138 lines
6.2 KiB
Ada
138 lines
6.2 KiB
Ada
------------------------------------------------------------------------------
|
|
-- --
|
|
-- GNAT LIBRARY COMPONENTS --
|
|
-- --
|
|
-- ADA.CONTAINERS.UNBOUNDED_PRIORITY_QUEUES --
|
|
-- --
|
|
-- S p e c --
|
|
-- --
|
|
-- Copyright (C) 2011-2016, Free Software Foundation, Inc. --
|
|
-- --
|
|
-- This specification is derived from the Ada Reference Manual for use with --
|
|
-- GNAT. The copyright notice above, and the license provisions that follow --
|
|
-- apply solely to the contents of the part following the private keyword. --
|
|
-- --
|
|
-- 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 --
|
|
-- <http://www.gnu.org/licenses/>. --
|
|
-- --
|
|
-- This unit was originally developed by Matthew J Heaney. --
|
|
------------------------------------------------------------------------------
|
|
|
|
with System;
|
|
with Ada.Containers.Ordered_Sets;
|
|
with Ada.Containers.Synchronized_Queue_Interfaces;
|
|
|
|
generic
|
|
with package Queue_Interfaces is
|
|
new Ada.Containers.Synchronized_Queue_Interfaces (<>);
|
|
|
|
type Queue_Priority is private;
|
|
|
|
with function Get_Priority
|
|
(Element : Queue_Interfaces.Element_Type) return Queue_Priority is <>;
|
|
|
|
with function Before
|
|
(Left, Right : Queue_Priority) return Boolean is <>;
|
|
|
|
Default_Ceiling : System.Any_Priority := System.Priority'Last;
|
|
|
|
package Ada.Containers.Unbounded_Priority_Queues is
|
|
pragma Annotate (CodePeer, Skip_Analysis);
|
|
pragma Preelaborate;
|
|
|
|
package Implementation is
|
|
|
|
-- All identifiers in this unit are implementation defined
|
|
|
|
pragma Implementation_Defined;
|
|
|
|
-- We use an ordered set to hold the queue elements. This gives O(lg N)
|
|
-- performance in the worst case for Enqueue and Dequeue.
|
|
-- Sequence_Number is used to distinguish equivalent items. Each Enqueue
|
|
-- uses a higher Sequence_Number, so that a new item is placed after
|
|
-- already-enqueued equivalent items.
|
|
--
|
|
-- At any time, the first set element is the one to be dequeued next (if
|
|
-- the queue is not empty).
|
|
|
|
type Set_Elem is record
|
|
Sequence_Number : Count_Type;
|
|
Item : Queue_Interfaces.Element_Type;
|
|
end record;
|
|
|
|
function "=" (X, Y : Queue_Interfaces.Element_Type) return Boolean is
|
|
(not Before (Get_Priority (X), Get_Priority (Y))
|
|
and then not Before (Get_Priority (Y), Get_Priority (X)));
|
|
-- Elements are equal if neither is Before the other
|
|
|
|
function "=" (X, Y : Set_Elem) return Boolean is
|
|
(X.Sequence_Number = Y.Sequence_Number and then X.Item = Y.Item);
|
|
-- Set_Elems are equal if the elements are equal, and the
|
|
-- Sequence_Numbers are equal. This is passed to Ordered_Sets.
|
|
|
|
function "<" (X, Y : Set_Elem) return Boolean is
|
|
(if X.Item = Y.Item
|
|
then X.Sequence_Number < Y.Sequence_Number
|
|
else Before (Get_Priority (X.Item), Get_Priority (Y.Item)));
|
|
-- If the items are equal, Sequence_Number breaks the tie. Otherwise,
|
|
-- use Before. This is passed to Ordered_Sets.
|
|
|
|
pragma Suppress (Container_Checks);
|
|
package Sets is new Ada.Containers.Ordered_Sets (Set_Elem);
|
|
|
|
end Implementation;
|
|
|
|
use Implementation, Implementation.Sets;
|
|
|
|
protected type Queue (Ceiling : System.Any_Priority := Default_Ceiling)
|
|
with
|
|
Priority => Ceiling
|
|
is new Queue_Interfaces.Queue with
|
|
|
|
overriding entry Enqueue (New_Item : Queue_Interfaces.Element_Type);
|
|
|
|
overriding entry Dequeue (Element : out Queue_Interfaces.Element_Type);
|
|
|
|
-- The priority queue operation Dequeue_Only_High_Priority had been a
|
|
-- protected entry in early drafts of AI05-0159, but it was discovered
|
|
-- that that operation as specified was not in fact implementable. The
|
|
-- operation was changed from an entry to a protected procedure per the
|
|
-- ARG meeting in Edinburgh (June 2011), with a different signature and
|
|
-- semantics.
|
|
|
|
procedure Dequeue_Only_High_Priority
|
|
(At_Least : Queue_Priority;
|
|
Element : in out Queue_Interfaces.Element_Type;
|
|
Success : out Boolean);
|
|
|
|
overriding function Current_Use return Count_Type;
|
|
|
|
overriding function Peak_Use return Count_Type;
|
|
|
|
private
|
|
Q_Elems : Set;
|
|
-- Elements of the queue
|
|
|
|
Max_Length : Count_Type := 0;
|
|
-- The current length of the queue is the Length of Q_Elems. This is the
|
|
-- maximum value of that, so far. Updated by Enqueue.
|
|
|
|
Next_Sequence_Number : Count_Type := 0;
|
|
-- Steadily increasing counter
|
|
end Queue;
|
|
|
|
end Ada.Containers.Unbounded_Priority_Queues;
|