(* Copyright (C) 2000, HELM Team.
 * 
 * This file is part of HELM, an Hypertextual, Electronic
 * Library of Mathematics, developed at the Computer Science
 * Department, University of Bologna, Italy.
 * 
 * HELM is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * HELM is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with HELM; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA  02111-1307, USA.
 * 
 * For details, see the HELM World-Wide-Web page,
 * http://www.cs.unibo.it/helm/.
 *)

(*
 * implementazione dei comandi LETIN e REF
 *)

open MathQL;;

let letin_pool = ref None;;

let see_pool () =
 match !letin_pool with
    None -> print_endline "None"
  | Some c -> List.iter (fun elem -> print_endline (fst elem)) c
;;

let letin_ex rvar alist =
 let _ = 
  match !letin_pool with
     Some pool -> letin_pool := Some ((rvar,alist)::(List.remove_assoc rvar pool))
   | None -> letin_pool := Some ([(rvar,alist)])
 in
(*  let _ = see_pool () in*)
  []
;;

let letref_ex rvar =
 match !letin_pool with
    None -> []
  | Some pool ->
     (
      try
       List.assoc rvar pool
      with
       Not_found -> []
     )
;;

let letdispose () =
 let _ = letin_pool = ref None in ()
;;