gcc/ada/s-finroo.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                S Y S T E M . F I N A L I Z A T I O N _ R O O T           --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2009, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNAT was originally developed  by the GNAT team at  New York University. --
  28 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  This unit provides the basic support for controlled (finalizable) types
  33
  34 with Ada.Streams;
  35 with Ada.Unchecked_Conversion;
  36
  37 package System.Finalization_Root is
  38    pragma Preelaborate;
  39
  40    type Root_Controlled is tagged;
  41
  42    type Finalizable_Ptr is access all Root_Controlled'Class;
  43
  44    function To_Finalizable_Ptr is
  45      new Ada.Unchecked_Conversion (Address, Finalizable_Ptr);
  46
  47    function To_Addr is
  48      new Ada.Unchecked_Conversion (Finalizable_Ptr, Address);
  49
  50    type Empty_Root_Controlled is abstract tagged null record;
  51    --  Just for the sake of Controlled equality (see Ada.Finalization)
  52
  53    type Root_Controlled is new Empty_Root_Controlled with record
  54       Prev, Next : Finalizable_Ptr;
  55    end record;
  56    subtype Finalizable is Root_Controlled'Class;
  57
  58    procedure Initialize (Object : in out Root_Controlled);
  59    procedure Finalize   (Object : in out Root_Controlled);
  60    procedure Adjust     (Object : in out Root_Controlled);
  61
  62    --  Stream-oriented attributes for Root_Controlled. These must be empty so
  63    --  as to not copy the finalization chain pointers. They are declared in
  64    --  a nested package so that they do not create primitive operations of
  65    --  Root_Controlled. Otherwise this would add unwanted primitives to (the
  66    --  full view of) Ada.Finalization.Limited_Controlled, which would cause
  67    --  trouble in cases where a limited controlled type is used as the
  68    --  designated type of a remote access-to-classwide type.
  69
  70    package Stream_Attributes is
  71
  72       procedure Write
  73         (Stream : not null access Ada.Streams.Root_Stream_Type'Class;
  74          Item   : Root_Controlled) is null;
  75
  76       procedure Read
  77         (Stream : not null access Ada.Streams.Root_Stream_Type'Class;
  78          Item   : out Root_Controlled) is null;
  79
  80    end Stream_Attributes;
  81
  82    for Root_Controlled'Read use Stream_Attributes.Read;
  83    for Root_Controlled'Write use Stream_Attributes.Write;
  84
  85 end System.Finalization_Root;