$re = '/std::shared_ptr\h*<(?\'type\'[A-Z:_a-z<>]*)>\h*\(\h*new\h*\k\'type\'(?\'args\'\([^()]*+(?:(?&args)[^()]*+)*+\))/';
$str = 'tf->get_TextState()->set_TextMatrix(std::shared_ptr<DOM::Matrix>(new DOM::Matrix(m->get_M11(), -m->get_M12())));';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($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