refactoring ...

[helm.git] / helm / software / helena / src / basic_rg / brgSubstitution.ml

diff --git a/helm/software/helena/src/basic_rg/brgSubstitution.ml b/helm/software/helena/src/basic_rg/brgSubstitution.ml
new file mode 100644 (file)
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+++ b/helm/software/helena/src/basic_rg/brgSubstitution.ml
@@ -0,0 +1,50 @@
+(*
+    ||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_______________________________________________________________ *)
+
+module G = Options
+module B = Brg
+
+let rec icm a = function
+   | B.Sort _
+   | B.LRef _
+   | B.GRef _                     -> succ a
+   | B.Bind (_, B.Void, t)        -> icm (succ a) t
+   | B.Cast (_, u, t)             -> icm (icm a u) t
+   | B.Appl (_, u, t)
+   | B.Bind (_, B.Abst (_, u), t)
+   | B.Bind (_, B.Abbr u, t)      -> icm (icm (succ a) u) t
+
+let iter map d =
+   let rec iter_bind d = function
+      | B.Void        -> B.Void
+      | B.Abst (n, w) -> B.Abst (n, iter_term d w)
+      | B.Abbr v      -> B.Abbr (iter_term d v)
+   and iter_term d = function
+      | B.Sort _ as t      -> t
+      | B.GRef _ as t      -> t
+      | B.LRef (a, i) as t -> if i < d then t else map d a i
+      | B.Cast (a, w, v)   -> B.Cast (a, iter_term d w, iter_term d v)
+      | B.Appl (a, w, u)   -> B.Appl (a, iter_term d w, iter_term d u)
+      | B.Bind (a, b, u)   -> B.Bind (a, iter_bind d b, iter_term (succ d) u)
+   in
+   iter_term d
+
+let lift_map h _ a i =
+   if i + h >= 0 then B.LRef (a, i + h) else assert false
+
+let lift h d t =
+   if h = 0 then t else begin
+(*
+      G.icm := succ !G.icm; 
+      G.icm := icm !G.icm t;
+*)
+      iter (lift_map h) d t
+   end