DateTimeFormatConstructor.cpp 22 KB

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  1. /*
  2. * Copyright (c) 2021-2024, Tim Flynn <trflynn89@serenityos.org>
  3. *
  4. * SPDX-License-Identifier: BSD-2-Clause
  5. */
  6. #include <LibJS/Runtime/AbstractOperations.h>
  7. #include <LibJS/Runtime/Array.h>
  8. #include <LibJS/Runtime/Date.h>
  9. #include <LibJS/Runtime/GlobalObject.h>
  10. #include <LibJS/Runtime/Intl/AbstractOperations.h>
  11. #include <LibJS/Runtime/Intl/DateTimeFormat.h>
  12. #include <LibJS/Runtime/Intl/DateTimeFormatConstructor.h>
  13. #include <LibJS/Runtime/Temporal/TimeZone.h>
  14. #include <LibLocale/DateTimeFormat.h>
  15. #include <LibLocale/Locale.h>
  16. namespace JS::Intl {
  17. JS_DEFINE_ALLOCATOR(DateTimeFormatConstructor);
  18. // 11.1 The Intl.DateTimeFormat Constructor, https://tc39.es/ecma402/#sec-intl-datetimeformat-constructor
  19. DateTimeFormatConstructor::DateTimeFormatConstructor(Realm& realm)
  20. : NativeFunction(realm.vm().names.DateTimeFormat.as_string(), realm.intrinsics().function_prototype())
  21. {
  22. }
  23. void DateTimeFormatConstructor::initialize(Realm& realm)
  24. {
  25. Base::initialize(realm);
  26. auto& vm = this->vm();
  27. // 11.2.1 Intl.DateTimeFormat.prototype, https://tc39.es/ecma402/#sec-intl.datetimeformat.prototype
  28. define_direct_property(vm.names.prototype, realm.intrinsics().intl_date_time_format_prototype(), 0);
  29. u8 attr = Attribute::Writable | Attribute::Configurable;
  30. define_native_function(realm, vm.names.supportedLocalesOf, supported_locales_of, 1, attr);
  31. define_direct_property(vm.names.length, Value(0), Attribute::Configurable);
  32. }
  33. // 11.1.1 Intl.DateTimeFormat ( [ locales [ , options ] ] ), https://tc39.es/ecma402/#sec-intl.datetimeformat
  34. ThrowCompletionOr<Value> DateTimeFormatConstructor::call()
  35. {
  36. // 1. If NewTarget is undefined, let newTarget be the active function object, else let newTarget be NewTarget.
  37. return TRY(construct(*this));
  38. }
  39. // 11.1.1 Intl.DateTimeFormat ( [ locales [ , options ] ] ), https://tc39.es/ecma402/#sec-intl.datetimeformat
  40. ThrowCompletionOr<NonnullGCPtr<Object>> DateTimeFormatConstructor::construct(FunctionObject& new_target)
  41. {
  42. auto& vm = this->vm();
  43. auto locales = vm.argument(0);
  44. auto options = vm.argument(1);
  45. // 2. Let dateTimeFormat be ? CreateDateTimeFormat(newTarget, locales, options, any, date).
  46. auto date_time_format = TRY(create_date_time_format(vm, new_target, locales, options, OptionRequired::Any, OptionDefaults::Date));
  47. // 3. If the implementation supports the normative optional constructor mode of 4.3 Note 1, then
  48. // a. Let this be the this value.
  49. // b. Return ? ChainDateTimeFormat(dateTimeFormat, NewTarget, this).
  50. // 4. Return dateTimeFormat.
  51. return date_time_format;
  52. }
  53. // 11.2.2 Intl.DateTimeFormat.supportedLocalesOf ( locales [ , options ] ), https://tc39.es/ecma402/#sec-intl.datetimeformat.supportedlocalesof
  54. JS_DEFINE_NATIVE_FUNCTION(DateTimeFormatConstructor::supported_locales_of)
  55. {
  56. auto locales = vm.argument(0);
  57. auto options = vm.argument(1);
  58. // 1. Let availableLocales be %DateTimeFormat%.[[AvailableLocales]].
  59. // 2. Let requestedLocales be ? CanonicalizeLocaleList(locales).
  60. auto requested_locales = TRY(canonicalize_locale_list(vm, locales));
  61. // 3. Return ? SupportedLocales(availableLocales, requestedLocales, options).
