(* Copyright (C) 2002, 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/.
 *)

open ProofEngineTypes

(* Note: this code is almost identical to PrimitiveTactics.change_tac and
*  it could be unified by making the change function a callback *)
let reduction_tac ~reduction ~pattern
 (proof,goal)
=
  let curi,metasenv,pbo,pty = proof in
  let (metano,context,ty) as conjecture = CicUtil.lookup_meta goal metasenv in
  let change where terms =
   if terms = [] then where
   else
    let terms, terms' = 
      List.split (List.map (fun (context, t) -> t, reduction context t) terms)
    in
     ProofEngineReduction.replace ~equality:(==) ~what:terms ~with_what:terms'
      ~where:where in
  let (selected_context,selected_ty) =
   ProofEngineHelpers.select ~metasenv ~conjecture ~pattern in
  let ty' = change ty selected_ty in
  let context' =
   List.fold_right2
    (fun entry selected_entry context' ->
      match entry,selected_entry with
         None,None -> None::context'
       | Some (name,Cic.Decl ty),Some (`Decl selected_ty) ->
          let ty' = change ty selected_ty in
           Some (name,Cic.Decl ty')::context'
       | Some (name,Cic.Def (bo,ty)),Some (`Def (selected_bo,selected_ty)) ->
          let bo' = change bo selected_bo in
          let ty' =
           match ty,selected_ty with
              None,None -> None
            | Some ty,Some selected_ty -> Some (change ty selected_ty)
            | _,_ -> assert false
          in
           Some (name,Cic.Def (bo',ty'))::context'
       | _,_ -> assert false
    ) context selected_context [] in
  let metasenv' = 
    List.map (function 
      | (n,_,_) when n = metano -> (metano,context',ty')
      | _ as t -> t
    ) metasenv
  in
  (curi,metasenv',pbo,pty), [metano]
;;

let simpl_tac ~pattern = 
 mk_tactic (reduction_tac ~reduction:ProofEngineReduction.simpl ~pattern);;

let reduce_tac ~pattern = 
 mk_tactic (reduction_tac ~reduction:ProofEngineReduction.reduce ~pattern);;
  
let whd_tac ~pattern = 
 mk_tactic (reduction_tac ~reduction:CicReduction.whd ~pattern);;

let normalize_tac ~pattern = 
 mk_tactic (reduction_tac ~reduction:CicReduction.normalize ~pattern );;

let fold_tac ~reduction ~pattern =
(*
 let fold_tac ~reduction ~pattern:(hyp_patterns,goal_pattern) ~term (proof,goal)
 =
  let curi,metasenv,pbo,pty = proof in
  let metano,context,ty = CicUtil.lookup_meta goal metasenv in
   let term' = reduction context term in
    let replace =
     ProofEngineReduction.replace ~equality:(=) ~what:[term'] ~with_what:[term]
    in
     let ty' = replace ty in
     let metasenv' =
      let context' =
       if also_in_hypotheses then
        List.map
         (function
             Some (n,Cic.Decl t) -> Some (n,Cic.Decl (replace t))
           | Some (n,Cic.Def (t,None))  -> Some (n,Cic.Def ((replace t),None))
           | None -> None
           | Some (_,Cic.Def (_,Some _)) -> assert false
         ) context
       else
        context
      in
       List.map
        (function
            (n,_,_) when n = metano -> (metano,context',ty')
          | _ as t -> t
        ) metasenv
      
     in
      (curi,metasenv',pbo,pty), [metano]
 in
  mk_tactic (fold_tac ~reduction ~pattern ~term)
*) assert false
;;