$re = '/(?<=\[)([^\]]+)/';
$str = 'Your Name (required)
[text* your-name]
Your Email (required)
[email* your-email]
Subject
[text your-subject]
Your Message
[textarea your-message]
[submit "Send"]';
preg_match_all($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