DumperVisitor

DumperVisitor is the abstract base shared by StreamDumperVisitor and StringDumperVisitor. It implements the whole traversal side of rendering — indentation tracking and node formatting — and leaves only the sink itself abstract:

abstract class DumperVisitor extends Visitor
{
    public const string DEFAULT_SIMPLIFIED_NODE_NAMESPACE 
        = 'TypeLang\\Type\\';

    public function __construct(
        string $simplifyNodeNamespace 
            = self::DEFAULT_SIMPLIFIED_NODE_NAMESPACE,
    ) {}

    abstract protected function write(string $data): void;
}

Each visited node is rendered as <indent><ShortClassName>[(value)], one line per node: the class name has $simplifyNodeNamespace stripped off its front, and if the node implements \Stringable, its string representation is appended in parentheses.

Writing a Custom Sink

Extend DumperVisitor and implement write() to render anywhere you like — into an array of lines, a PSR logger, a buffer shared with other output, etc:

use TypeLang\Parser\Traverser;
use TypeLang\Parser\Traverser\DumperVisitor;

final class LineCollectorDumperVisitor extends DumperVisitor
{
    /** @var list<string> */
    public array $lines = [];

    protected function write(string $data): void
    {
        $this->lines[] = \rtrim($data, "\n");
    }
}

$type = new TypeLang\Parser\TypeParser()
    ->parse('int|null');

$visitor = new LineCollectorDumperVisitor();
Traverser::new([$visitor])->traverse([$type]);

var_dump($visitor->lines);

array(5) {
  [0]=> string(13) "UnionTypeNode"
  [1]=> string(15) "  NamedTypeNode"
  [2]=> string(13) "    Name(int)"
  [3]=> string(21) "      Identifier(int)"
  [4]=> string(31) "  Literal\NullLiteralNode(null)"
}

Disabling Namespace Simplification

Pass an empty string (or any prefix that won't match) as $simplifyNodeNamespace to render fully-qualified class names instead:

$visitor = new LineCollectorDumperVisitor(
    simplifyNodeNamespace: '',
);

TypeLang\Type\UnionTypeNode
  TypeLang\Type\NamedTypeNode
    TypeLang\Type\Name(int)
      TypeLang\Type\Identifier(int)
  TypeLang\Type\Literal\NullLiteralNode(null)

05 July 2026