X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fcomponents%2Fng_refiner%2FnCicMetaSubst.ml;h=60abe85c37c08879ea80d01ededa27c158d0192f;hb=d6ba7f4b8fbd98f2f1c848857022ef5fba80db53;hp=5e72d90c77eac85827b0cef8ae790b9f51b40396;hpb=2b1eb6d5cd2d3ff5024e48615df4b99692008690;p=helm.git

diff --git a/helm/software/components/ng_refiner/nCicMetaSubst.ml b/helm/software/components/ng_refiner/nCicMetaSubst.ml
index 5e72d90c7..60abe85c3 100644
--- a/helm/software/components/ng_refiner/nCicMetaSubst.ml
+++ b/helm/software/components/ng_refiner/nCicMetaSubst.ml
@@ -14,24 +14,27 @@
 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;;
 
-let position n (shift, lc) =
+let position to_skip n (shift, lc) =
   match lc with
+  | NCic.Irl _ when to_skip > 0 -> assert false  (* unclear to me *)
   | NCic.Irl len when n <= shift || n > shift + len -> raise NotInTheList
   | NCic.Irl _ -> n - shift
   | NCic.Ctx tl ->
-      let rec aux k = function 
+      let rec aux to_skip k = function 
          | [] -> raise NotInTheList
+         | _ :: tl when to_skip > 0 -> aux (to_skip - 1) (k+1) tl
          | (NCic.Rel m)::_ when m + shift = n -> k
-         | _::tl -> aux (k+1) tl 
+         | _::tl -> aux to_skip (k+1) tl 
       in
-       aux 1 tl
+       aux to_skip 1 tl
 ;;
 
 let pack_lc orig = 
@@ -69,31 +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 
@@ -193,23 +206,104 @@ and restrict metasenv subst i restrictions =
     | NCicUtils.Meta_not_found _ -> assert false
 ;;
 
+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 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 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 ;;
+let is_out_scope_tag tag =
+   String.length tag > String.length out_scope_tag_prefix &&
+   String.sub tag 0 (String.length out_scope_tag_prefix) = out_scope_tag_prefix 
+;;
+let int_of_out_scope_tag tag = 
+  int_of_string
+   (String.sub tag (String.length out_scope_tag_prefix)
+     (String.length tag - (String.length out_scope_tag_prefix)))
+;;
+
+
+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 metasenv subst context n l t =
-  let rec aux k (metasenv, subst as ms) = function
+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 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
+             let li = NCicSubstitution.lift (k+shift) li in
+             match unify metasenv subst context li t with
+             | Some (metasenv,subst) -> 
+                 Some ((metasenv, subst), NCic.Rel (i+1+k))
+             | None -> None)
+          lb
+  in
+  let rec aux (context,k,in_scope) (metasenv, subst as ms) t = 
+   match unify_list in_scope metasenv subst context k t with
+   | Some x -> x
+   | None -> 
+    match t with 
     | NCic.Rel n as t when n <= k -> ms, t
     | NCic.Rel n -> 
         (try
           match List.nth context (n-k-1) with
           | _,NCic.Def (bo,_) -> 
-                (try ms, NCic.Rel ((position (n-k) l) + k)
+                (try ms, NCic.Rel ((position in_scope (n-k) l) + k)
                  with NotInTheList ->
                 (* CSC: This bit of reduction hurts performances since it is
                  * possible to  have an exponential explosion of the size of the
                  * proof. required for nat/nth_prime.ma *)
-                  aux k ms (NCicSubstitution.lift n bo))
-          | _,NCic.Decl _ -> ms, NCic.Rel ((position (n-k) l) + k)
+                  aux (context,k,in_scope) ms (NCicSubstitution.lift n bo))
+          | _,NCic.Decl _ -> ms, NCic.Rel ((position in_scope (n-k) l) + k)
         with Failure _ -> assert false) (*Unbound variable found in delift*)
     | NCic.Meta (i,_) when i=n ->
          raise (MetaSubstFailure (lazy (Printf.sprintf (
@@ -219,8 +313,20 @@ let delift metasenv subst context n l t =
             (NCicPp.ppterm ~context ~metasenv ~subst t))))
     | NCic.Meta (i,l1) as orig ->
         (try
-           let _,_,t,_ = NCicUtils.lookup_subst i subst in
-           aux k ms (NCicSubstitution.subst_meta l1 t)
+           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, 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 _ ->
            if snd l1 = NCic.Irl 0 || snd l1 = NCic.Ctx [] then ms, orig
            else
@@ -289,7 +395,7 @@ let delift metasenv subst context n l t =
                     | t::tl ->
                         let ms, tbr, tl = deliftl tbr (j+1) ms tl in
                         try 
-                          let ms, t = aux k ms t in 
+                          let ms, t = aux (context,k,in_scope) ms t in 
                           ms, tbr, t::tl
                         with
                         | NotInTheList | MetaSubstFailure _ -> ms, j::tbr, tl
@@ -312,9 +418,11 @@ let delift metasenv subst context n l t =
                       restrict metasenv subst i to_be_r in
                     (metasenv, subst), NCic.Meta(newmeta,l1))
 
