(* Copyright (C) 2004, 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://helm.cs.unibo.it/
 *)


(*
  The strings contains an unreadable message
*)
exception UniverseInconsistency of string

(*
  Cic.Type of universe 
*)
type universe

(*
  Opaque data structure you will use to store constraints
*)
type universe_graph

(*
  returns a fresh universe
*)
val fresh: 
  unit -> universe

(*
  really useful at the begin and in all the functions that don't care 
  of universes
*)
val empty_ugraph: universe_graph

(*
  These are the real functions to add eq/ge/gt constraints 
  to the passed graph, returning an updated graph or raising
  UniverseInconsistency
*)
val add_eq: 
  ?fast:bool -> universe -> universe -> universe_graph -> universe_graph
val add_ge: 
  ?fast:bool -> universe -> universe -> universe_graph -> universe_graph
val add_gt: 
  ?fast:bool -> universe -> universe -> universe_graph -> universe_graph

(*
  debug function to print the graph to standard error
*)
val print_ugraph: 
  universe_graph -> unit

(*
  does what expected, but I don't remember why this was exported
*)
val string_of_universe: 
  universe -> string

(*
  given the list of visible universes (see universes_of_obj) returns a
  cleaned graph (cleaned from the not visible nodes) 
*)
val clean_ugraph: 
  universe_graph -> universe list -> universe_graph

(*
  Since fresh() can't add the right uri to each node, you
  must fill empty nodes with the uri before you serialize the graph to xml
*)
val fill_empty_nodes_with_uri:
  universe_graph -> UriManager.uri -> universe_graph

(*
  makes a union.
  TODO:
  - remember already merged uri so that we completely skip already merged
    graphs, this may include a dependecy graph (not merge a subpart of an
    already merged graph)
*)
val merge_ugraphs:
  universe_graph -> universe_graph -> universe_graph

(*
  ugraph to xml file and viceversa
*)
val write_xml_of_ugraph: 
  string -> universe_graph -> unit

(*
  given a filename parses the xml and returns the data structure
*)
val ugraph_of_xml:
  string -> universe_graph
val restart_numbering:
  unit -> unit

(*
  Benchmarking stuff
*)
val get_spent_time: unit -> float
val reset_spent_time: unit -> unit