Fast-path conversion of Temporal.ZonedDateTime to Temporal.TimeZone

If passing a Temporal.ZonedDateTime (that is, a Temporal object with a [[TimeZone]] internal slot) where a Temporal.TimeZone is expected, then read that slot instead of doing a Get on the "timeZone" property. The Get operation was also not consistently done throughout the existing spec text, so fix that as well. This means the TimeZoneFrom operation becomes redundant, so remove it. Additionally, the check for the "timeZone" property on plain objects was not implemented according to the consensus in #925 (comment) and this change fixes that as well. See: #1428
tc39 · Apr 16, 2021 · 3119ab8 · 3119ab8
1 parent 07f6379
commit 3119ab8
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Showing 27 changed files with 53 additions and 34 deletions.
diff --git a/polyfill/lib/ecmascript.mjs b/polyfill/lib/ecmascript.mjs
@@ -1509,7 +1509,8 @@ export const ES = ObjectAssign({}, ES2020, {
         calendar
       } = ES.ParseTemporalZonedDateTimeString(ES.ToString(item)));
       if (!ianaName) throw new RangeError('time zone ID required in brackets');
-      timeZone = ES.TimeZoneFrom(ianaName);
+      const TemporalTimeZone = GetIntrinsic('%Temporal.TimeZone%');
+      timeZone = new TemporalTimeZone(ianaName);
       if (!calendar) calendar = ES.GetISO8601Calendar();
       calendar = ES.ToTemporalCalendar(calendar);
     }
@@ -1701,22 +1702,20 @@ export const ES = ObjectAssign({}, ES2020, {
     if (!ES.IsTemporalMonthDay(result)) throw new TypeError('invalid result');
     return result;
   },
-  TimeZoneFrom: (item) => {
-    if (ES.Type(item) === 'Object') {
-      if (!('timeZone' in item)) return item;
-      item = item.timeZone;
-      if (ES.Type(item) === 'Object' && !('timeZone' in item)) return item;
-    }
-    const timeZone = ES.TemporalTimeZoneFromString(ES.ToString(item));
-    const TemporalTimeZone = GetIntrinsic('%Temporal.TimeZone%');
-    return new TemporalTimeZone(timeZone);
-  },
+
   ToTemporalTimeZone: (temporalTimeZoneLike) => {
     if (ES.Type(temporalTimeZoneLike) === 'Object') {
-      return temporalTimeZoneLike;
+      if (ES.IsTemporalZonedDateTime(temporalTimeZoneLike)) return GetSlot(temporalTimeZoneLike, TIME_ZONE);
+      if (!('timeZone' in temporalTimeZoneLike)) return temporalTimeZoneLike;
+      temporalTimeZoneLike = temporalTimeZoneLike.timeZone;
+      if (ES.Type(temporalTimeZoneLike) === 'Object' && !('timeZone' in temporalTimeZoneLike)) {
+        return temporalTimeZoneLike;
+      }
     }
     const identifier = ES.ToString(temporalTimeZoneLike);
-    return ES.TimeZoneFrom(identifier);
+    const timeZone = ES.TemporalTimeZoneFromString(identifier);
+    const TemporalTimeZone = GetIntrinsic('%Temporal.TimeZone%');
+    return new TemporalTimeZone(timeZone);
   },
   TimeZoneCompare: (one, two) => {
     const tz1 = ES.ToString(one);

diff --git a/polyfill/lib/timezone.mjs b/polyfill/lib/timezone.mjs
@@ -143,7 +143,7 @@ export class TimeZone {
     return ES.ToString(this);
   }
   static from(item) {
-    return ES.TimeZoneFrom(item);
+    return ES.ToTemporalTimeZone(item);
   }
 }
 

diff --git a/polyfill/test/Instant/prototype/toString/timezone.js b/polyfill/test/Instant/prototype/toString/timezone.js
@@ -8,6 +8,7 @@ includes: [compareArray.js]
 
 const actual = [];
 const expected = [
+  "has timeZone.timeZone",
   "get timeZone.getOffsetNanosecondsFor",
   "call timeZone.getOffsetNanosecondsFor",
   "get timeZone.getOffsetNanosecondsFor",

diff --git a/polyfill/test/Instant/prototype/toZonedDateTime/calendar-from-undefined.js b/polyfill/test/Instant/prototype/toZonedDateTime/calendar-from-undefined.js
@@ -7,7 +7,9 @@ includes: [compareArray.js]
 ---*/
 
