non-empty-string $pattern:
int-mask<PREG_UNMATCHED_AS_NULL> $flags PREG_UNMATCHED_AS_NULL is always set, no other flags are supported:
public static function matchAll(string $pattern, string $subject, int $flags = 0, int $offset = 0) : MatchAllResult { self::checkOffsetCapture($flags, 'matchAllWithOffsets'); self::checkSetOrder($flags); $count = Preg::matchAll($pattern, $subject, $matches, $flags, $offset); return new MatchAllResult($count, $matches); }