open Ocamlbuild_plugin
open Command

let menhir_flags() =
  (* Define two ocamlbuild flags [only_tokens] and [external_tokens(Foo)]
     which correspond to menhir's [--only-tokens] and [--external-tokens Foo].
     When they are used, these flags should be passed both to [menhir] and to
     [menhir --raw-depend]. *)
  List.iter (fun mode ->
    
    flag [ mode; "only_tokens" ] (S[A "--only-tokens"]);

    pflag [ mode ] "external_tokens" (fun name ->
      S[A "--external-tokens"; A name]
    )
  
  ) [ "menhir"; "menhir_ocamldep" ]

let () =
  dispatch (fun event ->
    match event with
    | After_rules ->
        menhir_flags()
    | _ -> ()
  )