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(************************************************************************)
(* * 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) *)
(************************************************************************)
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)
|
