday_to_integer(Optional<Unicode::Weekday> weekday, Unicode::Weekday falllback)
+{
+    // NOTE: This fallback will be used if LibUnicode data generation is disabled. Its value should
+    //       be that of the default region ("001") in the CLDR.
+    switch (weekday.value_or(falllback)) {
+    case Unicode::Weekday::Monday:
+        return 1;
+    case Unicode::Weekday::Tuesday:
+        return 2;
+    case Unicode::Weekday::Wednesday:
+        return 3;
+    case Unicode::Weekday::Thursday:
+        return 4;
+    case Unicode::Weekday::Friday:
+        return 5;
+    case Unicode::Weekday::Saturday:
+        return 6;
+    case Unicode::Weekday::Sunday:
+        return 7;
+    }
+
+    VERIFY_NOT_REACHED();
+}
+
+static Vector<u8> weekend_of_locale(StringView locale)
+{
+    auto weekend_start = weekday_to_integer(Unicode::get_locale_weekend_start(locale), Unicode::Weekday::Saturday);
+    auto weekend_end = weekday_to_integer(Unicode::get_locale_weekend_end(locale), Unicode::Weekday::Sunday);
+
+    // There currently aren't any regions in the CLDR which wrap around from Sunday (7) to Monday (1).
+    // If this changes, this logic will need to be updated to handle that.
+    VERIFY(weekend_start <= weekend_end);
+
+    Vector<u8> weekend;
+    weekend.ensure_capacity(weekend_end - weekend_start + 1);
+
+    for (auto day = weekend_start; day <= weekend_end; ++day)
+        weekend.unchecked_append(day);
+
+    return weekend;
+}
+
+// 1.1.8 WeekInfoOfLocale ( loc ), https://tc39.es/proposal-intl-locale-info/#sec-week-info-of-locale
+WeekInfo week_info_of_locale(Locale const& locale_object)
+{
+    // 1. Let locale be loc.[[Locale]].
+    auto const& locale = locale_object.locale();
+
+    // 2. Assert: locale matches the unicode_locale_id production.
+    VERIFY(Unicode::parse_unicode_locale_id(locale).has_value());
+
+    // 3. Return a record whose fields are defined by Table 1, with values based on locale.
+    WeekInfo week_info {};
+    week_info.minimal_days = Unicode::get_locale_minimum_days(locale).value_or(1);
+    week_info.first_day = weekday_to_integer(Unicode::get_locale_first_day(locale), Unicode::Weekday::Monday);
+    week_info.weekend = weekend_of_locale(locale);
+
+    return week_info;
+}
+
 }

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

@@ -74,11 +74,19 @@ private:
     bool m_numeric { false };            // [[Numeric]]
 };
 
+// Table 1: WeekInfo Record Fields, https://tc39.es/proposal-intl-locale-info/#table-locale-weekinfo-record
+struct WeekInfo {
+    u8 minimal_days { 0 }; // [[MinimalDays]]
+    u8 first_day { 0 };    // [[FirstDay]]
+    Vector<u8> weekend;    // [[Weekend]]
+};
+
 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);
 Array* numbering_systems_of_locale(GlobalObject& global_object, Locale const& locale);
 Array* time_zones_of_locale(GlobalObject& global_object, StringView region);
 StringView character_direction_of_locale(Locale const& locale);
+WeekInfo week_info_of_locale(Locale const& locale);
 
 }

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

@@ -49,6 +49,7 @@ void LocalePrototype::initialize(GlobalObject& global_object)
     define_native_accessor(vm.names.region, region, {}, Attribute::Configurable);
     define_native_accessor(vm.names.timeZones, time_zones, {}, Attribute::Configurable);
     define_native_accessor(vm.names.textInfo, text_info, {}, Attribute::Configurable);
+    define_native_accessor(vm.names.weekInfo, week_info, {}, Attribute::Configurable);
 }
 
 // 14.3.3 Intl.Locale.prototype.maximize ( ), https://tc39.es/ecma402/#sec-Intl.Locale.prototype.maximize
@@ -263,4 +264,33 @@ JS_DEFINE_NATIVE_FUNCTION(LocalePrototype::text_info)
     return info;
 }
 
