1 files changed, 43 insertions, 0 deletions
diff --git a/lib/dAst.ml b/lib/dAst.ml
new file mode 100644
index 00000000..f34ab956
--- /dev/null
+++ b/lib/dAst.ml
@@ -0,0 +1,43 @@
+(************************************************************************)
+(*         *   The Coq Proof Assistant / The Coq Development Team       *)
+(*  v      *   INRIA, CNRS and contributors - Copyright 1999-2018       *)
+(* <O___,, *       (see CREDITS file for the list of authors)           *)
+(*   \VV/  **************************************************************)
+(*    //   *    This file is distributed under the terms of the         *)
+(*         *     GNU Lesser General Public License Version 2.1          *)
+(*         *     (see LICENSE file for the text of the license)         *)
+(************************************************************************)
+
+open CAst
+
+type ('a, _) thunk =
+| Value : 'a -> ('a, 'b) thunk
+| Thunk : 'a Lazy.t -> ('a, [ `thunk ]) thunk
+
+type ('a, 'b) t = ('a, 'b) thunk CAst.t
+
+let map_thunk (type s) f : (_, s) thunk -> (_, s) thunk = function
+| Value x -> Value (f x)
+| Thunk k -> Thunk (lazy (f (Lazy.force k)))
+
+let get_thunk (type s) : ('a, s) thunk -> 'a = function
+| Value x -> x
+| Thunk k -> Lazy.force k
+
+let get x = get_thunk x.v
+
+let make ?loc v = CAst.make ?loc (Value v)
+
+let delay ?loc v = CAst.make ?loc (Thunk (Lazy.from_fun v))
+
+let map f n = CAst.map (fun x -> map_thunk f x) n
+
+let map_with_loc f n =
+  CAst.map_with_loc (fun ?loc x -> map_thunk (fun x -> f ?loc x) x) n
+
+let map_from_loc f (loc, x) =
+  make ?loc (f ?loc x)
+
+let with_val f n = f (get n)
+
+let with_loc_val f n = f ?loc:n.CAst.loc (get n)