private function readComment($start, $line, $col, Token $prev)
{
$body = $this->source->body;
$position = $start;
do {
$code = Utils::charCodeAt($body, ++$position);
} while ($code !== null && ($code > 0x1f || $code === 0x9));
return new Token(Token::COMMENT, $start, $position, $line, $col, $prev, mb_substr($body, $start + 1, $position - $start + 1, 'UTF-8'));
}