+// 1.4.22 get Intl.Locale.prototype.weekInfo, https://tc39.es/proposal-intl-locale-info/#sec-Intl.Locale.prototype.weekInfo
+JS_DEFINE_NATIVE_FUNCTION(LocalePrototype::week_info)
+{
+    // 1. Let loc be the this value.
+    // 2. Perform ? RequireInternalSlot(loc, [[InitializedLocale]]).
+    [[maybe_unused]] auto* locale_object = TRY(typed_this_object(global_object));
+
+    // 3. Let info be ! ObjectCreate(%Object.prototype%).
+    auto* info = Object::create(global_object, global_object.object_prototype());
+
+    // 4. Let wi be ! WeekInfoOfLocale(loc).
+    auto week_info = week_info_of_locale(*locale_object);
+
+    // 5. Let we be ! CreateArrayFromList( wi.[[Weekend]] ).
+    auto weekend = Array::create_from<u8>(global_object, week_info.weekend, [](auto day) { return Value(day); });
+
+    // 6. Perform ! CreateDataPropertyOrThrow(info, "firstDay", wi.[[FirstDay]]).
+    MUST(info->create_data_property_or_throw(vm.names.firstDay, Value(week_info.first_day)));
+
+    // 7. Perform ! CreateDataPropertyOrThrow(info, "weekend", we).
+    MUST(info->create_data_property_or_throw(vm.names.weekend, weekend));
+
+    // 8. Perform ! CreateDataPropertyOrThrow(info, "minimalDays", wi.[[MinimalDays]]).
+    MUST(info->create_data_property_or_throw(vm.names.minimalDays, Value(week_info.minimal_days)));
+
+    // 9. Return info.
+    return info;
+}
+
 }

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

@@ -40,6 +40,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(region);
     JS_DECLARE_NATIVE_FUNCTION(time_zones);
     JS_DECLARE_NATIVE_FUNCTION(text_info);
+    JS_DECLARE_NATIVE_FUNCTION(week_info);
 };
 
 }

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

@@ -0,0 +1,68 @@
+describe("errors", () => {
+    test("called on non-Locale object", () => {
+        expect(() => {
+            Intl.Locale.prototype.weekInfo;
+        }).toThrowWithMessage(TypeError, "Not an object of type Intl.Locale");
+    });
+});
+
+describe("normal behavior", () => {
+    test("basic functionality", () => {
+        const weekInfo = new Intl.Locale("en-US").weekInfo;
+
+        expect(weekInfo).toBeDefined();
+        expect(Object.getPrototypeOf(weekInfo)).toBe(Object.prototype);
+
+        expect(weekInfo.firstDay).toBeDefined();
+        expect(Object.getPrototypeOf(weekInfo.firstDay)).toBe(Number.prototype);
+        expect(weekInfo.firstDay).toBe(7);
+
+        expect(weekInfo.weekend).toBeDefined();
+        expect(Array.isArray(weekInfo.weekend)).toBeTrue();
+        expect(weekInfo.weekend).toEqual([6, 7]);
+
+        expect(weekInfo.minimalDays).toBeDefined();
+        expect(Object.getPrototypeOf(weekInfo.minimalDays)).toBe(Number.prototype);
+        expect(weekInfo.minimalDays).toBe(1);
+    });
+
+    test("regions with CLDR-specified firstDay", () => {
+        expect(new Intl.Locale("en-AG").weekInfo.firstDay).toBe(7);
+        expect(new Intl.Locale("en-SY").weekInfo.firstDay).toBe(6);
+        expect(new Intl.Locale("en-MV").weekInfo.firstDay).toBe(5);
+    });
+
+    test("firstDay falls back to default region 001", () => {
+        expect(new Intl.Locale("en-AC").weekInfo.firstDay).toBe(1);
+    });
+
+    test("regions with CLDR-specified weekend", () => {
+        expect(new Intl.Locale("en-AF").weekInfo.weekend).toEqual([4, 5]);
+        expect(new Intl.Locale("en-IN").weekInfo.weekend).toEqual([7]);
+        expect(new Intl.Locale("en-YE").weekInfo.weekend).toEqual([5, 6]);
+    });
+
+    test("weekend falls back to default region 001", () => {
+        expect(new Intl.Locale("en-AC").weekInfo.weekend).toEqual([6, 7]);
+    });
+
+    test("regions with CLDR-specified minimalDays", () => {
+        expect(new Intl.Locale("en-AD").weekInfo.minimalDays).toBe(4);
+        expect(new Intl.Locale("en-CZ").weekInfo.minimalDays).toBe(4);
+    });
+
+    test("minimalDays falls back to default region 001", () => {
+        expect(new Intl.Locale("en-AC").weekInfo.minimalDays).toBe(1);
+    });
+
+    test("likely regional subtags are added to locales without a region", () => {
+        const defaultRegion = new Intl.Locale("en-001").weekInfo;
+
+        // "en" expands to "en-US" when likely subtags are added.
+        const en = new Intl.Locale("en").weekInfo;
+        const enUS = new Intl.Locale("en-US").weekInfo;
+
+        expect(en).toEqual(enUS);
+        expect(en).not.toEqual(defaultRegion);
+    });
+});