(* Copyright (C) 2006, 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://cs.unibo.it/helm/.
 *)

let assume id t =
 Tacticals.then_
  ~start:
    (Tactics.intros ~howmany:1
      ~mk_fresh_name_callback:(fun _ _ _ ~typ -> Cic.Name id) ())
  ~continuation:
    (Tactics.change ~pattern:(None,[id,Cic.Implicit (Some `Hole)],None)
     (fun _ metasenv ugraph -> t,metasenv,ugraph))
;;

let suppose t id =
 Tacticals.then_
   ~start:
       (Tactics.intros ~howmany:1
             ~mk_fresh_name_callback:(fun _ _ _ ~typ -> Cic.Name id) ())
   ~continuation:
	    (Tactics.change ~pattern:(None,[id,Cic.Implicit (Some `Hole)],None)  
	      (fun _ metasenv ugraph -> t,metasenv,ugraph))
;;

let by_term_we_proved t ty id =
 Tacticals.thens
 ~start:
   (Tactics.cut ty
     ~mk_fresh_name_callback:(fun _ _ _  ~typ -> Cic.Name id))
 ~continuations:
   [ Tacticals.id_tac ; Tactics.apply t ]
;;

let bydone t =
   (Tactics.apply ~term:t)
;;

let we_need_to_prove t id =
 let aux status =
  let proof,goals =
   ProofEngineTypes.apply_tactic
    (Tactics.cut t
      ~mk_fresh_name_callback:(fun _ _ _  ~typ -> Cic.Name id))
    status
  in
   let goals' =
    match goals with
       [fst; snd] -> [snd; fst]
     | _ -> assert false
   in
    proof,goals'
 in
  ProofEngineTypes.mk_tactic aux
;;