------------------------------------------------------------------------------ -- -- -- GNAT LIBRARY COMPONENTS -- -- -- -- A D A . C O N T A I N E R S . H E L P E R S -- -- -- -- S p e c -- -- -- -- Copyright (C) 2015-2024, Free Software Foundation, Inc. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 3, or (at your option) any later ver- -- -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. -- -- -- -- As a special exception under Section 7 of GPL version 3, you are granted -- -- additional permissions described in the GCC Runtime Library Exception, -- -- version 3.1, as published by the Free Software Foundation. -- -- -- -- You should have received a copy of the GNU General Public License and -- -- a copy of the GCC Runtime Library Exception along with this program; -- -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- -- . -- ------------------------------------------------------------------------------ with Ada.Finalization; with System.Atomic_Counters; package Ada.Containers.Helpers is pragma Annotate (CodePeer, Skip_Analysis); pragma Pure; -- Miscellaneous helpers shared among various containers package SAC renames System.Atomic_Counters; Count_Type_Last : constant := Count_Type'Last; -- Count_Type'Last as a universal_integer, so we can compare Index_Type -- values against this without type conversions that might overflow. type Tamper_Counts is record Busy : aliased SAC.Atomic_Unsigned := 0; Lock : aliased SAC.Atomic_Unsigned := 0; end record; -- Busy is positive when tampering with cursors is prohibited. Busy and -- Lock are both positive when tampering with elements is prohibited. type Tamper_Counts_Access is access all Tamper_Counts; for Tamper_Counts_Access'Storage_Size use 0; generic package Generic_Implementation is -- Generic package used in the implementation of containers. -- This needs to be generic so that the 'Enabled attribute will return -- the value that is relevant at the point where a container generic is -- instantiated. For example: -- -- pragma Suppress (Container_Checks); -- package My_Vectors is new Ada.Containers.Vectors (...); -- -- should suppress all container-related checks within the instance -- My_Vectors. -- Shorthands for "checks enabled" and "tampering checks enabled". Note -- that suppressing either Container_Checks or Tampering_Check disables -- tampering checks. Note that this code needs to be in a generic -- package, because we want to take account of check suppressions at the -- instance. We use these flags, along with pragma Inline, to ensure -- that the compiler can optimize away the checks, as well as the -- tampering check machinery, when checks are suppressed. Checks : constant Boolean := Container_Checks'Enabled; T_Check : constant Boolean := Container_Checks'Enabled and Tampering_Check'Enabled; -- Reference_Control_Type is used as a component of reference types, to -- prohibit tampering with elements so long as references exist. type Reference_Control_Type is new Finalization.Controlled with record T_Counts : Tamper_Counts_Access; end record with Disable_Controlled => not T_Check; overriding procedure Adjust (Control : in out Reference_Control_Type); pragma Inline (Adjust); overriding procedure Finalize (Control : in out Reference_Control_Type); pragma Inline (Finalize); procedure Zero_Counts (T_Counts : out Tamper_Counts); pragma Inline (Zero_Counts); -- Set Busy and Lock to zero procedure Busy (T_Counts : in out Tamper_Counts); pragma Inline (Busy); -- Prohibit tampering with cursors procedure Unbusy (T_Counts : in out Tamper_Counts); pragma Inline (Unbusy); -- Allow tampering with cursors procedure Lock (T_Counts : in out Tamper_Counts); pragma Inline (Lock); -- Prohibit tampering with elements procedure Unlock (T_Counts : in out Tamper_Counts); pragma Inline (Unlock); -- Allow tampering with elements procedure TC_Check (T_Counts : Tamper_Counts); pragma Inline (TC_Check); -- Tampering-with-cursors check procedure TE_Check (T_Counts : Tamper_Counts); pragma Inline (TE_Check); -- Tampering-with-elements check --------------------------------------- -- Queries of busy and locked status -- --------------------------------------- -- These are never called when tampering checks are suppressed. use type SAC.Atomic_Unsigned; pragma Warnings (Off); -- Otherwise, the -gnatw.n switch triggers unwanted warnings on the -- references to atomic variables below. function Is_Busy (T_Counts : Tamper_Counts) return Boolean is (if T_Check then T_Counts.Busy > 0 else raise Program_Error); pragma Inline (Is_Busy); function Is_Locked (T_Counts : Tamper_Counts) return Boolean is (if T_Check then T_Counts.Lock > 0 else raise Program_Error); pragma Inline (Is_Locked); pragma Warnings (On); ---------------- -- RAII Types -- ---------------- -- Initialize of With_Busy increments the Busy count, and Finalize -- decrements it. Thus, to prohibit tampering with elements within a -- given scope, declare an object of type With_Busy. The Busy count -- will be correctly decremented in case of exception or abort. -- With_Lock is the same as With_Busy, except it increments/decrements -- BOTH Busy and Lock, thus prohibiting tampering with cursors. type With_Busy (T_Counts : not null access Tamper_Counts) is new Finalization.Limited_Controlled with null record with Disable_Controlled => not T_Check; overriding procedure Initialize (Busy : in out With_Busy); overriding procedure Finalize (Busy : in out With_Busy); type With_Lock (T_Counts : not null access Tamper_Counts) is new Finalization.Limited_Controlled with null record with Disable_Controlled => not T_Check; overriding procedure Initialize (Lock : in out With_Lock); overriding procedure Finalize (Lock : in out With_Lock); -- Variables of type With_Busy and With_Lock are declared only for the -- effects of Initialize and Finalize, so they are not referenced; -- disable warnings about that. Note that all variables of these types -- have names starting with "Busy" or "Lock". These pragmas need to be -- present wherever these types are used. pragma Warnings (Off, "variable ""Busy*"" is not referenced"); pragma Warnings (Off, "variable ""Lock*"" is not referenced"); end Generic_Implementation; end Ada.Containers.Helpers;