------------------------->  GNU Sather - sourcefile  <-------------------------
-- Copyright (C) 1995 by International Computer Science Institute            --
-- This file is part of the GNU Sather library. It is free software; you may --
-- redistribute  and/or modify it under the terms of the GNU Library General --
-- Public  License (LGPL)  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 Doc/LGPL for more details.       --
-- The license text is also available from:  Free Software Foundation, Inc., --
-- 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA                     --
-------------->  Please email comments to <bug-sather@gnu.org>  <--------------

-- Successor stream
-- Author: Benedict A. Gomes <gomes@samosa.ICSI.Berkeley.EDU>

abstract class $SUCC_STREAM{NTP} is
   -- An abstraction that specifies a generator of successive 
   -- unique values of type NTP
   
   next: NTP;
   -- Return the next unique value
   
end;
-------------------------------------------------------------------
class INT_STREAM < $SUCC_STREAM{INT} is
   -- Yield a stream of successive integers

   private attr val: INT;
   
   create(start_val: INT): SAME is
      -- Return a new integer stream whose next yielded
      -- value will be "start_val"
      res ::= new;
      res.val := start_val;
      return res;
   end;
   
   next: INT is
      -- Yield the next integer in this stream
      -- Wrap around is not permitted in this kind of integer stream
      res ::= val;
      assert val /= INT::maxint;
      val := val+1;
      return res;
   end;
   
   
   next!: INT is
      -- Keep yielding successive integers. 
      -- Will quit at maxint - 1
      if val = INT::maxint then quit end;
      yield next;
   end;
   
end;
-------------------------------------------------------------------


