src/timetable: Add equality metamethod

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

diff --git a/src/timetable.lua b/src/timetable.lua
index 9af79942cdd47883ebc137b2e602a022aaa8f73a..9b78576787c1585eafd80b2fccfb8ef8292a2fa9 100644 (file)
--- a/src/timetable.lua
+++ b/src/timetable.lua
@@ -63,14 +63,17 @@ local function increment ( tens , units , base )
        return tens , units
 end
 
-local function normalise ( tm )
-       local sec   = tm.sec  or 0
-       local min   = tm.min  or 0
-       local hour  = tm.hour or 12
-       local day   = assert ( tm.day   , "day required" )
-       local month = assert ( tm.month , "month required" )
-       local year  = assert ( tm.year  , "year required" )
+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
+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 )
@@ -92,23 +95,73 @@ local function normalise ( tm )
        year , month = increment ( year , month - 1 , 12 )
        month = month + 1
 
-       tm.sec   = sec
-       tm.min   = min
-       tm.hour  = hour
-       tm.day   = day
-       tm.month = month
-       tm.year  = year
+       return year , month , day , hour , min , sec
+end
+
+local function timestamp ( year , month , day , hour , min , sec )
+       return 60*60*24*(
+                       year * year_length ( year )
+                       + month * month_length ( month , year )
+                       + day
+               )
+               + hour  * (60*60)
+               + min   * 60
+               + sec
+end
+
+
+local timetable_methods = { }
+
+function timetable_methods:normalise ( )
+       local year , month , day
+       year , month , day , self.hour , self.min , self.sec = normalise ( unpack_tm ( self ) )
+
+       self.day   = day
+       self.month = month
+       self.year  = year
 
        local yday = day_of_year ( day , month , year )
        local wday = day_of_week ( yday , year )
 
-       tm.yday = yday
-       tm.wday = wday
+       self.yday = yday
+       self.wday = wday
+
+       return self
+end
+timetable_methods.normalize = timetable_methods.normalise -- American English
 
-       return tm
+function timetable_methods:timestamp ( )
+       return timestamp ( unpack_tm ( self ) )
+end
+
+local timetable_mt = {
+       __index    = timetable_methods ;
+       __eq = function ( a , b )
+               return a:timestamp() < b:timestamp()
+       end ;
+}
+
+local function cast_timetable ( tm )
+       return setmetatable ( tm , timetable_mt )
+end
+
+local function new_timetable ( year , month , day , hour , min , sec )
+       return cast_timetable {
+               year  = year ;
+               month = month ;
+               day   = day ;
+               hour  = hour ;
+               min   = min ;
+               sec   = sec ;
+       }
 end
 
 return {
        doomsday  = doomsday ;
        normalise = normalise ;
+       timestamp = timestamp ;
+
+       new = new_timetable ;
+       cast = cast_timetable ;
+       timetable_mt = timetable_mt ;
 }