LibJS: Implement Temporal.PlainYearMonth.prototype.until/since

Author: https://github.com/trflynn89 Commit: cb5d1b5086 Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/2496
2025-07-29 04:09:13 +00:00 · 2024-11-21 13:21:29 -05:00 · 2024-11-21 13:21:29 -05:00 · cb5d1b5086 · 2024-11-22 18:56:30 +00:00
commit cb5d1b5086
parent 203269fae2
26 changed files with 1586 additions and 1 deletions
--- a/Libraries/LibJS/Runtime/Temporal/DateEquations.cpp
+++ b/Libraries/LibJS/Runtime/Temporal/DateEquations.cpp
@ -79,6 +79,52 @@ u16 epoch_time_to_day_in_year(double time)
    return static_cast<u16>(epoch_time_to_day_number(time) - epoch_day_number_for_year(epoch_time_to_epoch_year(time)));
 }

+// https://tc39.es/proposal-temporal/#eqn-epochtimetomonthinyear
+u8 epoch_time_to_month_in_year(double time)
+{
+    auto day_in_year = epoch_time_to_day_in_year(time);
+    auto in_leap_year = mathematical_in_leap_year(time);
+
+    // EpochTimeToMonthInYear(t)
+    //     = 0 if 0 ≤ EpochTimeToDayInYear(t) < 31
+    //     = 1 if 31 ≤ EpochTimeToDayInYear(t) < 59 + MathematicalInLeapYear(t)
+    //     = 2 if 59 + MathematicalInLeapYear(t) ≤ EpochTimeToDayInYear(t) < 90 + MathematicalInLeapYear(t)
+    //     = 3 if 90 + MathematicalInLeapYear(t) ≤ EpochTimeToDayInYear(t) < 120 + MathematicalInLeapYear(t)
+    //     = 4 if 120 + MathematicalInLeapYear(t) ≤ EpochTimeToDayInYear(t) < 151 + MathematicalInLeapYear(t)
+    //     = 5 if 151 + MathematicalInLeapYear(t) ≤ EpochTimeToDayInYear(t) < 181 + MathematicalInLeapYear(t)
+    //     = 6 if 181 + MathematicalInLeapYear(t) ≤ EpochTimeToDayInYear(t) < 212 + MathematicalInLeapYear(t)
+    //     = 7 if 212 + MathematicalInLeapYear(t) ≤ EpochTimeToDayInYear(t) < 243 + MathematicalInLeapYear(t)
+    //     = 8 if 243 + MathematicalInLeapYear(t) ≤ EpochTimeToDayInYear(t) < 273 + MathematicalInLeapYear(t)
+    //     = 9 if 273 + MathematicalInLeapYear(t) ≤ EpochTimeToDayInYear(t) < 304 + MathematicalInLeapYear(t)
+    //     = 10 if 304 + MathematicalInLeapYear(t) ≤ EpochTimeToDayInYear(t) < 334 + MathematicalInLeapYear(t)
+    //     = 11 if 334 + MathematicalInLeapYear(t) ≤ EpochTimeToDayInYear(t) < 365 + MathematicalInLeapYear(t)
+    if (day_in_year < 31)
+        return 0;
+    if (day_in_year >= 31 && day_in_year < 59 + in_leap_year)
+        return 1;
+    if (day_in_year >= 59 + in_leap_year && day_in_year < 90 + in_leap_year)
+        return 2;
+    if (day_in_year >= 90 + in_leap_year && day_in_year < 120 + in_leap_year)
+        return 3;
+    if (day_in_year >= 120 + in_leap_year && day_in_year < 151 + in_leap_year)
+        return 4;
+    if (day_in_year >= 151 + in_leap_year && day_in_year < 181 + in_leap_year)
+        return 5;
+    if (day_in_year >= 181 + in_leap_year && day_in_year < 212 + in_leap_year)
+        return 6;
+    if (day_in_year >= 212 + in_leap_year && day_in_year < 243 + in_leap_year)
+        return 7;
+    if (day_in_year >= 243 + in_leap_year && day_in_year < 273 + in_leap_year)
+        return 8;
+    if (day_in_year >= 273 + in_leap_year && day_in_year < 304 + in_leap_year)
+        return 9;
+    if (day_in_year >= 304 + in_leap_year && day_in_year < 334 + in_leap_year)
+        return 10;
+    if (day_in_year >= 334 + in_leap_year && day_in_year < 365 + in_leap_year)
+        return 11;
+    VERIFY_NOT_REACHED();
+}
+
 // https://tc39.es/proposal-temporal/#eqn-epochtimetoweekday
 u8 epoch_time_to_week_day(double time)
 {
@ -86,4 +132,51 @@ u8 epoch_time_to_week_day(double time)
    return static_cast<u8>(modulo(epoch_time_to_day_number(time) + 4, 7.0));
 }