 const actual = [];
-const expected = [];
+const expected = [
+  "has timeZone.timeZone",
+];
 
 const instant = Temporal.Instant.from("1975-02-02T14:25:36.123456789Z");
 const dateTime = Temporal.PlainDateTime.from("1963-07-02T12:34:56.987654321");

diff --git a/polyfill/test/Instant/prototype/toZonedDateTime/calendar-function.js b/polyfill/test/Instant/prototype/toZonedDateTime/calendar-function.js
@@ -7,7 +7,9 @@ includes: [compareArray.js]
 ---*/
 
 const actual = [];
-const expected = [];
+const expected = [
+  "has timeZone.timeZone",
+];
 
 const instant = Temporal.Instant.from("1975-02-02T14:25:36.123456789Z");
 const dateTime = Temporal.PlainDateTime.from("1963-07-02T12:34:56.987654321");

diff --git a/polyfill/test/Instant/prototype/toZonedDateTime/calendar-object.js b/polyfill/test/Instant/prototype/toZonedDateTime/calendar-object.js
@@ -7,7 +7,9 @@ includes: [compareArray.js]
 ---*/
 
 const actual = [];
-const expected = [];
+const expected = [
+  "has timeZone.timeZone",
+];
 
 const instant = Temporal.Instant.from("1975-02-02T14:25:36.123456789Z");
 const dateTime = Temporal.PlainDateTime.from("1963-07-02T12:34:56.987654321");

diff --git a/polyfill/test/Instant/prototype/toZonedDateTime/plain-custom-timezone.js b/polyfill/test/Instant/prototype/toZonedDateTime/plain-custom-timezone.js
@@ -7,7 +7,9 @@ includes: [compareArray.js]
 ---*/
 
 const actual = [];
-const expected = [];
+const expected = [
+  "has timeZone.timeZone",
+];
 
 const instant = Temporal.Instant.from("1975-02-02T14:25:36.123456789Z");
 const dateTime = Temporal.PlainDateTime.from("1963-07-02T12:00:00.987654321");

diff --git a/polyfill/test/PlainDateTime/prototype/toZonedDateTime/plain-custom-timezone.js b/polyfill/test/PlainDateTime/prototype/toZonedDateTime/plain-custom-timezone.js
@@ -8,6 +8,7 @@ includes: [compareArray.js]
 
 const actual = [];
 const expected = [
+  "has timeZone.timeZone",
   "get options.disambiguation",
   "get disambiguation.toString",
   "call disambiguation.toString",

diff --git a/polyfill/test/ZonedDateTime/prototype/toPlainDateTime/plain-custom-timezone.js b/polyfill/test/ZonedDateTime/prototype/toPlainDateTime/plain-custom-timezone.js
@@ -8,6 +8,7 @@ includes: [compareArray.js]
 
 const actual = [];
 const expected = [
+  "has timeZone.timeZone",
   "get timeZone.getOffsetNanosecondsFor",
   "call timeZone.getOffsetNanosecondsFor",
 ];

diff --git a/polyfill/test/now/plainDate/calendar-from-undefined.js b/polyfill/test/now/plainDate/calendar-from-undefined.js
@@ -8,6 +8,7 @@ includes: [compareArray.js]
 
 const actual = [];
 const expected = [
+  "has timeZone.timeZone",
   "get timeZone.getOffsetNanosecondsFor",
   "call timeZone.getOffsetNanosecondsFor",
 ];

diff --git a/polyfill/test/now/plainDate/calendar-function.js b/polyfill/test/now/plainDate/calendar-function.js
@@ -8,6 +8,7 @@ includes: [compareArray.js]
 
 const actual = [];
 const expected = [
+  "has timeZone.timeZone",
   "get timeZone.getOffsetNanosecondsFor",
   "call timeZone.getOffsetNanosecondsFor",
 ];

diff --git a/polyfill/test/now/plainDate/calendar-object.js b/polyfill/test/now/plainDate/calendar-object.js
@@ -8,6 +8,7 @@ includes: [compareArray.js]
 
 const actual = [];
 const expected = [
+  "has timeZone.timeZone",
   "get timeZone.getOffsetNanosecondsFor",
   "call timeZone.getOffsetNanosecondsFor",
 ];

diff --git a/polyfill/test/now/plainDate/calendar.js b/polyfill/test/now/plainDate/calendar.js
@@ -8,6 +8,7 @@ includes: [compareArray.js]
 
