exception Macro_not_found of string
exception Utf8_not_found of string

let dump_file = "macro_table.dump"

let init () =
  let ic = open_in dump_file in
  let (macro2utf8, utf82macro):
    ((string, string) Hashtbl.t * (string, string) Hashtbl.t)
  =
    Marshal.from_channel ic
  in
  close_in ic;
  (macro2utf8, utf82macro)

let (macro2utf8, utf82macro) = init ()

let expand macro =
  try
    Hashtbl.find macro2utf8 macro
  with Not_found -> raise (Macro_not_found macro)

let contract utf8 =
  try
    Hashtbl.find utf82macro utf8
  with Not_found -> raise (Utf8_not_found utf8)