$re = '/(?s)(?=\()(?:(?=.*?\((?!.*?\1)(.*\)(?!.*\2).*))(?=.*?\)(?!.*?\2)(.*)).)+?.*?(?=\1)[^(]*(?=\2$)/';
$str = 'Hey! ( (Look,) (ma!) ( (no) r(e(c(u(r)s)i)o)n!! ) ) Woooo
( Matches (can (even
span ) multiple )
lines! ) yeah buddy!!
(((((((()(((((()(((((( NO LIMITS!!! ))))))())))))()))))))))))))';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php