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|
(******************************************************************************
* Core *
* *
* Copyright (C) 2008- Jane Street Holding, LLC *
* Contact: opensource@janestreet.com *
* WWW: http://www.janestreet.com/ocaml *
* *
* *
* This library 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; either *
* version 2 of the License, or (at your option) any later version. *
* *
* This library 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 library; if not, write to the Free Software *
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA *
* *
******************************************************************************)
(* belongs in Common, but moved here to avoid circular dependencies *)
type 'a return = { return : 'b. 'a -> 'b }
let with_return f =
let module M = struct
(* Raised to indicate ~return was called. Local so that the exception is tied to a
particular call of [with_return]. *)
exception Return
end
in
let r = ref None in (* stores the return value *)
let return = { (* closure passed to f *)
return = (fun x ->
r := Some x;
raise M.Return);
}
in
try
let rval = f return in
begin match !r with
| None -> rval
| Some _ -> failwith "with_return exited normally despite return being called"
end
with M.Return -> (* allows other exceptions through *)
match !r with
| None -> assert false
| Some x -> x
|
