X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fcomponents%2Fng_refiner%2FnCicMetaSubst.ml;h=60abe85c37c08879ea80d01ededa27c158d0192f;hb=3a4c39fc9c938ca155f0e807525cd38eec240a0d;hp=1a2b5471b0cf76910eb0666c1cba0fb96a59b7bb;hpb=d174e54c365ab9df38367de9336c213a03be3c27;p=helm.git

diff --git a/helm/software/components/ng_refiner/nCicMetaSubst.ml b/helm/software/components/ng_refiner/nCicMetaSubst.ml
index 1a2b5471b..60abe85c3 100644
--- a/helm/software/components/ng_refiner/nCicMetaSubst.ml
+++ b/helm/software/components/ng_refiner/nCicMetaSubst.ml
@@ -14,9 +14,10 @@
 exception MetaSubstFailure of string Lazy.t
 exception Uncertain of string Lazy.t
 
-let newmeta = 
+let newmeta,maxmeta = 
   let maxmeta = ref 0 in
-  fun () -> incr maxmeta; !maxmeta
+  (fun () -> incr maxmeta; !maxmeta),
+  (fun () -> !maxmeta)
 ;;
 
 exception NotInTheList;;
@@ -71,31 +72,41 @@ let rec force_does_not_occur metasenv subst restrictions t =
         in
         if amount > 0 then ms, NCic.Rel (r - amount) else ms, orig
     | NCic.Meta (n, (shift,lc as l)) as orig ->
-       (* we ignore the subst since restrict will take care of already
-        * instantiated/restricted metavariabels *)
-       let (metasenv,subst as ms), restrictions_for_n, l' =
-         let l = NCicUtils.expand_local_context lc in
-
-         let ms, _, restrictions_for_n, l =
-          List.fold_right
-            (fun t (ms, i, restrictions_for_n, l) ->
-              try 
-                let ms, t = aux (k-shift) ms t in
-                ms, i-1, restrictions_for_n, t::l
-              with Occur ->
-                ms, i-1, i::restrictions_for_n, l)
-            l (ms, List.length l, [], [])
-         in
-             
-          ms, restrictions_for_n, pack_lc (shift, NCic.Ctx l)
+       let meta_chain =
+        try
+         Some (NCicUtils.lookup_subst n subst)
+        with
+         NCicUtils.Subst_not_found _ -> None
        in
-       if restrictions_for_n = [] then
-         ms, if l = l' then orig else NCic.Meta (n, l')
-       else
-         let metasenv, subst, newmeta = 
-           restrict metasenv subst n restrictions_for_n 
-         in
-           (metasenv, subst), NCic.Meta (newmeta, l')
+        (match meta_chain with
+            Some (_,_,bo,_) ->
+             aux k ms (NCicSubstitution.subst_meta l bo)
+          | None ->
+             (* we ignore the subst since restrict will take care of already
+              * instantiated/restricted metavariabels *)
+             let (metasenv,subst as ms), restrictions_for_n, l' =
+               let l = NCicUtils.expand_local_context lc in
+         
+               let ms, _, restrictions_for_n, l =
+                List.fold_right
+                  (fun t (ms, i, restrictions_for_n, l) ->
+                    try 
+                      let ms, t = aux (k-shift) ms t in
+                      ms, i-1, restrictions_for_n, t::l
+                    with Occur ->
+                      ms, i-1, i::restrictions_for_n, l)
+                  l (ms, List.length l, [], [])
+               in
+                   
+                ms, restrictions_for_n, pack_lc (shift, NCic.Ctx l)
+             in
+             if restrictions_for_n = [] then
+               ms, if l = l' then orig else NCic.Meta (n, l')
+             else
+               let metasenv, subst, newmeta = 
+                 restrict metasenv subst n restrictions_for_n 
+               in
+                 (metasenv, subst), NCic.Meta (newmeta, l'))
     | t -> NCicUntrusted.map_term_fold_a (fun _ k -> k+1) k aux ms t
  in
    aux 0 (metasenv,subst) t 
@@ -195,17 +206,32 @@ and restrict metasenv subst i restrictions =
     | NCicUtils.Meta_not_found _ -> assert false
 ;;
 
