X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Flambda-delta%2Fbasic_ag%2FbagReduction.ml;fp=helm%2Fsoftware%2Flambda-delta%2Fbasic_ag%2FbagReduction.ml;h=0310e8d2833de378e435ae3ffcf80b998da5dcad;hb=338e3e5c639fbcfeeb347a0121cacc6c0f1fc42a;hp=0000000000000000000000000000000000000000;hpb=c87a73806365feadc23300194a42ab8edb0f8b1b;p=helm.git

diff --git a/helm/software/lambda-delta/basic_ag/bagReduction.ml b/helm/software/lambda-delta/basic_ag/bagReduction.ml
new file mode 100644
index 000000000..0310e8d28
--- /dev/null
+++ b/helm/software/lambda-delta/basic_ag/bagReduction.ml
@@ -0,0 +1,154 @@
+(*
+    ||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