--- /dev/null
+local strftime = require "luatz.strftime".strftime
+local strformat = string.format
+local floor = math.floor
+local idiv do
+ -- Try and use actual integer division when available (Lua 5.3+)
+ local idiv_loader = (loadstring or load)([[return function(n,d) return n//d end]], "idiv") -- luacheck: ignore 113
+ if idiv_loader then
+ idiv = idiv_loader()
+ else
+ idiv = function(n, d)
+ return floor(n/d)
+ end
+ end
+end
+
+
+local mon_lengths = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}
+-- Number of days in year until start of month; not corrected for leap years
+local months_to_days_cumulative = {0}
+for i = 2, 12 do
+ months_to_days_cumulative[i] = months_to_days_cumulative[i-1] + mon_lengths[i-1]
+end
+-- For Sakamoto's Algorithm (day of week)
+local sakamoto = {0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4};
+
+local function is_leap(y)
+ if (y % 4) ~= 0 then
+ return false
+ elseif (y % 100) ~= 0 then
+ return true
+ else
+ return (y % 400) == 0
+ end
+end
+
+local function month_length(m, y)
+ if m == 2 then
+ return is_leap(y) and 29 or 28
+ else
+ return mon_lengths[m]
+ end
+end
+
+local function leap_years_since(year)
+ return idiv(year, 4) - idiv(year, 100) + idiv(year, 400)
+end
+
+local function day_of_year(day, month, year)
+ local yday = months_to_days_cumulative[month]
+ if month > 2 and is_leap(year) then
+ yday = yday + 1
+ end
+ return yday + day
+end
+
+local function day_of_week(day, month, year)
+ if month < 3 then
+ year = year - 1
+ end
+ return(year + leap_years_since(year) + sakamoto[month] + day) % 7 + 1
+end
+
+local function borrow(tens, units, base)
+ local frac = tens % 1
+ units = units + frac * base
+ tens = tens - frac
+ return tens, units
+end
+
+local function carry(tens, units, base)
+ if units >= base then
+ tens = tens + idiv(units, base)
+ units = units % base
+ elseif units < 0 then
+ tens = tens + idiv(units, base)
+ units = (base + units) % base
+ end
+ return tens, units
+end
+
+-- Modify parameters so they all fit within the "normal" range
+local function normalise(year, month, day, hour, min, sec)
+ -- `month` and `day` start from 1, need -1 and +1 so it works modulo
+ month, day = month - 1, day - 1
+
+ -- Convert everything (except seconds) to an integer
+ -- by propagating fractional components down.
+ year , month = borrow(year , month, 12)
+ -- Carry from month to year first, so we get month length correct in next line around leap years
+ year , month = carry(year, month, 12)
+ month, day = borrow(month, day , month_length(floor(month + 1), year))
+ day , hour = borrow(day , hour , 24)
+ hour , min = borrow(hour , min , 60)
+ min , sec = borrow(min , sec , 60)
+
+ -- Propagate out of range values up
+ -- e.g. if `min` is 70, `hour` increments by 1 and `min` becomes 10
+ -- This has to happen for all columns after borrowing, as lower radixes may be pushed out of range
+ min , sec = carry(min , sec , 60) -- TODO: consider leap seconds?
