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) 2013-2020, 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 35private with Ada.Finalization; 36private with Ada.Streams; 37 38private with System.Atomic_Counters; 39private with Ada.Strings.Text_Output; 40 41generic 42 type Element_Type (<>) is private; 43 with function "=" (Left, Right : Element_Type) return Boolean is <>; 44 45package 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 procedure Update_Element 73 (Container : in out Holder; 74 Process : not null access procedure (Element : in out Element_Type)); 75 76 type Constant_Reference_Type 77 (Element : not null access constant Element_Type) is private 78 with 79 Implicit_Dereference => Element; 80 81 type Reference_Type 82 (Element : not null access Element_Type) is private 83 with 84 Implicit_Dereference => Element; 85 86 function Constant_Reference 87 (Container : aliased Holder) return Constant_Reference_Type; 88 pragma Inline (Constant_Reference); 89 90 function Reference 91 (Container : aliased in out Holder) return Reference_Type; 92 pragma Inline (Reference); 93 94 procedure Assign (Target : in out Holder; Source : Holder); 95 96 function Copy (Source : Holder) return Holder; 97 98 procedure Move (Target : in out Holder; Source : in out Holder); 99 100 procedure Swap (Left, Right : in out Holder); 101 102private 103 104 use Ada.Finalization; 105 use Ada.Streams; 106 107 type Element_Access is access all Element_Type; 108 type Holder_Access is access all Holder; 109 110 type Shared_Holder is record 111 Counter : System.Atomic_Counters.Atomic_Counter; 112 Element : Element_Access; 113 end record; 114 115 type Shared_Holder_Access is access all Shared_Holder; 116 117 procedure Reference (Item : not null Shared_Holder_Access); 118 -- Increment reference counter 119 120 procedure Unreference (Item : not null Shared_Holder_Access); 121 -- Decrement reference counter, deallocate Item when counter goes to zero 122 123 procedure Read 124 (Stream : not null access Ada.Streams.Root_Stream_Type'Class; 125 Container : out Holder); 126 127 procedure Write 128 (Stream : not null access Ada.Streams.Root_Stream_Type'Class; 129 Container : Holder); 130 131 type Holder is new Ada.Finalization.Controlled with record 132 Reference : Shared_Holder_Access; 133 Busy : Natural := 0; 134 end record with Put_Image => Put_Image; 135 136 procedure Put_Image 137 (S : in out Ada.Strings.Text_Output.Sink'Class; V : Holder); 138 139 for Holder'Read use Read; 140 for Holder'Write use Write; 141 142 overriding procedure Adjust (Container : in out Holder); 143 overriding procedure Finalize (Container : in out Holder); 144 145 type Reference_Control_Type is new Controlled with record 146 Container : Holder_Access; 147 end record; 148 149 overriding procedure Adjust (Control : in out Reference_Control_Type); 150 pragma Inline (Adjust); 151 152 overriding procedure Finalize (Control : in out Reference_Control_Type); 153 pragma Inline (Finalize); 154 155 type Constant_Reference_Type 156 (Element : not null access constant Element_Type) is 157 record 158 Control : Reference_Control_Type := 159 raise Program_Error with "uninitialized reference"; 160 -- The RM says, "The default initialization of an object of 161 -- type Constant_Reference_Type or Reference_Type propagates 162 -- Program_Error." 163 end record; 164 165 procedure Write 166 (Stream : not null access Root_Stream_Type'Class; 167 Item : Constant_Reference_Type); 168 169 for Constant_Reference_Type'Write use Write; 170 171 procedure Read 172 (Stream : not null access Root_Stream_Type'Class; 173 Item : out Constant_Reference_Type); 174 175 for Constant_Reference_Type'Read use Read; 176 177 type Reference_Type (Element : not null access Element_Type) is record 178 Control : Reference_Control_Type := 179 raise Program_Error with "uninitialized reference"; 180 -- The RM says, "The default initialization of an object of 181 -- type Constant_Reference_Type or Reference_Type propagates 182 -- Program_Error." 183 end record; 184 185 procedure Write 186 (Stream : not null access Root_Stream_Type'Class; 187 Item : Reference_Type); 188 189 for Reference_Type'Write use Write; 190 191 procedure Read 192 (Stream : not null access Root_Stream_Type'Class; 193 Item : out Reference_Type); 194 195 for Reference_Type'Read use Read; 196 197 Empty_Holder : constant Holder := (Controlled with null, 0); 198 199end Ada.Containers.Indefinite_Holders; 200