This is required for Temporal.Duration.prototype.round(). Subsequently,
this now returns ThrowCompletionOr<Optional<String>>, which brings the
signature in line with that of to_smallest_temporal_unit().
Much nicer! :^)
It's not the `to_uint<u8>()` call that would fail, if we have a value
for these productions they will always be valid numbers. We do need to
provide a fallback for when that's not the case and any of them is
undefined, i.e. an empty Optional.
This is the start of a parser for the ISO 8601 grammar used in the
Temporal spec:
https://tc39.es/proposal-temporal/#sec-temporal-iso8601grammar
We will, on purpose, not use a generic ISO 8601 parser from AK or
similar for two reasons:
- Many AOs make specific assumptions about which productions exist and
access them directly, even when they're part of a larger production.
- The spec says "The grammar deviates from the standard given in ISO
8601 in the following ways:" and then lists 17 of such deviations.
Making that work with a general purpose parser is not worth it.
The public API is not being used anywhere yet, but will be in the next
couple of commits. Likewise, the Production enum will be populated with
all the productions accessed directly (e.g. TemporalDateString).
Many thanks to Ali for showing me how to improve my initial approach
full of macros with a nice RAII helper - it's much nicer :^)
Co-Authored-By: Ali Mohammad Pur <mpfard@serenityos.org>
I changed this in 6ef1a27 to "match the spec", but the spec calls it
`match exactly` and `match minutes` - so what we had before was correct
and the change made no sense whatsoever.
Always throws at the moment, because parse_temporal_month_day_string()
is basically a stub, and parse_iso_date_time() isn't functional either.
The spec issue has been resolved though, so I figured we might as well
get one small step further :^)
With one caveat: in the PreparePartialTemporalFields AO I made a change
to fix a spec issue that would require the input object to always have a
month or monthCode property.
This is tracked in https://github.com/tc39/proposal-temporal/issues/1910
and may get accepted as-is, in which case we simply need to remove the
NOTE comment.
Unlike the spec we chose BigInt for the input and output types here as
it was being used with ℝ(ns), ns being of type BigInt, in one place and
a conversion to double would not be safe.
Since in many places we'll have double input values, let's add a double
overload of this function to avoid awkward conversions and expensive
allocations.
