/**
* @param String $input
* @return string
*/
public function parse($input)
{
if (empty($input)) {
return $input;
}
$this->parsing = true;
$this->preParse();
$parsed = parent::parse($input);
//there was a failure
if ($parsed === true) {
return null;
}
$this->parsing = false;
$output = $this->postParse($parsed);
return $output;
}