+ hour , min = carry(hour, min , 60)
+ day , hour = carry(day , hour, 24)
+ -- Ensure `day` is not underflowed
+ -- Add a whole year of days at a time, this is later resolved by adding months
+ -- TODO[OPTIMIZE]: This could be slow if `day` is far out of range
+ while day < 0 do
+ month = month - 1
+ if month < 0 then
+ year = year - 1
+ month = 11
+ end
+ day = day + month_length(month + 1, year)
+ end
+ year, month = carry(year, month, 12)
+
+ -- TODO[OPTIMIZE]: This could potentially be slow if `day` is very large
+ while true do
+ local i = month_length(month + 1, year)
+ if day < i then break end
+ day = day - i
+ month = month + 1
+ if month >= 12 then
+ month = 0
+ year = year + 1
+ end
+ end
+
+ -- Now we can place `day` and `month` back in their normal ranges
+ -- e.g. month as 1-12 instead of 0-11
+ month, day = month + 1, day + 1
+
+ return year, month, day, hour, min, sec
+end
+
+local leap_years_since_1970 = leap_years_since(1970)
+local function timestamp(year, month, day, hour, min, sec)
+ year, month, day, hour, min, sec = normalise(year, month, day, hour, min, sec)
+
+ local days_since_epoch = day_of_year(day, month, year)
+ + 365 * (year - 1970)
+ -- Each leap year adds one day
+ + (leap_years_since(year - 1) - leap_years_since_1970) - 1
+
+ return days_since_epoch * (60*60*24)
+ + hour * (60*60)
+ + min * 60
+ + sec
+end
+
+
+local timetable_methods = {}
+
+function timetable_methods:unpack()
+ return assert(self.year , "year required"),
+ assert(self.month, "month required"),
+ assert(self.day , "day required"),
+ self.hour or 12,
+ self.min or 0,
+ self.sec or 0,
+ self.yday,
+ self.wday
+end
+
+function timetable_methods:normalise()
+ local year, month, day
+ year, month, day, self.hour, self.min, self.sec = normalise(self:unpack())
+
+ self.day = day
+ self.month = month
+ self.year = year
+ self.yday = day_of_year(day, month, year)
+ self.wday = day_of_week(day, month, year)
+
+ return self
+end
+timetable_methods.normalize = timetable_methods.normalise -- American English
+
+function timetable_methods:timestamp()
+ return timestamp(self:unpack())
+end
+
+function timetable_methods:rfc_3339()
+ local year, month, day, hour, min, fsec = self:unpack()
+ local sec, msec = borrow(fsec, 0, 1000)
+ msec = math.floor(msec)
+ return strformat("%04u-%02u-%02uT%02u:%02u:%02d.%03d", year, month, day, hour, min, sec, msec)
+end
+
+function timetable_methods:strftime(format_string)
+ return strftime(format_string, self)
+end
+
+local timetable_mt
+
+local function coerce_arg(t)
+ if getmetatable(t) == timetable_mt then
+ return t:timestamp()
+ end
+ return t
+end
+
+timetable_mt = {
+ __index = timetable_methods;
+ __tostring = timetable_methods.rfc_3339;
+ __eq = function(a, b)
+ return a:timestamp() == b:timestamp()
+ end;
+ __lt = function(a, b)
+ return a:timestamp() < b:timestamp()
+ end;
+ __sub = function(a, b)
+ return coerce_arg(a) - coerce_arg(b)
+ end;
+}
+
+local function cast_timetable(tm)
+ return setmetatable(tm, timetable_mt)
+end
+
+local function new_timetable(year, month, day, hour, min, sec, yday, wday)
+ return cast_timetable {
+ year = year;
+ month = month;
+ day = day;
+ hour = hour;
+ min = min;
+ sec = sec;
+ yday = yday;
+ wday = wday;
+ }
+end
+
+function timetable_methods:clone()
+ return new_timetable(self:unpack())
+end
+
+local function new_from_timestamp(ts)
+ if type(ts) ~= "number" then
+ error("bad argument #1 to 'new_from_timestamp' (number expected, got " .. type(ts) .. ")", 2)
+ end
+ return new_timetable(1970, 1, 1, 0, 0, ts):normalise()
+end
+
+return {
+ is_leap = is_leap;
+ day_of_year = day_of_year;
+ day_of_week = day_of_week;
+ normalise = normalise;
+ timestamp = timestamp;
+
+ new = new_timetable;
+ new_from_timestamp = new_from_timestamp;
+ cast = cast_timetable;
+ timetable_mt = timetable_mt;
+}
projects / etc / awesome.git / blobdiff