`orca.tz`

Time zones, from the system's TZif files (RFC 8536).

var ny = Zone.load("America/New_York")
var offset = ny.offset_at(utc(2024, 7, 1))   # -14400, EDT

A TZif file of version 2 or later lists the zone's transitions as 64-bit times, each with the UTC offset in force from then on, and ends with a POSIX TZ string (EST5EDT,M3.2.0,M11.1.0) that gives the rule after the last transition. "Slim" files, which some systems install, list transitions only up to when the current rule began and rely on that string for every year since; "fat" ones list them to 2037. Zone reads both, and a version 1 file, which has only 32-bit times and no rule. Leap-second records are skipped: orca's times are POSIX times, as the right/ zones' aren't.

Files are read from ORCA_ZONEINFO, default /usr/share/zoneinfo. UTC needs no file.

Structs

`PosixTZ`

struct PosixTZ

A POSIX TZ rule: a standard offset, and maybe a daylight one with the rules for when it starts and ends.

Implements Copyable, Movable

Fields: std: Int: Seconds east of UTC.; dst: Int; has_dst: Bool; start: _Rule; end: _Rule

`init`

def __init__(out self, std: Int)

`parse`

def parse(s: String) -> Self

Reads std offset [dst [offset] [,start[/time],end[/time]]]. A daylight zone without rules gets the US ones, as glibc does.

`offset_at`

def offset_at(self, t: Int64) -> Int

`last_change`

def last_change(self, t: Int64) -> Int64

The latest change at or before t; Int64.MIN if none.

`Zone`

struct Zone

A time zone: its transitions, and the rule after the last one.

Implements Copyable, Movable

Fields: name: String; times: List[Int64]: Transition times, ascending.; offsets: List[Int]: The offset (seconds east of UTC) from each transition on.; first: Int: The offset before the first transition.; footer: Optional[PosixTZ]

`init`

def __init__(out self, name: String, offset: Int = Int(0))

A fixed offset, such as UTC.

`load`

def load(name: String) -> Self

The zone name, such as America/New_York, from the TZif file under ORCA_ZONEINFO (default /usr/share/zoneinfo).

`parse`

def parse(name: String, data: List[UInt8]) -> Self

Reads a TZif file.

`offset_at`

def offset_at(self, t: Int64) -> Int

The offset in seconds east of UTC at t.

`last_change`

def last_change(self, t: Int64) -> Int64

The latest transition at or before t; Int64.MIN if none.

`to_local`

def to_local(self, t: Int64) -> Int64

t read on this zone's wall clock.