 const actual = [];
 const expected = [
+  "has timeZone.timeZone",
   "get timeZone.getOffsetNanosecondsFor",
   "call timeZone.getOffsetNanosecondsFor",
 ];

diff --git a/polyfill/test/now/plainDate/timezone-object.js b/polyfill/test/now/plainDate/timezone-object.js
@@ -8,6 +8,7 @@ includes: [compareArray.js]
 
 const actual = [];
 const expected = [
+  "has timeZone.timeZone",
   "get timeZone.getOffsetNanosecondsFor",
   "call timeZone.getOffsetNanosecondsFor",
 ];

diff --git a/polyfill/test/now/plainDate/timezone.js b/polyfill/test/now/plainDate/timezone.js
@@ -8,6 +8,7 @@ includes: [compareArray.js]
 
 const actual = [];
 const expected = [
+  "has timeZone.timeZone",
   "get timeZone.getOffsetNanosecondsFor",
   "call timeZone.getOffsetNanosecondsFor",
 ];

diff --git a/polyfill/test/now/plainDate/toDate-override.js b/polyfill/test/now/plainDate/toDate-override.js
@@ -8,6 +8,7 @@ includes: [compareArray.js]
 
 const actual = [];
 const expected = [
+  "has timeZone.timeZone",
   "get timeZone.getOffsetNanosecondsFor",
   "call timeZone.getOffsetNanosecondsFor",
 ];

diff --git a/polyfill/test/now/plainDateTime/calendar-from-undefined.js b/polyfill/test/now/plainDateTime/calendar-from-undefined.js
@@ -8,6 +8,7 @@ includes: [compareArray.js]
 
 const actual = [];
 const expected = [
+  "has timeZone.timeZone",
   "get timeZone.getOffsetNanosecondsFor",
   "call timeZone.getOffsetNanosecondsFor",
 ];

diff --git a/polyfill/test/now/plainDateTime/calendar-function.js b/polyfill/test/now/plainDateTime/calendar-function.js
@@ -8,6 +8,7 @@ includes: [compareArray.js]
 
 const actual = [];
 const expected = [
+  "has timeZone.timeZone",
   "get timeZone.getOffsetNanosecondsFor",
   "call timeZone.getOffsetNanosecondsFor",
 ];

diff --git a/polyfill/test/now/plainDateTime/calendar-object.js b/polyfill/test/now/plainDateTime/calendar-object.js
@@ -8,6 +8,7 @@ includes: [compareArray.js]
 
 const actual = [];
 const expected = [
+  "has timeZone.timeZone",
   "get timeZone.getOffsetNanosecondsFor",
   "call timeZone.getOffsetNanosecondsFor",
 ];

diff --git a/polyfill/test/now/plainDateTime/calendar.js b/polyfill/test/now/plainDateTime/calendar.js
@@ -8,6 +8,7 @@ includes: [compareArray.js]
 
 const actual = [];
 const expected = [
+  "has timeZone.timeZone",
   "get timeZone.getOffsetNanosecondsFor",
   "call timeZone.getOffsetNanosecondsFor",
 ];

diff --git a/polyfill/test/now/plainDateTime/timezone-object.js b/polyfill/test/now/plainDateTime/timezone-object.js
@@ -8,6 +8,7 @@ includes: [compareArray.js]
 
 const actual = [];
 const expected = [
+  "has timeZone.timeZone",
   "get timeZone.getOffsetNanosecondsFor",
   "call timeZone.getOffsetNanosecondsFor",
 ];

diff --git a/polyfill/test/now/plainDateTime/timezone.js b/polyfill/test/now/plainDateTime/timezone.js
@@ -8,6 +8,7 @@ includes: [compareArray.js]
 
 const actual = [];
 const expected = [
+  "has timeZone.timeZone",
   "get timeZone.getOffsetNanosecondsFor",
   "call timeZone.getOffsetNanosecondsFor",
 ];

diff --git a/polyfill/test/now/plainTimeISO/timezone-object.js b/polyfill/test/now/plainTimeISO/timezone-object.js
@@ -8,6 +8,7 @@ includes: [compareArray.js]
 
 const actual = [];
 const expected = [
+  "has timeZone.timeZone",
   "get timeZone.getOffsetNanosecondsFor",
   "call timeZone.getOffsetNanosecondsFor",
 ];

