LibJS: Move regulating and balancing logic into ISODateSurpasses

This is an editorial change in the Temporal proposal. See:
eddb77f

Libraries/LibJS/Runtime/Temporal/Calendar.cpp

@@ -395,8 +395,8 @@ DateDuration calendar_date_until(VM& vm, StringView calendar, ISODate one, ISODa
             if (candidate_years != 0)
                 candidate_years -= sign;
 
-            // d.ii. Repeat, while ISODateSurpasses(sign, one.[[Year]] + candidateYears, one.[[Month]], one.[[Day]], two) is false,
-            while (!iso_date_surpasses(sign, static_cast<double>(one.year) + candidate_years, one.month, one.day, two)) {
+            // d.ii. Repeat, while ISODateSurpasses(sign, one, two, candidateYears, 0, 0, 0) is false,
+            while (!iso_date_surpasses(vm, sign, one, two, candidate_years, 0, 0, 0)) {
                 // 1. Set years to candidateYears.
                 years = candidate_years;
 
@@ -407,19 +407,13 @@ DateDuration calendar_date_until(VM& vm, StringView calendar, ISODate one, ISODa
             // f.i. Let candidateMonths be sign.
             double candidate_months = sign;
 
-            // f.ii. Let intermediate be BalanceISOYearMonth(one.[[Year]] + years, one.[[Month]] + candidateMonths).
-            auto intermediate = balance_iso_year_month(static_cast<double>(one.year) + years, static_cast<double>(one.month) + candidate_months);
-
-            // f.iii. Repeat, while ISODateSurpasses(sign, intermediate.[[Year]], intermediate.[[Month]], one.[[Day]], two) is false,
-            while (!iso_date_surpasses(sign, intermediate.year, intermediate.month, one.day, two)) {
+            // f.ii. Repeat, while ISODateSurpasses(sign, one, two, years, candidateMonths, 0, 0) is false,
+            while (!iso_date_surpasses(vm, sign, one, two, years, candidate_months, 0, 0)) {
                 // 1. Set months to candidateMonths.
                 months = candidate_months;
 
                 // 2. Set candidateMonths to candidateMonths + sign.
                 candidate_months += sign;
-
-                // 3. Set intermediate to BalanceISOYearMonth(intermediate.[[Year]], intermediate.[[Month]] + sign).
-                intermediate = balance_iso_year_month(intermediate.year, static_cast<double>(intermediate.month) + sign);
             }
 
             if (largest_unit == Unit::Month) {
@@ -428,28 +422,24 @@ DateDuration calendar_date_until(VM& vm, StringView calendar, ISODate one, ISODa
             }
         }
 
-        // g. Set intermediate to BalanceISOYearMonth(one.[[Year]] + years, one.[[Month]] + months).
-        auto intermediate = balance_iso_year_month(static_cast<double>(one.year) + years, static_cast<double>(one.month) + months);
-
-        // h. Let constrained be ! RegulateISODate(intermediate.[[Year]], intermediate.[[Month]], one.[[Day]], CONSTRAIN).
-        auto constrained = MUST(regulate_iso_date(vm, intermediate.year, intermediate.month, one.day, Overflow::Constrain));
-
-        // i. Let weeks be 0.
+        // g. Let weeks be 0.
         double weeks = 0;
 
         // OPTIMIZATION: If the largestUnit is DAY, we do not want to enter an ISODateSurpasses loop. The loop would have
         //               us increment the intermediate ISOYearMonth one day at time, which will take an extremely long
         //               time if the difference is a large number of years. Instead, we can compute the day difference,
         //               and convert to weeks if needed.
+        auto year_month = balance_iso_year_month(static_cast<double>(one.year) + years, static_cast<double>(one.month) + months);
+        auto regulated_date = MUST(regulate_iso_date(vm, year_month.year, year_month.month, one.day, Overflow::Constrain));
 
-        auto days = iso_date_to_epoch_days(two.year, two.month - 1, two.day) - iso_date_to_epoch_days(constrained.year, constrained.month - 1, constrained.day);
+        auto days = iso_date_to_epoch_days(two.year, two.month - 1, two.day) - iso_date_to_epoch_days(regulated_date.year, regulated_date.month - 1, regulated_date.day);
 
         if (largest_unit == Unit::Week) {
             weeks = trunc(days / 7.0);
             days = fmod(days, 7.0);
         }
 
-        // o. Return ! CreateDateDurationRecord(years, months, weeks, days).
+        // l. Return ! CreateDateDurationRecord(years, months, weeks, days).
         return MUST(create_date_duration_record(vm, years, months, weeks, days));
     }
 

Libraries/LibJS/Runtime/Temporal/PlainDate.cpp

@@ -18,6 +18,7 @@
 #include <LibJS/Runtime/Temporal/PlainDateConstructor.h>
 #include <LibJS/Runtime/Temporal/PlainDateTime.h>
 #include <LibJS/Runtime/Temporal/PlainTime.h>
+#include <LibJS/Runtime/Temporal/PlainYearMonth.h>
 #include <LibJS/Runtime/Temporal/TimeZone.h>
 #include <LibJS/Runtime/Temporal/ZonedDateTime.h>
 
