let nsplitf str f =
if str = "" then
[]
else
let buf = Buffer.create 13 in
let lst = ref [] in
let push () =
lst := Buffer.contents buf :: !lst;
Buffer.clear buf
in
let str_len = String.length str in
for i = 0 to str_len - 1 do
if f str.[i] then
push ()
else
Buffer.add_char buf str.[i]
done;
push ();
List.rev !lst