-let rec flexible_arg subst = function 
+let rec flexible_arg context subst = function 
   | NCic.Meta (i,_) | NCic.Appl (NCic.Meta (i,_) :: _)-> 
       (try 
         let _,_,t,_ = List.assoc i subst in
-        flexible_arg subst t
+        flexible_arg context subst t
       with Not_found -> true)
+   (* this is a cheap whd, it only performs zeta-reduction.
+    * 
+    * it works when the **omissis** disambiguation algorithm
+    * is run on `let x := K a b in t`, K is substituted for a 
+    * ? and thus in t metavariables have a flexible Rel
+    *)
+  | NCic.Rel i ->
+      (try
+         match List.nth context (i-1)
+         with 
+         | _,NCic.Def (bo,_) ->
+               flexible_arg context subst
+                 (NCicSubstitution.lift i bo)
+         | _ -> false
+      with 
+      | Failure _ -> assert false
+      | Invalid_argument _ -> assert false)
   | _ -> false
 ;;
 
-let flexible subst l = List.exists (flexible_arg subst) l;;
-
 let in_scope_tag  = "tag:in_scope" ;;
 let out_scope_tag_prefix = "tag:out_scope:" 
 let out_scope_tag n = out_scope_tag_prefix ^ string_of_int n ;;
@@ -220,16 +246,37 @@ let int_of_out_scope_tag tag =
 ;;
 
 
+exception Found;;
+
 (* INVARIANT: we suppose that t is not another occurrence of Meta(n,_), 
    otherwise the occur check does not make sense in case of unification
    of ?n with ?n *)
 let delift ~unify metasenv subst context n l t =
+  let is_in_scope_meta subst = function
+    | NCic.Meta (i,_) ->
+        (try 
+           let tag, _, _, _ = NCicUtils.lookup_subst i subst in 
+           tag = Some in_scope_tag 
+        with NCicUtils.Subst_not_found _ -> false)
+    | _ -> false
+  in
+  let contains_in_scope subst t = 
+    let rec aux _ () = function
+      | NCic.Meta _ as t ->
+          if is_in_scope_meta subst t then raise Found
+          else ()
+      | t -> 
+          if is_in_scope_meta subst t then raise Found
+          else NCicUtils.fold (fun _ () -> ()) () aux () t
+    in
+    try aux () () t; false with Found -> true
+  in
   let unify_list in_scope = 
     match l with
     | _, NCic.Irl _ -> fun _ _ _ _ _ -> None
     | shift, NCic.Ctx l -> fun metasenv subst context k t ->
-       if flexible_arg subst t then None else
-         let lb = List.map (fun t -> t, flexible_arg subst t) l in
+       if flexible_arg context subst t || contains_in_scope subst t then None else
+         let lb = List.map (fun t -> t, flexible_arg context subst t) l in
          HExtlib.list_findopt
           (fun (li,flexible) i ->
             if flexible || i < in_scope then None else
@@ -266,12 +313,18 @@ let delift ~unify metasenv subst context n l t =
             (NCicPp.ppterm ~context ~metasenv ~subst t))))
     | NCic.Meta (i,l1) as orig ->
         (try
-           let tag,_,t,_ = NCicUtils.lookup_subst i subst in
-           let in_scope = 
+           let tag,c,t,ty = NCicUtils.lookup_subst i subst in
+           let in_scope, clear = 
              match tag with 
-             | Some tag when tag = in_scope_tag -> 0
-             | Some tag when is_out_scope_tag tag -> int_of_out_scope_tag tag
-             | _ -> in_scope
+             | Some tag when tag = in_scope_tag -> 0, true
+             | Some tag when is_out_scope_tag tag->int_of_out_scope_tag tag,true
+             | _ -> in_scope, false
+           in
+           let ms = 
+             if not clear then ms
+             else 
+               metasenv, 
+               (i,(None,c,t,ty)) :: List.filter (fun j,_ -> i <> j) subst
            in
            aux (context,k,in_scope) ms (NCicSubstitution.subst_meta l1 t)
          with NCicUtils.Subst_not_found _ ->
@@ -386,10 +439,7 @@ let delift ~unify metasenv subst context n l t =
       let lc = NCicUtils.expand_local_context lc in
       let l = List.map (NCicSubstitution.lift shift) lc in
        if
-         List.exists
-          (fun t -> 
-                  NCicUntrusted.metas_of_term subst context t = [])
-            l
+        List.exists (fun t-> NCicUntrusted.metas_of_term subst context t <> [])l
        then
         raise (Uncertain msg)
        else