format_performance_test.ml

type 'a printer = Format.formatter -> 'a -> unit
type 'a rand =  unit -> 'a

let flushed_list pr ppf x =
  List.iter (Format.fprintf ppf "%a@." pr) x


module type testable = sig
  type t
  val pp: t printer
  val rand: t rand
end

(* the exponential distribution is the minimal-entropy distribution for a fixed mean *)
let randexp scale () =
  int_of_float ( float_of_int scale *. -. (log (Random.float 1.)))

module String = struct
  type t = string
  let pp ppf s = Format.fprintf ppf "%s" s
  let rand () = String.init (randexp 100 ()) (fun _ -> Char.chr (32 + Random.int 95))
end

module Flushed_list_f(X:testable) = struct
  type t = X.t list
  let pp ppf x = flushed_list X.pp ppf x
  let rand () = List.init (randexp 100_000 ()) (fun _ -> X.rand ())

end


module T = Flushed_list_f(String)

let tests: (module testable) list = [
  (module T);
]

let test (module X:testable) = Format.printf "@[%a@]@." X.pp (X.rand ())

(* Compatibility *)
module Domain = struct
  let spawn f = ()
  let join () = ()
end
open Stdlib


let () =
  let spawn = ref false in
  let seed = 10 in
  let args =
    [
      "-spawn", Arg.Set spawn, "spawn a domain";
    ]
  in
  Arg.parse args ignore "test -spawn=<bool> -seed=<int>...";
  let () = Random.init seed in
  let maybe_join_later =
    if !spawn then
      let d = Domain.spawn ignore in
      fun () -> Domain.join d
    else ignore
  in
  Format.set_geometry ~margin:100 ~max_indent:99;
  List.iter test tests;
  maybe_join_later ()