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Separate out NanosecondsToDays from DifferenceZonedDateTime
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This new abstract operation will be used in more places when converting
nanoseconds to time-zone-aware days.

See: #1171
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@ptomato
ptomato committed Nov 13, 2020
1 parent a744300 commit 97d30d3
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Showing 2 changed files with 110 additions and 61 deletions.
125 changes: 74 additions & 51 deletions polyfill/lib/ecmascript.mjs
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Original file line number Diff line number Diff line change
Expand Up @@ -1947,6 +1947,52 @@ export const ES = ObjectAssign({}, ES2020, {
microseconds = bigInt(microseconds).add(milliseconds.multiply(1000));
return bigInt(nanoseconds).add(microseconds.multiply(1000));
},
NanosecondsToDays: (nanoseconds, relativeTo) => {
const TemporalInstant = GetIntrinsic('%Temporal.Instant%');
const sign = MathSign(nanoseconds);
nanoseconds = bigInt(nanoseconds);
let dayLengthNs = 86400e9;
if (sign === 0) return { days: 0, nanoseconds: bigInt.zero };
if (!ES.IsTemporalZonedDateTime(relativeTo)) {
let days;
({ quotient: days, remainder: nanoseconds } = nanoseconds.divmod(dayLengthNs));
days = days.toJSNumber();
return { days, nanoseconds };
}
let isOverflow = false;
let days = 0;
let relativeInstant = GetSlot(relativeTo, INSTANT);
const timeZone = GetSlot(relativeTo, TIME_ZONE);
const calendar = GetSlot(relativeTo, CALENDAR);
do {
// calculate length of the next day (day that contains the time remainder)
const oneDayFartherNs = ES.AddZonedDateTime(
relativeInstant,
timeZone,
calendar,
0,
0,
0,
sign,
0,
0,
0,
0,
0,
0,
'constrain'
);
const relativeNs = GetSlot(relativeInstant, EPOCHNANOSECONDS);
dayLengthNs = oneDayFartherNs.subtract(relativeNs).toJSNumber();
isOverflow = nanoseconds.subtract(dayLengthNs).multiply(sign).geq(0);
if (isOverflow) {
nanoseconds = nanoseconds.subtract(dayLengthNs);
relativeInstant = new TemporalInstant(oneDayFartherNs);
days += sign;
}
} while (isOverflow);
return { days, nanoseconds };
},
BalanceDuration: (days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds, largestUnit) => {
nanoseconds = ES.TotalDurationNanoseconds(
days,
Expand Down Expand Up @@ -2626,57 +2672,34 @@ export const ES = ObjectAssign({}, ES2020, {
); // may do disambiguation
}

let isOverflow = false;
let timeRemainderNs = 0;
do {
// calculate length of the next day (day that contains the time remainder)
const oneDayFartherDuration = ES.AddDuration(
years,
months,
weeks,
days,
0,
0,
0,
0,
0,
0,
0,
0,
0,
direction,
0,
0,
0,
0,
0,
0,
dtStart
);
const oneDayFartherNs = ES.AddZonedDateTime(
GetSlot(start, INSTANT),
timeZone,
calendar,
oneDayFartherDuration.years,
oneDayFartherDuration.months,
oneDayFartherDuration.weeks,
oneDayFartherDuration.days,
0,
0,
0,
0,
0,
0,
'constrain'
);
const dayLengthNs = oneDayFartherNs.subtract(intermediateNs).toJSNumber();
timeRemainderNs = ns2.subtract(intermediateNs).toJSNumber();
isOverflow = (timeRemainderNs - dayLengthNs) * direction >= 0;
if (isOverflow) {
({ years, months, weeks, days } = oneDayFartherDuration);
intermediateNs = oneDayFartherNs;
}
} while (isOverflow);
let timeRemainderNs = ns2.subtract(intermediateNs).toJSNumber();
let deltaDays;
const TemporalZonedDateTime = GetIntrinsic('%Temporal.ZonedDateTime%');
const intermediate = new TemporalZonedDateTime(intermediateNs, timeZone, calendar);
({ nanoseconds: timeRemainderNs, days: deltaDays } = ES.NanosecondsToDays(timeRemainderNs, intermediate));
({ years, months, weeks, days } = ES.AddDuration(
years,
months,
weeks,
days,
0,
0,
0,
0,
0,
0,
0,
0,
0,
deltaDays,
0,
0,
0,
0,
0,
0,
dtStart
));

// Finally, merge the date and time durations and return the merged result.