diff --git a/polyfill/test/now/plainTimeISO/timezone.js b/polyfill/test/now/plainTimeISO/timezone.js
@@ -8,6 +8,7 @@ includes: [compareArray.js]
 
 const actual = [];
 const expected = [
+  "has timeZone.timeZone",
   "get timeZone.getOffsetNanosecondsFor",
   "call timeZone.getOffsetNanosecondsFor",
 ];

diff --git a/polyfill/test/now/plainTimeISO/toTime-override.js b/polyfill/test/now/plainTimeISO/toTime-override.js
@@ -8,6 +8,7 @@ includes: [compareArray.js]
 
 const actual = [];
 const expected = [
+  "has timeZone.timeZone",
   "get timeZone.getOffsetNanosecondsFor",
   "call timeZone.getOffsetNanosecondsFor",
 ];

diff --git a/spec/timezone.html b/spec/timezone.html
@@ -150,7 +150,7 @@ <h1>Temporal.TimeZone.from ( _item_ )</h1>
         The following steps are taken:
       </p>
       <emu-alg>
-        1. Return ? TimeZoneFrom(_item_).
+        1. Return ? ToTemporalTimeZone(_item_).
       </emu-alg>
     </emu-clause>
   </emu-clause>
@@ -534,21 +534,14 @@ <h1>FormatTimeZoneOffsetString ( _offsetNanoseconds_ )</h1>
     <emu-clause id="sec-temporal-totemporaltimezone" aoid="ToTemporalTimeZone">
       <h1>ToTemporalTimeZone ( _temporalTimeZoneLike_ )</h1>
       <emu-alg>
-        1. If Type(_temporalTimeZoneLike_) is Object, return _temporalTimeZoneLike_.
+        1. If Type(_temporalTimeZoneLike_) is Object, then
+          1. If _temporalTimeZoneLike_ has an [[InitializedTemporalZonedDateTime]] internal slot, then
+            1. Return _temporalTimeZoneLike_.[[TimeZone]].
+          1. If ? HasProperty(_temporalTimeZoneLike_, *"timeZone"*) is *false*, return _temporalTimeZoneLike_.
+          1. Set _temporalTimeZoneLike_ to ? Get(_temporalTimeZoneLike_, *"timeZone"*).
+          1. If Type(_temporalTimeZoneLike_) is Object and ? HasProperty(_temporalTimeZoneLike_, *"timeZone"*) is *false*, return _temporalTimeZoneLike_.
         1. Let _identifier_ be ? ToString(_temporalTimeZoneLike_).
-        1. Return ? TimeZoneFrom(_identifier_).
-      </emu-alg>
-    </emu-clause>
-
-    <emu-clause id="sec-temporal-timezonefrom" aoid="TimeZoneFrom">
-      <h1>TimeZoneFrom ( _identifier_ )</h1>
-      <emu-alg>
-        1. If Type(_item_) is Object, then
-          1. If ? HasProperty(_item_, *"timeZone"*) is *false*, return _item_.
-          1. Set _item_ to ? Get(_item_, *"timeZone"*).
-          1. If Type(_item_) is Object and ? HasProperty(_item_, *"timeZone"*) is *false*, return _item_.
-        1. Let _string_ be ? ToString(_item_).
-        1. Let _result_ be ? ParseTemporalTimeZone(_string_).
+        1. Let _result_ be ? ParseTemporalTimeZone(_identifier_).
         1. Return ? CreateTemporalTimeZone(_result_).
       </emu-alg>
     </emu-clause>

diff --git a/spec/zoneddatetime.html b/spec/zoneddatetime.html
@@ -1120,7 +1120,7 @@ <h1>ToTemporalZonedDateTime ( _item_ [ , _options_ ] )</h1>
           1. Let _string_ be ? ToString(_item_).
           1. Let _result_ be ? ParseTemporalZonedDateTimeString(_string_).
           1. If _result_.[[TimeZoneName]] is *undefined*, throw a *RangeError* exception.
-          1. Let _timeZone_ be ? TimeZoneFrom(_result_.[[TimeZoneName]]).
+          1. Let _timeZone_ be ? CreateTemporalTimeZone(_result_.[[TimeZoneName]]).
           1. Let _offsetString_ be _result_.[[TimeZoneOffsetString]].
           1. Let _calendar_ be ? ToOptionalTemporalCalendar(_result_.[[Calendar]]).
         1. Let _offsetNanoseconds_ be ? ParseTimeZoneOffsetString(_offsetString_).