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|
(***********************************************************************)
(* sStream.ml - simple stream with 1-step lookahead. *)
(* *)
(* Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, *)
(* 2011, 2012, 2013 Yaron Minsky and Contributors *)
(* *)
(* This file is part of SKS. SKS is free software; you can *)
(* redistribute it and/or modify it under the terms of the GNU General *)
(* Public License as published by the Free Software Foundation; either *)
(* version 2 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 *)
(* General Public License for more details. *)
(* *)
(* You should have received a copy of the GNU 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 or see <http://www.gnu.org/licenses/>. *)
(***********************************************************************)
type 'b sstream = { mutable first: 'b option;
next: unit -> 'b option;
}
let make ?first next = { first = first;
next = next;
}
let next s =
match s.first with
None -> s.next ()
| v ->
s.first <- None;
v
let peek s =
if s.first = None
then s.first <- s.next ();
s.first
let junk s =
if s.first = None
then ignore (s.next ())
else s.first <- None
|
