(*
    ||M||  This file is part of HELM, an Hypertextual, Electronic        
    ||A||  Library of Mathematics, developed at the Computer Science     
    ||T||  Department, University of Bologna, Italy.                     
    ||I||                                                                
    ||T||  HELM is free software; you can redistribute it and/or         
    ||A||  modify it under the terms of the GNU General Public License   
    \   /  version 2 or (at your option) any later version.              
     \ /   This software is distributed as is, NO WARRANTY.              
      V_______________________________________________________________ *)

module H = Hashtbl
module S = Scanf
module C = Cps

type graph = string * (int -> int)

let sorts = 2
let sort = H.create sorts

(* Internal functions *******************************************************)

let set_sort h s =
   H.add sort h s; succ h

(* Interface functions ******************************************************)

let set_sorts ss i =   
   List.fold_left set_sort i ss

let get_sort err f h =
   try f (H.find sort h) with Not_found -> err ()

let string_of_graph (s, _) = s

let apply (_, g) h = (g h)

let graph_of_string err f s =
   try 
      let x = S.sscanf s "Z%u" C.start in 
      if x > 0 then f (s, fun h -> x + h) else err ()
   with
      S.Scan_failure _ | Failure _ | End_of_file -> err ()