luatz/timetable: Rename `increment` to `carry`

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

diff --git a/luatz/timetable.lua b/luatz/timetable.lua
index 10af17018f90a9f14f5ef0c2ce72af9f9e367616..879f0a226fe6839b8c5424112d0945a91899063c 100644 (file)
--- a/luatz/timetable.lua
+++ b/luatz/timetable.lua
@@ -16,7 +16,13 @@ end
 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
+       if (y % 4) ~= 0 then
+               return false
+       elseif (y % 100) ~= 0 then
+               return true
+       else
+               return (y % 400) == 0
+       end
 end
 
 local function year_length ( y )
@@ -50,7 +56,7 @@ local function day_of_week ( day , month , year )
        return ( year + leap_years_since ( year ) + sakamoto[month] + day ) % 7 + 1
 end
 
-local function increment ( tens , units , base )
+local function carry ( tens , units , base )
        if units >= base then
                tens  = tens + idiv ( units , base )
                units = units % base
@@ -63,9 +69,11 @@ 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 )
+       -- Propagate out of range values up
+       -- e.g. if `min` is 70, `hour` increments by 1 and `min` becomes 10
+       min   , sec   = carry ( min   , sec   , 60 ) -- TODO: consider leap seconds?
+       hour  , min   = carry ( hour  , min   , 60 )
+       day   , hour  = carry ( day   , hour  , 24 )
 
        while day <= 0 do
                year = year - 1
@@ -74,7 +82,7 @@ local function normalise ( year , month , day , hour , min , sec )
 
        -- Lua months start from 1, need -1 and +1 around this increment
        month = month - 1
-       year , month = increment ( year , month , 12 )
+       year , month = carry ( year , month , 12 )
        month = month + 1
 
        -- This could potentially be slow if `day` is very large
@@ -193,10 +201,14 @@ function timetable_methods:clone ( )
 end
 
 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 )
 end
 
 return {
+       is_leap = is_leap ;
        day_of_year = day_of_year ;
        day_of_week = day_of_week ;
        normalise = normalise ;