$re = '/^(?!.*([,\._\- ]).*\1)(?!.*[\',\._\- ]{2})(?!.*([\'])(?:.*\2){2})[\',\._\- \p{L}]+$/m';
$str = 'O\'Leary-Smith
O\'Leary-Sm-ith
O\'Lea\'ry-Smith
John
O\'Lea.ry-Smith
O\'\'Leary
O Leary Smith
O Leary-Smith
O\'Leary-D\'angelo
O\'Leary-D\'angelo\'dfff
O\'Leary-Dangelo
O\'\'Leary-Dangelo
Test-.ffoof
';
preg_match_all($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