+local strftime = require "luatz.strftime".strftime
local strformat = string.format
local floor = math.floor
-local function idiv ( n , d )
- return floor ( n / d )
+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 }
+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 }
+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 ]
+ 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 )
- return (y % 4) == 0 and (y % 100) ~= 0 or (y % 400) == 0
-end
-
-local function year_length ( y )
- return is_leap ( y ) and 366 or 365
+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 )
+local function month_length(m, y)
if m == 2 then
- return is_leap ( y ) and 29 or 28
+ return is_leap(y) and 29 or 28
else
- return mon_lengths [ m ]
+ 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 doomsday ( year )
- return ( 3 -- Tuesday
- - 1 + year + leap_years_since ( year ) )
- % 7 + 1
+local function leap_years_since(year)
+ return idiv(year, 4) - idiv(year, 100) + idiv(year, 400)
end
-local doomsday_cache = setmetatable ( { } , {
- __index = function ( cache , year )
- local d = doomsday ( year )
- cache [ year ] = d
- return d
- end ;
-} )
-local function day_of_year ( day , month , year )
- local yday = months_to_days_cumulative [ month ]
- if month > 2 and is_leap ( year ) then
+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 ( yday , year )
- return ( yday - doomsday_cache [ year ] - 1 ) % 7 + 1
+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 increment ( tens , units , base )
+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 )
+ tens = tens + idiv(units, base)
units = units % base
elseif units < 0 then
- tens = tens - 1 + idiv ( -units , base )
- units = base - ( -units % base )
+ tens = tens + idiv(units, base)
+ units = (base + units) % base
end
- return tens , units
+ return tens, units
end
-- Modify parameters so they all fit within the "normal" range
-local function normalise ( year , month , day , hour , min , sec )
- min , sec = increment ( min , sec , 60 ) -- TODO: consider leap seconds?
- hour , min = increment ( hour , min , 60 )
- day , hour = increment ( day , hour , 24 )
-
- while day <= 0 do
- year = year - 1
- day = day + year_length ( year )
+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)
- -- Lua months start from 1, need -1 and +1 around this increment
- month = month - 1
- year , month = increment ( year , month , 12 )
- month = month + 1
-
- -- This could potentially be slow if `day` is very large
+ -- TODO[OPTIMIZE]: This could potentially be slow if `day` is very large
while true do
- local i = month_length ( month , year )
- if day <= i then break end
+ local i = month_length(month + 1, year)
+ if day < i then break end
day = day - i
month = month + 1
- if month > 12 then
- month = 1
+ if month >= 12 then
+ month = 0
year = year + 1
end
end
- return year , month , day , hour , min , sec
+ -- 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 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 )
+ 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
+ + (leap_years_since(year - 1) - leap_years_since_1970) - 1
return days_since_epoch * (60*60*24)
- + hour * (60*60)
- + min * 60
+ + hour * (60*60)
+ + min * 60
+ sec
end
-local timetable_methods = { }
+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 ,
+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 ( ) )
+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
-
- local yday = day_of_year ( day , month , year )
- local wday = day_of_week ( yday , year )
-
- self.yday = yday
- self.wday = wday
+ 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 ( ) )
+function timetable_methods:timestamp()
+ return timestamp(self:unpack())
end
-function timetable_methods:rfc_3339 ( )
- -- %06.3f gives 3 (=6-3) digits after decimal
- return strformat ( "%04u-%02u-%02uT%02u:%02u:%06.3f" , self:unpack ( ) )
+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 ( )
+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 coerce_arg ( a ) == coerce_arg ( b )
- end ;
- __lt = function ( a , b )
- return coerce_arg ( a ) < coerce_arg ( b )
- end ;
+ __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 )
+local function cast_timetable(tm)
+ return setmetatable(tm, timetable_mt)
end
-local function new_timetable ( year , month , day , hour , min , sec , yday , wday )
+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 ;
+ 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 ( ) )
+function timetable_methods:clone()
+ return new_timetable(self:unpack())
end
-local function new_from_timestamp ( ts )
- return new_timetable ( 1970 , 1 , 1 , 0 , 0 , ts )
+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 {
- doomsday = doomsday ;
- normalise = normalise ;
- timestamp = timestamp ;
-
- new = new_timetable ;
- new_from_timestamp = new_from_timestamp ;
- cast = cast_timetable ;
- timetable_mt = timetable_mt ;
+ 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