  62. return TRY(supported_locales(vm, requested_locales, options));
  63. }
  64. // 11.1.2 CreateDateTimeFormat ( newTarget, locales, options, required, defaults ), https://tc39.es/ecma402/#sec-createdatetimeformat
  65. ThrowCompletionOr<NonnullGCPtr<DateTimeFormat>> create_date_time_format(VM& vm, FunctionObject& new_target, Value locales_value, Value options_value, OptionRequired required, OptionDefaults defaults)
  66. {
  67. // 1. Let dateTimeFormat be ? OrdinaryCreateFromConstructor(newTarget, "%DateTimeFormat.prototype%", « [[InitializedDateTimeFormat]], [[Locale]], [[Calendar]], [[NumberingSystem]], [[TimeZone]], [[Weekday]], [[Era]], [[Year]], [[Month]], [[Day]], [[DayPeriod]], [[Hour]], [[Minute]], [[Second]], [[FractionalSecondDigits]], [[TimeZoneName]], [[HourCycle]], [[DateStyle]], [[TimeStyle]], [[Pattern]], [[RangePatterns]], [[BoundFormat]] »).
  68. auto date_time_format = TRY(ordinary_create_from_constructor<DateTimeFormat>(vm, new_target, &Intrinsics::intl_date_time_format_prototype));
  69. // 2. Let requestedLocales be ? CanonicalizeLocaleList(locales).
  70. auto requested_locales = TRY(canonicalize_locale_list(vm, locales_value));
  71. // 3. Set options to ? CoerceOptionsToObject(options).
  72. auto* options = TRY(coerce_options_to_object(vm, options_value));
  73. // 4. Let opt be a new Record.
  74. LocaleOptions opt {};
  75. // 5. Let matcher be ? GetOption(options, "localeMatcher", string, « "lookup", "best fit" », "best fit").
  76. auto matcher = TRY(get_option(vm, *options, vm.names.localeMatcher, OptionType::String, AK::Array { "lookup"sv, "best fit"sv }, "best fit"sv));
  77. // 6. Set opt.[[localeMatcher]] to matcher.
  78. opt.locale_matcher = matcher;
  79. // 7. Let calendar be ? GetOption(options, "calendar", string, empty, undefined).
  80. auto calendar = TRY(get_option(vm, *options, vm.names.calendar, OptionType::String, {}, Empty {}));
  81. // 8. If calendar is not undefined, then
  82. if (!calendar.is_undefined()) {
  83. // a. If calendar cannot be matched by the type Unicode locale nonterminal, throw a RangeError exception.
  84. if (!::Locale::is_type_identifier(calendar.as_string().utf8_string_view()))
  85. return vm.throw_completion<RangeError>(ErrorType::OptionIsNotValidValue, calendar, "calendar"sv);
  86. }
  87. // 9. Set opt.[[ca]] to calendar.
  88. opt.ca = locale_key_from_value(calendar);
  89. // 10. Let numberingSystem be ? GetOption(options, "numberingSystem", string, empty, undefined).
  90. auto numbering_system = TRY(get_option(vm, *options, vm.names.numberingSystem, OptionType::String, {}, Empty {}));
  91. // 11. If numberingSystem is not undefined, then
  92. if (!numbering_system.is_undefined()) {
  93. // a. If numberingSystem cannot be matched by the type Unicode locale nonterminal, throw a RangeError exception.
  94. if (!::Locale::is_type_identifier(numbering_system.as_string().utf8_string_view()))
  95. return vm.throw_completion<RangeError>(ErrorType::OptionIsNotValidValue, numbering_system, "numberingSystem"sv);
  96. }
  97. // 12. Set opt.[[nu]] to numberingSystem.
  98. opt.nu = locale_key_from_value(numbering_system);
  99. // 13. Let hour12 be ? GetOption(options, "hour12", boolean, empty, undefined).
  100. auto hour12 = TRY(get_option(vm, *options, vm.names.hour12, OptionType::Boolean, {}, Empty {}));
  101. // 14. Let hourCycle be ? GetOption(options, "hourCycle", string, « "h11", "h12", "h23", "h24" », undefined).
  102. auto hour_cycle = TRY(get_option(vm, *options, vm.names.hourCycle, OptionType::String, AK::Array { "h11"sv, "h12"sv, "h23"sv, "h24"sv }, Empty {}));
  103. // 15. If hour12 is not undefined, then
  104. if (!hour12.is_undefined()) {
  105. // a. Set hourCycle to null.
