$re = '/(?:{{(?=[^{}]*(?:{(?!{)|}(?:!}))*}})|\G(?!^))(?:\(?\K[A-Za-z_]\w*)/m';
$str = 'Test Test2\'{{TimeStamps(Descending(1))(7:8)}}/{{TimeStamps(Descending(1))(1:4)}} - \'
\'{{ListHeight + 4}}, {{(ListWidth / 2) + 0.5}}, cc 6, \'';
preg_match_all($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