gcc/ada/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) 2013-2015, 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
  40 generic
  41    type Element_Type (<>) is private;
  42    with function "=" (Left, Right : Element_Type) return Boolean is <>;
  43
  44 package Ada.Containers.Indefinite_Holders is
  45    pragma Preelaborate (Indefinite_Holders);
  46    pragma Remote_Types (Indefinite_Holders);
  47
  48    type Holder is tagged private;
  49    pragma Preelaborable_Initialization (Holder);
  50
  51    Empty_Holder : constant Holder;
  52
  53    function "=" (Left, Right : Holder) return Boolean;
  54
  55    function To_Holder (New_Item : Element_Type) return Holder;
  56
  57    function Is_Empty (Container : Holder) return Boolean;
  58
  59    procedure Clear (Container : in out Holder);
  60
  61    function Element (Container : Holder) return Element_Type;
  62
  63    procedure Replace_Element
  64      (Container : in out Holder;
  65       New_Item  : Element_Type);
  66
  67    procedure Query_Element
  68      (Container : Holder;
  69       Process   : not null access procedure (Element : Element_Type));
  70    procedure Update_Element
  71      (Container : in out Holder;
  72       Process   : not null access procedure (Element : in out Element_Type));
  73
  74    type Constant_Reference_Type
  75       (Element : not null access constant Element_Type) is private
  76    with
  77       Implicit_Dereference => Element;
  78
  79    type Reference_Type
  80      (Element : not null access Element_Type) is private
  81    with
  82       Implicit_Dereference => Element;
  83
  84    function Constant_Reference
  85      (Container : aliased Holder) return Constant_Reference_Type;
  86    pragma Inline (Constant_Reference);
  87
  88    function Reference
  89      (Container : aliased in out Holder) return Reference_Type;
  90    pragma Inline (Reference);
  91
  92    procedure Assign (Target : in out Holder; Source : Holder);
  93
  94    function Copy (Source : Holder) return Holder;
  95
  96    procedure Move (Target : in out Holder; Source : in out Holder);
  97
  98 private
  99
 100    use Ada.Finalization;
 101    use Ada.Streams;
 102
 103    type Element_Access is access all Element_Type;
 104    type Holder_Access is access all Holder;
 105
 106    type Shared_Holder is record
 107       Counter : System.Atomic_Counters.Atomic_Counter;
 108       Element : Element_Access;
 109    end record;
 110
 111    type Shared_Holder_Access is access all Shared_Holder;
 112
 113    procedure Reference (Item : not null Shared_Holder_Access);
 114    --  Increment reference counter
 115
 116    procedure Unreference (Item : not null Shared_Holder_Access);
 117    --  Decrement reference counter, deallocate Item when counter goes to zero
 118
 119    procedure Read
 120      (Stream    : not null access Ada.Streams.Root_Stream_Type'Class;
 121       Container : out Holder);
 122
 123    procedure Write
 124      (Stream    : not null access Ada.Streams.Root_Stream_Type'Class;
 125       Container : Holder);
 126
 127    type Holder is new Ada.Finalization.Controlled with record
 128       Reference : Shared_Holder_Access;
 129       Busy      : Natural := 0;
 130    end record;
 131    for Holder'Read use Read;
 132    for Holder'Write use Write;
 133
 134    overriding procedure Adjust (Container : in out Holder);
 135    overriding procedure Finalize (Container : in out Holder);
 136
 137    type Reference_Control_Type is new Controlled with record
 138       Container : Holder_Access;
 139    end record;
 140
 141    overriding procedure Adjust (Control : in out Reference_Control_Type);
 142    pragma Inline (Adjust);
 143
 144    overriding procedure Finalize (Control : in out Reference_Control_Type);
 145    pragma Inline (Finalize);
 146
 147    type Constant_Reference_Type
 148      (Element : not null access constant Element_Type) is
 149       record
 150          Control : Reference_Control_Type :=
 151            raise Program_Error with "uninitialized reference";
 152          --  The RM says, "The default initialization of an object of
 153          --  type Constant_Reference_Type or Reference_Type propagates
 154          --  Program_Error."
 155       end record;
 156
 157    procedure Write
 158      (Stream : not null access Root_Stream_Type'Class;
 159       Item   : Constant_Reference_Type);
 160
 161    for Constant_Reference_Type'Write use Write;
 162
 163    procedure Read
 164      (Stream : not null access Root_Stream_Type'Class;
 165       Item   : out Constant_Reference_Type);
 166
 167    for Constant_Reference_Type'Read use Read;
 168
 169    type Reference_Type (Element : not null access Element_Type) is record
 170       Control : Reference_Control_Type :=
 171         raise Program_Error with "uninitialized reference";
 172       --  The RM says, "The default initialization of an object of
 173       --  type Constant_Reference_Type or Reference_Type propagates
 174       --  Program_Error."
 175    end record;
 176
 177    procedure Write
 178      (Stream : not null access Root_Stream_Type'Class;
 179       Item   : Reference_Type);
 180
 181    for Reference_Type'Write use Write;
 182
 183    procedure Read
 184      (Stream : not null access Root_Stream_Type'Class;
 185       Item   : out Reference_Type);
 186
 187    for Reference_Type'Read use Read;
 188
 189    Empty_Holder : constant Holder := (Controlled with null, 0);
 190
 191 end Ada.Containers.Indefinite_Holders;