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) 2013-2018, 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; 39 40generic 41 type Element_Type (<>) is private; 42 with function "=" (Left, Right : Element_Type) return Boolean is <>; 43 44package Ada.Containers.Indefinite_Holders is 45 pragma Annotate (CodePeer, Skip_Analysis); 46 pragma Preelaborate (Indefinite_Holders); 47 pragma Remote_Types (Indefinite_Holders); 48 49 type Holder is tagged private; 50 pragma Preelaborable_Initialization (Holder); 51 52 Empty_Holder : constant Holder; 53 54 function "=" (Left, Right : Holder) return Boolean; 55 56 function To_Holder (New_Item : Element_Type) return Holder; 57 58 function Is_Empty (Container : Holder) return Boolean; 59 60 procedure Clear (Container : in out Holder); 61 62 function Element (Container : Holder) return Element_Type; 63 64 procedure Replace_Element 65 (Container : in out Holder; 66 New_Item : Element_Type); 67 68 procedure Query_Element 69 (Container : Holder; 70 Process : not null access procedure (Element : Element_Type)); 71 procedure Update_Element 72 (Container : in out Holder; 73 Process : not null access procedure (Element : in out Element_Type)); 74 75 type Constant_Reference_Type 76 (Element : not null access constant Element_Type) is private 77 with 78 Implicit_Dereference => Element; 79 80 type Reference_Type 81 (Element : not null access Element_Type) is private 82 with 83 Implicit_Dereference => Element; 84 85 function Constant_Reference 86 (Container : aliased Holder) return Constant_Reference_Type; 87 pragma Inline (Constant_Reference); 88 89 function Reference 90 (Container : aliased in out Holder) return Reference_Type; 91 pragma Inline (Reference); 92 93 procedure Assign (Target : in out Holder; Source : Holder); 94 95 function Copy (Source : Holder) return Holder; 96 97 procedure Move (Target : in out Holder; Source : in out Holder); 98 99private 100 101 use Ada.Finalization; 102 use Ada.Streams; 103 104 type Element_Access is access all Element_Type; 105 type Holder_Access is access all Holder; 106 107 type Shared_Holder is record 108 Counter : System.Atomic_Counters.Atomic_Counter; 109 Element : Element_Access; 110 end record; 111 112 type Shared_Holder_Access is access all Shared_Holder; 113 114 procedure Reference (Item : not null Shared_Holder_Access); 115 -- Increment reference counter 116 117 procedure Unreference (Item : not null Shared_Holder_Access); 118 -- Decrement reference counter, deallocate Item when counter goes to zero 119 120 procedure Read 121 (Stream : not null access Ada.Streams.Root_Stream_Type'Class; 122 Container : out Holder); 123 124 procedure Write 125 (Stream : not null access Ada.Streams.Root_Stream_Type'Class; 126 Container : Holder); 127 128 type Holder is new Ada.Finalization.Controlled with record 129 Reference : Shared_Holder_Access; 130 Busy : Natural := 0; 131 end record; 132 for Holder'Read use Read; 133 for Holder'Write use Write; 134 135 overriding procedure Adjust (Container : in out Holder); 136 overriding procedure Finalize (Container : in out Holder); 137 138 type Reference_Control_Type is new Controlled with record 139 Container : Holder_Access; 140 end record; 141 142 overriding procedure Adjust (Control : in out Reference_Control_Type); 143 pragma Inline (Adjust); 144 145 overriding procedure Finalize (Control : in out Reference_Control_Type); 146 pragma Inline (Finalize); 147 148 type Constant_Reference_Type 149 (Element : not null access constant Element_Type) is 150 record 151 Control : Reference_Control_Type := 152 raise Program_Error with "uninitialized reference"; 153 -- The RM says, "The default initialization of an object of 154 -- type Constant_Reference_Type or Reference_Type propagates 155 -- Program_Error." 156 end record; 157 158 procedure Write 159 (Stream : not null access Root_Stream_Type'Class; 160 Item : Constant_Reference_Type); 161 162 for Constant_Reference_Type'Write use Write; 163 164 procedure Read 165 (Stream : not null access Root_Stream_Type'Class; 166 Item : out Constant_Reference_Type); 167 168 for Constant_Reference_Type'Read use Read; 169 170 type Reference_Type (Element : not null access Element_Type) is record 171 Control : Reference_Control_Type := 172 raise Program_Error with "uninitialized reference"; 173 -- The RM says, "The default initialization of an object of 174 -- type Constant_Reference_Type or Reference_Type propagates 175 -- Program_Error." 176 end record; 177 178 procedure Write 179 (Stream : not null access Root_Stream_Type'Class; 180 Item : Reference_Type); 181 182 for Reference_Type'Write use Write; 183 184 procedure Read 185 (Stream : not null access Root_Stream_Type'Class; 186 Item : out Reference_Type); 187 188 for Reference_Type'Read use Read; 189 190 Empty_Holder : constant Holder := (Controlled with null, 0); 191 192end Ada.Containers.Indefinite_Holders; 193