Routing dynamic controller with placeholder

I was struggling with a Placeholder for the Controller, what I wanted to achieve is to define the controller in the URL like this:

PHP Code:

$routes->get('{locale}/(:segment)', '$1::index'); 


This doesn't work because of the Router, which replaces the Placeholder with preg_replace and the backslash of the generated Namespace tells it, to ignore the next special character:
input:
\App\Controllers\$1::index
output:
\App\Controllers$1::index

To solve the problem, i did rewrite a small piece of code in the Router.php, line 467:
Old code:

PHP Code:

if (strpos($val, '$') !== false && strpos($key, '(') !== false && strpos($key, '/') !== false) {
    $replacekey = str_replace('/(.*)', '', $key);
    $val = preg_replace('#^' . $key . '$#', $val, $uri);
    $val = str_replace($replacekey, str_replace('/', '\\', $replacekey), $val);
} elseif (strpos($val, '$') !== false && strpos($key, '(') !== false) {
    $val = preg_replace('#^' . $key . '$#', $val, $uri);
} elseif (strpos($val, '/') !== false) {
    [
            $controller,
            $method,
            ] = explode('::', $val);

    // Only replace slashes in the controller, not in the method.
    $controller = str_replace('/', '\\', $controller);

    $val = $controller . '::' . $method;
} 


New code:

PHP Code:

if (strpos($val, '$') !== false && strpos($key, '(') !== false) {
    // Tell preg_replace to consider the backslash as a literal character.
    $val = str_replace('\\', '\\\\', $val);
    $val = preg_replace('#^' . $key . '$#', $val, $uri);
    if (strpos($key, '/') !== false) {
        $replacekey = str_replace('/(.*)', '', $key);
        $val = str_replace($replacekey, str_replace('/', '\\', $replacekey), $val);
    }
}

// Replace slashes in the controller with backslashes and capitalize the first letter.
[$controller, $method,] = explode('::', $val);
$controller = str_replace('/', '\\', $controller);
$controller = ucwords($controller, '\\');
$val = $controller . '::' . $method; 


In addition to dynamic controllers it's also possible to nest the controllers inside the Namespace.
Following routes are working:

PHP Code:

$routes->get('{locale}/(:segment)', '$1::index');

$routes->get('{locale}/(:segment)', 'Home/$1::index'); 


It would be nice to add this or something similar to the official version.

That's not a feature that we're interested in adding to the Routing system due to security concerns. If you need that type of matching you can do that with the auto-matching like all previous versions of CodeIgniter have had.

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I came to this issue because of the language segment, according to Google SEO it's recommended to have this in the URL. I try to negotiate the language if none is defined and reload the page with the evaluated one. So the first segment is always the {local} segment.
Another solution would be to offset the auto-routing like this:

$routes->setAutoRoute(true, 1); \\ second parameter as the offset, first segment is ignored.

Would that be a better solution? Or is there another/better way without defining all routes?