COPYING: Update year

[etc/awesome.git] / luatz / timetable.lua

diff --git a/luatz/timetable.lua b/luatz/timetable.lua
index 3b3b2ed89c1205a6abf4099d7f25f6a2f8802a65..1a304e21ef58f468b477b32c1667f2cee42cb371 100644 (file)
--- a/luatz/timetable.lua
+++ b/luatz/timetable.lua
@@ -1,212 +1,254 @@
+local strftime = require "luatz.strftime".strftime

 local strformat = string.format
 local floor = math.floor
 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
 
 
 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
 -- 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
 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
 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
 
 end
 

-local function month_length ( m , y )
+local function month_length(m, y)

        if m == 2 then
        if m == 2 then

-               return is_leap ( y ) and 29 or 28
+               return is_leap(y) and 29 or 28

        else
        else

-               return mon_lengths [ m ]
+               return mon_lengths[m]

        end
 end
 
        end
 end
 

-local function leap_years_since ( year )
-       return idiv ( year , 4 ) - idiv ( year , 100 ) + idiv ( year , 400 )
+local function leap_years_since(year)
+       return idiv(year, 4) - idiv(year, 100) + idiv(year, 400)

 end
 
 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
+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
 
                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
 
 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
        if units >= base then

-               tens  = tens + idiv ( units , base )
+               tens  = tens + idiv(units, base)

                units = units % base
        elseif units < 0 then
                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
        end

-       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
+       return tens, units

 end
 
 -- Modify parameters so they all fit within the "normal" range
 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
        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
        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
                day = day - i
                month = month + 1

-               if month > 12 then
-                       month = 1
+               if month >= 12 then
+                       month = 0

                        year = year + 1
                end
        end
 
                        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
 
 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
                -- 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)
 
        return days_since_epoch * (60*60*24)

-               + hour  * (60*60)
-               + min   * 60
+               + hour * (60*60)
+               + min  * 60

                + sec
 end
 
 
                + sec
 end
 
 

-local timetable_methods = { }
+local timetable_methods = {}

 
 

-function timetable_methods:normalise ( )
-       local year , month , day
-       year , month , day , self.hour , self.min , self.sec = normalise ( unpack_tm ( self ) )
+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.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
 
 
        return self
 end
 timetable_methods.normalize = timetable_methods.normalise -- American English
 

-function timetable_methods:timestamp ( )
-       return timestamp ( unpack_tm ( self ) )
+function timetable_methods:timestamp()
+       return timestamp(self:unpack())

 end
 
 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 ) )
+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
 
 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 = {
        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
 
 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 {
        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
 
        }
 end
 

-function timetable_methods:clone ( )
-       return new_timetable ( unpack_tm ( self ) )
+function timetable_methods:clone()
+       return new_timetable(self:unpack())

 end
 
 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 {
 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;

 }
 }