let max_profilers = 20;;
let profiler_no = ref 0;;
let profiler_label2int = Hashtbl.create 3;;
let name = ref "";;


let banner _ pname = 
  name := pname; 
 "(Array.make "^string_of_int max_profilers^" (0,0.)),
  (Array.make "^string_of_int max_profilers^" (0.))"
;;

let profile_start _ label =
  if !profiler_no > max_profilers then
    raise (Invalid_argument "Too many profilers.");
  if not (Hashtbl.mem profiler_label2int label) then
    begin
      Hashtbl.add profiler_label2int label !profiler_no;
      incr profiler_no;
    end;
  let id = Hashtbl.find profiler_label2int label in
  " ((snd "^ !name^").("^string_of_int id^") <- Unix.gettimeofday()) "
;;
      
let profile_stop _ label =
  if not (Hashtbl.mem profiler_label2int label) then
    raise (Invalid_argument "Profiler 'stop' before 'begin'.");
  let id = Hashtbl.find profiler_label2int label in
  " (
    let interval = 
      Unix.gettimeofday () -. (snd "^ !name^").("^string_of_int id^") 
    in
    let oldcount,oldval = (fst "^ !name^").("^string_of_int id^") in
    (fst "^ !name^").("^string_of_int id^") <- (oldcount+1,interval +. oldval)
   ) "
;;

let profile_show _ _ =
  (Hashtbl.fold 
    (fun k v acc -> 
      acc ^ 
      "let t = (fst "^ !name^").("^string_of_int v^") in "^
      "let acc = acc ^ Printf.sprintf \"%20s: %5d %8.4f\" \""^k^"\" (fst t) (snd t) in")
    profiler_label2int "let acc = \"\" in ") ^ " acc "
;;

Quotation.add "profiler" (Quotation.ExStr banner);;
Quotation.add "start" (Quotation.ExStr profile_start);;
Quotation.add "stop" (Quotation.ExStr profile_stop);;
Quotation.add "show" (Quotation.ExStr profile_show);;