From 7cfc4e5146be5666419451bdd516f1f3f264d24a Mon Sep 17 00:00:00 2001
From: Enrico Tassi <gareuselesinge@debian.org>
Date: Sun, 25 Jan 2015 14:42:51 +0100
Subject: Imported Upstream version 8.5~beta1+dfsg

---
 lib/hook.ml | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 lib/hook.ml

(limited to 'lib/hook.ml')

diff --git a/lib/hook.ml b/lib/hook.ml
new file mode 100644
index 00000000..0aa373c2
--- /dev/null
+++ b/lib/hook.ml
@@ -0,0 +1,32 @@
+(************************************************************************)
+(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
+(* <O___,, *   INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2015     *)
+(*   \VV/  **************************************************************)
+(*    //   *      This file is distributed under the terms of the       *)
+(*         *       GNU Lesser General Public License Version 2.1        *)
+(************************************************************************)
+
+type 'a content =
+| Unset
+| Default of 'a
+| Set of 'a
+
+type 'a t = 'a content ref
+
+type 'a value = 'a t
+
+let get (hook : 'a value) = match !hook with
+| Unset -> assert false
+| Default data | Set data -> data
+
+let set (hook : 'a t) data = match !hook with
+| Unset | Default _ -> hook := Set data
+| Set _ -> assert false
+
+let make ?default () =
+  let data = match default with
+  | None -> Unset
+  | Some data -> Default data
+  in
+  let ans = ref data in
+  (ans, ans)
-- 
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