-    | t -> NCicUntrusted.map_term_fold_a (fun _ k -> k+1) k aux ms t
+    | t -> 
+        NCicUntrusted.map_term_fold_a 
+          (fun e (c,k,s) -> (e::c,k+1,s)) (context,k,in_scope) aux ms t
   in
-   try aux 0 (metasenv,subst) t
+   try aux (context,0,0) (metasenv,subst) t
    with NotInTheList ->
       (* This is the case where we fail even first order unification. *)
       (* The reason is that our delift function is weaker than first  *)
@@ -331,10 +439,7 @@ let delift 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
@@ -347,27 +452,27 @@ let mk_meta ?name metasenv context ty =
   | `WithType ty ->
     let len = List.length context in
     let menv_entry = (n, (name, context, ty)) in
-    menv_entry :: metasenv, NCic.Meta (n, (0,NCic.Irl len)), ty
+    menv_entry :: metasenv, n, NCic.Meta (n, (0,NCic.Irl len)), ty
   | `Sort ->
     let ty = NCic.Implicit (`Typeof n) in
     mk_meta (tyof name) n metasenv [] (`WithType ty)
   | `Type ->
-    let metasenv, ty, _ = 
+    let metasenv, _, ty, _ = 
       mk_meta (tyof name) (newmeta ()) metasenv context `Sort in
     mk_meta name n metasenv context (`WithType ty)
   | `Term ->
-    let metasenv, ty, _ = 
+    let metasenv, _, ty, _ = 
       mk_meta (tyof name) (newmeta ()) metasenv context `Type in
     mk_meta name n metasenv context (`WithType ty)
   in
     mk_meta name (newmeta ()) metasenv context ty
 ;;
 
-let saturate ?(delta=0) metasenv context ty goal_arity =
+let saturate ?(delta=0) metasenv subst context ty goal_arity =
  assert (goal_arity >= 0);
   let rec aux metasenv = function
-   | NCic.Prod (name,s,t) ->
-       let metasenv1, arg,_ = 
+   | NCic.Prod (name,s,t) as ty ->
+       let metasenv1, _, arg,_ = 
           mk_meta ~name:name metasenv context (`WithType s) in            
        let t, metasenv1, args, pno = 
            aux metasenv1 (NCicSubstitution.subst arg t) 
@@ -377,7 +482,7 @@ let saturate ?(delta=0) metasenv context ty goal_arity =
        else
          t, metasenv1, arg::args, pno+1
    | ty ->
-        match NCicReduction.whd context ty ~delta with
+        match NCicReduction.whd ~subst context ty ~delta with
         | NCic.Prod _ as ty -> aux metasenv ty
         | ty -> ty, metasenv, [], 0
   in