gcc/ada/libgnat/a-cbsyqu.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT LIBRARY COMPONENTS                          --
   4 --                                                                          --
   5 --                ADA.CONTAINERS.BOUNDED_SYNCHRONIZED_QUEUES                --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --            Copyright (C) 2011-2017, Free Software Foundation, Inc.       --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- This unit was originally developed by Matthew J Heaney.                  --
  28 ------------------------------------------------------------------------------
  29
  30 package body Ada.Containers.Bounded_Synchronized_Queues is
  31
  32    package body Implementation is
  33
  34       -------------
  35       -- Dequeue --
  36       -------------
  37
  38       procedure Dequeue
  39         (List    : in out List_Type;
  40          Element : out Queue_Interfaces.Element_Type)
  41       is
  42          EE : Element_Array renames List.Elements;
  43
  44       begin
  45          Element := EE (List.First);
  46          List.Length := List.Length - 1;
  47
  48          if List.Length = 0 then
  49             List.First := 0;
  50             List.Last := 0;
  51
  52          elsif List.First <= List.Last then
  53             List.First := List.First + 1;
  54
  55          else
  56             List.First := List.First + 1;
  57
  58             if List.First > List.Capacity then
  59                List.First := 1;
  60             end if;
  61          end if;
  62       end Dequeue;
  63
  64       -------------
  65       -- Enqueue --
  66       -------------
  67
  68       procedure Enqueue
  69         (List     : in out List_Type;
  70          New_Item : Queue_Interfaces.Element_Type)
  71       is
  72       begin
  73          if List.Length >= List.Capacity then
  74             raise Capacity_Error with "No capacity for insertion";
  75          end if;
  76
  77          if List.Length = 0 then
  78             List.Elements (1) := New_Item;
  79             List.First := 1;
  80             List.Last := 1;
  81
  82          elsif List.First <= List.Last then
  83             if List.Last < List.Capacity then
  84                List.Elements (List.Last + 1) := New_Item;
  85                List.Last := List.Last + 1;
  86
  87             else
  88                List.Elements (1) := New_Item;
  89                List.Last := 1;
  90             end if;
  91
  92          else
  93             List.Elements (List.Last + 1) := New_Item;
  94             List.Last := List.Last + 1;
  95          end if;
  96
  97          List.Length := List.Length + 1;
  98
  99          if List.Length > List.Max_Length then
 100             List.Max_Length := List.Length;
 101          end if;
 102       end Enqueue;
 103
 104       ------------
 105       -- Length --
 106       ------------
 107
 108       function Length (List : List_Type) return Count_Type is
 109       begin
 110          return List.Length;
 111       end Length;
 112
 113       ----------------
 114       -- Max_Length --
 115       ----------------
 116
 117       function Max_Length (List : List_Type) return Count_Type is
 118       begin
 119          return List.Max_Length;
 120       end Max_Length;
 121
 122    end Implementation;
 123
 124    protected body Queue is
 125
 126       -----------------
 127       -- Current_Use --
 128       -----------------
 129
 130       function Current_Use return Count_Type is
 131       begin
 132          return List.Length;
 133       end Current_Use;
 134
 135       -------------
 136       -- Dequeue --
 137       -------------
 138
 139       entry Dequeue (Element : out Queue_Interfaces.Element_Type)
 140         when List.Length > 0
 141       is
 142       begin
 143          List.Dequeue (Element);
 144       end Dequeue;
 145
 146       -------------
 147       -- Enqueue --
 148       -------------
 149
 150       entry Enqueue (New_Item : Queue_Interfaces.Element_Type)
 151         when List.Length < Capacity
 152       is
 153       begin
 154          List.Enqueue (New_Item);
 155       end Enqueue;
 156
 157       --------------
 158       -- Peak_Use --
 159       --------------
 160
 161       function Peak_Use return Count_Type is
 162       begin
 163          return List.Max_Length;
 164       end Peak_Use;
 165
 166    end Queue;
 167
 168 end Ada.Containers.Bounded_Synchronized_Queues;