/**
* @param array|NormalizedProduction[] $productions
* @param Symbol $startSymbol
* @param ParseSets $followSets
* @param ParseSets $firstSets
*
* @return \Helstern\Nomsky\GrammarAnalysis\ParseSets\SetsGenerator
*/
public function generateFollowSets(array $productions, Symbol $startSymbol, ParseSets $followSets, ParseSets $firstSets)
{
$followSets->addEpsilon($startSymbol);
$occurrences = new \ArrayObject();
foreach ($productions as $production) {
$symbol = $production->getLeftHandSide();
$rhs = $production->getRightHandSide();
$this->followSetCalculator->addNonTerminalOccurrences($occurrences, $symbol, $rhs);
}
do {
$changes = false;
/** @var SymbolOccurrence $occurrence */
foreach ($occurrences as $occurrence) {
$set = new ArraySet();
if ($this->followSetCalculator->processOccurrence($set, $occurrence, $followSets, $firstSets)) {
$symbol = $occurrence->getSymbol();
$changes |= $followSets->addAllTerminals($symbol, $set);
}
}
} while ($changes);
return $this;
}
