(* 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/.
 *)

(*  AUTOR: Ferruccio Guidi <fguidi@cs.unibo.it>
 *)

type value = string list (* a linearized attribute value *)

type path  = string list (* the name of an attribute *)

module type Type = sig 

   type group               (* an group of attribures *)

   type avs                 (* a set of attributed values *)

   type peek_t = Empty
               | Single of (string * group list)
	       | Many of (string * group list)


   val grp_empty  : group

   val grp_make   : path -> string -> group 

   val grp_union  : group -> group -> group

   val grp_read   : group -> path -> avs

   val grps_make  : group list -> group -> group list 

   val empty      : avs

   val make       : string -> group -> avs

   val iter       : ('a -> string -> bool -> 'a) -> 'a -> avs -> 'a

   val x_iter     : ('a -> string -> group list -> bool -> 'a) -> 
                    'a -> avs -> 'a

   val x_grp_iter : ('a -> path -> value -> bool -> 'a) -> 'a -> group -> 'a

   val single     : avs -> string option

   val sub        : avs -> avs -> bool

   val meet       : avs -> avs -> bool

   val eq         : avs -> avs -> bool

   val union      : avs -> avs -> avs (* without attr. distribution *)

   val intersect  : avs -> avs -> avs (* without attr. distribution *)

   val diff       : avs -> avs -> avs

   val d_union    : avs -> avs -> avs (* with attr. distribution *)

   val peek       : avs -> peek_t

   val optimize   : avs -> avs

end