--- /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 U = NUri
+module C = Cps
+module L = Log
+module E = Entity
+module J = Marks
+module Z = Bag
+module ZO = BagOutput
+module ZE = BagEnvironment
+module ZS = BagSubstitution
+
+type machine = {
+ i: int;
+ c: Z.lenv;
+ s: Z.term list
+}
+
+type whd_result =
+ | Sort_ of int
+ | LRef_ of int * Z.term option
+ | GRef_ of Z.entity
+ | Bind_ of Z.attrs * int * Z.term * Z.term
+
+type ho_whd_result =
+ | Sort of int
+ | Abst of Z.term
+
+(* Internal functions *******************************************************)
+
+let term_of_whdr = function
+ | Sort_ h -> Z.Sort h
+ | LRef_ (i, _) -> Z.LRef i
+ | GRef_ (_, uri, _) -> Z.GRef uri
+ | Bind_ (a, l, w, t) -> Z.bind_abst a l w t
+
+let level = 5
+
+let log1 s c t =
+ let sc, st = s ^ " in the environment", "the term" in
+ L.log ZO.specs level (L.et_items1 sc c st t)
+
+let log2 s cu u ct t =
+ let s1, s2, s3 = s ^ " in the environment", "the term", "and in the environment" in
+ L.log ZO.specs level (L.et_items2 s1 cu s2 u ~sc2:s3 ~c2:ct s2 t)
+
+let empty_machine = {i = 0; c = Z.empty_lenv; s = []}
+
+let inc m = {m with i = succ m.i}
+
+let unwind_to_term f m t =
+ let map f t (a, l, b) = f (Z.Bind (a, l, b, t)) in
+ let f mc = C.list_fold_left f map t mc in
+ Z.contents f m.c
+
+let unwind_stack f m =
+ let map f v = unwind_to_term f m v in
+ C.list_map f map m.s
+
+let get f c m i =
+ let f _ b = f b in
+ let f c = Z.get C.err f c i in
+ Z.append f c m.c
+
+let push msg f c m a l w =
+ assert (m.s = []);
+ let f w = Z.push msg f c a l (Z.Abst w) in
+ unwind_to_term f m w
+
+(* to share *)
+let rec whd f c m x =
+(* L.warn "entering R.whd"; *)
+ match x with
+ | Z.Sort h -> f m (Sort_ h)
+ | Z.GRef uri ->
+ let f entry = f m (GRef_ entry) in
+ ZE.get_entity f uri
+ | Z.LRef i ->
+ let f = function
+ | Z.Void -> f m (LRef_ (i, None))
+ | Z.Abst t -> f m (LRef_ (i, Some t))
+ | Z.Abbr t -> whd f c m t
+ in
+ get f c m i
+ | Z.Cast (_, t) -> whd f c m t
+ | Z.Appl (v, t) -> whd f c {m with s = v :: m.s} t
+ | Z.Bind (a, l, Z.Abst w, t) ->
+ begin match m.s with
+ | [] -> f m (Bind_ (a, l, w, t))
+ | v :: tl ->
+ let nl = J.new_location () in
+ let f mc = ZS.subst (whd f c {m with c = mc; s = tl}) nl l t in
+ Z.push "!" f m.c a nl (Z.Abbr (Z.Cast (w, v)))
+ end
+ | Z.Bind (a, l, b, t) ->
+ let nl = J.new_location () in
+ let f mc = ZS.subst (whd f c {m with c = mc}) nl l t in
+ Z.push "!" f m.c a nl b
+
+(* Interface functions ******************************************************)
+
+let rec ho_whd f c m x =
+(* L.warn "entering R.ho_whd"; *)
+ let aux m = function
+ | Sort_ h -> f (Sort h)
+ | Bind_ (_, _, w, _) ->
+ let f w = f (Abst w) in unwind_to_term f m w
