public function enterNode(Node $node): void
    {
        $name = null;

        if ($node instanceof Name) {
            $name = $node->toString();
        }

        if ($name === null
            || (array_key_exists($name, $this->symbols)
                && $this->symbols[$name] === false
            )
        ) {
            return;
        }

        if (!$this->filter->__invoke($name)) {
            $this->symbols[$name] = false;
            return;
        }

        if (!array_key_exists($name, $this->symbols)) {
            $this->symbols[$name] = [];
        }

        $this->symbols[$name][] = $node;
    }