X-Git-Url: https://git.madduck.net/etc/awesome.git/blobdiff_plain/88cbee758e827b9b3a1c9a6be61f1fc3d65b6575..bab202dc11e948f75e617b39024dc67f9a11691f:/src/timetable.lua

diff --git a/src/timetable.lua b/src/timetable.lua
index c71c59b..1ce701c 100644
--- 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 ;
 }