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Editorial: Define IsBuiltinCalendar in terms of AvailableCalendars
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AvailableCalendars is an abstract operation defined in the
Intl.Enumeration proposal. Sharing AvailableCalendars between ECMA-262 and
ECMA-402 should allow us to stipulate that if an implementation supports
any calendar for formatting in Intl.DateTimeFormat, it must support it
for Temporal as well.

The operation in the ECMA-402 part may change when it is resolved at some
point whether AvailableCalendars should return only canonicalized names or
also names like `islamicc` (instead of the canonical `islamic-civil`):
tc39/proposal-intl-enumeration#37

Closes: #541
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@ptomato
ptomato committed Apr 26, 2022
1 parent 8b8a9c3 commit 9fc3031
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81 changes: 64 additions & 17 deletions spec/calendar.html
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Expand Up @@ -5,36 +5,83 @@
<h1>Temporal.Calendar Objects</h1>
<p>A Temporal.Calendar object is an Object representing a calendar.</p>

<emu-clause id="sec-calendar-types">
<h1>Calendar Types</h1>

<emu-note type="editor">
<p>
This section shares some text with the <a href="https://tc39.es/proposal-intl-enumeration/">Intl.Enumeration proposal</a>.
</p>
</emu-note>

<p>
At a minimum, ECMAScript implementations must support a built-in calendar named *"iso8601"*, representing the ISO 8601 calendar.
In addition, implementations may support any number of other built-in calendars.
</p>
<p>
ECMAScript implementations identify built-in calendars using a <dfn variants="calendar types">calendar type</dfn> as defined by <a href="https://unicode.org/reports/tr35/tr35-dates.html#Calendar_Elements">Unicode Technical Standard #35, Part 4, Section 2</a>.
Their canonical form is a string containing all lower case letters with zero or more hyphens.
</p>
<p>
<emu-xref href="#sec-temporal-calendar-constructor">The `Temporal.Calendar` constructor</emu-xref>, when called with the name of a built-in calendar as the argument, will return a valid `Temporal.Calendar` object.
When called with any other string, it will throw a *RangeError* exception.
</p>

<emu-clause id="sec-temporal-isbuiltincalendar" type="abstract operation">
<h1>
IsBuiltinCalendar (
_id_: a String,
): a Boolean
</h1>
<dl class="header">
<dt>description</dt>
<dd>The returned value is *true* if _id_ is a calendar type denoting a built-in calendar, and *false* otherwise.</dd>
</dl>
<emu-alg>
1. Let _calendars_ be AvailableCalendars().
1. If _calendars_ contains _id_, return *true*.
1. Return *false*.
</emu-alg>
</emu-clause>

<emu-clause id="sec-temporal-availablecalendars" type="abstract operation">
<h1>
AvailableCalendars (
): a List of Strings
</h1>
<dl class="header">
<dt>description</dt>
<dd>The returned List contains a single calendar type, *"iso8601"*.</dd>
</dl>

<p>
An ECMAScript implementation that includes the ECMA-402 Internationalization API must implement the AvailableCalendars abstract operation as specified in the ECMA-402 specification.
If an ECMAScript implementation does not include the ECMA-402 API the following specification of the AvailableCalendars abstract operation is used.
</p>
<emu-alg>
1. Return « *"iso8601"* ».
</emu-alg>
</emu-clause>
</emu-clause>

<emu-clause id="sec-temporal-calendar-abstract-ops">
<h1>Abstract Operations for Temporal.Calendar Objects</h1>

<emu-clause id="sec-temporal-createtemporalcalendar" aoid="CreateTemporalCalendar">
<h1>CreateTemporalCalendar ( _identifier_ [ , _newTarget_ ] )</h1>
<emu-alg>
1. Assert: ! IsBuiltinCalendar(_identifier_) is *true*.
1. Assert: IsBuiltinCalendar(_identifier_) is *true*.
1. If _newTarget_ is not provided, set _newTarget_ to %Temporal.Calendar%.
1. Let _object_ be ? OrdinaryCreateFromConstructor(_newTarget_, *"%Temporal.Calendar.prototype%"*, « [[InitializedTemporalCalendar]], [[Identifier]] »).
1. Set _object_.[[Identifier]] to _identifier_.
1. Return _object_.
</emu-alg>
</emu-clause>

<emu-clause id="sec-temporal-isbuiltincalendar" aoid="IsBuiltinCalendar">
<h1>IsBuiltinCalendar ( _id_ )</h1>
<p>
An ECMAScript implementation that includes the ECMA-402 Internationalization API must implement the *IsBuiltinCalendar* abstract operation as specified in the ECMA-402 specification.
If an ECMAScript implementation does not include the ECMA-402 API the following specification of the *IsBuiltinCalendar* abstract operation is used.
</p>
<emu-alg>
1. If _id_ is not *"iso8601"*, return *false*.
1. Return *true*.
</emu-alg>
</emu-clause>