let { hours, minutes, seconds, milliseconds, microseconds, nanoseconds } = ES.BalanceDuration(
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46 changes: 36 additions & 10 deletions spec/zoneddatetime.html
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Original file line number Diff line number Diff line change
Expand Up @@ -1350,20 +1350,46 @@ <h1>DifferenceZonedDateTime ( _ns1_, _ns2_, _timeZone_, _calendar_, _largestUnit
1. Repeat, while ! DurationSign(_dateDifference_.[[Years]], _dateDifference_.[[Months]], _dateDifference_.[[Weeks]], _dateDifference_.[[Days]], 0, 0, 0, 0, 0, 0) = 1 and _intermediateNs_ &gt; _ns2_,
1. Set _dateDifference_ to ? AddDuration(_dateDifference_.[[Years]], _dateDifference_.[[Months]], _dateDifference_.[[Weeks]], _dateDifference_.[[Days]], 0, 0, 0, 0, 0, 0, 0, 0, 0, −1, 0, 0, 0, 0, 0, 0, _startDateTime_).
1. Set _intermediateNs_ to ? AddZonedDateTime(_ns1_, _timeZone_, _calendar_, _dateDifference_.[[Years]], _dateDifference_.[[Months]], _dateDifference_.[[Weeks]], _dateDifference_.[[Days]], 0, 0, 0, 0, 0, 0, *"constrain"*).
1. Let _timeRemainderNs_ be 0.
1. Let _timeRemainderNs_ be _ns2_ − _intermediateNs_.
1. Let _intermediate_ be ? CreateTemporalZonedDateTime(_intermediateNs_, _timeZone_, _calendar_).
1. Let _result_ be ? NanosecondsToDays(_timeRemainderNs_, _intermediate_).
1. Let _timeDifference_ be ! BalanceDuration(0, 0, 0, 0, 0, 0, _result_.[[Nanoseconds]], *"hours"*).
1. Let _dateDifference_ be ? AddDuration(_dateDifference_.[[Years]], _dateDifference_.[[Months]], _dateDifference_.[[Weeks]], _dateDifference_.[[Days]], 0, 0, 0, 0, 0, 0, 0, 0, 0, _result_.[[Days]], 0, 0, 0, 0, 0, 0, _startDateTime_).
1. Return the new Record { [[Years]]: _dateDifference_.[[Years]], [[Months]]: _dateDifference_.[[Months]], [[Weeks]]: _dateDifference_.[[Weeks]], [[Days]]: _dateDifference_.[[Days]], [[Hours]]: _timeDifference_.[[Hours]], [[Minutes]]: _timeDifference_.[[Minutes]], [[Seconds]]: _timeDifference_.[[Seconds]], [[Milliseconds]]: _timeDifference_.[[Milliseconds]], [[Microseconds]]: _timeDifference_.[[Microseconds]], [[Nanoseconds]]: _timeDifference_.[[Nanoseconds]] }.
</emu-alg>
</emu-clause>

<emu-clause id="sec-temporal-nanosecondstodays" aoid="NanosecondsToDays">
<h1>NanosecondsToDays ( _nanoseconds_, _relativeTo_ )</h1>
<p>
The abstract operation NanosecondsToDays takes a number of nanoseconds relative to a Temporal.ZonedDateTime _relativeTo_, and converts it into a number of days and remainder of nanoseconds, taking into account any offset changes in the time zone of _relativeTo_.
