/**
* Calculates the first set of the symbol $source and adds it's elements to $set
*
* @param \Helstern\Nomsky\Grammar\Symbol\SymbolSet $set
* @param \Helstern\Nomsky\Grammar\Symbol\Symbol $source
* @param \Helstern\Nomsky\GrammarAnalysis\ParseSets\ParseSets $firstSets
*
* @return boolean if the epsilon symbol was added to $set
*/
public function processSymbol(SymbolSet $set, Symbol $source, ParseSets $firstSets)
{
$symbolIsEpsilon = SymbolIsEpsilon::singletonInstance();
if ($symbolIsEpsilon->matchSymbol($source)) {
$set->add(new EpsilonSymbol());
return true;
}
$symbolsIsNonTerminal = SymbolTypeEquals::newInstanceMatchingNonTerminals();
if ($symbolsIsNonTerminal->matchSymbol($source)) {
$epsilonCounter = new MatchCountingInterceptor($symbolIsEpsilon);
$acceptPredicate = Inverter::newInstance($epsilonCounter);
$otherSet = $firstSets->filterTerminalSet($source, $acceptPredicate);
$set->addAll($otherSet);
if ($epsilonCounter->getMatchCount() > 0) {
$set->add(new EpsilonSymbol());
return true;
}
return false;
}
$set->add($source);
return false;
}
