Object-oriented Software in Ada 95

Exceptions 197
14.3.1 Putting it all together
The new package Class_stack_int is tested by the following program unit which is identical to the code
seen in Section 13.5 except the with’ed and used’ed package is Class_Stack_Int rather than
Class_Stack..
with Ada.Text_Io, Ada.Integer_Text_Io, Class_Stack_Int;
use Ada.Text_Io, Ada.Integer_Text_Io, Class_Stack_Int;
procedure Main is
Number_Stack : Stack; --Stack of numbers
Action : Character; --Action
Number : Integer; --Number processed
begin
while not End_Of_File loop
while not End_Of_Line loop
begin
Get( Action );
case Action is --Process action
when '+' =>
Get( Number ); Push(Number_Stack,Number);
Put("push number = "); Put(Number); New_Line;
when '-' =>
Pop(Number_Stack,Number);
Put("Pop number = "); Put(Number); New_Line;
when others =>
Put("Invalid action"); New_Line;
end case;
exception
when Stack_Error =>
Put("Stack_error"); New_Line;
when Data_Error =>
Put("Not a number"); New_Line; Skip_Line;
when End_Error =>
Put("Unexpected end of file"); New_Line; exit;
end;
end loop;
Skip_Line;
end loop;
Reset( Number_Stack );
end Main;
When run with the following data:
+1+2+3+4----
the following results will be produced:
push number = 1
push number = 2
push number = 3
Stack_error
Pop number = 3
Pop number = 2
Pop number = 1
Stack_error
© M A Smith - May not be reproduced without permission