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   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 _ I M P L E M E N T A T I O N   --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2003 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 2,  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.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  19 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  20 -- MA 02111-1307, USA.                                                      --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNAT was originally developed  by the GNAT team at  New York University. --
  30 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 with System.Finalization_Root;
  35
  36 package System.Finalization_Implementation is
  37 pragma Elaborate_Body (Finalization_Implementation);
  38
  39    package SFR renames System.Finalization_Root;
  40
  41    ------------------------------------------------
  42    -- Finalization Management Abstract Interface --
  43    ------------------------------------------------
  44
  45    Global_Final_List : SFR.Finalizable_Ptr;
  46    --  This list stores the controlled objects defined in library-level
  47    --  packages. They will be finalized after the main program completion.
  48
  49    procedure Finalize_Global_List;
  50    --  The procedure to be called in order to finalize the global list;
  51
  52    procedure Attach_To_Final_List
  53      (L       : in out SFR.Finalizable_Ptr;
  54       Obj     : in out SFR.Finalizable;
  55       Nb_Link : Short_Short_Integer);
  56    --  Attach finalizable object Obj to the linked list L. Nb_Link controls
  57    --  the number of link of the linked_list, and can be either 0 for no
  58    --  attachement, 1 for simple linked lists or 2 for doubly linked lists
  59    --  or even 3 for a simple attachement of a whole array of elements.
  60    --  Attachement to a simply linked list is not protected against
  61    --  concurrent access and should only be used in contexts where it
  62    --  doesn't matter, such as for objects allocated on the stack. In the
  63    --  case of an attachment on a doubly linked list, L must not be null
  64    --  and Obj will be inserted AFTER the first element and the attachment
  65    --  is protected against concurrent call. Typically used to attach to
  66    --  a dynamically allocated object to a List_Controller (whose first
  67    --  element is always a dummy element)
  68
  69    procedure Finalize_List (L : SFR.Finalizable_Ptr);
  70    --  Call Finalize on each element of the list L;
  71
  72    procedure Finalize_One (Obj  : in out SFR.Finalizable);
  73    --  Call Finalize on Obj and remove its final list.
  74
  75    ---------------------
  76    -- Deep Procedures --
  77    ---------------------
  78
  79    procedure Deep_Tag_Initialize
  80      (L : in out SFR.Finalizable_Ptr;
  81       A : System.Address;
  82       B : Short_Short_Integer);
  83    --  Generic initialize for tagged objects with controlled components.
  84    --  A is the address of the object, L the finalization list when it needs
  85    --  to be attached and B the attachement level (see Attach_To_Final_List).
  86
  87    procedure Deep_Tag_Adjust
  88      (L : in out SFR.Finalizable_Ptr;
  89       A : System.Address;
  90       B : Short_Short_Integer);
  91    --  Generic adjust for tagged objects with controlled components.
  92    --  A is the address of the object, L the finalization list when it needs
  93    --  to be attached and B the attachement level (see Attach_To_Final_List).
  94
  95    procedure Deep_Tag_Finalize
  96      (L : in out SFR.Finalizable_Ptr;
  97       A : System.Address;
  98       B : Boolean);
  99    --  Generic finalize for tagged objects with controlled components.
 100    --  A is the address of the object, L the finalization list when it needs
 101    --  to be attached and B the attachement level (see Attach_To_Final_List).
 102
 103    procedure Deep_Tag_Attach
 104      (L : in out SFR.Finalizable_Ptr;
 105       A : System.Address;
 106       B : Short_Short_Integer);
 107    --  Generic attachement for tagged objects with controlled components.
 108    --  A is the address of the object, L the finalization list when it needs
 109    --  to be attached and B the attachement level (see Attach_To_Final_List).
 110
 111    -----------------------------
 112    -- Record Controller Types --
 113    -----------------------------
 114
 115    --  Definition of the types of the controller component that is included
 116    --  in records containing controlled components. This controller is
 117    --  attached to the finalization chain of the upper-level and carries
 118    --  the pointer of the finalization chain for the lower level.
 119
 120    type Limited_Record_Controller is new SFR.Root_Controlled with record
 121       F : SFR.Finalizable_Ptr;
 122    end record;
 123
 124    procedure Initialize (Object : in out Limited_Record_Controller);
 125    --  Does nothing.
 126
 127    procedure Finalize (Object : in out Limited_Record_Controller);
 128    --  Finalize the controlled components of the enclosing record by
 129    --  following the list starting at Object.F.
 130
 131    type Record_Controller is
 132       new Limited_Record_Controller with record
 133          My_Address : System.Address;
 134       end record;
 135
 136    procedure Initialize (Object : in out Record_Controller);
 137    --  Initialize the field My_Address to the Object'Address
 138
 139    procedure Adjust (Object : in out Record_Controller);
 140    --  Adjust the components and their finalization pointers by substracting
 141    --  by the offset of the target and the source addresses of the assignment.
 142
 143    --  Inherit Finalize from Limited_Record_Controller
 144
 145    procedure Detach_From_Final_List (Obj : in out SFR.Finalizable);
 146    --  Remove the specified object from its Final list, which must be a
 147    --  doubly linked list.
 148
 149 end System.Finalization_Implementation;