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
36 | GRef of U.uri * B.term list
39 (* Internal functions *******************************************************)
41 let term_of_whdr = function
43 | LRef_ (i, _) -> B.LRef i
44 | GRef_ (_, uri, _) -> B.GRef uri
45 | Bind_ (l, id, w, t) -> B.bind_abst l id w t
49 let error i = raise (LRefNotFound (L.items1 (string_of_int i)))
52 let sc, st = s ^ " in the context", "the term" in
53 L.log O.specs level (L.ct_items1 sc c st t)
56 let sc, su, st = s ^ " in the context", "the term", "and the term" in
57 L.log O.specs level (L.ct_items2 sc c su u st t)
59 let empty_machine = {i = 0; c = B.empty_context; s = []}
61 let inc m = {m with i = succ m.i}
63 let unwind_to_term f m t =
64 let map f t (l, id, b) = f (B.Bind (l, id, b, t)) in
65 let f mc = C.list_fold_left f map t mc in
68 let unwind_stack f m =
69 let map f v = unwind_to_term f m v in
77 let f c = B.get f c i in
80 let push f c m l id w =
82 let f w = B.push f c l id (B.Abst w) in
86 let rec whd f c m x = match x with
87 | B.Sort h -> f m (Sort_ h)
89 let f obj = f m (GRef_ obj) in
93 | B.Void -> f m (LRef_ (i, None))
94 | B.Abst t -> f m (LRef_ (i, Some t))
95 | B.Abbr t -> whd f c m t
98 | B.Cast (_, t) -> whd f c m t
99 | B.Appl (v, t) -> whd f c {m with s = v :: m.s} t
100 | B.Bind (l, id, B.Abst w, t) ->
102 | [] -> f m (Bind_ (l, id, w, t))
104 let f mc = whd f c {m with c = mc; s = tl} t in
105 B.push f m.c l id (B.Abbr (B.Cast (w, v)))
107 | B.Bind (l, id, b, t) ->
108 let f mc = whd f c {m with c = mc} t in
111 (* Interface functions ******************************************************)
115 let rec ho_whd f c m x =
117 | Sort_ h -> f (Sort h)
118 | Bind_ (_, _, w, _) ->
119 let f w = f (Abst w) in unwind_to_term f m w
120 | LRef_ (_, Some w) -> ho_whd f c m w
121 | GRef_ (_, _, B.Abst w) -> ho_whd f c m w
122 | GRef_ (_, _, B.Abbr v) -> ho_whd f c m v
123 | LRef_ (_, None) -> assert false
124 | GRef_ (_, _, B.Void) -> assert false
129 let f r = L.unbox level; f r in
130 L.box level; log1 "Now scanning" c t;
131 ho_whd f c empty_machine t
133 let rec are_convertible f a c m1 t1 m2 t2 =
134 let rec aux m1 r1 m2 r2 =
135 let u, t = term_of_whdr r1, term_of_whdr r2 in
136 log2 "Now really converting" c u t;
138 | Sort_ h1, Sort_ h2 ->
139 if h1 = h2 then f a else f false
140 | LRef_ (i1, _), LRef_ (i2, _) ->
141 if i1 = i2 then are_convertible_stacks f a c m1 m2 else f false
142 | GRef_ (a1, _, B.Abst _), GRef_ (a2, _, B.Abst _) ->
143 if a1 = a2 then are_convertible_stacks f a c m1 m2 else f false
144 | GRef_ (a1, _, B.Abbr v1), GRef_ (a2, _, B.Abbr v2) ->
146 let f a = if a then f a else are_convertible f true c m1 v1 m2 v2 in
147 are_convertible_stacks f a c m1 m2
149 if a1 < a2 then whd (aux m1 r1) c m2 v2 else
150 whd (aux_rev m2 r2) c m1 v1
151 | _, GRef_ (_, _, B.Abbr v2) ->
152 whd (aux m1 r1) c m2 v2
153 | GRef_ (_, _, B.Abbr v1), _ ->
154 whd (aux_rev m2 r2) c m1 v1
155 | Bind_ (l1, id1, w1, t1), Bind_ (l2, id2, w2, t2) ->
157 let m1, m2 = inc m1, inc m2 in
158 S.subst (are_convertible f a c m1 t1 m2) l1 l2 t2
160 let f r = if r then push h c m1 l1 id1 w1 else f false in
161 are_convertible f a c m1 w1 m2 w2
162 (* we detect the AUT-QE reduction rule for type/prop inclusion *)
163 | Sort_ _, Bind_ (l2, id2, w2, t2) when !nsi ->
164 let m1, m2 = inc m1, inc m2 in
165 let f c = are_convertible f a c m1 (term_of_whdr r1) m2 t2 in
166 push f c m2 l2 id2 w2
168 and aux_rev m2 r2 m1 r1 = aux m1 r1 m2 r2 in
169 let g m1 r1 = whd (aux m1 r1) c m2 t2 in
170 if a = false then f false else whd g c m1 t1
172 and are_convertible_stacks f a c m1 m2 =
173 let mm1, mm2 = {m1 with s = []}, {m2 with s = []} in
174 let map f a v1 v2 = are_convertible f a c mm1 v1 mm2 v2 in
175 if List.length m1.s <> List.length m2.s then
177 L.warn (Printf.sprintf "Different lengths: %u %u"
178 (List.length m1.s) (List.length m2.s)
183 C.list_fold_left2 f map a m1.s m2.s
185 let are_convertible f c u t =
186 let f b = L.unbox level; f b in
187 L.box level; log2 "Now converting" c u t;
188 are_convertible f true c empty_machine u empty_machine t