-- F340A000.A
--
--                             Grant of Unlimited Rights
--
--     Under contracts F33600-87-D-0337, F33600-84-D-0280, MDA903-79-C-0687,
--     F08630-91-C-0015, and DCA100-97-D-0025, the U.S. Government obtained 
--     unlimited rights in the software and documentation contained herein.
--     Unlimited rights are defined in DFAR 252.227-7013(a)(19).  By making 
--     this public release, the Government intends to confer upon all 
--     recipients unlimited rights  equal to those held by the Government.  
--     These rights include rights to use, duplicate, release or disclose the 
--     released technical data and computer software in whole or in part, in 
--     any manner and for any purpose whatsoever, and to have or permit others 
--     to do so.
--
--                                    DISCLAIMER
--
--     ALL MATERIALS OR INFORMATION HEREIN RELEASED, MADE AVAILABLE OR
--     DISCLOSED ARE AS IS.  THE GOVERNMENT MAKES NO EXPRESS OR IMPLIED 
--     WARRANTY AS TO ANY MATTER WHATSOEVER, INCLUDING THE CONDITIONS OF THE
--     SOFTWARE, DOCUMENTATION OR OTHER INFORMATION RELEASED, MADE AVAILABLE 
--     OR DISCLOSED, OR THE OWNERSHIP, MERCHANTABILITY, OR FITNESS FOR A
--     PARTICULAR PURPOSE OF SAID MATERIAL.
--*
--
-- FOUNDATION DESCRIPTION:
--      This file simulates a generic linked list abstraction for use in tests
--      covering tagged types and type extensions.
--
-- TEST FILES:
--      This foundation consists of the following files:
--
--      => F340A000.A
--         F340A001.A
--
-- CHANGE HISTORY:
--      06 Dec 94   SAIC    ACVC 2.0
--      12 Jun 96   SAIC    ACVC 2.1: Modified prologue. Added pragma
--                          Elaborate_Body.
--
--!

generic  -- Singly-linked list abstraction.
   type Parent_Type is tagged private;                   -- Actual is parent
package F340A000 is                                      -- tagged type.

   pragma Elaborate_Body;


   -- Declarations for visible linked list nodes:

   type Node_Type;

   type Node_Ptr is access Node_Type;

   type Node_Type is new Parent_Type with record         -- Record extension
      Next : Node_Ptr := null;                           -- of parent type.
   end record;


   -- Inherits primitive operations of actual type corresponding
   -- to Parent_Type.

   -- Add node at head of list.
   procedure Add (Item : in     Node_Ptr;
                  Head : in out Node_Ptr);

   -- Remove node from head of list and return it.
   procedure Remove (Head : in out Node_Ptr;
                     Item :    out Node_Ptr);



   -- Declarations for private linked list nodes:

   type Priv_Node_Type is new Parent_Type with private;  -- Private extension
                                                         -- of parent type.

   -- Inherits primitive operations of actual parameter corresponding
   -- to Parent_Type.


   type Priv_Node_Ptr is access Priv_Node_Type;


   -- Add node at head of list.
   procedure Add (Item : in     Priv_Node_Ptr;
                  Head : in out Priv_Node_Ptr);

   -- Remove node from head of list and return it.
   procedure Remove (Head : in out Priv_Node_Ptr;
                     Item :    out Priv_Node_Ptr);
                     

private

   type Priv_Node_Type is new Parent_Type with record
      Next : Priv_Node_Ptr := null;
   end record;

end F340A000;


     --==================================================================--


package body F340A000 is  -- Singly-linked list abstraction.

   procedure Add (Item : in     Node_Ptr;
                  Head : in out Node_Ptr) is
   begin
      if Item /= null then
         Item.Next := Head;
         Head := Item;
      end if;
   end Add;


   procedure Remove (Head : in out Node_Ptr;
                     Item :    out Node_Ptr) is
   begin
      Item := Head;
      if Head /= null then
         Head := Head.Next;
      end if;
   end Remove;


   procedure Add (Item : in     Priv_Node_Ptr;
                  Head : in out Priv_Node_Ptr) is
   begin
      if Item /= null then
         Item.Next := Head;
         Head := Item;
      end if;
   end Add;


   procedure Remove (Head : in out Priv_Node_Ptr;
                     Item :    out Priv_Node_Ptr) is
   begin
      Item := Head;
      if Head /= null then
         Head := Head.Next;
      end if;
   end Remove;


end F340A000;