  106. hour_cycle = js_null();
  107. }
  108. // 16. Set opt.[[hc]] to hourCycle.
  109. opt.hc = locale_key_from_value(hour_cycle);
  110. // 17. Let localeData be %DateTimeFormat%.[[LocaleData]].
  111. // 18. Let r be ResolveLocale(%DateTimeFormat%.[[AvailableLocales]], requestedLocales, opt, %DateTimeFormat%.[[RelevantExtensionKeys]], localeData).
  112. auto result = resolve_locale(requested_locales, opt, DateTimeFormat::relevant_extension_keys());
  113. // 19. Set dateTimeFormat.[[Locale]] to r.[[locale]].
  114. date_time_format->set_locale(move(result.locale));
  115. // 20. Let resolvedCalendar be r.[[ca]].
  116. // 21. Set dateTimeFormat.[[Calendar]] to resolvedCalendar.
  117. if (auto* resolved_calendar = result.ca.get_pointer<String>())
  118. date_time_format->set_calendar(move(*resolved_calendar));
  119. // 22. Set dateTimeFormat.[[NumberingSystem]] to r.[[nu]].
  120. if (auto* resolved_numbering_system = result.nu.get_pointer<String>())
  121. date_time_format->set_numbering_system(move(*resolved_numbering_system));
  122. // 23. Let dataLocale be r.[[dataLocale]].
  123. auto data_locale = move(result.data_locale);
  124. // Non-standard, the data locale is needed for LibUnicode lookups while formatting.
  125. date_time_format->set_data_locale(data_locale);
  126. // 24. Let dataLocaleData be localeData.[[<dataLocale>]].
  127. Optional<::Locale::HourCycle> hour_cycle_value;
  128. Optional<bool> hour12_value;
  129. // 25. If hour12 is true, then
  130. // a. Let hc be dataLocaleData.[[hourCycle12]].
  131. // 26. Else if hour12 is false, then
  132. // a. Let hc be dataLocaleData.[[hourCycle24]].
  133. if (hour12.is_boolean()) {
  134. // NOTE: We let LibLocale figure out the appropriate hour cycle.
  135. hour12_value = hour12.as_bool();
  136. }
  137. // 27. Else,
  138. else {
  139. // a. Assert: hour12 is undefined.
  140. VERIFY(hour12.is_undefined());
  141. // b. Let hc be r.[[hc]].
  142. if (auto* resolved_hour_cycle = result.hc.get_pointer<String>())
  143. hour_cycle_value = ::Locale::hour_cycle_from_string(*resolved_hour_cycle);
  144. // c. If hc is null, set hc to dataLocaleData.[[hourCycle]].
  145. if (!hour_cycle_value.has_value())
  146. hour_cycle_value = ::Locale::default_hour_cycle(data_locale);
  147. }
  148. // 28. Set dateTimeFormat.[[HourCycle]] to hc.
  149. date_time_format->hour_cycle = hour_cycle_value;
  150. // 29. Let timeZone be ? Get(options, "timeZone").
  151. auto time_zone_value = TRY(options->get(vm.names.timeZone));
  152. String time_zone;
  153. // 30. If timeZone is undefined, then
  154. if (time_zone_value.is_undefined()) {
  155. // a. Set timeZone to DefaultTimeZone().
  156. time_zone = MUST(String::from_utf8(system_time_zone_identifier()));
  157. }
  158. // 31. Else,
  159. else {
  160. // a. Set timeZone to ? ToString(timeZone).
  161. time_zone = TRY(time_zone_value.to_string(vm));
  162. }
  163. // 32. If IsTimeZoneOffsetString(timeZone) is true, then
  164. bool is_time_zone_offset_string = JS::is_time_zone_offset_string(time_zone);
  165. if (is_time_zone_offset_string) {
  166. // a. Let parseResult be ParseText(StringToCodePoints(timeZone), UTCOffset).
  167. auto parse_result = Temporal::parse_iso8601(Temporal::Production::TimeZoneNumericUTCOffset, time_zone);
  168. // b. Assert: parseResult is a Parse Node.
  169. VERIFY(parse_result.has_value());
  170. // c. If parseResult contains more than one MinuteSecond Parse Node, throw a RangeError exception.
  171. if (parse_result->time_zone_utc_offset_second.has_value())
  172. return vm.throw_completion<RangeError>(ErrorType::OptionIsNotValidValue, time_zone, vm.names.timeZone);
  173. // d. Let offsetNanoseconds be ParseTimeZoneOffsetString(timeZone).
