src/timetable: Multiplication is left associative, add brackets so that constants...

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

diff --git a/src/timetable.lua b/src/timetable.lua
index c71c59bc25d737ebc27c60b0586b719dd1d25c8f..bacc58cbfe136d46cb8448915987d94d69d5ca6e 100644 (file)
--- a/src/timetable.lua
+++ b/src/timetable.lua
@@ -1,3 +1,4 @@
+local strformat = string.format
 local floor = math.floor
 local function idiv ( n , d )
        return floor ( n / d )
@@ -27,9 +28,13 @@ local function month_length ( m , y )
        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 + idiv ( year , 4 ) - idiv ( year , 100 ) + idiv ( year , 400 ) )
+               - 1 + year + leap_years_since ( year ) )
                % 7 + 1
 end
 local doomsday_cache = setmetatable ( { } , {
@@ -98,12 +103,16 @@ local function normalise ( year , month , day , hour , min , sec )
        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 )
-       return 60*60*24*(
-                       year * year_length ( year )
-                       + month * month_length ( month , year )
-                       + day
-               )
+       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
@@ -143,6 +152,9 @@ local 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 ;
 }
@@ -162,12 +174,17 @@ local function new_timetable ( year , month , day , hour , min , sec )
        }
 end
 
+local function new_from_timestamp ( ts )
+       return new_timetable ( 1970 , 1 , 1 , 0 , 0 , ts )
+end
+
 return {
        doomsday  = doomsday ;
        normalise = normalise ;
        timestamp = timestamp ;
 
        new = new_timetable ;
+       new_from_timestamp = new_from_timestamp ;
        cast = cast_timetable ;
        timetable_mt = timetable_mt ;
 }