cc30001.a

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-- CC30001.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.
--*
--
-- OBJECTIVE:
--      Check that if a non-overriding primitive subprogram is declared for
--      a type derived from a formal derived tagged type, the copy of that
--      subprogram in an instance can override a subprogram inherited from the
--      actual type.
--
-- TEST DESCRIPTION:
--      User writes program to handle both mail messages and system messages.
--
--      Mail messages are created by instantiating a generic "mail" package
--      with a root message type. System messages are created by
--      instantiating the generic with a system message type derived from the
--      root in a separate package. The system message type has a primitive
--      subprogram called Send.
--
--      Inside the generic, a "mail" type is derived from the generic formal
--      derived type, and a "Send" operation is declared.
--
--      Declare a root tagged type T. Declare a generic package with a formal
--      derived type using the root tagged type as ancestor. In the generic,
--      derive a type from the formal derived type and declare a primitive
--      subprogram for it. In a separate package, declare a derivative DT of
--      the root tagged type T and declare a primitive subprogram which is
--      type conformant with (and hence, overridable for) the primitive
--      declared in the generic. Instantiate the generic for DT. Make both
--      dispatching and non-dispatching calls to the primitive subprogram. In
--      both cases the version of the subprogram in the instance should be
--      called (since it overrides the implementation inherited from the
--      actual).
--
--
-- CHANGE HISTORY:
--      06 Dec 94   SAIC    ACVC 2.0
--      13 Apr 95   SAIC    Replaced call involving instance for root tagged
--                          type with a dispatching call involving instance
--                          for derived type. Updated commentary. Moved
--                          instantiations (and related commentary) to
--                          library-level to avoid accessibility violation.
--                          Commented out instantiation for root tagged type.
--      27 Feb 97   PWB.CTA Added elaboration pragma.
--!

package CC30001_0 is  -- Root message type.

   type Msg_Type is tagged record
      Text         : String (1 .. 20);
      Message_Sent : Boolean;
   end record;

end CC30001_0;


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


with CC30001_0;  -- Root message type.
generic          -- Generic "mail" package.
   type Message is new CC30001_0.Msg_Type with private;
package CC30001_1 is

   type Mail_Type is new Message with record   -- Derived from formal type.
      To : String (1 .. 8);
   end record;

   procedure Send (M : in out Mail_Type);      -- For this test, this version
                                               -- of Send should be called in
   -- ... Other operations.                    -- all cases.

end CC30001_1;


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


package body CC30001_1 is

   procedure Send (M : in out Mail_Type) is
   begin
      -- ... Code to send message omitted for brevity.
      M.Message_Sent := True;
   end Send;

end CC30001_1;


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


with CC30001_0;       -- Root message type.
package CC30001_2 is  -- System message type and operations.

   type Signal_Type is (Note, Warning, Error);

   type Sys_Message is new CC30001_0.Msg_Type with record   -- Derived from
      Signal : Signal_Type := Warning;                      -- root type.
   end record;

   procedure Send (Item : in out Sys_Message); -- For this test, this version
                                               -- of Send should never be
   -- ... Other operations.                    -- called (it will have been
                                               -- overridden).
end CC30001_2;


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


package body CC30001_2 is

   procedure Send (Item : in out Sys_Message) is
   begin
      -- ... Code to send message omitted for brevity.
      Item.Message_Sent := False;  -- Ensure this procedure gives a different
   end Send;                       -- result than CC30001_1.Send.

end CC30001_2;


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


-- User first sets up support for mail messages by instantiating the
-- generic mail package for the root message type. An operation "Send" is
-- declared for the mail message type in the instance.
--
-- with CC30001_0;  -- Root message type.
-- with CC30001_1;  -- Generic "mail" package.
-- package Mail_Messages is new CC30001_1 (CC30001_0.Msg_Type);


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


-- Next, the user sets up support for system messages by instantiating the
-- generic mail package with the system message type. An operation "Send"
-- is declared for the "system" mail message type in the instance. This
-- operation overrides the "Send" operation inherited from the system
-- message type actual (a situation the user may not have intended).

with CC30001_1;  -- Generic "mail" package.
with CC30001_2;  -- System message type and operations.
pragma Elaborate (CC30001_1);
package CC30001_3 is new CC30001_1 (CC30001_2.Sys_Message);


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

with CC30001_2;  -- System message type and operations.
with CC30001_3;  -- Instance with mail type and operations.

with Report;
procedure CC30001 is

   package System_Messages renames CC30001_3;


   Sys_Msg1 : System_Messages.Mail_Type := (Text   => "System shutting down",
                                            Signal => CC30001_2.Warning,
                                            To     => "AllUsers",
                                            Message_Sent => False);

   Sys_Msg2 : System_Messages.Mail_Type'Class := Sys_Msg1;


   use System_Messages, CC30001_2;                 -- All versions of "Send"
                                                   -- directly visible.

begin

   Report.Test ("CC30001", "Check that if a non-overriding primitive "     &
                "subprogram is declared for a type derived from a formal " &
                "derived tagged type, the copy of that subprogram in an "  &
                "instance can override a subprogram inherited from the "   &
                "actual type");


   Send (Sys_Msg1);   -- Calls version declared in instance (version declared
                      -- in CC30001_2 has been overridden).

   if not Sys_Msg1.Message_Sent then
      Report.Failed ("Non-dispatching call: instance operation not called");
   end if;


   Send (Sys_Msg2);   -- Calls version declared in instance (version declared
                      -- in CC30001_2 has been overridden).

   if not Sys_Msg2.Message_Sent then
      Report.Failed ("Dispatching call: instance operation not called");
   end if;


   Report.Result;
end CC30001;