  174. auto offset_nanoseconds = parse_time_zone_offset_string(time_zone);
  175. // e. Let offsetMinutes be offsetNanoseconds / (6 × 10^10).
  176. auto offset_minutes = offset_nanoseconds / 60'000'000'000;
  177. // f. Assert: offsetMinutes is an integer.
  178. VERIFY(trunc(offset_minutes) == offset_minutes);
  179. // g. Set timeZone to FormatOffsetTimeZoneIdentifier(offsetMinutes).
  180. time_zone = format_offset_time_zone_identifier(offset_minutes);
  181. }
  182. // 33. Else if IsValidTimeZoneName(timeZone) is true, then
  183. else if (Temporal::is_available_time_zone_name(time_zone)) {
  184. // a. Set timeZone to CanonicalizeTimeZoneName(timeZone).
  185. time_zone = MUST(Temporal::canonicalize_time_zone_name(vm, time_zone));
  186. }
  187. // 34. Else,
  188. else {
  189. // a. Throw a RangeError exception.
  190. return vm.throw_completion<RangeError>(ErrorType::OptionIsNotValidValue, time_zone, vm.names.timeZone);
  191. }
  192. // 35. Set dateTimeFormat.[[TimeZone]] to timeZone.
  193. date_time_format->set_time_zone(time_zone);
  194. // NOTE: ICU requires time zone offset strings to be of the form "GMT+00:00"
  195. if (is_time_zone_offset_string)
  196. time_zone = MUST(String::formatted("GMT{}", time_zone));
  197. // 36. Let formatOptions be a new Record.
  198. ::Locale::CalendarPattern format_options {};
  199. // 37. Set formatOptions.[[hourCycle]] to hc.
  200. format_options.hour_cycle = hour_cycle_value;
  201. format_options.hour12 = hour12_value;
  202. // 38. Let hasExplicitFormatComponents be false.
  203. // NOTE: Instead of using a boolean, we track any explicitly provided component name for nicer exception messages.
  204. PropertyKey const* explicit_format_component = nullptr;
  205. // 39. For each row of Table 6, except the header row, in table order, do
  206. TRY(for_each_calendar_field(vm, format_options, [&](auto& option, PropertyKey const& property, auto const& values) -> ThrowCompletionOr<void> {
  207. using ValueType = typename RemoveReference<decltype(option)>::ValueType;
  208. // a. Let prop be the name given in the Property column of the row.
  209. // b. If prop is "fractionalSecondDigits", then
  210. if constexpr (IsIntegral<ValueType>) {
  211. // i. Let value be ? GetNumberOption(options, "fractionalSecondDigits", 1, 3, undefined).
  212. auto value = TRY(get_number_option(vm, *options, property, 1, 3, {}));
  213. // d. Set formatOptions.[[<prop>]] to value.
  214. if (value.has_value()) {
  215. option = static_cast<ValueType>(value.value());
  216. // e. If value is not undefined, then
  217. // i. Set hasExplicitFormatComponents to true.
  218. explicit_format_component = &property;
  219. }
  220. }
  221. // c. Else,
  222. else {
  223. // i. Let values be a List whose elements are the strings given in the Values column of the row.
  224. // ii. Let value be ? GetOption(options, prop, string, values, undefined).
  225. auto value = TRY(get_option(vm, *options, property, OptionType::String, values, Empty {}));
  226. // d. Set formatOptions.[[<prop>]] to value.
  227. if (!value.is_undefined()) {
  228. option = ::Locale::calendar_pattern_style_from_string(value.as_string().utf8_string_view());
  229. // e. If value is not undefined, then
  230. // i. Set hasExplicitFormatComponents to true.
  231. explicit_format_component = &property;
  232. }
  233. }
  234. return {};
  235. }));
  236. // 40. Let matcher be ? GetOption(options, "formatMatcher", string, « "basic", "best fit" », "best fit").
  237. matcher = TRY(get_option(vm, *options, vm.names.formatMatcher, OptionType::String, AK::Array { "basic"sv, "best fit"sv }, "best fit"sv));
  238. // 41. Let dateStyle be ? GetOption(options, "dateStyle", string, « "full", "long", "medium", "short" », undefined).
