From 46aef7e789424049c13689f4ff1736d77dfc87bc Mon Sep 17 00:00:00 2001
From: Enrico Tassi <enrico.tassi@inria.fr>
Date: Thu, 27 Mar 2008 10:50:09 +0000
Subject: [PATCH] added iterators over NCic terms

---
 .../components/ng_kernel/nCicUtils.ml         | 81 +++++++++++++------
 .../components/ng_kernel/nCicUtils.mli        |  4 +
 2 files changed, 61 insertions(+), 24 deletions(-)

diff --git a/helm/software/components/ng_kernel/nCicUtils.ml b/helm/software/components/ng_kernel/nCicUtils.ml
index 965f1cf2b..5d3304f60 100644
--- a/helm/software/components/ng_kernel/nCicUtils.ml
+++ b/helm/software/components/ng_kernel/nCicUtils.ml
@@ -1,27 +1,13 @@
-(* Copyright (C) 2000, HELM Team.
- * 
- * This file is part of HELM, an Hypertextual, Electronic
- * Library of Mathematics, developed at the Computer Science
- * Department, University of Bologna, Italy.
- * 
- * HELM is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- * 
- * HELM is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with HELM; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston,
- * MA  02111-1307, USA.
- * 
- * For details, see the HELM World-Wide-Web page,
- * http://cs.unibo.it/helm/.
- *)
+(*
+    ||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_______________________________________________________________ *)
 
 (* $Id: nCicSubstitution.ml 8135 2008-02-13 15:35:43Z tassi $ *)
 
@@ -42,3 +28,50 @@ let lookup_subst n subst =
     List.assoc n subst
   with Not_found -> raise (Subst_not_found n)
 
+let fold f g acc = function
+ | NCic.Implicit _
+ | NCic.Sort _
+ | NCic.Const _
+ | NCic.Meta _
+ | NCic.Rel _ -> acc
+ | NCic.Appl l -> List.fold_left f acc l
+ | NCic.Prod (_,s,t)
+ | NCic.Lambda (_,s,t) -> f (g (f acc s)) t
+ | NCic.LetIn (_,ty,t,bo) -> f (g (f (f acc ty) t)) bo
+ | NCic.Match (_,oty,t,pl) -> List.fold_left f (f (f acc oty) t) pl
+;;
+
+let sharing_map f l =
+  let unchanged = ref true in
+  let rec aux b = function
+    | [] as t -> unchanged := b; t
+    | he::tl ->
+        let he1 = f he in
+        he1 :: aux (b && he1 == he) tl
+  in
+  let l1 = aux true l in
+  if !unchanged then l else l1
+;;
+        
+let map f g k = function
+ | NCic.Implicit _
+ | NCic.Sort _
+ | NCic.Const _
+ | NCic.Meta _
+ | NCic.Rel _ as t -> t
+ | NCic.Appl l -> NCic.Appl (sharing_map (f k) l)
+ | NCic.Prod (n,s,t) as orig ->
+     let s1 = f k s in let t1 = f (g k) t in
+     if t1 == t && s1 == s then orig else NCic.Prod (n,s1,t1)
+ | NCic.Lambda (n,s,t) as orig -> 
+     let s1 = f k s in let t1 = f (g k) t in
+     if t1 == t && s1 == s then orig else NCic.Prod (n,s1,t1)
+ | NCic.LetIn (n,ty,t,b) as orig -> 
+     let ty1 = f k ty in let t1 = f k t in let b1 = f (g k) b in
+     if ty1 == ty && t1 == t && b1 == b then orig else NCic.LetIn (n,ty1,t1,b1)
+ | NCic.Match (r,oty,t,pl) as orig -> 
+     let oty1 = f k oty in let t1 = f k t in let pl1 = sharing_map (f k) pl in
+     if oty1 == oty && t1 == t && pl1 == pl then orig 
+     else NCic.Match(r,oty1,t1,pl1)
+;;
+
diff --git a/helm/software/components/ng_kernel/nCicUtils.mli b/helm/software/components/ng_kernel/nCicUtils.mli
index 6af6ac8f0..506af8c0b 100644
--- a/helm/software/components/ng_kernel/nCicUtils.mli
+++ b/helm/software/components/ng_kernel/nCicUtils.mli
@@ -31,3 +31,7 @@ val expand_local_context : NCic.lc_kind -> NCic.term list
 
 val lookup_subst: int ->  NCic.substitution -> NCic.subst_entry
 
+(* both Meta agnostic, map attempts to preserve sharing.
+ * call the 'a->'a function when a binder is crossed *)
+val fold: ('a -> NCic.term -> 'a) -> ('a -> 'a) -> 'a -> NCic.term -> 'a
+val map: ('a -> NCic.term -> NCic.term) -> ('a -> 'a) -> 'a -> NCic.term -> NCic.term
-- 
2.39.2