<emu-clause id="sec-temporal-getbuiltincalendar" aoid="GetBuiltinCalendar">
<h1>GetBuiltinCalendar ( _id_ )</h1>
<emu-alg>
1. If ! IsBuiltinCalendar(_id_) is *false*, throw a *RangeError* exception.
1. If IsBuiltinCalendar(_id_) is *false*, throw a *RangeError* exception.
1. Return ! CreateTemporalCalendar(_id_).
</emu-alg>
</emu-clause>
Expand Down Expand Up @@ -249,9 +296,9 @@ <h1>ToTemporalCalendar ( _temporalCalendarLike_ )</h1>
1. Set _temporalCalendarLike_ to ? Get(_temporalCalendarLike_, *"calendar"*).
1. If Type(_temporalCalendarLike_) is Object and ? HasProperty(_temporalCalendarLike_, *"calendar"*) is *false*, return _temporalCalendarLike_.
1. Let _identifier_ be ? ToString(_temporalCalendarLike_).
1. If ! IsBuiltinCalendar(_identifier_) is *false*, then
1. If IsBuiltinCalendar(_identifier_) is *false*, then
1. Set _identifier_ to ? ParseTemporalCalendarString(_identifier_).
1. If ! IsBuiltinCalendar(_identifier_) is *false*, throw a *RangeError* exception.
1. If IsBuiltinCalendar(_identifier_) is *false*, throw a *RangeError* exception.
1. Return ! CreateTemporalCalendar(_identifier_).
</emu-alg>
</emu-clause>
Expand Down Expand Up @@ -671,7 +718,7 @@ <h1>Temporal.Calendar ( _id_ )</h1>
1. If NewTarget is *undefined*, then
1. Throw a *TypeError* exception.
1. Set _id_ to ? ToString(_id_).
1. If ! IsBuiltinCalendar(_id_) is *false*, then
1. If IsBuiltinCalendar(_id_) is *false*, then
1. Throw a *RangeError* exception.
1. Return ? CreateTemporalCalendar(_id_, NewTarget).
</emu-alg>
Expand Down
36 changes: 26 additions & 10 deletions spec/intl.html
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Expand Up @@ -84,6 +84,32 @@ <h1><a href="https://tc39.es/ecma402/#sec-defaulttimezone">DefaultTimeZone</a> (
The DefaultTimeZone abstract operation returns a String value representing the valid (<emu-xref href="#sec-isvalidtimezonename"></emu-xref>) and canonicalized (<emu-xref href="#sec-canonicalizetimezonename"></emu-xref>) time zone name for the host environment's current time zone.
</p>
</emu-clause>

<ins class="block">
<emu-clause id="sup-calendar-types">
<h1>Calendar Types</h1>

<p>
The ECMAScript 2022 Internationalization API Specification identifies calendars using a <em>calendar type</em> as defined by <a href="https://unicode.org/reports/tr35/tr35-dates.html#Calendar_Elements">Unicode Technical Standard #35, Part 4, Section 2</a>. Their canonical form is a string containing all lower case letters with zero or more hyphens.
</p>

<emu-clause id="sup-availablecalendars" type="abstract operation">
<h1>
AvailableCalendars (
): a List of Strings
</h1>
<dl class="header">
<dt>description</dt>
<dd>The returned List is ordered as if an Array of the same values had been sorted using %Array.prototype.sort% using *undefined* as _comparefn_, and contains unique calendar types identifying the calendars for which the implementation provides the functionality of Intl.DateTimeFormat objects.
The list must include *"iso8601"*.</dd>
<dt>redefinition</dt>
<dd>true</dd>
</dl>

<p>This definition supersedes the definition provided in <emu-xref href="#sec-temporal-availablecalendars"></emu-xref>.</p>
</emu-clause>
</emu-clause>
</ins>
</emu-clause>

<emu-clause id="sec-abstract-operations">
Expand Down Expand Up @@ -1301,16 +1327,6 @@ <h1><a href="https://tc39.es/ecma402/#locale-sensitive-functions">Locale Sensiti
<emu-clause id="sup-temporal-calendar-abstract-ops">
<h1>Abstract Operations for Temporal.Calendar Objects</h1>

<emu-clause id="sup-temporal-isbuiltincalendar" aoid="IsBuiltinCalendar402">
<h1>IsBuiltinCalendar ( _id_ )</h1>
<p>This definition supersedes the definition provided in <emu-xref href="#sec-temporal-isbuiltincalendar"></emu-xref>.</p>
<emu-alg>
1. Let _builtinCalendars_ be a List of Unicode BCP 47 calendar identifiers identifying the calendars for which the implementation provides the functionality of the constructed `Temporal.Calendar` objects. The list must include *"iso8601"*. The ordering is irrelevant.
1. If _builtinCalendars_ contains _id_, return *true*.
1. Return *false*.
</emu-alg>
</emu-clause>

<emu-clause id="sec-temporal-calendarera" aoid="CalendarEra">
<h1>CalendarEra ( _calendar_, _dateLike_ )</h1>
<p>
Expand Down

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