rfc3986_regex.pl

my $regex = qr/
    \A
    (
        [a-z][a-z0-9+\-.]*:
        (
            \/\/
            ([a-z0-9\-._~%!$&'()*+,;=]+@)?
            ([a-z0-9\-._~%]+
            |\[[a-f0-9:.]+\]
            |\[v[a-f0-9][a-z0-9\-._~%!$&'()*+,;=:]+\])
            (:[0-9]+)?
            (\/[a-z0-9\-._~%!$&'()*+,;=:@]+)*\/?
        |
            (\/?[a-z0-9\-._~%!$&'()*+,;=:@]+(\/[a-z0-9\-._~%!\$&'()*+,;=:@]+)*\/?)?
        )
    |
        (
            [a-z0-9\-._~%!$&'()*+,;=@]+(\/[a-z0-9\-._~%!\$&'()*+,;=:@]+)*\/?
        |
            (\/[a-z0-9\-._~%!$&'()*+,;=:@]+)+\/?
        )
    )
    (\?[a-z0-9\-._~%!$&'()*+,;=:@\/?]*)?
    (\#[a-z0-9\-._~%!$&'()*+,;=:@\/?]*)?
\Z
/x;