luatz/timetable.lua: Fix incorrect normalisation logic for negative day field

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

diff --git a/luatz/timetable.lua b/luatz/timetable.lua
index 3e802428310822aae1162df923aede765174f094..6bae913470bbd151ea4f2384210b448391f2547e 100644 (file)
--- a/luatz/timetable.lua
+++ b/luatz/timetable.lua
@@ -1,8 +1,16 @@
 local strftime = require "luatz.strftime".strftime
 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
 
 
@@ -68,8 +76,8 @@ local function carry ( tens , units , base )
                tens  = tens + idiv ( units , base )
                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
        return tens , units
 end
@@ -99,8 +107,12 @@ local function normalise ( year , month , day , hour , min , sec )
        -- 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
-               year = year - 1
-               day  = day + year_length ( year )
+               month = month - 1
+               if month < 0 then
+                       year = year - 1
+                       month = 11
+               end
+               day = day + month_length ( month + 1 , year )
        end
        year , month = carry ( year , month , 12 )
 
@@ -171,8 +183,10 @@ function timetable_methods:timestamp ( )
 end
 
 function timetable_methods:rfc_3339 ( )
-       -- %06.3f gives 3 (=6-3) digits after decimal
-       return strformat ( "%04u-%02u-%02uT%02u:%02u:%06.3f" , self:unpack ( ) )
+       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 )
@@ -227,7 +241,7 @@ 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 )
+       return new_timetable ( 1970 , 1 , 1 , 0 , 0 , ts ):normalise ( )
 end
 
 return {