All patches and comments are welcome. Please squash your changes to logical
commits before using git-format-patch and git-send-email to
patches@git.madduck.net.
If you'd read over the Git project's submission guidelines and adhered to them,
I'd be especially grateful.
1 local strformat = string.format
2 local floor = math.floor
3 local function idiv ( n , d )
8 local mon_lengths = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
9 -- Number of days in year until start of month; not corrected for leap years
10 local months_to_days_cumulative = { 0 }
12 months_to_days_cumulative [ i ] = months_to_days_cumulative [ i-1 ] + mon_lengths [ i-1 ]
15 local function is_leap ( y )
16 return (y % 4) == 0 and (y % 100) ~= 0 or (y % 400) == 0
19 local function year_length ( y )
20 return is_leap ( y ) and 366 or 365
23 local function month_length ( m , y )
25 return is_leap ( y ) and 29 or 28
27 return mon_lengths [ m ]
31 local function leap_years_since ( year )
32 return idiv ( year , 4 ) - idiv ( year , 100 ) + idiv ( year , 400 )
35 local function doomsday ( year )
37 - 1 + year + leap_years_since ( year ) )
40 local doomsday_cache = setmetatable ( { } , {
41 __index = function ( cache , year )
42 local d = doomsday ( year )
48 local function day_of_year ( day , month , year )
49 local yday = months_to_days_cumulative [ month ]
50 if month > 2 and is_leap ( year ) then
56 local function day_of_week ( yday , year )
57 return ( yday - doomsday_cache [ year ] - 1 ) % 7 + 1
60 local function increment ( tens , units , base )
62 tens = tens + idiv ( units , base )
65 tens = tens - 1 + idiv ( -units , base )
66 units = base - ( -units % base )
71 -- Modify parameters so they all fit within the "normal" range
72 local function normalise ( year , month , day , hour , min , sec )
73 min , sec = increment ( min , sec , 60 ) -- TODO: consider leap seconds?
74 hour , min = increment ( hour , min , 60 )
75 day , hour = increment ( day , hour , 24 )
79 day = day + year_length ( year )
82 -- Lua months start from 1, need -1 and +1 around this increment
84 year , month = increment ( year , month , 12 )
87 -- This could potentially be slow if `day` is very large
89 local i = month_length ( month , year )
90 if day <= i then break end
99 return year , month , day , hour , min , sec
102 local leap_years_since_1970 = leap_years_since ( 1970 )
103 local function timestamp ( year , month , day , hour , min , sec )
104 year , month , day , hour , min , sec = normalise ( year , month , day , hour , min , sec )
106 local days_since_epoch = day_of_year ( day , month , year )
107 + 365 * ( year - 1970 )
108 -- Each leap year adds one day
109 + ( leap_years_since ( year - 1 ) - leap_years_since_1970 ) - 1
111 return days_since_epoch * (60*60*24)
118 local timetable_methods = { }
120 function timetable_methods:unpack ( )
121 return assert ( self.year , "year required" ) ,
122 assert ( self.month , "month required" ) ,
123 assert ( self.day , "day required" ) ,
131 function timetable_methods:normalise ( )
132 local year , month , day
133 year , month , day , self.hour , self.min , self.sec = normalise ( self:unpack ( ) )
139 local yday = day_of_year ( day , month , year )
140 local wday = day_of_week ( yday , year )
147 timetable_methods.normalize = timetable_methods.normalise -- American English
149 function timetable_methods:timestamp ( )
150 return timestamp ( self:unpack ( ) )
153 function timetable_methods:rfc_3339 ( )
154 -- %06.4g gives 3 (=6-4+1) digits after decimal
155 return strformat ( "%04u-%02u-%02uT%02u:%02u:%06.4g" , self:unpack ( ) )
160 local function coerce_arg ( t )
161 if getmetatable ( t ) == timetable_mt then
162 return t:timestamp ( )
168 __index = timetable_methods ;
169 __tostring = timetable_methods.rfc_3339 ;
170 __eq = function ( a , b )
171 return coerce_arg ( a ) == coerce_arg ( b )
173 __lt = function ( a , b )
174 return coerce_arg ( a ) < coerce_arg ( b )
178 local function cast_timetable ( tm )
179 return setmetatable ( tm , timetable_mt )
182 local function new_timetable ( year , month , day , hour , min , sec , yday , wday )
183 return cast_timetable {
195 function timetable_methods:clone ( )
196 return new_timetable ( self:unpack ( ) )
199 local function new_from_timestamp ( ts )
200 return new_timetable ( 1970 , 1 , 1 , 0 , 0 , ts )
204 doomsday = doomsday ;
205 normalise = normalise ;
206 timestamp = timestamp ;
208 new = new_timetable ;
209 new_from_timestamp = new_from_timestamp ;
210 cast = cast_timetable ;
211 timetable_mt = timetable_mt ;