+// https://tc39.es/proposal-temporal/#eqn-epochtimetodate
+u8 epoch_time_to_date(double time)
+{
+    auto day_in_year = epoch_time_to_day_in_year(time);
+    auto month_in_year = epoch_time_to_month_in_year(time);
+    auto in_leap_year = mathematical_in_leap_year(time);
+
+    // EpochTimeToDate(t)
+    //     = EpochTimeToDayInYear(t) + 1 if EpochTimeToMonthInYear(t) = 0
+    //     = EpochTimeToDayInYear(t) - 30 if EpochTimeToMonthInYear(t) = 1
+    //     = EpochTimeToDayInYear(t) - 58 - MathematicalInLeapYear(t) if EpochTimeToMonthInYear(t) = 2
+    //     = EpochTimeToDayInYear(t) - 89 - MathematicalInLeapYear(t) if EpochTimeToMonthInYear(t) = 3
+    //     = EpochTimeToDayInYear(t) - 119 - MathematicalInLeapYear(t) if EpochTimeToMonthInYear(t) = 4
+    //     = EpochTimeToDayInYear(t) - 150 - MathematicalInLeapYear(t) if EpochTimeToMonthInYear(t) = 5
+    //     = EpochTimeToDayInYear(t) - 180 - MathematicalInLeapYear(t) if EpochTimeToMonthInYear(t) = 6
+    //     = EpochTimeToDayInYear(t) - 211 - MathematicalInLeapYear(t) if EpochTimeToMonthInYear(t) = 7
+    //     = EpochTimeToDayInYear(t) - 242 - MathematicalInLeapYear(t) if EpochTimeToMonthInYear(t) = 8
+    //     = EpochTimeToDayInYear(t) - 272 - MathematicalInLeapYear(t) if EpochTimeToMonthInYear(t) = 9
+    //     = EpochTimeToDayInYear(t) - 303 - MathematicalInLeapYear(t) if EpochTimeToMonthInYear(t) = 10
+    //     = EpochTimeToDayInYear(t) - 333 - MathematicalInLeapYear(t) if EpochTimeToMonthInYear(t) = 11
+    if (month_in_year == 0)
+        return day_in_year + 1;
+    if (month_in_year == 1)
+        return day_in_year - 30;
+    if (month_in_year == 2)
+        return day_in_year - 58 - in_leap_year;
+    if (month_in_year == 3)
+        return day_in_year - 89 - in_leap_year;
+    if (month_in_year == 4)
+        return day_in_year - 119 - in_leap_year;
+    if (month_in_year == 5)
+        return day_in_year - 150 - in_leap_year;
+    if (month_in_year == 6)
+        return day_in_year - 180 - in_leap_year;
+    if (month_in_year == 7)
+        return day_in_year - 211 - in_leap_year;
+    if (month_in_year == 8)
+        return day_in_year - 242 - in_leap_year;
+    if (month_in_year == 9)
+        return day_in_year - 272 - in_leap_year;
+    if (month_in_year == 10)
+        return day_in_year - 303 - in_leap_year;
+    if (month_in_year == 11)
+        return day_in_year - 333 - in_leap_year;
+    VERIFY_NOT_REACHED();
+}
+
 }