Source file polytables.ml

(* Ocsigen
 * Copyright (C) 2009
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, with linking exception;
 * either version 2.1 of the License, or (at your option) any later version.
 *
 * This program 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *)
(**
   @author Vincent Balat
   @author Jérôme Vouillon
*)

type 'a key = int * 'a option ref

module T = Map.Make (struct
  type t = int

  let compare = compare
end)

type t = (unit -> unit) T.t ref

let create () = ref T.empty
let c = ref (-1)

let make_key () =
  c := !c + 1;
  !c, ref None

let set ~(table : t) ~key:((k, r) : 'a key) ~(value : 'a) =
  table := T.add k (fun () -> r := Some value) !table

let get ~(table : t) ~key:((k, r) : 'a key) =
  (T.find k !table) ();
  match !r with
  | Some v ->
      r := None;
      v
  | None -> failwith "Polytables.get"

let remove ~(table : t) ~key:((k, _r) : 'a key) = table := T.remove k !table
let clear ~(table : t) = table := T.empty