ref: 0d7d70e5b1a4b5c7ae618d6d04fb30848b18c08f
dir: /lib/date/date.myr/
use std use "types" use "zoneinfo" pkg date = /* useful constructors */ const utcnow : (-> instant) const now : (tz : byte[:] -> instant) const tozone : (d : instant, zone : byte[:] -> instant) const mkdate : (y : int, m : int, day : int, zone : byte[:] -> instant) const mkdatetime : (year : int, mon : int, day : int, \ h : int, m : int, s : int, zone : byte[:] -> instant) const mkinstant : (tm : std.time, zone : byte[:] -> instant) const localoff : (tm : std.time -> duration) const tzoff : (tzname : byte[:], tm : std.time -> duration) const isleap : (d : instant -> bool) /* date differences */ const add : (d : instant, dt : duration -> instant) const sub : (d : instant, dt : duration -> instant) const addperiod : (d : instant, dt : period -> instant) const subperiod : (d : instant, dt : period -> instant) const duration : (a : instant, b : instant -> duration) pkglocal const recalc : (inst : instant# -> std.time) ;; const Days400y = 365*400 + 4*25 - 3 const Days4y = 365*4 + 1 const DayUsec = (24*60*60*1_000_000) const Mdays = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31] const utcnow = { -> mkinstantoff(std.now(), "", 0) } const now = {tz : byte[:] var tm tm = std.now() -> mkinstant(tm, tz) } const tozone = {d, tz -> mkinstant(d.actual, tz) } const mkdate = {y, m, d, tz -> mkinstant(recalc(&[.year=y, .mon=m, .day=d]), tz) } const mkdatetime = {year, mon, day, h, m, s, tz var tm tm = recalc(&[.year=year, .mon=mon, .day=day, .h=h, .m=m, .s=s,]) match _zoneinfo.findtzoff(tz, tm) | `std.Some off: -> mkinstantoff(tm, tz, off) | `std.None: std.fatal("invalid timezone {}\n", tz) ;; } const mkinstant = {tm, tz match _zoneinfo.findtzoff(tz, tm) | `std.Some o: -> mkinstantoff(tm, tz, o) | `std.None: std.fatal("no zone named {}\n", tz) ;; } const mkinstantoff = {tm, tz, tzoff var j, y, m, d var t, e var inst inst.actual = tm /* time zones */ std.assert(tz.len <= inst._tzbuf.len, "time zone name too long\n") std.slcp(inst._tzbuf[:tz.len], tz) inst.tzname = inst._tzbuf[:tz.len] inst.tzoff = tzoff tm += (inst.tzoff : std.time) /* break up time */ t = tm % DayUsec /* time */ e = tm / DayUsec /* epoch day */ if t < 0 t += DayUsec e -= 1 ;; /* microseconds, seconds, minutes, hours */ inst.us = (t % 1_000_000 : int) t /= 1_000_000 inst.s = (t % 60 : int) t /= 60 inst.m = (t % 60 : int) t /= 60 inst.h = (t : int) /* weekday */ inst.wday = ((e + 4) % 7 : 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 = (tm + 2440588 * DayUsec) / DayUsec j -= 1721119 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++ ;; /* there's no year 0 */ if y <= 0 y-- ;; /* and if j negative, the day and month are also negative */ if m < 0 m += 12 ;; if d < 0 d += Mdays[m - 1] ;; inst.year = (y : int) inst.mon = (m : int) inst.day = (d : int) -> inst } const localoff = {tm -> tzoff("local", tm) } const tzoff = {tz, tm match _zoneinfo.findtzoff(tz, tm) | `std.Some dt: -> dt | `std.None: std.fatal("unable to load zoneinfo\n") ;; } const isleap = {d -> d.year % 4 == 0 && (d.year % 100 != 0 || d.year % 400 == 0) } const add = {d, dt -> mkinstantoff(d.actual + (dt : std.time), d.tzname, d.tzoff) } const sub = {d, dt -> mkinstantoff(d.actual - (dt : std.time), d.tzname, d.tzoff) } const addperiod = {inst, p match p | `Year y: inst.year += y | `Month m: inst.mon += m | `Day d: inst.day += d | `Hour h: inst.h += h | `Minute m: inst.m += m | `Second s: inst.s += s ;; -> mkinstantoff(recalc(&inst), inst.tzname, inst.tzoff) } const subperiod = {inst, p match p | `Year y: inst.year -= y | `Month m: inst.mon -= m | `Day d: inst.day -= d | `Hour h: inst.h -= h | `Minute m: inst.m -= m | `Second s: inst.s -= s ;; -> mkinstantoff(recalc(&inst), inst.tzname, inst.tzoff) } const duration = {a, b -> (b.actual - a.actual : duration) } const recalc = {inst var c, ya, j, tm var y, m, d if inst.mon > 2 m = (inst.mon - 3 : std.time) y = (inst.year : std.time) else m = (inst.mon + 9 : std.time) y = (inst.year - 1 : std.time) ;; d = (inst.day : std.time) c = y / 100 ya = y - 100 * c j = c * Days400y / 4 + \ Days4y * ya / 4 + \ (153 * m + 2)/5 + d - \ 719469 tm = j * DayUsec tm += (inst.h : std.time) * 3600*1_000_000 tm += (inst.m : std.time) * 60*1_000_000 tm += (inst.s : std.time) * 1_000_000 tm += (inst.us : std.time) -> tm }