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Collapse grammar nonterminals that are only distinct for the purposes of disambiguation #2006

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ptomato opened this issue Jan 18, 2022 · 3 comments · May be fixed by #2767
Open

Collapse grammar nonterminals that are only distinct for the purposes of disambiguation #2006

ptomato opened this issue Jan 18, 2022 · 3 comments · May be fixed by #2767
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editorial has-consensus iso8601-grammar ISO 8061 grammar spec-text Specification text involved
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Stage "3.5"

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@ptomato
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ptomato commented Jan 18, 2022

@gibson042 pointed out that we don't need to have separate nonterminals such as TimeZoneNumericUTCOffset and TimeZoneUTCOffsetName in order to disambiguate in cases such as #1796. We can refer to things like "the first |FractionalPart|, if present", cf. https://tc39.es/ecma262/multipage/ecmascript-language-statements-and-declarations.html#sec-runtime-semantics-forloopevaluation
@ptomato ptomato added spec-text Specification text involved editorial labels Jan 18, 2022
@ptomato ptomato mentioned this issue Jan 18, 2022
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gibson042 commented May 10, 2022 •
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Related improvements are also possible with nonterminal parameterization, e.g.

       TimeZoneNumericUTCOffset :
-          TimeZoneUTCOffsetSign TimeZoneUTCOffsetHour
-          TimeZoneUTCOffsetSign TimeZoneUTCOffsetHour `:` TimeZoneUTCOffsetMinute
-          TimeZoneUTCOffsetSign TimeZoneUTCOffsetHour TimeZoneUTCOffsetMinute
-          TimeZoneUTCOffsetSign TimeZoneUTCOffsetHour `:` TimeZoneUTCOffsetMinute `:` TimeZoneUTCOffsetSecond TimeZoneUTCOffsetFraction? 
-          TimeZoneUTCOffsetSign TimeZoneUTCOffsetHour TimeZoneUTCOffsetMinute TimeZoneUTCOffsetSecond TimeZoneUTCOffsetFraction?
+          Sign HourComponents[+Extended]?
+          Sign HourComponents[~Extended]?
+
+      HourComponents[Extended] :
+          Hour
+          Hour TimeSeparator[?Extended] Minute
+          Hour TimeSeparator[?Extended] Minute TimeSeparator[?Extended] Second Fraction?
+
+      TimeSeparator[Extended] :
+          [+Extended] `:`
+          [~Extended] [empty]

@ptomato ptomato added the iso8601-grammar ISO 8061 grammar label Aug 11, 2022
@ptomato ptomato added this to the Stage "3.5" milestone Dec 8, 2022
@ptomato ptomato mentioned this issue Jul 13, 2023
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@justingrant
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Offset grammar will be different between ISO string offsets and offset time zone identifiers after the minutes PR is merged. Does that change any of the simplifications planned here?

@gibson042
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Not really; UTCOffset nonterminals are now distinct for a legitimate reason and already incorporate parameterization as appropriate. But I still think some improvements are possible with respect to e.g. |TimeHour|/|TimeMinute|/|TimeFraction|/|TimeSpec| and the Duration productions.

@ptomato ptomato self-assigned this Feb 1, 2024
ptomato added a commit that referenced this issue Feb 2, 2024
@ptomato
Editorial: Collapse nonterminals only used for disambiguation
d9d1722 
Prefer language like "the first |TemporalDecimalFraction|, if present"
rather than defining several nonterminals such as |TimeFraction|,
|DurationHoursFraction|, etc.

Closes: #2006
@ptomato ptomato linked a pull request Feb 2, 2024 that will close this issue
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Editorial: Collapse nonterminals only used for disambiguation tc39/proposal-temporal
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