(* stripcomments.ml - Don Yang (uguu.org)

   Remove non-BF characters from stream.

   09/02/04
                                                                           *)

(* Open first argument for input if available, otherwise use stdin *)
let input () =
   if Array.length Sys.argv > 1
   then open_in_bin Sys.argv.(1)
   else stdin;;

(* Open second argument for input if available, otherwise use stdout *)
let output () =
   if Array.length Sys.argv > 2
   then open_out_bin Sys.argv.(2)
   else stdout;;

(* Filter out non-BF characters *)
let filter outfile c =
   match c with
     '[' -> output_char outfile c
   | ']' -> output_char outfile c
   | '<' -> output_char outfile c
   | '>' -> output_char outfile c
   | '-' -> output_char outfile c
   | '+' -> output_char outfile c
   | ',' -> output_char outfile c
   | '.' -> output_char outfile c
   | _ -> ();;

(* Parse file character by character *)
let rec parse_bf infile outfile =
   let eof =
      try (filter outfile (input_char infile); 0)
      with End_of_file -> ((); 1) in
   if eof != 0 then output_char outfile '\n'
   else parse_bf infile outfile;;


(* Program entry point *)
let infile = input() in
   let outfile = output() in
      parse_bf infile outfile;
      close_out outfile;
      close_in infile;;