Can you share your code? From what I understand, you are applying validation logic inside constraints, but this should go inside the validator.

The correct steps to achieve the desired results are:

1. Create custom constraints that do not contain validation logic
2. Create a custom validator for this constraint and configure it as a service. The validator should accept your service as constructor parameter.

one example:

twig_char_lenght_validator:
    class: ...\TwigCharLengthValidator
    arguments:
        - "@your.service"

3. Complete your validator logic using injected services.

Official documentation: https://symfony.com/doc/current/validation/ custom_constraint.html

I'm not 100% sure this is what you're asking for, but you can create a template based on your input and then render it. Of course remove all the branches, although I'm not sure you always know what the variables are.

I checked and all the examples look very old and I'm not sure if things still work. I can't even find an example in the documentation, although I'm sure it's there somewhere. anyway:

use Twig\Environment;

#[AsCommand(
    name: 'app:twig',
    description: 'Add a short description for your command',
)]
class TwigCommand extends Command
{
    public function __construct(private Environment $twig)
    {
        parent::__construct();
    }

    protected function execute(InputInterface $input, OutputInterface $output): int
    {
        $input = '{{ hello }}';
        // This is the important line
        $template = $this->twig->createTemplate($input);
        $rendered = $template->render(['hello' => 'Hello World']);
        echo $rendered . "\n";

        return Command::SUCCESS;
    }
}

If nothing else, this also lets you verify the actual template. But as already mentioned, I'm not quite sure what parsed length means. Anyway, createTemplate is (to me) an interesting method.