@@ -165,29 +166,65 @@ ThrowCompletionOr<GC::Ref<PlainDate>> to_temporal_date(VM& vm, Value item, Value
     return TRY(create_temporal_date(vm, iso_date, move(calendar)));
 }
 
-// 3.5.5 ISODateSurpasses ( sign, y1, m1, d1, isoDate2 ), https://tc39.es/proposal-temporal/#sec-temporal-isodatesurpasses
-bool iso_date_surpasses(i8 sign, double year1, double month1, double day1, ISODate iso_date2)
+// 3.5.5 ISODateSurpasses ( sign, baseDate, isoDate2, years, months, weeks, days ), https://tc39.es/proposal-temporal/#sec-temporal-isodatesurpasses
+bool iso_date_surpasses(VM& vm, i8 sign, ISODate base_date, ISODate iso_date2, double years, double months, double weeks, double days)
 {
-    // 1. If y1 ≠ isoDate2.[[Year]], then
+    // 1. Let yearMonth be BalanceISOYearMonth(baseDate.[[Year]] + years, baseDate.[[Month]] + months).
+    auto year_month = balance_iso_year_month(static_cast<double>(base_date.year) + years, static_cast<double>(base_date.month) + months);
+
+    i32 year1 = 0;
+    u8 month1 = 0;
+    u8 day1 = 0;
+
+    // 2. If weeks is not 0 or days is not 0, then
+    if (weeks != 0 || days != 0) {
+        // a. Let regulatedDate be ! RegulateISODate(yearMonth.[[Year]], yearMonth.[[Month]], baseDate.[[Day]], CONSTRAIN).
+        auto regulated_date = MUST(regulate_iso_date(vm, year_month.year, year_month.month, base_date.day, Overflow::Constrain));
+
+        // b. Let balancedDate be BalanceISODate(regulatedDate.[[Year]], regulatedDate.[[Month]], regulatedDate.[[Day]] + 7 * weeks + days).
+        auto balanced_date = balance_iso_date(regulated_date.year, regulated_date.month, static_cast<double>(regulated_date.day) + (7 * weeks) + days);
+
+        // c. Let y1 be balancedDate.[[Year]].
+        year1 = balanced_date.year;
+
+        // d. Let m1 be balancedDate.[[Month]].
+        month1 = balanced_date.month;
+
+        // e. Let d1 be balancedDate.[[Day]].
+        day1 = balanced_date.day;
+    }
+    // 3. Else,
+    else {
+        // a. Let y1 be yearMonth.[[Year]].
+        year1 = year_month.year;
+
+        // b. Let m1 be yearMonth.[[Month]].
+        month1 = year_month.month;
+
+        // c. Let d1 be baseDate.[[Day]].
+        day1 = base_date.day;
+    }
+
+    // 4. If y1 ≠ isoDate2.[[Year]], then
     if (year1 != iso_date2.year) {
         // a. If sign × (y1 - isoDate2.[[Year]]) > 0, return true.
         if (sign * (year1 - iso_date2.year) > 0)
             return true;
     }
-    // 2. Else if m1 ≠ isoDate2.[[Month]], then
+    // 5. Else if m1 ≠ isoDate2.[[Month]], then
     else if (month1 != iso_date2.month) {
         // a. If sign × (m1 - isoDate2.[[Month]]) > 0, return true.
         if (sign * (month1 - iso_date2.month) > 0)
             return true;
     }
-    // 3. Else if d1 ≠ isoDate2.[[Day]], then
+    // 6. Else if d1 ≠ isoDate2.[[Day]], then
     else if (day1 != iso_date2.day) {
         // a. If sign × (d1 - isoDate2.[[Day]]) > 0, return true.
         if (sign * (day1 - iso_date2.day) > 0)
             return true;
     }
 
-    // 4. Return false.
+    // 7. Return false.
     return false;
 }
 

Libraries/LibJS/Runtime/Temporal/PlainDate.h

@@ -2,7 +2,7 @@
  * Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
  * Copyright (c) 2021-2023, Linus Groh <linusg@serenityos.org>
  * Copyright (c) 2024, Shannon Booth <shannon@serenityos.org>
- * Copyright (c) 2024, Tim Flynn <trflynn89@ladybird.org>
+ * Copyright (c) 2024-2025, Tim Flynn <trflynn89@ladybird.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -37,7 +37,7 @@ private:
 ISODate create_iso_date_record(double year, double month, double day);
 ThrowCompletionOr<GC::Ref<PlainDate>> to_temporal_date(VM& vm, Value item, Value options = js_undefined());
 ThrowCompletionOr<GC::Ref<PlainDate>> create_temporal_date(VM&, ISODate, String calendar, GC::Ptr<FunctionObject> new_target = {});
-bool iso_date_surpasses(i8 sign, double year1, double month1, double day1, ISODate iso_date2);
+bool iso_date_surpasses(VM&, i8 sign, ISODate base_date, ISODate iso_date2, double years, double months, double weeks, double days);
 ThrowCompletionOr<ISODate> regulate_iso_date(VM& vm, double year, double month, double day, Overflow overflow);
 bool is_valid_iso_date(double year, double month, double day);
 ISODate balance_iso_date(double year, double month, double day);