1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT LIBRARY COMPONENTS                          --
4--                                                                          --
5--                 ADA.CONTAINERS.UNBOUNDED_PRIORITY_QUEUES                 --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 2011-2013, 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-- This unit was originally developed by Matthew J Heaney.                  --
32------------------------------------------------------------------------------
33
34with System;
35with Ada.Containers.Synchronized_Queue_Interfaces;
36with Ada.Finalization;
37
38generic
39   with package Queue_Interfaces is
40     new Ada.Containers.Synchronized_Queue_Interfaces (<>);
41
42   type Queue_Priority is private;
43
44   with function Get_Priority
45     (Element : Queue_Interfaces.Element_Type) return Queue_Priority is <>;
46
47   with function Before
48     (Left, Right : Queue_Priority) return Boolean is <>;
49
50   Default_Ceiling : System.Any_Priority := System.Priority'Last;
51
52package Ada.Containers.Unbounded_Priority_Queues is
53   pragma Preelaborate;
54
55   package Implementation is
56
57      --  All identifiers in this unit are implementation defined
58
59      pragma Implementation_Defined;
60
61      type List_Type is tagged limited private;
62
63      procedure Enqueue
64        (List     : in out List_Type;
65         New_Item : Queue_Interfaces.Element_Type);
66
67      procedure Dequeue
68        (List    : in out List_Type;
69         Element : out Queue_Interfaces.Element_Type);
70
71      procedure Dequeue
72        (List     : in out List_Type;
73         At_Least : Queue_Priority;
74         Element  : in out Queue_Interfaces.Element_Type;
75         Success  : out Boolean);
76
77      function Length (List : List_Type) return Count_Type;
78
79      function Max_Length (List : List_Type) return Count_Type;
80
81   private
82
83      type Node_Type;
84      type Node_Access is access Node_Type;
85
86      type Node_Type is limited record
87         Element : Queue_Interfaces.Element_Type;
88         Next    : Node_Access;
89      end record;
90
91      type List_Type is new Ada.Finalization.Limited_Controlled with record
92         First, Last : Node_Access;
93         Length      : Count_Type := 0;
94         Max_Length  : Count_Type := 0;
95      end record;
96
97      overriding procedure Finalize (List : in out List_Type);
98
99   end Implementation;
100
101   protected type Queue (Ceiling : System.Any_Priority := Default_Ceiling)
102   with
103     Priority => Ceiling
104   is new Queue_Interfaces.Queue with
105
106      overriding entry Enqueue (New_Item : Queue_Interfaces.Element_Type);
107
108      overriding entry Dequeue (Element : out Queue_Interfaces.Element_Type);
109
110      --  The priority queue operation Dequeue_Only_High_Priority had been a
111      --  protected entry in early drafts of AI05-0159, but it was discovered
112      --  that that operation as specified was not in fact implementable. The
113      --  operation was changed from an entry to a protected procedure per the
114      --  ARG meeting in Edinburgh (June 2011), with a different signature and
115      --  semantics.
116
117      procedure Dequeue_Only_High_Priority
118        (At_Least : Queue_Priority;
119         Element  : in out Queue_Interfaces.Element_Type;
120         Success  : out Boolean);
121
122      overriding function Current_Use return Count_Type;
123
124      overriding function Peak_Use return Count_Type;
125
126   private
127      List : Implementation.List_Type;
128   end Queue;
129
130end Ada.Containers.Unbounded_Priority_Queues;
131