From: Andrea Asperti <andrea.asperti@unibo.it>
Date: Wed, 27 Jan 2010 08:47:27 +0000 (+0000)
Subject: Added a parameter no_implicit (default true) to choose between raising
X-Git-Tag: make_still_working~3091
X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=commitdiff_plain;h=c35e139601a743e7e4b6f4abda745628efdb4744;p=helm.git

Added a parameter no_implicit (default true) to choose between raising
assert false or returning the identity.
---

diff --git a/helm/software/components/ng_kernel/nCicSubstitution.ml b/helm/software/components/ng_kernel/nCicSubstitution.ml
index 43a2f8174..d3e6756d8 100644
--- a/helm/software/components/ng_kernel/nCicSubstitution.ml
+++ b/helm/software/components/ng_kernel/nCicSubstitution.ml
@@ -22,7 +22,7 @@ module Ref = NReference
 
 let debug_print = fun _ -> ();;
 
-let lift_from k n =
+let lift_from ?(no_implicit=true) k n =
  let rec liftaux k = function
     | C.Rel m as t -> if m < k then t else C.Rel (m + n)
     | C.Meta (i,(m,(C.Irl 0 as l))) when k <= m+1 -> C.Meta (i,(m,l))
@@ -31,15 +31,16 @@ let lift_from k n =
     | C.Meta (i,(m,l)) -> 
        let lctx = NCicUtils.expand_local_context l in
        C.Meta (i, (m, C.Ctx (HExtlib.sharing_map (liftaux (k-m)) lctx)))
-    | C.Implicit _ -> (* was the identity *) assert false
+    | C.Implicit _ as t -> (* was the identity *) 
+	if no_implicit then assert false
+	else t
     | t -> NCicUtils.map (fun _ k -> k + 1) k liftaux t
  in
  liftaux k
 ;;
 
-let lift ?(from=1) n t =
-  if n = 0 then t
-  else lift_from from n t
+let lift ?(from=1) ?(no_implicit=true) n t =
+  if n = 0 then t else lift_from ~no_implicit from n t
 ;;
 
 
@@ -50,7 +51,7 @@ let lift ?(from=1) n t =
 (*  well typed and avoid_beta_redexes is true.                          *)
 (*  map_arg is ReductionStrategy.from_env_for_unwind when psubst is     *)
 (*  used to implement nCicReduction.unwind'                             *)
-let rec psubst ?(avoid_beta_redexes=false) map_arg args = 
+let rec psubst ?(avoid_beta_redexes=false) ?(no_implicit=true) map_arg args = 
  let nargs = List.length args in
  let rec substaux k = function
    | C.Rel n as t ->
@@ -59,7 +60,7 @@ let rec psubst ?(avoid_beta_redexes=false) map_arg args =
          if nargs <> 0 then C.Rel (n - nargs) else t
       | n when n < k -> t
       | n (* k <= n < k+nargs *) ->
-       (try lift (k-1) (map_arg (List.nth args (n-k)))
+       (try lift ~no_implicit (k-1) (map_arg (List.nth args (n-k)))
         with Failure _ | Invalid_argument _ -> assert false))
    | C.Meta (i,(m,l)) as t when m >= k + nargs - 1 -> 
        if nargs <> 0 then C.Meta (i,(m-nargs,l)) else t
@@ -67,8 +68,11 @@ let rec psubst ?(avoid_beta_redexes=false) map_arg args =
    | C.Meta (i,(m,l)) -> 
       let lctx = NCicUtils.expand_local_context l in
        C.Meta (i,(0, 
-         C.Ctx (HExtlib.sharing_map (fun x -> substaux k (lift m x)) lctx)))
-   | C.Implicit _ -> assert false (* was identity *)
+         C.Ctx (HExtlib.sharing_map 
+		  (fun x -> substaux k (lift ~no_implicit m x)) lctx)))
+   | C.Implicit _ as t -> 
+       if no_implicit then assert false (* was identity *)
+       else t
    | C.Appl (he::tl) as t ->
       (* Invariant: no Appl applied to another Appl *)
       let rec avoid he' = function
@@ -80,7 +84,8 @@ let rec psubst ?(avoid_beta_redexes=false) map_arg args =
                 (* map_arg is here \x.x, Obj magic is needed because 
                  * we don't have polymorphic recursion w/o records *)
                 avoid (psubst 
-                  ~avoid_beta_redexes Obj.magic [Obj.magic arg] bo) tl'
+                  ~avoid_beta_redexes ~no_implicit
+		  Obj.magic [Obj.magic arg] bo) tl'
             | _ -> if he == he' && args == tl then t else C.Appl (he'::args))
       in
       let tl = HExtlib.sharing_map (substaux k) tl in
@@ -90,8 +95,8 @@ let rec psubst ?(avoid_beta_redexes=false) map_arg args =
   substaux 1
 ;;
 
-let subst ?avoid_beta_redexes arg = 
-  psubst ?avoid_beta_redexes (fun x -> x)[arg];;
+let subst ?avoid_beta_redexes ?no_implicit arg = 
+  psubst ?avoid_beta_redexes ?no_implicit(fun x -> x)[arg];;
 
 (* subst_meta (n, C.Ctx [t_1 ; ... ; t_n]) t                                 *)
 (*  returns the term [t] where [Rel i] is substituted with [t_i] lifted by n *)
diff --git a/helm/software/components/ng_kernel/nCicSubstitution.mli b/helm/software/components/ng_kernel/nCicSubstitution.mli
index 38408fe13..ad8074dc7 100644
--- a/helm/software/components/ng_kernel/nCicSubstitution.mli
+++ b/helm/software/components/ng_kernel/nCicSubstitution.mli
@@ -22,14 +22,16 @@ val set_ppterm : (context:NCic.context ->
 (*  [from] default 1, lifts only indexes >= [from]                       *)
 (*  NOTE: the opposite function (delift_rels) is defined in CicMetaSubst *)
 (*  since it needs to restrict the metavariables in case of failure      *)
-val lift : ?from:int -> int -> NCic.term -> NCic.term
+val lift : ?from:int -> ?no_implicit:bool -> int -> NCic.term -> NCic.term
 
 (* subst t1 t2                                                          *)
 (*  substitutes [t1] for [Rel 1] in [t2]                                *)
 (*  if avoid_beta_redexes is true (default: false) no new beta redexes  *)
 (*  are generated. WARNING: the substitution can diverge when t2 is not *)
 (*  well typed and avoid_beta_redexes is true.                          *)
-val subst : ?avoid_beta_redexes:bool -> NCic.term -> NCic.term -> NCic.term
+val subst : 
+  ?avoid_beta_redexes:bool -> ?no_implicit:bool -> 
+  NCic.term -> NCic.term -> NCic.term
 
 (* psubst [avoid] [map_arg] [args] [t]            
  *  [avoid] : do not leave newly created beta-redexes, default false
@@ -39,7 +41,7 @@ val subst : ?avoid_beta_redexes:bool -> NCic.term -> NCic.term -> NCic.term
  *    the function is ReductionStrategy.from_env_for_unwind when psubst is
  *    used to implement nCicReduction.unwind'                              *)
 val psubst : 
-  ?avoid_beta_redexes:bool ->  
+  ?avoid_beta_redexes:bool -> ?no_implicit:bool ->
   ('a -> NCic.term) -> 'a list -> NCic.term -> 
     NCic.term