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lib/Algorithm/CheckDigits/M43_001.pm  view on Meta::CPAN

	'C' => 12, 'D' => 13, 'E' => 14, 'F' => 15,
	'G' => 16, 'H' => 17, 'I' => 18, 'J' => 19,
	'K' => 20, 'L' => 21, 'M' => 22, 'N' => 23,
	'O' => 24, 'P' => 25, 'Q' => 26, 'R' => 27,
	'S' => 28, 'T' => 29, 'U' => 30, 'V' => 31,
	'W' => 32, 'X' => 33, 'Y' => 34, 'Z' => 35,
	'-' => 36, '.' => 37, ' ' => 38, '$' => 39,
	'/' => 40, '+' => 41, '%' => 42,
);

my %keymap = reverse %keytable;

sub new {
	my $proto = shift;
	my $type  = shift;
	my $class = ref($proto) || $proto;
	my $self  = bless({}, $class);
	$self->{type} = lc($type);
	return $self;
} # new()

sub is_valid {
	my ($self,$number) = @_;
	if ($number =~ /^(.*)(.)$/i) {
		return $2 eq $self->_compute_checkdigit($1);
	}
	return ''
} # is_valid()

sub complete {
	my ($self,$number) = @_;
	if ($number =~ /^(.*)$/i) {
		return $number . $self->_compute_checkdigit($1);
	}
	return '';
} # complete()

sub basenumber {
	my ($self,$number) = @_;
	if ($number =~ /^(.*)(.)$/i) {
		return $1 if (uc($2) eq $self->_compute_checkdigit($1));
	}
	return '';
} # basenumber()

sub checkdigit {
	my ($self,$number) = @_;
	if ($number =~ /^(.*)(.)$/i) {
		return $2 if (uc($2) eq $self->_compute_checkdigit($1));
	}
	return '';
} # checkdigit()

sub _compute_checkdigit {
	my $self   = shift;
	my $number = shift;
	my $sum    = 0;

	my @digits = split(//,$number);

	for (my $i = 0; $i < length($number); $i++) {
		$sum += $keytable{$digits[$i]};
	}
	$sum %= 43;
	return $keymap{$sum};
} # _compute_checkdigit()

# Preloaded methods go here.

1;
__END__

=head1 NAME

CheckDigits::M43_001 - compute check digits for Code-39

=head1 SYNOPSIS

  use Algorithm::CheckDigits;

  $c39 = CheckDigits('code_39');

  if ($c39->is_valid('AB-123K')) {
	# do something
  }

  $cn = $c39->complete('AB-123');
  # $cn = 'AB-123K'

  $cd = $c39->checkdigit('AB-123K');
  # $cd = 'K'

  $bn = $c39->basenumber('AB-123K');
  # $bn = 'AB-123'
  
=head1 DESCRIPTION

=head2 ALGORITHM

=over 4

=item 1

After replacing all non numeric letters with their respective values,
the sum of all numbers is computers

=item 2

The checkdigit is the sum from step 1 taken modulo 43.

=back

=head2 METHODS

=over 4

=item is_valid($number)

Returns true only if C<$number> consists solely of numbers and the last digit
is a valid check digit according to the algorithm given above.