  239. auto date_style = TRY(get_option(vm, *options, vm.names.dateStyle, OptionType::String, AK::Array { "full"sv, "long"sv, "medium"sv, "short"sv }, Empty {}));
  240. // 42. Set dateTimeFormat.[[DateStyle]] to dateStyle.
  241. if (!date_style.is_undefined())
  242. date_time_format->set_date_style(date_style.as_string().utf8_string_view());
  243. // 43. Let timeStyle be ? GetOption(options, "timeStyle", string, « "full", "long", "medium", "short" », undefined).
  244. auto time_style = TRY(get_option(vm, *options, vm.names.timeStyle, OptionType::String, AK::Array { "full"sv, "long"sv, "medium"sv, "short"sv }, Empty {}));
  245. // 44. Set dateTimeFormat.[[TimeStyle]] to timeStyle.
  246. if (!time_style.is_undefined())
  247. date_time_format->set_time_style(time_style.as_string().utf8_string_view());
  248. // 45. If dateStyle is not undefined or timeStyle is not undefined, then
  249. if (date_time_format->has_date_style() || date_time_format->has_time_style()) {
  250. // a. If hasExplicitFormatComponents is true, then
  251. if (explicit_format_component != nullptr) {
  252. // i. Throw a TypeError exception.
  253. return vm.throw_completion<TypeError>(ErrorType::IntlInvalidDateTimeFormatOption, *explicit_format_component, "dateStyle or timeStyle"sv);
  254. }
  255. // b. If required is date and timeStyle is not undefined, then
  256. if (required == OptionRequired::Date && !time_style.is_undefined()) {
  257. // i. Throw a TypeError exception.
  258. return vm.throw_completion<TypeError>(ErrorType::IntlInvalidDateTimeFormatOption, "timeStyle"sv, "date"sv);
  259. }
  260. // c. If required is time and dateStyle is not undefined, then
  261. if (required == OptionRequired::Time && !date_style.is_undefined()) {
  262. // i. Throw a TypeError exception.
  263. return vm.throw_completion<TypeError>(ErrorType::IntlInvalidDateTimeFormatOption, "dateStyle"sv, "time"sv);
  264. }
  265. // d. Let styles be dataLocaleData.[[styles]].[[<resolvedCalendar>]].
  266. // e. Let bestFormat be DateTimeStyleFormat(dateStyle, timeStyle, styles).
  267. auto formatter = ::Locale::DateTimeFormat::create_for_date_and_time_style(
  268. date_time_format->data_locale(),
  269. time_zone,
  270. format_options.hour_cycle,
  271. format_options.hour12,
  272. date_time_format->date_style(),
  273. date_time_format->time_style());
  274. date_time_format->set_formatter(move(formatter));
  275. }
  276. // 46. Else,
  277. else {
  278. // a. Let needDefaults be true.
  279. bool needs_defaults = true;
  280. // b. If required is date or any, then
  281. if (required == OptionRequired::Date || required == OptionRequired::Any) {
  282. // i. For each property name prop of « "weekday", "year", "month", "day" », do
  283. auto check_property_value = [&](auto const& value) {
  284. // 1. Let value be formatOptions.[[<prop>]].
  285. // 2. If value is not undefined, let needDefaults be false.
  286. if (value.has_value())
  287. needs_defaults = false;
  288. };
  289. check_property_value(format_options.weekday);
  290. check_property_value(format_options.year);
  291. check_property_value(format_options.month);
  292. check_property_value(format_options.day);
  293. }
  294. // c. If required is time or any, then
  295. if (required == OptionRequired::Time || required == OptionRequired::Any) {
  296. // i. For each property name prop of « "dayPeriod", "hour", "minute", "second", "fractionalSecondDigits" », do
  297. auto check_property_value = [&](auto const& value) {
  298. // 1. Let value be formatOptions.[[<prop>]].
  299. // 2. If value is not undefined, let needDefaults be false.
  300. if (value.has_value())
  301. needs_defaults = false;
  302. };
  303. check_property_value(format_options.day_period);
  304. check_property_value(format_options.hour);
  305. check_property_value(format_options.minute);
  306. check_property_value(format_options.second);
  307. check_property_value(format_options.fractional_second_digits);
  308. }
  309. // d. If needDefaults is true and defaults is either date or all, then
  310. if (needs_defaults && (defaults == OptionDefaults::Date || defaults == OptionDefaults::All)) {
  311. // i. For each property name prop of « "year", "month", "day" », do
  312. auto set_property_value = [&](auto& value) {
  313. // 1. Set formatOptions.[[<prop>]] to "numeric".
