Ada Programming/Libraries/GNAT.Bounded Buffers

-- --                                                                         -- --                         GNAT LIBRARY COMPONENTS                          -- --                                                                         -- --                  G N A T. B O U N D E D _ B U F F E R S                -- --                                                                         -- --                                 S p e c                                  -- --                                                                         -- --                     Copyright (C) 2003-2006, AdaCore                     -- --                                                                         -- -- 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 2,  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. See the GNU General Public License -- -- for more details. You should have received  a copy of the GNU General -- -- Public License distributed with GNAT;  see file COPYING. If not, write -- -- to the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, -- -- Boston, MA 02110-1301, USA. -- --                                                                         -- -- -- -- -- -- -- -- -- GNAT was originally developed  by the GNAT team at  New York University. -- -- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). -- --                                                                         -- --

-- This package provides a thread-safe generic bounded buffer abstraction. -- Instances are useful directly or as parts of the implementations of other -- abstractions, such as mailboxes.

-- Bounded_Buffer is declared explicitly as a protected type, rather than as --  a simple limited private type completed as a protected type, so that -- clients may make calls accordingly (i.e., conditional/timed entry calls).

with System;

generic type Element is private; -- The type of the values contained within buffer objects

package GNAT.Bounded_Buffers is  pragma Pure;

type Content is array (Positive range <>) of Element; -- Content is an internal artefact that cannot be hidden because protected -- types cannot contain type declarations.

Default_Ceiling : constant System.Priority := System.Default_Priority; -- A convenience value for the Ceiling discriminant

protected type Bounded_Buffer (Capacity : Positive;     --  Objects of type Bounded_Buffer specify the maximum number of Element      --  values they can hold via the discriminant Capacity.

Ceiling : System.Priority)     --  Users must specify the ceiling priority for the object. If the      --  Real-Time Systems Annex is not in use this value is not important.   is      pragma Priority (Ceiling);

entry Insert (Item : Element); -- Insert Item into the buffer, blocks caller until space is available

entry Remove (Item : out Element); -- Remove next available Element from buffer. Blocks caller until an     --  Element is available.

function Empty return Boolean; -- Returns whether the instance contains any Elements. -- Note: State may change immediately after call returns.

function Full return Boolean; -- Returns whether any space remains within the instance. -- Note: State may change immediately after call returns.

function Extent return Natural; -- Returns the number of Element values currently held -- within the instance. -- Note: State may change immediately after call returns.

private Values  : Content (1 .. Capacity); -- The container for the values held by the buffer instance

Next_In : Positive := 1; -- The index of the next Element inserted. Wraps around

Next_Out : Positive := 1; -- The index of the next Element removed. Wraps around

Count   : Natural  := 0; -- The number of Elements currently held end Bounded_Buffer;

end GNAT.Bounded_Buffers; |GNAT.Bounded Buffers