/**
* @param \Helstern\Nomsky\Grammar\Symbol\SymbolSet $set
* @param NormalizedProduction $production
* @param \Helstern\Nomsky\GrammarAnalysis\ParseSets\ParseSets $followSets
* @param \Helstern\Nomsky\GrammarAnalysis\ParseSets\ParseSets $firstSets
*
* @return bool
*/
public function processProduction(SymbolSet $set, NormalizedProduction $production, ParseSets $followSets, ParseSets $firstSets)
{
$rhs = $production->getRightHandSide();
$epsilonAdded = $this->firstSetCalculator->processSymbolList($set, $rhs, $firstSets);
if ($epsilonAdded) {
$lhs = $production->getLeftHandSide();
$otherSet = $followSets->getTerminalSet($lhs);
$set->addAll($otherSet);
}
return $epsilonAdded;
}
/**
* @param NormalizedProduction $production
* @param SymbolSet $alreadyAdded
*
* @return bool
*/
private function indirectlyGeneratesEpsilon(NormalizedProduction $production, SymbolSet $alreadyAdded)
{
$rhsItems = $production->getRightHandSide();
/** @var Symbol $item */
$item = reset($rhsItems);
$answer = $alreadyAdded->contains($item);
for (next($rhsItems); $answer && !is_null(key($rhsItems)); next($rhsItems)) {
$item = current($rhsItems);
$answer = $answer && $alreadyAdded->contains($item);
}
$answer = is_null(key($rhsItems)) && $answer;
return $answer;
}
