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LibJS: Use fully spec'd algorithm for ToISOWeekOfYear

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This is an editorial change in the Temporal spec.

See: 33b62a3
This commit is contained in:
Linus Groh 2022-08-25 22:28:11 +01:00
parent b438839fcc
commit 741cc08221
3 changed files with 113 additions and 48 deletions
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130
Userland/Libraries/LibJS/Runtime/Temporal/Calendar.cpp
View file

@ -607,35 +607,78 @@ u8 iso_days_in_month(i32 year, u8 month)
// 12.2.31 ToISOWeekOfYear ( year, month, day ), https://tc39.es/proposal-temporal/#sec-temporal-toisoweekofyear
u8 to_iso_week_of_year(i32 year, u8 month, u8 day)
{
// 1. Assert: year is an integer.
// 2. Assert: month is an integer.
// 3. Assert: day is an integer.
// 1. Assert: IsValidISODate(year, month, day) is true.
VERIFY(is_valid_iso_date(year, month, day));
// 4. Let date be the date given by year, month, and day.
// 5. Return date's week number according to ISO-8601 as an integer.
auto t = make_date(make_day(year, month - 1, day), 0);
auto day_of_year = day_within_year(t) + 1;
auto day_of_week = week_day(t);
if (day_of_week == 0)
day_of_week = 7;
auto week = (day_of_year - day_of_week + 10) / 7;
// 2. Let wednesday be 3.
constexpr auto wednesday = 3;
// 3. Let thursday be 4.
constexpr auto thursday = 4;
// 4. Let friday be 5.
constexpr auto friday = 5;
// 5. Let saturday be 6.
constexpr auto saturday = 6;
// 6. Let daysInWeek be 7.
constexpr auto days_in_week = 7;
// 7. Let maxWeekNumber be 53.
constexpr auto max_week_number = 53;
// 8. Let dayOfYear be ToISODayOfYear(year, month, day).
auto day_of_year = to_iso_day_of_year(year, month, day);
// 9. Let dayOfWeek be ToISODayOfWeek(year, month, day).
auto day_of_week = to_iso_day_of_week(year, month, day);
// 10. Let week be floor((dayOfYear + daysInWeek - dayOfWeek + wednesday ) / daysInWeek).
auto week = static_cast<i32>(floor(static_cast<double>(day_of_year + days_in_week - day_of_week + wednesday) / days_in_week));
// 11. If week < 1, then
if (week < 1) {
// NOTE: The resulting week is actually part of the previous year. If that year ends with a
// Thursday (i.e. the first day of the given year is a Friday, or day 5), or the previous
// year is a leap year and ends with a Friday (i.e. the first day of the given year is a
// Saturday, or day 6), it has 53 weeks, and 52 weeks otherwise.
auto day_of_jump = week_day(make_date(make_day(year, 0, 1), 0));
if (day_of_jump == 5 || (in_leap_year(time_from_year(year - 1)) && day_of_jump == 6))
return 53;
else
return 52;
} else if (week == 53) {
auto days_in_year = JS::days_in_year(year);
if (days_in_year - day_of_year < 4 - day_of_week)
return 1;
// a. NOTE: This is the last week of the previous year.
// b. Let dayOfJan1st be ToISODayOfWeek(year, 1, 1).
auto day_of_jan_1st = to_iso_day_of_week(year, 1, 1);
// c. If dayOfJan1st is friday, then
if (day_of_jan_1st == friday) {
// i. Return maxWeekNumber.
return max_week_number;
}
// d. If dayOfJan1st is saturday, and InLeapYear(TimeFromYear(𝔽(year - 1))) is 1𝔽, then
if (day_of_jan_1st == saturday && in_leap_year(time_from_year(year - 1))) {
// i. Return maxWeekNumber.
return max_week_number;
}
// e. Return maxWeekNumber - 1.
return max_week_number - 1;
}
// 12. If week is maxWeekNumber, then
if (week == max_week_number) {
// a. Let daysInYear be DaysInYear(𝔽(year)).
auto days_in_year = JS::days_in_year(year);
// b. Let daysLaterInYear be daysInYear - dayOfYear.
auto days_later_in_year = days_in_year - day_of_year;
// c. Let daysAfterThursday be thursday - dayOfWeek.
auto days_after_thursday = thursday - day_of_week;
// d. If daysLaterInYear < daysAfterThursday, then
if (days_later_in_year < days_after_thursday) {
// i. Return 1.
return 1;
}
}
// 13. Return week.
return week;
}
@ -971,4 +1014,43 @@ ThrowCompletionOr<Object*> default_merge_calendar_fields(VM& vm, Object const& f
return merged;
}
// 12.2.42 ToISODayOfYear ( year, month, day ), https://tc39.es/proposal-temporal/#sec-temporal-toisodayofyear
u16 to_iso_day_of_year(i32 year, u8 month, u8 day)
{
// 1. Assert: IsValidISODate(year, month, day) is true.
VERIFY(is_valid_iso_date(year, month, day));
// 2. Let epochDays be MakeDay(𝔽(year), 𝔽(month - 1), 𝔽(day)).
auto epoch_days = make_day(year, month - 1, day);
// 3. Assert: epochDays is finite.
VERIFY(isfinite(epoch_days));
// 4. Return ℝ(DayWithinYear(MakeDate(epochDays, +0𝔽))) + 1.
return day_within_year(make_date(epoch_days, 0)) + 1;
}
// 12.2.43 ToISODayOfWeek ( year, month, day ), https://tc39.es/proposal-temporal/#sec-temporal-toisodayofweek
u8 to_iso_day_of_week(i32 year, u8 month, u8 day)
{
// 1. Assert: IsValidISODate(year, month, day) is true.
VERIFY(is_valid_iso_date(year, month, day));
// 2. Let epochDays be MakeDay(𝔽(year), 𝔽(month - 1), 𝔽(day)).
auto epoch_days = make_day(year, month - 1, day);
// 3. Assert: epochDays is finite.
VERIFY(isfinite(epoch_days));
// 4. Let dayOfWeek be WeekDay(MakeDate(epochDays, +0𝔽)).
auto day_of_week = week_day(make_date(epoch_days, 0));
// 5. If dayOfWeek = +0𝔽, return 7.
if (day_of_week == 0)
return 7;
// 6. Return ℝ(dayOfWeek).
return day_of_week;
}
}

