/**
* Recursively filters out start and end markers
*
* Recursively filter out start and end markers from the regular expression
* structure, since they do not have any real meaning, but were required to
* create correct automatons.
*
* @param slRegularExpression $regularExpression
* @return slRegularExpression
*/
protected function filterStartEndMarkers(slRegularExpression $regularExpression)
{
if ($regularExpression instanceof slRegularExpressionMultiple) {
foreach ($regularExpression->getChildren() as $nr => $child) {
if ($child instanceof slRegularExpressionElement && ($child->getContent() === 0 || $child->getContent() === 1)) {
$regularExpression[$nr] = new slRegularExpressionEmpty();
} else {
$this->filterStartEndMarkers($child);
}
}
}
if ($regularExpression instanceof slRegularExpressionSingular) {
$child = $regularExpression->getChild();
if ($child instanceof slRegularExpressionElement && ($child->getContent() === 0 || $child->getContent() === 1)) {
$regularExpression->setChild(new slRegularExpressionEmpty());
} else {
$this->filterStartEndMarkers($child);
}
}
return $regularExpression;
}