</p>
<emu-alg>
1. Let _sign_ be ! Sign(_nanoseconds_).
1. Let _dayLengthNs_ be 8.64 × 10<sup>13</sup><sub>ℝ</sub>.
1. If _sign_ = 0, then
1. Return the new Record { [[Days]]: 0, [[Nanoseconds]]: 0 }.
1. If _relativeTo_ does not have an [[InitializedTemporalZonedDateTime]] internal slot, then
1. Return the new Record {
[[Days]]: the integral part of _nanoseconds_ ÷ _dayLengthNs_,
[[Nanoseconds]]: _nanoseconds_ modulo _dayLengthNs_
}.
1. Let _days_ be 0.
1. Let _done_ be *false*.
1. Let _relativeNs_ be _relativeTo_.[[Nanoseconds]].
1. Repeat, while _done_ is *false*,
1. Let _oneDayFartherDuration_ be ? AddDuration(_dateDifference_.[[Years]], _dateDifference_.[[Months]], _dateDifference_.[[Weeks]], _dateDifference_.[[Days]], 0, 0, 0, 0, 0, 0, 0, 0, 0, _direction_, 0, 0, 0, 0, 0, 0, _startDateTime_).
1. Let _oneDayFartherNs_ be ? AddZonedDateTime(_ns1_, _timeZone, _calendar_, _oneDayFartherDuration_.[[Years]], _oneDayFartherDuration_.[[Months]], _oneDayFartherDuration_.[[Weeks]], _oneDayFartherDuration_.[[Days]], 0, 0, 0, 0, 0, 0, *"constrain"*).
1. Let _dayLengthNs_ be _oneDayFartherNs_ − _intermediateNs_.
1. Set _timeRemainderNs_ to _ns2_ − _intermediateNs_.
1. If (_timeRemainderNs_ − _dayLengthNs_) × _direction_ ≥ 0, then
1. Set _dateDifference_ to _oneDayFartherDuration_.
1. Set _intermediateNs_ to _oneDayFartherNs_.
1. Let _oneDayFartherNs_ be ? AddZonedDateTime(_relativeNs_, _relativeTo_.[[TimeZone]], _relativeTo_.[[Calendar]], 0, 0, 0, _sign_, 0, 0, 0, 0, 0, 0, *"constrain"*).
1. Let _dayLengthNs_ be _oneDayFartherNs_ − _relativeNs_.
1. If (_nanoseconds_ − _dayLengthNs_) × _sign_ ≥ 0, then
1. Set _nanoseconds_ to _nanoseconds_ − _dayLengthNs_.
1. Set _relativeNs_ to _oneDayFartherNs_.
1. Set _days_ to _days_ + _sign_.
1. Else,
1. Set _done_ to *true*.
1. Let _timeDifference_ be ! BalanceDuration(0, 0, 0, 0, 0, 0, _roundedTimeRemainderNs_, *"hours"*).
1. Return the new Record { [[Years]]: _dateDifference_.[[Years]], [[Months]]: _dateDifference_.[[Months]], [[Weeks]]: _dateDifference_.[[Weeks]], [[Days]]: _dateDifference_.[[Days]], [[Hours]]: _timeDifference_.[[Hours]], [[Minutes]]: _timeDifference_.[[Minutes]], [[Seconds]]: _timeDifference_.[[Seconds]], [[Milliseconds]]: _timeDifference_.[[Milliseconds]], [[Microseconds]]: _timeDifference_.[[Microseconds]], [[Nanoseconds]]: _timeDifference_.[[Nanoseconds]] }.
1. Return the new Record {
[[Days]]: _days_,
[[Nanoseconds]]: _nanoseconds_
}.
</emu-alg>
</emu-clause>
</emu-clause>
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