Day and month name constants are defined in numerous places. This
pulls them together into a single place and eliminates the
duplication. It also ensures they are `constexpr`.
This also moves the open_file helper to the utility file. It's currently
a lambda redefined in each TZDB/Unicode generator. It used to display
the missing command line flag and other info local to each generator.
After switching to LibMain, it just returns a generic error message, and
is duplicated several times.
Added the call to generate_available_values(), then realized it is the
exact same as the existing, manually written implementation. So let's
use the new utility.
This just splits up the method to find the active DST rule for specified
time and time zone. This is to allow re-using the now split-off function
in upcoming commits.
For example, today, America/New_York has the format string "E%sT" and
uses US DST rules. Those rules indicate the %s should be replaced by a
"D" in daylight time and "S" in standard time.
Each ZONE entry contains a RULES segment with one of the following:
* A DST rule name, which links the ZONE to a RULE entry holding the
DST rules to apply.
* A static offset to be applied to the STDOFF offset. This implicitly
means that the time zone is in DST during that time frame.
* A "-" string, meaning no offset is applied to the STDOFF offset, and
the time zone is in standard time during that time frame.
This is a rather naive implementation, but serves as a first pass at
determining the GMT offset for a time zone at a particular point in
time. This implementation ignores DST (because we are not parsing any
RULE entries yet), and ignores any offset patterns of the form "Mon>4"
or "lastSun".
For example, generate "Etc/GMT+12" as "Etc_GMT_Ahead_12" (instead of as
"Etc_GMT_P12"). A little clearer what the name means without having to
know off-hand what "P" was representing.
When compiled using clang, an ambiguity error is detected between
`class AK::Time` aliased to `::Time` and the `struct ::Time` provided
in `GenerateTimeZoneData.cpp`. Solve this by moving most of the code in
an anonymous namespace.
The IANA Time Zone Database contains data needed, at least, for various
JavaScript objects. This adds plumbing for a parser and code generator
for this data. The generated data will be made available by LibTimeZone,
much like how UCD and CLDR data is available through LibUnicode.
