ref: cdc1fad5a1a7e95a7fe7e70f06365c3c47f585b1
dir: /lib/date/date.myr/
use std use "types.use" use "zoneinfo.use" pkg date = /* useful constructors */ const utcnow : (-> instant) const now : (tz : byte[:] -> instant) const tozone : (d : instant, zone : byte[:] -> instant) const mkdate : (tm : std.time, zone : byte[:] -> instant) const localoff : (tm : std.time -> diff) const tzoff : (tzname : byte[:], tm : std.time -> diff) const isleap : (d : instant -> bool) /* date differences */ const add : (d : instant, dt : diff -> instant) const sub : (d : instant, dt : diff -> instant) const diff : (a : instant, b : instant -> diff) const duradd : (d : instant, dt : duration -> instant) const dursub : (d : instant, dt : duration -> instant) ;; const Unix2Julian = 719468 const Days400y = 365*400 + 4*25 - 3 const Days4y = 365*4 + 1 const utcnow = { -> mkdate(std.now(), "") } const now = {tz : byte[:] var tm tm = std.now() -> mkdate(tm, tz) } const tozone = {d, tz -> mkdate(d.actual, tz) } const mkdate = {tm, tz var j, y, m, d var t, e var date var off date.actual = tm /* time zones */ std.assert(tz.len <= date._tzbuf.len, "time zone name too long\n") off =_zoneinfo.findtzoff(tz, tm) date.tzoff = off std.slcp(date._tzbuf[:tz.len], tz) date.tzname = date._tzbuf[:tz.len] tm += off castto(std.time) /* break up time */ t = tm % (24*60*60*1_000_000) /* time */ e = tm / (24*60*60*1_000_000) /* epoch days */ /* microseconds, seconds, minutes, hours */ date.us = (t % 1_000_000) castto(int) t /= 1_000_000 date.s = (t % 60) castto(int) t /= 60 date.m = (t % 60) castto(int) t /= 60 date.h = t castto(int) /* weekday */ date.wday = ((e + 4) % 7) castto(int) /* the world started on Thursday */ /* split up year, month, day. Implemented according to "Algorithm 199, conversions between calendar date and Julian day number", Robert G. Tantzen, Air Force Missile Development Center, Holloman AFB, New Mex. Lots of magic. Yer a wizard, 'arry. */ j = e + Unix2Julian y = (4 * j - 1) / Days400y j = 4 * j - 1 - Days400y * y d = j / 4 j = (4 * d + 3) / Days4y d = 4 * d + 3 - Days4y * j d = (d + 4) / 4 ; m = (5 * d - 3) / 153 d = 5 * d - 3 - 153 * m d = (d + 5) / 5 y = 100 * y + j if m < 10 m += 3 else m -= 9 y++ ;; date.year = y castto(int) date.mon = m castto(int) date.day = (d + 1) castto(int) -> date } const localoff = {tm -> _zoneinfo.findtzoff("local", tm) } const tzoff = {tz, tm -> _zoneinfo.findtzoff(tz, tm) } const isleap = {d -> d.year % 4 == 0 && (d.year % 100 != 0 || d.year % 400 == 0) } const add = {d, dt -> mkdate(d.actual + (dt castto(std.time)), d.tzname) } const sub = {d, dt -> mkdate(d.actual - (dt castto(std.time)), d.tzname) } const diff = {a, b -> (b.actual - a.actual) castto(diff) }