class TwigNodeVisitor

class TwigNodeVisitor implements NodeVisitorInterface {
  
  /**
   * Tracks whether there is a render array aware filter active already.
   */
  protected ?bool $skipRenderVarFunction;
  
  /**
   * {@inheritdoc}
   */
  public function enterNode(Node $node, Environment $env) : Node {
    return $node;
  }
  
  /**
   * {@inheritdoc}
   */
  public function leaveNode(Node $node, Environment $env) : ?Node {
    // We use this to inject a call to render_var -> TwigExtension->renderVar()
    // before anything is printed.
    if ($node instanceof PrintNode) {
      if (!empty($this->skipRenderVarFunction)) {
        // No need to add the callback, we have escape active already.
        unset($this->skipRenderVarFunction);
        return $node;
      }
      $class = get_class($node);
      $line = $node->getTemplateLine();
      return new $class(new FunctionExpression(new TwigFunction('render_var', [
        $env->getExtension(TwigExtension::class),
        'renderVar',
      ]), new Node([
        $node->getNode('expr'),
      ]), $line), $line);
    }
    elseif ($node instanceof FilterExpression) {
      $name = $node->getAttribute('twig_callable')
        ->getName();
      if ('escape' == $name || 'e' == $name) {
        // Use our own escape filter that is MarkupInterface aware.
        $node->setAttribute('twig_callable', $env->getFilter('drupal_escape'));
        // Store that we have a filter active already that knows
        // how to deal with render arrays.
        $this->skipRenderVarFunction = TRUE;
      }
    }
    return $node;
  }
  
  /**
   * {@inheritdoc}
   */
  public function getPriority() {
    // Just above the Optimizer, which is the normal last one.
    return 256;
  }

}