Normative: Look up calendar methods only once

Introduce a new spec type, Calendar Record, which stores a calendar
object's dateAdd, dateFromFields, and dateUntil methods once they have
been observably looked up. The record is passed around into abstract
operations instead of the calendar object itself.

These three are the only methods that are called more than once within
the same API call. Others are called only once and can be looked up as
needed.

This is a large commit but most of it is mechanical replacement of
Temporal.Calendar variables with Calendar Record variables.

Author: ptomato

polyfill/lib/duration.mjs

@@ -2,6 +2,7 @@
 
 import * as ES from './ecmascript.mjs';
 import { MakeIntrinsicClass } from './intrinsicclass.mjs';
+import { MethodRecord } from './methodrecord.mjs';
 import {
   YEARS,
   MONTHS,
@@ -308,13 +309,40 @@ export class Duration {
       plainRelativeTo = ES.TemporalDateTimeToDate(dt);
     }
 
+    let calendar, calendarRec;
+    if (zonedRelativeTo) {
+      calendar = GetSlot(zonedRelativeTo, CALENDAR);
+    } else if (plainRelativeTo) {
+      calendar = GetSlot(plainRelativeTo, CALENDAR);
+    }
+    if (calendar) {
+      calendarRec = new MethodRecord(calendar);
+      if (
+        years !== 0 ||
+        months !== 0 ||
+        weeks !== 0 ||
+        largestUnit === 'year' ||
+        largestUnit === 'month' ||
+        largestUnit === 'week' ||
+        smallestUnit === 'year' ||
+        smallestUnit === 'month' ||
+        smallestUnit === 'week'
+      ) {
+        calendarRec.lookup('dateAdd');
+      }
+      if (largestUnit === 'year' || (largestUnit === 'month' && years !== 0) || smallestUnit === 'year') {
+        calendarRec.lookup('dateUntil');
+      }
+    }
+
     ({ years, months, weeks, days } = ES.UnbalanceDurationRelative(
       years,
       months,
       weeks,
       days,
       largestUnit,
-      plainRelativeTo
+      plainRelativeTo,
+      calendarRec
     ));
     ({ years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds } =
       ES.RoundDuration(
@@ -332,6 +360,7 @@ export class Duration {
         smallestUnit,
         roundingMode,
         plainRelativeTo,
+        calendarRec,
         zonedRelativeTo,
         timeZoneRec
       ));
@@ -352,6 +381,7 @@ export class Duration {
           smallestUnit,
           roundingMode,
           zonedRelativeTo,
+          calendarRec,
           timeZoneRec
         ));
     }
@@ -373,7 +403,8 @@ export class Duration {
       weeks,
       days,
       largestUnit,
-      plainRelativeTo
+      plainRelativeTo,
+      calendarRec
     ));
 
     return new Duration(years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds);
@@ -417,12 +448,36 @@ export class Duration {
       plainRelativeTo = ES.TemporalDateTimeToDate(dt);
     }
 
+    let calendar, calendarRec;
+    if (zonedRelativeTo) {
+      calendar = GetSlot(zonedRelativeTo, CALENDAR);
+    } else if (plainRelativeTo) {
+      calendar = GetSlot(plainRelativeTo, CALENDAR);
+    }
+    if (calendar) {
+      calendarRec = new MethodRecord(calendar);
+      if (years !== 0 || months !== 0 || weeks !== 0 || unit === 'year' || unit === 'month' || unit === 'week') {
+        calendarRec.lookup('dateAdd');
+      }
+      if (unit === 'year' || (unit === 'month' && years !== 0)) {
+        calendarRec.lookup('dateUntil');
+      }
+    }
+
     // Convert larger units down to days
-    ({ years, months, weeks, days } = ES.UnbalanceDurationRelative(years, months, weeks, days, unit, plainRelativeTo));
+    ({ years, months, weeks, days } = ES.UnbalanceDurationRelative(
+      years,
+      months,
+      weeks,
+      days,
+      unit,
+      plainRelativeTo,
+      calendarRec
+    ));
     // If the unit we're totalling is smaller than `days`, convert days down to that unit.
     let intermediate;
     if (zonedRelativeTo) {
-      intermediate = ES.MoveRelativeZonedDateTime(zonedRelativeTo, timeZoneRec, years, months, weeks, 0);
+      intermediate = ES.MoveRelativeZonedDateTime(zonedRelativeTo, calendarRec, timeZoneRec, years, months, weeks, 0);
     }
     let balanceResult = ES.BalancePossiblyInfiniteDuration(
       days,
@@ -458,6 +513,7 @@ export class Duration {
       unit,
       'trunc',
       plainRelativeTo,
+      calendarRec,
       zonedRelativeTo,
       timeZoneRec
     );
@@ -550,15 +606,20 @@ export class Duration {
 
     const calendarUnitsPresent = y1 !== 0 || y2 !== 0 || mon1 !== 0 || mon2 !== 0 || w1 !== 0 || w2 !== 0;
 
+    let calendarRec;
+    if (relativeTo) {
+      calendarRec = new MethodRecord(GetSlot(relativeTo, CALENDAR));
+      if (calendarUnitsPresent) calendarRec.lookup('dateAdd');
+    }
+
     if (ES.IsTemporalZonedDateTime(relativeTo) && (calendarUnitsPresent || d1 != 0 || d2 !== 0)) {
       const instant = GetSlot(relativeTo, INSTANT);
-      const calendar = GetSlot(relativeTo, CALENDAR);
-      const precalculatedDateTime = ES.GetPlainDateTimeFor(timeZoneRec, instant, calendar);
+      const precalculatedDateTime = ES.GetPlainDateTimeFor(timeZoneRec, instant, calendarRec.receiver);
 
       const after1 = ES.AddZonedDateTime(
         instant,
         timeZoneRec,
-        calendar,
+        calendarRec,
         y1,
         mon1,
         w1,
@@ -574,7 +635,7 @@ export class Duration {
       const after2 = ES.AddZonedDateTime(
         instant,
         timeZoneRec,
-        calendar,
+        calendarRec,
         y2,
         mon2,
         w2,
@@ -592,8 +653,8 @@ export class Duration {
 
     if (calendarUnitsPresent) {
       // relativeTo is PlainDate or undefined
-      ({ days: d1 } = ES.UnbalanceDurationRelative(y1, mon1, w1, d1, 'day', relativeTo));
-      ({ days: d2 } = ES.UnbalanceDurationRelative(y2, mon2, w2, d2, 'day', relativeTo));
+      ({ days: d1 } = ES.UnbalanceDurationRelative(y1, mon1, w1, d1, 'day', relativeTo, calendarRec));
+      ({ days: d2 } = ES.UnbalanceDurationRelative(y2, mon2, w2, d2, 'day', relativeTo, calendarRec));
     }
     ns1 = ES.TotalDurationNanoseconds(d1, h1, min1, s1, ms1, µs1, ns1);
     ns2 = ES.TotalDurationNanoseconds(d2, h2, min2, s2, ms2, µs2, ns2);