-- File Queueg.ads
--  This is a generic queue package, built on top of a generic list
--  package (listg) that handles most of the pointer manipulation.
--  It will later be used in a graph traversal program.

with listg;

generic

   type Element is private;

package Queueg is

   type Queue is limited private;

-- constructors

   procedure Copy (From: in Queue;
                   To: in out Queue);

   procedure Clear (AQueue: in out Queue);

   procedure Add (Item: in Element;
                  ToQueue: in out Queue);

   procedure Pop (AQueue: in out Queue);

-- selectors

   function Equal (Left: in Queue;
                   Right: in Queue) return Boolean;

   function Empty (AQueue: in Queue) return Boolean;

   function First (OfQueue: in Queue) return Element;
     -- datum of front of queue

-- exceptions

   Underflow, Overflow: exception;

private

   package AList is new Listg (Element);
   use AList;

   type Queue is
      record
         Front,
         Rear:  List;
      end record;

end Queueg;