1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT LIBRARY COMPONENTS                          --
4--                                                                          --
5--                  ADA.CONTAINERS.BOUNDED_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;
35
36with Ada.Containers.Synchronized_Queue_Interfaces;
37with Ada.Containers.Bounded_Doubly_Linked_Lists;
38
39generic
40   with package Queue_Interfaces is
41     new Ada.Containers.Synchronized_Queue_Interfaces (<>);
42
43   type Queue_Priority is private;
44
45   with function Get_Priority
46     (Element : Queue_Interfaces.Element_Type) return Queue_Priority is <>;
47
48   with function Before
49     (Left, Right : Queue_Priority) return Boolean is <>;
50
51   Default_Capacity : Count_Type;
52   Default_Ceiling  : System.Any_Priority := System.Priority'Last;
53
54package Ada.Containers.Bounded_Priority_Queues is
55   pragma Preelaborate;
56
57   package Implementation is
58
59      --  All identifiers in this unit are implementation defined
60
61      pragma Implementation_Defined;
62
63      type List_Type (Capacity : Count_Type) is tagged limited private;
64
65      procedure Enqueue
66        (List     : in out List_Type;
67         New_Item : Queue_Interfaces.Element_Type);
68
69      procedure Dequeue
70        (List    : in out List_Type;
71         Element : out Queue_Interfaces.Element_Type);
72
73      procedure Dequeue
74        (List     : in out List_Type;
75         At_Least : Queue_Priority;
76         Element  : in out Queue_Interfaces.Element_Type;
77         Success  : out Boolean);
78
79      function First_Element
80        (List : List_Type) return Queue_Interfaces.Element_Type;
81
82      function Length (List : List_Type) return Count_Type;
83
84      function Max_Length (List : List_Type) return Count_Type;
85
86   private
87
88      --  We need a better data structure here, such as a proper heap.  ???
89
90      package List_Types is new Bounded_Doubly_Linked_Lists
91        (Element_Type => Queue_Interfaces.Element_Type,
92         "="          => Queue_Interfaces."=");
93
94      type List_Type (Capacity : Count_Type) is tagged limited record
95         Container  : List_Types.List (Capacity);
96         Max_Length : Count_Type := 0;
97      end record;
98
99   end Implementation;
100
101   protected type Queue
102     (Capacity : Count_Type := Default_Capacity;
103      Ceiling  : System.Any_Priority := Default_Ceiling)
104   with
105     Priority => Ceiling
106   is new Queue_Interfaces.Queue with
107
108      overriding entry Enqueue (New_Item : Queue_Interfaces.Element_Type);
109
110      overriding entry Dequeue (Element : out Queue_Interfaces.Element_Type);
111
112      --  The priority queue operation Dequeue_Only_High_Priority had been a
113      --  protected entry in early drafts of AI05-0159, but it was discovered
114      --  that that operation as specified was not in fact implementable. The
115      --  operation was changed from an entry to a protected procedure per the
116      --  ARG meeting in Edinburgh (June 2011), with a different signature and
117      --  semantics.
118
119      procedure Dequeue_Only_High_Priority
120        (At_Least : Queue_Priority;
121         Element  : in out Queue_Interfaces.Element_Type;
122         Success  : out Boolean);
123
124      overriding function Current_Use return Count_Type;
125
126      overriding function Peak_Use return Count_Type;
127
128   private
129      List : Implementation.List_Type (Capacity);
130   end Queue;
131
132end Ada.Containers.Bounded_Priority_Queues;
133