2 ||M|| This file is part of HELM, an Hypertextual, Electronic
3 ||A|| Library of Mathematics, developed at the Computer Science
4 ||T|| Department, University of Bologna, Italy.
6 ||T|| HELM is free software; you can redistribute it and/or
7 ||A|| modify it under the terms of the GNU General Public License
8 \ / version 2 or (at your option) any later version.
9 \ / This software is distributed as is, NO WARRANTY.
10 V_______________________________________________________________ *)
17 module E = BagEnvironment
18 module S = BagSubstitution
20 exception LRefNotFound of B.message
30 | LRef_ of int * B.term option
32 | Bind_ of int * B.id * B.term * B.term
38 (* Internal functions *******************************************************)
40 let term_of_whdr = function
42 | LRef_ (i, _) -> B.LRef i
43 | GRef_ (_, uri, _) -> B.GRef uri
44 | Bind_ (l, id, w, t) -> B.bind_abst l id w t
48 let error i = raise (LRefNotFound (L.items1 (string_of_int i)))
51 let sc, st = s ^ " in the context", "the term" in
52 L.log O.specs level (L.ct_items1 sc c st t)
55 let sc, su, st = s ^ " in the context", "the term", "and the term" in
56 L.log O.specs level (L.ct_items2 sc c su u st t)
58 let empty_machine = {i = 0; c = B.empty_context; s = []}
60 let inc m = {m with i = succ m.i}
62 let unwind_to_term f m t =
63 let map f t (l, id, b) = f (B.Bind (l, id, b, t)) in
64 let f mc = C.list_fold_left f map t mc in
67 let unwind_stack f m =
68 let map f v = unwind_to_term f m v in
76 let f c = B.get f c i in
79 let push msg f c m l id w =
81 let f w = B.push msg f c l id (B.Abst w) in
86 (* L.warn "entering R.whd"; *)
88 | B.Sort h -> f m (Sort_ h)
90 let f obj = f m (GRef_ obj) in
94 | B.Void -> f m (LRef_ (i, None))
95 | B.Abst t -> f m (LRef_ (i, Some t))
96 | B.Abbr t -> whd f c m t
99 | B.Cast (_, t) -> whd f c m t
100 | B.Appl (v, t) -> whd f c {m with s = v :: m.s} t
101 | B.Bind (l, id, B.Abst w, t) ->
103 | [] -> f m (Bind_ (l, id, w, t))
105 let nl = B.new_location () in
106 let f mc = S.subst (whd f c {m with c = mc; s = tl}) nl l t in
107 B.push "!" f m.c nl id (B.Abbr (B.Cast (w, v)))
109 | B.Bind (l, id, b, t) ->
110 let nl = B.new_location () in
111 let f mc = S.subst (whd f c {m with c = mc}) nl l t in
112 B.push "!" f m.c nl id b
114 (* Interface functions ******************************************************)
118 let rec ho_whd f c m x =
119 (* L.warn "entering R.ho_whd"; *)
121 | Sort_ h -> f (Sort h)
122 | Bind_ (_, _, w, _) ->
123 let f w = f (Abst w) in unwind_to_term f m w
124 | LRef_ (_, Some w) -> ho_whd f c m w
125 | GRef_ (_, _, B.Abst w) -> ho_whd f c m w
126 | GRef_ (_, _, B.Abbr v) -> ho_whd f c m v
127 | LRef_ (_, None) -> assert false
128 | GRef_ (_, _, B.Void) -> assert false
133 let f r = L.unbox level; f r in
134 L.box level; log1 "Now scanning" c t;
135 ho_whd f c empty_machine t
137 let rec are_convertible f a c m1 t1 m2 t2 =
138 (* L.warn "entering R.are_convertible"; *)
139 let rec aux m1 r1 m2 r2 =
140 (* L.warn "entering R.are_convertible_aux"; *)
141 let u, t = term_of_whdr r1, term_of_whdr r2 in
142 log2 "Now really converting" c u t;
144 | Sort_ h1, Sort_ h2 ->
145 if h1 = h2 then f a else f false
146 | LRef_ (i1, _), LRef_ (i2, _) ->
147 if i1 = i2 then are_convertible_stacks f a c m1 m2 else f false
148 | GRef_ (a1, _, B.Abst _), GRef_ (a2, _, B.Abst _) ->
149 if a1 = a2 then are_convertible_stacks f a c m1 m2 else f false
150 | GRef_ (a1, _, B.Abbr v1), GRef_ (a2, _, B.Abbr v2) ->
152 let f a = if a then f a else are_convertible f true c m1 v1 m2 v2 in
153 are_convertible_stacks f a c m1 m2
155 if a1 < a2 then whd (aux m1 r1) c m2 v2 else
156 whd (aux_rev m2 r2) c m1 v1
157 | _, GRef_ (_, _, B.Abbr v2) ->
158 whd (aux m1 r1) c m2 v2
159 | GRef_ (_, _, B.Abbr v1), _ ->
160 whd (aux_rev m2 r2) c m1 v1
161 | Bind_ (l1, id1, w1, t1), Bind_ (l2, id2, w2, t2) ->
162 let l = B.new_location () in
164 let m1, m2 = inc m1, inc m2 in
165 let f t1 = S.subst (are_convertible f a c m1 t1 m2) l l2 t2 in
168 let f r = if r then push "!" h c m1 l id1 w1 else f false in
169 are_convertible f a c m1 w1 m2 w2
170 (* we detect the AUT-QE reduction rule for type/prop inclusion *)
171 | Sort_ _, Bind_ (l2, id2, w2, t2) when !nsi ->
172 let m1, m2 = inc m1, inc m2 in
173 let f c = are_convertible f a c m1 (term_of_whdr r1) m2 t2 in
174 push "nsi" f c m2 l2 id2 w2
176 and aux_rev m2 r2 m1 r1 = aux m1 r1 m2 r2 in
177 let g m1 r1 = whd (aux m1 r1) c m2 t2 in
178 if a = false then f false else whd g c m1 t1
180 and are_convertible_stacks f a c m1 m2 =
181 (* L.warn "entering R.are_convertible_stacks"; *)
182 let mm1, mm2 = {m1 with s = []}, {m2 with s = []} in
183 let map f a v1 v2 = are_convertible f a c mm1 v1 mm2 v2 in
184 if List.length m1.s <> List.length m2.s then
186 (* L.warn (Printf.sprintf "Different lengths: %u %u"
187 (List.length m1.s) (List.length m2.s)
192 C.list_fold_left2 f map a m1.s m2.s
194 let are_convertible f c u t =
195 let f b = L.unbox level; f b in
196 L.box level; log2 "Now converting" c u t;
197 are_convertible f true c empty_machine u empty_machine t