File Coverage

blib/lib/Regexp/Common/_support.pm

Criterion	Covered	Total	%
statement	30	30	100.0
branch	3	4	75.0
condition	4	6	66.6
subroutine	7	7	100.0
pod	1	1	100.0
total	45	48	93.7

package Regexp::Common::_support;

use 5.10.0;

use strict;
use warnings;
no  warnings 'syntax';

our $VERSION = '2017060201';

#
# Returns true/false, depending whether the given the argument
# satisfies the LUHN checksum.
# See http://www.webopedia.com/TERM/L/Luhn_formula.html.
#
# Note that this function is intended to be called from regular
# expression, so it should NOT use a regular expression in any way.
#
sub luhn {
    my $arg  = shift;
    my $even = 0;
    my $sum  = 0;
    while (length $arg) {
        my $num = chop $arg;
        return if $num lt '0' || $num gt '9';
        if ($even && (($num *= 2) > 9)) {$num = 1 + ($num % 10)}
        $even = 1 - $even;
        $sum += $num;
    }
    !($sum % 10)
}

sub import {
    my $pack   = shift;
    my $caller = caller;
    no strict 'refs';
    *{$caller . "::" . $_} = \&{$pack . "::" . $_} for @_;
}


1;

__END__