2
Userland/Libraries/LibJS/Runtime/Temporal/Calendar.h
View file

@ -75,5 +75,7 @@ u8 iso_month(Object& temporal_object);
String iso_month_code(Object& temporal_object);
u8 iso_day(Object& temporal_object);
ThrowCompletionOr<Object*> default_merge_calendar_fields(VM&, Object const& fields, Object const& additional_fields);
u16 to_iso_day_of_year(i32 year, u8 month, u8 day);
u8 to_iso_day_of_week(i32 year, u8 month, u8 day);
}

29
Userland/Libraries/LibJS/Runtime/Temporal/CalendarPrototype.cpp
View file

@ -328,21 +328,8 @@ JS_DEFINE_NATIVE_FUNCTION(CalendarPrototype::day_of_week)
// 4. Let temporalDate be ? ToTemporalDate(temporalDateLike).
auto* temporal_date = TRY(to_temporal_date(vm, vm.argument(0)));
// 5. Let epochDays be MakeDay(𝔽(temporalDate.[[ISOYear]]), 𝔽(temporalDate.[[ISOMonth]] - 1), 𝔽(temporalDate.[[ISODay]])).
auto epoch_days = make_day(temporal_date->iso_year(), temporal_date->iso_month() - 1, temporal_date->iso_day());
// 6. Assert: epochDays is finite.
VERIFY(isfinite(epoch_days));
// 7. Let dayOfWeek be WeekDay(MakeDate(epochDays, +0𝔽)).
auto day_of_week = week_day(make_date(epoch_days, 0));
// 8. If dayOfWeek = +0𝔽, return 7𝔽.
if (day_of_week == 0)
return Value(7);
// 9. Return dayOfWeek.
return Value(day_of_week);
// 5. Return 𝔽(ToISODayOfWeek(temporalDate.[[ISOYear]], temporalDate.[[ISOMonth]], temporalDate.[[ISODay]])).
return Value(to_iso_day_of_week(temporal_date->iso_year(), temporal_date->iso_month(), temporal_date->iso_day()));
}
// 12.4.14 Temporal.Calendar.prototype.dayOfYear ( temporalDateLike ), https://tc39.es/proposal-temporal/#sec-temporal.calendar.prototype.dayofyear
@ -359,14 +346,8 @@ JS_DEFINE_NATIVE_FUNCTION(CalendarPrototype::day_of_year)
// 4. Let temporalDate be ? ToTemporalDate(temporalDateLike).
auto* temporal_date = TRY(to_temporal_date(vm, vm.argument(0)));
// 5. Let epochDays be MakeDay(𝔽(temporalDate.[[ISOYear]]), 𝔽(temporalDate.[[ISOMonth]] - 1), 𝔽(temporalDate.[[ISODay]])).
auto epoch_days = make_day(temporal_date->iso_year(), temporal_date->iso_month() - 1, temporal_date->iso_day());
// 6. Assert: epochDays is finite.
VERIFY(isfinite(epoch_days));
// 7. Return DayWithinYear(MakeDate(epochDays, +0𝔽)) + 1𝔽.
return Value(day_within_year(make_date(epoch_days, 0)) + 1);
// 5. Return 𝔽(ToISODayOfYear(temporalDate.[[ISOYear]], temporalDate.[[ISOMonth]], temporalDate.[[ISODay]])).
return Value(to_iso_day_of_year(temporal_date->iso_year(), temporal_date->iso_month(), temporal_date->iso_day()));
}
// 12.4.15 Temporal.Calendar.prototype.weekOfYear ( temporalDateLike ), https://tc39.es/proposal-temporal/#sec-temporal.calendar.prototype.weekofyear
@ -383,7 +364,7 @@ JS_DEFINE_NATIVE_FUNCTION(CalendarPrototype::week_of_year)
// 4. Let temporalDate be ? ToTemporalDate(temporalDateLike).
auto* temporal_date = TRY(to_temporal_date(vm, vm.argument(0)));
// 5. Return 𝔽(! ToISODayOfYear(temporalDate.[[ISOYear]], temporalDate.[[ISOMonth]], temporalDate.[[ISODay]])).
// 5. Return 𝔽(ToISODayOfYear(temporalDate.[[ISOYear]], temporalDate.[[ISOMonth]], temporalDate.[[ISODay]])).
return Value(to_iso_week_of_year(temporal_date->iso_year(), temporal_date->iso_month(), temporal_date->iso_day()));
}