From b873fcd647e7b30e486eac5c5470762c9bc79e93 Mon Sep 17 00:00:00 2001
From: Claudio Sacerdoti Coen <claudio.sacerdoticoen@unibo.it>
Date: Wed, 22 Jul 2009 16:39:32 +0000
Subject: [PATCH] Major speed-up: meta-chains are now expanded during
 restriction to avoid creating longer ones and to avoid restricting twice the
 same conjecture.

---
 .../components/ng_refiner/nCicMetaSubst.ml    | 58 +++++++++++--------
 1 file changed, 34 insertions(+), 24 deletions(-)

diff --git a/helm/software/components/ng_refiner/nCicMetaSubst.ml b/helm/software/components/ng_refiner/nCicMetaSubst.ml
index 26dc85cac..a445d16be 100644
--- a/helm/software/components/ng_refiner/nCicMetaSubst.ml
+++ b/helm/software/components/ng_refiner/nCicMetaSubst.ml
@@ -72,31 +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 
-- 
2.39.2