Yurttas/PL/IL/Ada-95/F/06/trains/trains 08.adb

 1--
 2-- Copyright(C) 1998
 3-- All Rights Reserved. Salih Yurttas, ZCubes, BitsOfCode Software Systems, Inc..
 4--
 5-- Permission to use, copy, modify, and distribute this
 6-- software and its documentation for EDUCATIONAL purposes
 7-- and without fee is hereby granted provided that this
 8-- copyright notice appears in all copies.
 9--
10 
11-- date   : January 1, 1998.
12-- author : Salih Yurttas.
13
14-- trains_08.adb
15
16
17with Ada.Text_IO;
18use Ada.Text_IO;
19
20procedure Trains_08 is
21
22  type Train is(One,Two,Three);
23
24  package EIO is new Enumeration_IO(Train);
25  use EIO;
26
27  procedure Approach_Points(T : in Train) is
28  begin
29    Put("...Approach_Points");
30    Put(T);
31    New_Line;
32  end Approach_Points;
33
34  procedure Cross_Points(T : in Train) is
35  begin
36    Put(T);
37    Put_Line(" Crossing_Points");
38  end Cross_Points;
39
40  procedure Go_Away_From_Points(T : in Train) is
41  begin
42    Put("     Go_Away_From_Points...");
43    Put(T);
44    New_Line;
45  end Go_Away_From_Points;
46
47  task Points is
48    entry Cross(T : in Train);
49  end Points;
50
51  task body Points is
52  begin
53    loop
54      select
55        accept Cross(T : in Train) do
56          Cross_Points(T);
57        end Cross;
58      or terminate;
59      end select;
60    end loop;
61  end Points;
62
63  task Train1;
64
65  task body Train1 is
66  begin
67    Approach_Points(One);
68    Points.Cross(One);
69    Go_Away_From_Points(One);
70  end Train1;
71
72  task Train2;
73
74  task body Train2 is
75  begin
76    Approach_Points(Two);
77    Points.Cross(Two);
78    Go_Away_From_Points(Two);
79  end Train2;
80
81  task Train3;
82
83  task body Train3 is
84  begin
85    Approach_Points(Three);
86    Points.Cross(Three);
87    Go_Away_From_Points(Three);
88  end Train3;
89
90begin
91
92  null;
93
94end Trains_08;