Daring Fireball URI regex

qr{
    \b
    (
        # scheme or schemeless
        ([\w-]+://? | www[.])

        # anything but whitespace or brackets
        [^\s()<>]+

        # letters and numbers in parens
        # or anything but punctuation and whitespace
        #   or a close paren
        (?: \([\w\d]+\)           |
            ([^[:punct:]\s] | /)
        )
    )
}x;