/**
* @return string
*/
public function mutate()
{
$running_delta = 0;
foreach ($this->selector->getSelection() as $range) {
//if anything has adjusted the delta
$range->setOffset($running_delta);
//after correcting the offset, it's safe to split it
$temp = $range->parts($this->selector->getSource());
//once we split it we have the middle string and can calculate the new delta
$running_delta += $this->subDelta($temp['mid']);
$temp['mid'] = $this->subMutate($temp['mid']);
$this->selector->setSource(implode('', $temp));
}
return $this->selector->getSource();
}