X-Git-Url: https://git.madduck.net/etc/awesome.git/blobdiff_plain/e5c87b4489b0881b7b9903733478f0d11ac96ab7..6ba1e0b1252c68552bf5aa841a95f63eb04b7050:/luatz/timetable.lua?ds=sidebyside diff --git a/luatz/timetable.lua b/luatz/timetable.lua index 3b3b2ed..879f0a2 100644 --- a/luatz/timetable.lua +++ b/luatz/timetable.lua @@ -1,3 +1,4 @@ +local strftime = require "luatz.strftime".strftime local strformat = string.format local floor = math.floor local function idiv ( n , d ) @@ -11,9 +12,17 @@ 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 ) - return (y % 4) == 0 and (y % 100) ~= 0 or (y % 400) == 0 + if (y % 4) ~= 0 then + return false + elseif (y % 100) ~= 0 then + return true + else + return (y % 400) == 0 + end end local function year_length ( y ) @@ -32,19 +41,6 @@ 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 -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 @@ -53,11 +49,14 @@ local function day_of_year ( day , month , year ) 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 carry ( tens , units , base ) if units >= base then tens = tens + idiv ( units , base ) units = units % base @@ -68,22 +67,13 @@ local function increment ( tens , units , base ) return tens , units end -local function unpack_tm ( tm ) - return assert ( tm.year , "year required" ) , - assert ( tm.month , "month required" ) , - assert ( tm.day , "day required" ) , - tm.hour or 12 , - tm.min or 0 , - tm.sec or 0 , - tm.yday , - tm.wday -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 ) + -- Propagate out of range values up + -- e.g. if `min` is 70, `hour` increments by 1 and `min` becomes 10 + min , sec = carry ( min , sec , 60 ) -- TODO: consider leap seconds? + hour , min = carry ( hour , min , 60 ) + day , hour = carry ( day , hour , 24 ) while day <= 0 do year = year - 1 @@ -92,7 +82,7 @@ local function normalise ( year , month , day , hour , min , sec ) -- Lua months start from 1, need -1 and +1 around this increment month = month - 1 - year , month = increment ( year , month , 12 ) + year , month = carry ( year , month , 12 ) month = month + 1 -- This could potentially be slow if `day` is very large @@ -128,31 +118,42 @@ 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 ( unpack_tm ( self ) ) + 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 ( unpack_tm ( self ) ) + return timestamp ( self:unpack ( ) ) end function timetable_methods:rfc_3339 ( ) - -- %06.4g gives 3 (=6-4+1) digits after decimal - return strformat ( "%04u-%02u-%02uT%02u:%02u:%06.4g" , unpack_tm ( self ) ) + -- %06.3f gives 3 (=6-3) digits after decimal + return strformat ( "%04u-%02u-%02uT%02u:%02u:%06.3f" , self:unpack ( ) ) +end + +function timetable_methods:strftime ( format_string ) + return strftime ( format_string , self ) end local timetable_mt @@ -168,10 +169,13 @@ timetable_mt = { __index = timetable_methods ; __tostring = timetable_methods.rfc_3339 ; __eq = function ( a , b ) - return coerce_arg ( a ) == coerce_arg ( b ) + return a:timestamp ( ) == b:timestamp ( ) end ; __lt = function ( a , b ) - return coerce_arg ( a ) < coerce_arg ( b ) + return a:timestamp ( ) < b:timestamp ( ) + end ; + __sub = function ( a , b ) + return coerce_arg ( a ) - coerce_arg ( b ) end ; } @@ -193,15 +197,20 @@ local function new_timetable ( year , month , day , hour , min , sec , yday , wd end function timetable_methods:clone ( ) - return new_timetable ( unpack_tm ( self ) ) + 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 ) end return { - doomsday = doomsday ; + is_leap = is_leap ; + day_of_year = day_of_year ; + day_of_week = day_of_week ; normalise = normalise ; timestamp = timestamp ;