  314. value = ::Locale::CalendarPatternStyle::Numeric;
  315. };
  316. set_property_value(format_options.year);
  317. set_property_value(format_options.month);
  318. set_property_value(format_options.day);
  319. }
  320. // e. If needDefaults is true and defaults is either time or all, then
  321. if (needs_defaults && (defaults == OptionDefaults::Time || defaults == OptionDefaults::All)) {
  322. // i. For each property name prop of « "hour", "minute", "second" », do
  323. auto set_property_value = [&](auto& value) {
  324. // 1. Set formatOptions.[[<prop>]] to "numeric".
  325. value = ::Locale::CalendarPatternStyle::Numeric;
  326. };
  327. set_property_value(format_options.hour);
  328. set_property_value(format_options.minute);
  329. set_property_value(format_options.second);
  330. }
  331. // f. Let formats be dataLocaleData.[[formats]].[[<resolvedCalendar>]].
  332. // g. If matcher is "basic", then
  333. // i. Let bestFormat be BasicFormatMatcher(formatOptions, formats).
  334. // h. Else,
  335. // i. Let bestFormat be BestFitFormatMatcher(formatOptions, formats).
  336. auto formatter = ::Locale::DateTimeFormat::create_for_pattern_options(
  337. date_time_format->data_locale(),
  338. time_zone,
  339. format_options);
  340. date_time_format->set_formatter(move(formatter));
  341. }
  342. // 47. For each row in Table 6, except the header row, in table order, do
  343. date_time_format->for_each_calendar_field_zipped_with(date_time_format->formatter().chosen_pattern(), [&](auto& date_time_format_field, auto const& best_format_field) {
  344. // a. Let prop be the name given in the Property column of the row.
  345. // b. If bestFormat has a field [[<prop>]], then
  346. if (best_format_field.has_value()) {
  347. // i. Let p be bestFormat.[[<prop>]].
  348. // ii. Set dateTimeFormat's internal slot whose name is the Internal Slot column of the row to p.
  349. date_time_format_field = best_format_field;
  350. }
  351. });
  352. // 48. If dateTimeFormat.[[Hour]] is undefined, then
  353. if (!date_time_format->hour.has_value()) {
  354. // a. Set dateTimeFormat.[[HourCycle]] to undefined.
  355. date_time_format->hour_cycle.clear();
  356. }
  357. // 49. If dateTimeFormat.[[HourCycle]] is "h11" or "h12", then
  358. // a. Let pattern be bestFormat.[[pattern12]].
  359. // b. Let rangePatterns be bestFormat.[[rangePatterns12]].
  360. // 50. Else,
  361. // a. Let pattern be bestFormat.[[pattern]].
  362. // b. Let rangePatterns be bestFormat.[[rangePatterns]].
  363. // 51. Set dateTimeFormat.[[Pattern]] to pattern.
  364. // 52. Set dateTimeFormat.[[RangePatterns]] to rangePatterns.
  365. // 53. Return dateTimeFormat.
  366. return date_time_format;
  367. }
  368. // 11.1.3 FormatOffsetTimeZoneIdentifier ( offsetMinutes ), https://tc39.es/ecma402/#sec-formatoffsettimezoneidentifier
  369. String format_offset_time_zone_identifier(double offset_minutes)
  370. {
  371. // 1. If offsetMinutes ≥ 0, let sign be the code unit 0x002B (PLUS SIGN); otherwise, let sign be the code unit 0x002D (HYPHEN-MINUS).
  372. auto sign = offset_minutes >= 0.0 ? '+' : '-';
  373. // 2. Let absoluteMinutes be abs(offsetMinutes).
  374. auto absolute_minutes = fabs(offset_minutes);
  375. // 3. Let hours be floor(absoluteMinutes / 60).
  376. auto hours = static_cast<i64>(floor(absolute_minutes / 60.0));
  377. // 4. Let minutes be absoluteMinutes modulo 60.
  378. auto minutes = static_cast<i64>(modulo(absolute_minutes, 60.0));
  379. // 5. Return the string-concatenation of sign, ToZeroPaddedDecimalString(hours, 2), the code unit 0x003A (COLON), and ToZeroPaddedDecimalString(minutes, 2).
  380. return MUST(String::formatted("{}{:02}:{:02}", sign, hours, minutes));
  381. }
  382. }