In cxx-basic,  "split" is written  with ast but inconsistant  with the
new one.  You can rewrite it with concrete syntax as an exercise.
Remember  that this  filter is  not so  simple as  it can  be believed
(e.g., "T  T, S;" is not  equivalent to "T  T; T S;", see  the ISO/IEC
std).
Have a good work.
-- 
Valentin David
valentin(a)lrde.epita.fr