gcc/ada/libgnat/a-coinho__shared.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT LIBRARY COMPONENTS                          --
   4 --                                                                          --
   5 --    A D A . C O N T A I N E R S . I N D E F I N I T E _ H O L D E R S     --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 2013-2023, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- This specification is derived from the Ada Reference Manual for use with --
  12 -- GNAT. The copyright notice above, and the license provisions that follow --
  13 -- apply solely to the  contents of the part following the private keyword. --
  14 --                                                                          --
  15 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  16 -- terms of the  GNU General Public License as published  by the Free Soft- --
  17 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  18 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  19 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  20 -- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
  21 --                                                                          --
  22 -- As a special exception under Section 7 of GPL version 3, you are granted --
  23 -- additional permissions described in the GCC Runtime Library Exception,   --
  24 -- version 3.1, as published by the Free Software Foundation.               --
  25 --                                                                          --
  26 -- You should have received a copy of the GNU General Public License and    --
  27 -- a copy of the GCC Runtime Library Exception along with this program;     --
  28 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  29 -- <http://www.gnu.org/licenses/>.                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  This is an optimized version of Indefinite_Holders using copy-on-write.
  33 --  It is used on platforms that support atomic built-ins.
  34
  35 private with Ada.Finalization;
  36 private with Ada.Streams;
  37
  38 private with System.Atomic_Counters;
  39 private with Ada.Strings.Text_Buffers;
  40
  41 generic
  42    type Element_Type (<>) is private;
  43    with function "=" (Left, Right : Element_Type) return Boolean is <>;
  44
  45 package Ada.Containers.Indefinite_Holders is
  46    pragma Annotate (CodePeer, Skip_Analysis);
  47    pragma Preelaborate (Indefinite_Holders);
  48    pragma Remote_Types (Indefinite_Holders);
  49
  50    type Holder is tagged private;
  51    pragma Preelaborable_Initialization (Holder);
  52
  53    Empty_Holder : constant Holder;
  54
  55    function "=" (Left, Right : Holder) return Boolean;
  56
  57    function To_Holder (New_Item : Element_Type) return Holder;
  58
  59    function Is_Empty (Container : Holder) return Boolean;
  60
  61    procedure Clear (Container : in out Holder);
  62
  63    function Element (Container : Holder) return Element_Type;
  64
  65    procedure Replace_Element
  66      (Container : in out Holder;
  67       New_Item  : Element_Type);
  68
  69    procedure Query_Element
  70      (Container : Holder;
  71       Process   : not null access procedure (Element : Element_Type));
  72
  73    procedure Update_Element
  74      (Container : in out Holder;
  75       Process   : not null access procedure (Element : in out Element_Type));
  76
  77    type Constant_Reference_Type
  78       (Element : not null access constant Element_Type) is private
  79    with
  80       Implicit_Dereference => Element;
  81
  82    type Reference_Type
  83      (Element : not null access Element_Type) is private
  84    with
  85       Implicit_Dereference => Element;
  86
  87    function Constant_Reference
  88      (Container : aliased Holder) return Constant_Reference_Type;
  89    pragma Inline (Constant_Reference);
  90
  91    function Reference
  92      (Container : aliased in out Holder) return Reference_Type;
  93    pragma Inline (Reference);
  94
  95    procedure Assign (Target : in out Holder; Source : Holder);
  96
  97    function Copy (Source : Holder) return Holder;
  98
  99    procedure Move (Target : in out Holder; Source : in out Holder);
 100
 101    procedure Swap (Left, Right : in out Holder);
 102
 103 private
 104
 105    use Ada.Finalization;
 106    use Ada.Streams;
 107
 108    type Element_Access is access all Element_Type;
 109
 110    type Holder_Access is access all Holder;
 111
 112    type Shared_Holder is record
 113       Counter : System.Atomic_Counters.Atomic_Counter;
 114       Element : Element_Access;
 115    end record;
 116
 117    type Shared_Holder_Access is access all Shared_Holder;
 118
 119    procedure Reference (Item : not null Shared_Holder_Access);
 120    --  Increment reference counter
 121
 122    procedure Unreference (Item : not null Shared_Holder_Access);
 123    --  Decrement reference counter, deallocate Item when counter goes to zero
 124
 125    procedure Read
 126      (Stream    : not null access Ada.Streams.Root_Stream_Type'Class;
 127       Container : out Holder);
 128
 129    procedure Write
 130      (Stream    : not null access Ada.Streams.Root_Stream_Type'Class;
 131       Container : Holder);
 132
 133    type Holder is new Ada.Finalization.Controlled with record
 134       Reference : Shared_Holder_Access;
 135       Busy      : Natural := 0;
 136    end record with Put_Image => Put_Image;
 137
 138    procedure Put_Image
 139      (S : in out Ada.Strings.Text_Buffers.Root_Buffer_Type'Class; V : Holder);
 140
 141    for Holder'Read use Read;
 142    for Holder'Write use Write;
 143
 144    overriding procedure Adjust (Container : in out Holder);
 145    overriding procedure Finalize (Container : in out Holder);
 146
 147    type Reference_Control_Type is new Controlled with record
 148       Container : Holder_Access;
 149    end record;
 150
 151    overriding procedure Adjust (Control : in out Reference_Control_Type);
 152    pragma Inline (Adjust);
 153
 154    overriding procedure Finalize (Control : in out Reference_Control_Type);
 155    pragma Inline (Finalize);
 156
 157    type Constant_Reference_Type
 158      (Element : not null access constant Element_Type) is
 159       record
 160          Control : Reference_Control_Type :=
 161            raise Program_Error with "uninitialized reference";
 162          --  The RM says, "The default initialization of an object of
 163          --  type Constant_Reference_Type or Reference_Type propagates
 164          --  Program_Error."
 165       end record;
 166
 167    procedure Write
 168      (Stream : not null access Root_Stream_Type'Class;
 169       Item   : Constant_Reference_Type);
 170
 171    for Constant_Reference_Type'Write use Write;
 172
 173    procedure Read
 174      (Stream : not null access Root_Stream_Type'Class;
 175       Item   : out Constant_Reference_Type);
 176
 177    for Constant_Reference_Type'Read use Read;
 178
 179    type Reference_Type (Element : not null access Element_Type) is record
 180       Control : Reference_Control_Type :=
 181         raise Program_Error with "uninitialized reference";
 182       --  The RM says, "The default initialization of an object of
 183       --  type Constant_Reference_Type or Reference_Type propagates
 184       --  Program_Error."
 185    end record;
 186
 187    procedure Write
 188      (Stream : not null access Root_Stream_Type'Class;
 189       Item   : Reference_Type);
 190
 191    for Reference_Type'Write use Write;
 192
 193    procedure Read
 194      (Stream : not null access Root_Stream_Type'Class;
 195       Item   : out Reference_Type);
 196
 197    for Reference_Type'Read use Read;
 198
 199    Empty_Holder : constant Holder := (Controlled with null, 0);
 200
 201 end Ada.Containers.Indefinite_Holders;