+ | LRef_ (_, Some w) -> ho_whd f c m w
+ | GRef_ (_, _, E.Abst (_, w)) -> ho_whd f c m w
+ | GRef_ (_, _, E.Abbr v) -> ho_whd f c m v
+ | LRef_ (_, None) -> assert false
+ | GRef_ (_, _, E.Void) -> assert false
+ in
+ whd aux c m x
+
+let ho_whd f c t =
+ let f r = L.unbox level; f r in
+ L.box level; log1 "Now scanning" c t;
+ ho_whd f c empty_machine t
+
+let rec are_convertible f ~si a c m1 t1 m2 t2 =
+(* L.warn "entering R.are_convertible"; *)
+ let rec aux m1 r1 m2 r2 =
+(* L.warn "entering R.are_convertible_aux"; *)
+ let u, t = term_of_whdr r1, term_of_whdr r2 in
+ log2 "Now really converting" c u c t;
+ match r1, r2 with
+ | Sort_ h1, Sort_ h2 ->
+ if h1 = h2 then f a else f false
+ | LRef_ (i1, _), LRef_ (i2, _) ->
+ if i1 = i2 then are_convertible_stacks f ~si a c m1 m2 else f false
+ | GRef_ ((E.Apix a1 :: _), _, E.Abst _),
+ GRef_ ((E.Apix a2 :: _), _, E.Abst _) ->
+ if a1 = a2 then are_convertible_stacks f ~si a c m1 m2 else f false
+ | GRef_ ((E.Apix a1 :: _), _, E.Abbr v1),
+ GRef_ ((E.Apix a2 :: _), _, E.Abbr v2) ->
+ if a1 = a2 then
+ let f a =
+ if a then f a else are_convertible f ~si true c m1 v1 m2 v2
+ in
+ are_convertible_stacks f ~si a 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_ (_, _, E.Abbr v2) ->
+ whd (aux m1 r1) c m2 v2
+ | GRef_ (_, _, E.Abbr v1), _ ->
+ whd (aux_rev m2 r2) c m1 v1
+ | Bind_ (a1, l1, w1, t1), Bind_ (a2, l2, w2, t2) ->
+ let l = J.new_location () in
+ let h c =
+ let m1, m2 = inc m1, inc m2 in
+ let f t1 = ZS.subst (are_convertible f ~si a c m1 t1 m2) l l2 t2 in
+ ZS.subst f l l1 t1
+ in
+ let f r = if r then push "!" h c m1 a1 l w1 else f false in
+ are_convertible f ~si a c m1 w1 m2 w2
+(* we detect the AUT-QE reduction rule for type/prop inclusion *)
+ | Sort_ _, Bind_ (a2, l2, w2, t2) when si ->
+ let m1, m2 = inc m1, inc m2 in
+ let f c = are_convertible f ~si a c m1 (term_of_whdr r1) m2 t2 in
+ push "nsi" f c m2 a2 l2 w2
+ | _ -> f false
+ and aux_rev m2 r2 m1 r1 = aux m1 r1 m2 r2 in
+ let g m1 r1 = whd (aux m1 r1) c m2 t2 in
+ if a = false then f false else whd g c m1 t1
+
+and are_convertible_stacks f ~si a c m1 m2 =
+(* L.warn "entering R.are_convertible_stacks"; *)
+ let mm1, mm2 = {m1 with s = []}, {m2 with s = []} in
+ let map f a v1 v2 = are_convertible f ~si a c mm1 v1 mm2 v2 in
+ if List.length m1.s <> List.length m2.s then
+ begin
+(* L.warn (Printf.sprintf "Different lengths: %u %u"
+ (List.length m1.s) (List.length m2.s)
+ ); *)
+ f false
+ end
+ else
+ C.list_fold_left2 f map a m1.s m2.s
+
+let are_convertible f ?(si=false) c u t =
+ let f b = L.unbox level; f b in
+ L.box level; log2 "Now converting" c u c t;
+ are_convertible f ~si true c empty_machine u empty_machine t
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