--- /dev/null
+(*
+ ||M|| This file is part of HELM, an Hypertextual, Electronic
+ ||A|| Library of Mathematics, developed at the Computer Science
+ ||T|| Department, University of Bologna, Italy.
+ ||I||
+ ||T|| HELM is free software; you can redistribute it and/or
+ ||A|| modify it under the terms of the GNU General Public License
+ \ / version 2 or (at your option) any later version.
+ \ / This software is distributed as is, NO WARRANTY.
+ V_______________________________________________________________ *)
+
+module C = Cps
+module L = Log
+module B = Bag
+module O = BagOutput
+module E = BagEnvironment
+module S = BagSubstitution
+
+exception LRefNotFound of B.message
+
+type machine = {
+ c: B.context;
+ s: B.term list
+}
+
+type whd_result =
+ | Sort_ of int
+ | LRef_ of int * B.term option
+ | GRef_ of int * B.bind
+ | Bind_ of int * B.id * B.term * B.term
+
+type ho_whd_result =
+ | Sort of int
+ | Abst of B.term
+
+(* Internal functions *******************************************************)
+
+let level = 5
+
+let error i = raise (LRefNotFound (L.items1 (string_of_int i)))
+
+let empty_machine = {c = B.empty_context; s = []}
+
+let contents f c m =
+ let f gl ges = B.contents (f gl ges) m.c in
+ B.contents f c
+
+let unwind_to_context f c m = B.append f c m.c
+
+let unwind_to_term f m t =
+ let map f t (l, id, b) = f (B.Bind (l, id, b, t)) in
+ let f mc = C.list_fold_left f map t mc in
+ B.contents f m.c
+
+let get f c m i =
+ let f = function
+ | Some (_, b) -> f b
+ | None -> error i
+ in
+ let f c = B.get f c i in
+ unwind_to_context f c m
+
+let push f c m l id w =
+ assert (m.s = []);
+ let f w = B.push f c l id (B.Abst w) in
+ unwind_to_term f m w
+
+(* to share *)
+let rec whd f c m x = match x with
+ | B.Sort h -> f m (Sort_ h)
+ | B.GRef uri ->
+ let f (i, _, b) = f m (GRef_ (i, b)) in
+ E.get_obj f uri
+ | B.LRef i ->
+ let f = function
+ | B.Void -> f m (LRef_ (i, None))
+ | B.Abst t -> f m (LRef_ (i, Some t))
+ | B.Abbr t -> whd f c m t
+ in
+ get f c m i
+ | B.Cast (_, t) -> whd f c m t
+ | B.Appl (v, t) -> whd f c {m with s = v :: m.s} t
+ | B.Bind (l, id, B.Abst w, t) ->
+ begin match m.s with
+ | [] -> f m (Bind_ (l, id, w, t))
+ | v :: tl ->
+ let f mc = whd f c {c = mc; s = tl} t in
+ B.push f m.c l id (B.Abbr (B.Cast (w, v)))
+ end
+ | B.Bind (l, id, b, t) ->
+ let f mc = whd f c {m with c = mc} t in
+ B.push f m.c l id b
+
+(* Interface functions ******************************************************)
+
+let rec ho_whd f c m x =
+ let aux m = function
+ | Sort_ h -> f c (Sort h)
+ | Bind_ (_, _, w, _) ->
+ let f c = f c (Abst w) in unwind_to_context f c m
+ | LRef_ (_, Some w) -> ho_whd f c m w
+ | GRef_ (_, B.Abst u) -> ho_whd f c m u
+ | GRef_ (_, B.Abbr t) -> ho_whd f c m t
+ | LRef_ (_, None) -> assert false
+ | GRef_ (_, B.Void) -> assert false
+ in
+ whd aux c m x
+
+let ho_whd f c t =
+ let f c r = L.unbox (); f c r in
+ L.box (); L.log O.specs level (L.ct_items1 "Now scanning" c t);
+ ho_whd f c empty_machine t
+
+let rec are_convertible f c m1 t1 m2 t2 =
+ let rec aux m1 r1 m2 r2 = match r1, r2 with
+ | Sort_ h1, Sort_ h2 -> f (h1 = h2)
+ | LRef_ (i1, _), LRef_ (i2, _) ->
+ if i1 = i2 then are_convertible_stacks f c m1 m2 else f false
+ | GRef_ (a1, B.Abst _), GRef_ (a2, B.Abst _) ->
+ if a1 = a2 then are_convertible_stacks f c m1 m2 else f false
+ | GRef_ (a1, B.Abbr v1), GRef_ (a2, B.Abbr v2) ->
+ if a1 = a2 then are_convertible_stacks f c m1 m2 else
+ if a1 < a2 then whd (aux m1 r1) c m2 v2 else
+ whd (aux_rev m2 r2) c m1 v1
+ | _, GRef_ (_, B.Abbr v2) ->
+ whd (aux m1 r1) c m2 v2
+ | GRef_ (_, B.Abbr v1), _ ->
+ whd (aux_rev m2 r2) c m1 v1
+ | Bind_ (l1, id1, w1, t1), Bind_ (l2, id2, w2, t2) ->
+ let f b =
+ if b then
+ let f c =
+ S.subst (are_convertible f c m1 t1 m2) l1 l2 t2
+ in
+ push f c m1 l1 id1 w1
+ else f false
+ in
+ are_convertible f c m1 w1 m2 w2
+ | _ -> f false
+ and aux_rev m2 r2 m1 r1 = aux m1 r1 m2 r2 in
+ let f m1 r1 = whd (aux m1 r1) c m2 t2 in
+ whd f c m1 t1
+
+and are_convertible_stacks f c m1 m2 =
+ let mm1, mm2 = {m1 with s = []}, {m2 with s = []} in
+ let map f v1 v2 = are_convertible f c mm1 v1 mm2 v2 in
+ if List.length m1.s <> List.length m2.s then f false else
+ C.forall2 f map m1.s m2.s
+
+let are_convertible f c t1 t2 =
+ let f b = L.unbox (); f b in
+ L.box ();
+ L.log O.specs level (L.ct_items2 "Now converting" c t1 "and" c t2);
+ are_convertible f c empty_machine t1 empty_machine t2
projects / helm.git / blobdiff