(* Copyright (C) 2003-2005, 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/.
 *)

module C = Cic

let rec need_whd i = function
   | C.ACast (_, t, _)               -> need_whd i t
   | C.AProd (_, _, _, t) when i > 0 -> need_whd (pred i) t
   | _                    when i > 0 -> true
   | _                               -> false

let lift k n =
   let rec lift_xns k (uri, t) = uri, lift_term k t
   and lift_ms k = function
      | None   -> None
      | Some t -> Some (lift_term k t)
   and lift_fix len k (id, name, i, ty, bo) =
      id, name, i, lift_term k ty, lift_term (k + len) bo
   and lift_cofix len k (id, name, ty, bo) =
      id, name, lift_term k ty, lift_term (k + len) bo
   and lift_term k = function
      | C.ASort _ as t -> t
      | C.AImplicit _ as t -> t
      | C.ARel (id, rid, m, b) as t -> if m < k then t else C.ARel (id, rid, m + n, b)
      | C.AConst (id, uri, xnss) -> C.AConst (id, uri, List.map (lift_xns k) xnss)
      | C.AVar (id, uri, xnss) -> C.AVar (id, uri, List.map (lift_xns k) xnss)
      | C.AMutInd (id, uri, tyno, xnss) -> C.AMutInd (id, uri, tyno, List.map (lift_xns k) xnss)
      | C.AMutConstruct (id, uri, tyno, consno, xnss) -> C.AMutConstruct (id, uri,tyno,consno, List.map (lift_xns k) xnss)
      | C.AMeta (id, i, mss) -> C.AMeta(id, i, List.map (lift_ms k) mss)
      | C.AAppl (id, ts) -> C.AAppl (id, List.map (lift_term k) ts)
      | C.ACast (id, te, ty) -> C.ACast (id, lift_term k te, lift_term k ty)
      | C.AMutCase (id, sp, i, outty, t, pl) -> C.AMutCase (id, sp, i, lift_term k outty, lift_term k t, List.map (lift_term k) pl)
      | C.AProd (id, n, s, t) -> C.AProd (id, n, lift_term k s, lift_term (succ k) t)
      | C.ALambda (id, n, s, t) -> C.ALambda (id, n, lift_term k s, lift_term (succ k) t)
      | C.ALetIn (id, n, s, t) -> C.ALetIn (id, n, lift_term k s, lift_term (succ k) t)
      | C.AFix (id, i, fl) -> C.AFix (id, i, List.map (lift_fix (List.length fl) k) fl)
      | C.ACoFix (id, i, fl) -> C.ACoFix (id, i, List.map (lift_cofix (List.length fl) k) fl)
   in
   lift_term k