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--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                S Y S T E M . F I N A L I Z A T I O N _ R O O T           --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--          Copyright (C) 1992-2009, Free Software Foundation, Inc.         --

--                                                                          --

-- GNAT is free software;  you can  redistribute it  and/or modify it under --

-- terms of the  GNU General Public License as published  by the Free Soft- --

-- ware  Foundation;  either version 3,  or (at your option) any later ver- --

-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --

-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --

-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --

--                                                                          --

-- As a special exception under Section 7 of GPL version 3, you are granted --

-- additional permissions described in the GCC Runtime Library Exception,   --

-- version 3.1, as published by the Free Software Foundation.               --

--                                                                          --

-- You should have received a copy of the GNU General Public License and    --

-- a copy of the GCC Runtime Library Exception along with this program;     --

-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --

-- <http://www.gnu.org/licenses/>.                                          --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

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--  This unit provides the basic support for controlled (finalizable) types

with Ada.Streams;

with Ada.Unchecked_Conversion;

package System.Finalization_Root is

   pragma Preelaborate;

   type Root_Controlled is tagged;

   type Finalizable_Ptr is access all Root_Controlled'Class;

   function To_Finalizable_Ptr is

     new Ada.Unchecked_Conversion (Address, Finalizable_Ptr);

   function To_Addr is

     new Ada.Unchecked_Conversion (Finalizable_Ptr, Address);

   type Empty_Root_Controlled is abstract tagged null record;

   --  Just for the sake of Controlled equality (see Ada.Finalization)

   type Root_Controlled is new Empty_Root_Controlled with record

      Prev, Next : Finalizable_Ptr;

   end record;

   subtype Finalizable is Root_Controlled'Class;

   procedure Initialize (Object : in out Root_Controlled);

   procedure Finalize   (Object : in out Root_Controlled);

   procedure Adjust     (Object : in out Root_Controlled);

   --  Stream-oriented attributes for Root_Controlled. These must be empty so

   --  as to not copy the finalization chain pointers. They are declared in

   --  a nested package so that they do not create primitive operations of

   --  Root_Controlled. Otherwise this would add unwanted primitives to (the

   --  full view of) Ada.Finalization.Limited_Controlled, which would cause

   --  trouble in cases where a limited controlled type is used as the

   --  designated type of a remote access-to-classwide type.

   package Stream_Attributes is

      procedure Write

        (Stream : not null access Ada.Streams.Root_Stream_Type'Class;

         Item   : Root_Controlled) is null;

      procedure Read

        (Stream : not null access Ada.Streams.Root_Stream_Type'Class;

         Item   : out Root_Controlled) is null;

   end Stream_Attributes;

   for Root_Controlled'Read use Stream_Attributes.Read;

   for Root_Controlled'Write use Stream_Attributes.Write;

end System.Finalization_Root;