1------------------------------------------------------------------------------ 2-- -- 3-- GNAT LIBRARY COMPONENTS -- 4-- -- 5-- A D A . C O N T A I N E R S . H E L P E R S -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 2015, 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 3, 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. -- 17-- -- 18-- As a special exception under Section 7 of GPL version 3, you are granted -- 19-- additional permissions described in the GCC Runtime Library Exception, -- 20-- version 3.1, as published by the Free Software Foundation. -- 21-- -- 22-- You should have received a copy of the GNU General Public License and -- 23-- a copy of the GCC Runtime Library Exception along with this program; -- 24-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- 25-- <http://www.gnu.org/licenses/>. -- 26------------------------------------------------------------------------------ 27 28with Ada.Finalization; 29with System.Atomic_Counters; 30 31package Ada.Containers.Helpers is 32 pragma Annotate (CodePeer, Skip_Analysis); 33 pragma Pure; 34 35 -- Miscellaneous helpers shared among various containers 36 37 package SAC renames System.Atomic_Counters; 38 39 Count_Type_Last : constant := Count_Type'Last; 40 -- Count_Type'Last as a universal_integer, so we can compare Index_Type 41 -- values against this without type conversions that might overflow. 42 43 type Tamper_Counts is record 44 Busy : aliased SAC.Atomic_Unsigned := 0; 45 Lock : aliased SAC.Atomic_Unsigned := 0; 46 end record; 47 48 -- Busy is positive when tampering with cursors is prohibited. Busy and 49 -- Lock are both positive when tampering with elements is prohibited. 50 51 type Tamper_Counts_Access is access all Tamper_Counts; 52 for Tamper_Counts_Access'Storage_Size use 0; 53 54 generic 55 package Generic_Implementation is 56 57 -- Generic package used in the implementation of containers. 58 -- ???????????????????Currently used by Vectors; not yet by all other 59 -- containers. 60 61 -- This needs to be generic so that the 'Enabled attribute will return 62 -- the value that is relevant at the point where a container generic is 63 -- instantiated. For example: 64 -- 65 -- pragma Suppress (Container_Checks); 66 -- package My_Vectors is new Ada.Containers.Vectors (...); 67 -- 68 -- should suppress all container-related checks within the instance 69 -- My_Vectors. 70 71 -- Shorthands for "checks enabled" and "tampering checks enabled". Note 72 -- that suppressing either Container_Checks or Tampering_Check disables 73 -- tampering checks. Note that this code needs to be in a generic 74 -- package, because we want to take account of check suppressions at the 75 -- instance. We use these flags, along with pragma Inline, to ensure 76 -- that the compiler can optimize away the checks, as well as the 77 -- tampering check machinery, when checks are suppressed. 78 79 Checks : constant Boolean := Container_Checks'Enabled; 80 T_Check : constant Boolean := 81 Container_Checks'Enabled and Tampering_Check'Enabled; 82 83 -- Reference_Control_Type is used as a component of reference types, to 84 -- prohibit tampering with elements so long as references exist. 85 86 type Reference_Control_Type is 87 new Finalization.Controlled with record 88 T_Counts : Tamper_Counts_Access; 89 end record 90 with Disable_Controlled => not T_Check; 91 92 overriding procedure Adjust (Control : in out Reference_Control_Type); 93 pragma Inline (Adjust); 94 95 overriding procedure Finalize (Control : in out Reference_Control_Type); 96 pragma Inline (Finalize); 97 98 procedure Zero_Counts (T_Counts : out Tamper_Counts); 99 pragma Inline (Zero_Counts); 100 -- Set Busy and Lock to zero 101 102 procedure Busy (T_Counts : in out Tamper_Counts); 103 pragma Inline (Busy); 104 -- Prohibit tampering with cursors 105 106 procedure Unbusy (T_Counts : in out Tamper_Counts); 107 pragma Inline (Unbusy); 108 -- Allow tampering with cursors 109 110 procedure Lock (T_Counts : in out Tamper_Counts); 111 pragma Inline (Lock); 112 -- Prohibit tampering with elements 113 114 procedure Unlock (T_Counts : in out Tamper_Counts); 115 pragma Inline (Unlock); 116 -- Allow tampering with elements 117 118 procedure TC_Check (T_Counts : Tamper_Counts); 119 pragma Inline (TC_Check); 120 -- Tampering-with-cursors check 121 122 procedure TE_Check (T_Counts : Tamper_Counts); 123 pragma Inline (TE_Check); 124 -- Tampering-with-elements check 125 126 ----------------- 127 -- RAII Types -- 128 ----------------- 129 130 -- Initialize of With_Busy increments the Busy count, and Finalize 131 -- decrements it. Thus, to prohibit tampering with elements within a 132 -- given scope, declare an object of type With_Busy. The Busy count 133 -- will be correctly decremented in case of exception or abort. 134 135 -- With_Lock is the same as With_Busy, except it increments/decrements 136 -- BOTH Busy and Lock, thus prohibiting tampering with cursors. 137 138 type With_Busy (T_Counts : not null access Tamper_Counts) is 139 new Finalization.Limited_Controlled with null record 140 with Disable_Controlled => not T_Check; 141 overriding procedure Initialize (Busy : in out With_Busy); 142 overriding procedure Finalize (Busy : in out With_Busy); 143 144 type With_Lock (T_Counts : not null access Tamper_Counts) is 145 new Finalization.Limited_Controlled with null record 146 with Disable_Controlled => not T_Check; 147 overriding procedure Initialize (Lock : in out With_Lock); 148 overriding procedure Finalize (Lock : in out With_Lock); 149 150 -- Variables of type With_Busy and With_Lock are declared only for the 151 -- effects of Initialize and Finalize, so they are not referenced; 152 -- disable warnings about that. Note that all variables of these types 153 -- have names starting with "Busy" or "Lock". These pragmas need to be 154 -- present wherever these types are used. 155 156 pragma Warnings (Off, "variable ""Busy*"" is not referenced"); 157 pragma Warnings (Off, "variable ""Lock*"" is not referenced"); 158 159 end Generic_Implementation; 160 161end Ada.Containers.Helpers; 162