#!/usr/bin/perl -w

#
# Calculator Module Base Program.  You are to write the
# "Calculator.pm" module that is used by this program.  It should
# export the subroutines parse_line, plus, minus, divide, and
# multiply.
#

use strict;
use Calculator;

my %operator = ( "+" => \&plus,
                 "-" => \&minus,
                 "/" => \&divide,
                 "*" => \&multiply );

while(<>)
{
    chomp;
    last if /^exit$/;
    my($op, $n1, $n2) = parse_line($_);
    if (exists $operator{$op})
    {
        my $result = $operator{$op}->($n1, $n2);
        print "$n1 $op $n2 = $result\n";
    }
    else
    {
        warn "Invalid operator \"$op\"\n";
        next;
    }
}