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A Raku module containing data (as well as some support routines) based on IANA's TZ database. This module is not normally expected to be consumed on its own — it is designed to be as light weight as possible. Its intended use is for authors of various time-related tools.
Current IANA database version: 2022f
When updating this module, ensure all modules that depend on it are recompiled.
The first four subs are exported by default. All methods work on times with integral seconds. It is currently left to the end user to handle any fractional seconds.
sub timezones-as-set(:$standard = True, :$aliases = False, :$historical = False --> Set) .keys). By default it does not include various aliases (generally, but not always, spell changes in identifiers like Kiev→Kyiv). Historical zones are those that go back to the early part of the 20th century and farther back and rarely if ever needed. They are currently NYI.timezone-data (Str() $olson-id --> State) Etc/GMT is provided as a fallback. See below for details on the State class.sub calendar-from-posix (int64 $time, State $tz-data, :$leapadjusted = False --> Time) time_t stamp, provides the associated date/time (in a Time structure) for the timezone. Passing :leapadjusted indicates that leapseconds are already included in the timestamp (this is not POSIX standard, but may be preferable for some applications).sub posix-from-calendar (Time $tm-struct, State $tz-data, :$leapadjust = False --> int64) Time object (only ymdHMS values are used), provides the associated POSIX time_t timestamp and GMT offsets. Pay close attention to the dst attribute: use 1 or 0 if you know the time to be in daylight savings time or not, use -1 if you are not sure. Passing :leapadjust will include leap seconds in the timestamp (not POSIX standard, but may be preferable for some applications). The final two methods are available by providing the tz-shift option in the use statement. They will return a time in the same format provided.
sub next-tz-shift (Time|int64 $time, State $tz-data, :$leapadjust = False --> Time|int64) Time object (only ymdHMS values are used) or a POSIX time_t timestamp, indicates when the next shift in GMT offsets will occur. Generally, that's when daylight savings time will start or end, but it may also be when an area shifts timezones entirely (e.g. when Russia makes adjustments to its timezones at various periods throughout the year). Passing :leapadjust will include leap seconds in the timestamp (not POSIX standard, but may be preferable for some applications). This routine returns values in the same format provided.sub prev-tz-shift (Time|int64 $time, State $tz-data, :$leapadjust = False --> Time|int64) next-tz-shift but in reverse. Finds the most recent previous shift in timezone data.Both next-tz-shift and prev-tz-shift can potentially return a special extremely small or large integer value.
Such values are intended to represent an “infinite” past or future, but may be different given compiler/architecture/system.
Timezones::ZoneInfo will detect your system's maximum and minimum time values upon installation and those
values can be obtained using the constants max-posix-time and min-posix-time (exported with :constants in the use statement).
On my system, for instance, these are 263 - 1 - 27, and 0 - 263, where 27 is the current number of leapseconds.
A Raku version of the POSIX tm struct (with BSD/GNU extension). Attributes include
.year (-∞..∞, years since 1900, 1910 = 10).month (0..11, months since January).day (1..31).hour (0..23).minute (0..59).second (0..61, values of 60-61 for leapseconds).weekday (0..6, days since Sunday; Monday = 1).yearday (0..365, day index in year, 0 = January 1st).dst (-1..1; 0 standard time, 1 summer time, -1 unknown/automatic).gmt-offset (-∞..∞, offset of GMT, positive = east of GMT).tz-abbr (three or four letter abbreviation, non-unique)The infinite ranged elements aren't actually that as they're stored as int32.
A Raku version of tz's state struct. It will be made more easily introspectable in the future. For now, these are the attributes:
* .leapcnt (number of leap seconds)
* .lsis (array of LeapSecInfo, describing when they occur and by how much)
* .timecnt (number of moments when time shifts)
* .ats (array of moments, as time_t when time shifts)
* .typecnt (number of transition types)
* .ttis (array of TransTimeInfo, providing meta data for time shifts)
* .types (array of indexes pointing to meta data for time shifts)
* .chars (c-style string data indicating timezone abbreviations)
* .charcnt (length of chars)
* .name (the Olson ID for the zone)
The data comes from IANA's tz database.
GMT is now the standard form for Etc/GMT (both will still work)next-tz-rule-change and prev-tz-rule-change)resources and into tools (they aren't needed at runtime)timezones-as-setThe tz database and the code in it is public domain. Therefore, the author of this module (Matthew Stephen Stuckwisch) would find it unconscionable to release this module under any license, even for his own additions. Consequently, this module is similarly expressly released into the public domain. For jurisdictions where that is not possible, this module may be considered © 2021–2022 and licensed under CC0 v1.0 (see accompanying license file).