public function addVisitor($visitor, array $args = [])
{
if (is_string($visitor)) {
$args = array_merge([$this->traverser, $this->context, $this->errors], $args);
$refl = new \ReflectionClass($visitor);
$visitor = $refl->newInstanceArgs($args);
}
if (!$visitor instanceof NodeVisitorInterface) {
throw new \InvalidArgumentException('Visitor must be instance of NodeVisitorInterface');
}
$this->traverser->addVisitor($visitor);
}
