protected function guards(&$guards)
{
$s = $this->seek();
if (!$this->literal("when")) {
$this->seek($s);
return false;
}
$guards = array();
while ($this->guardGroup($g)) {
$guards[] = $g;
if (!$this->literal(",")) {
break;
}
}
if (count($guards) == 0) {
$guards = null;
$this->seek($s);
return false;
}
return true;
}