luatz/timetable: Add __sub metamethod to allow subtraction of timetables. Reintroduce...

diff --git a/luatz/timetable.lua b/luatz/timetable.lua
index 6a39a132fc8d59a1c53c7e6d39ed6740ba9d6146..10af17018f90a9f14f5ef0c2ce72af9f9e367616 100644 (file)
--- a/luatz/timetable.lua
+++ b/luatz/timetable.lua
@@ -148,7 +148,16 @@ function timetable_methods:strftime ( format_string )
        return strftime ( format_string , self )
 end
 
-local timetable_mt = {
+local timetable_mt
+
+local function coerce_arg ( t )
+       if getmetatable ( t ) == timetable_mt then
+               return t:timestamp ( )
+       end
+       return t
+end
+
+timetable_mt = {
        __index    = timetable_methods ;
        __tostring = timetable_methods.rfc_3339 ;
        __eq = function ( a , b )
@@ -157,6 +166,9 @@ local timetable_mt = {
        __lt = function ( a , b )
                return a:timestamp ( ) < b:timestamp ( )
        end ;
+       __sub = function ( a , b )
+               return coerce_arg ( a ) - coerce_arg ( b )
+       end ;
 }
 
 local function cast_timetable ( tm )