register_rest_route regex option for base64 or alternate

by

I got curious, so I tested this barebone demo:

add_action( 'rest_api_init', function () {
    register_rest_route( 'wpse/v1', '/post_by_permalink/(?P<path>[\S]+)', [
        'methods'      => WP_REST_Server::READABLE,
        'callback'     => 'wpse_callback',
        'show_in_rest' => true
    ] );
});

function wpse_callback( $request ) {
    $data = [ 'path' => base64_decode( $request['path'] ) ];
    return $data;
}

Testing:

https://example.com/wp-json/wpse/v1/post_by_permalink/aHR0cHM6Ly93b3JkcHJlc3Muc3RhY2tleGNoYW5nZS5jb20vcS8zMDEwNjcv

gives

{
   path: "https://wordpress.stackexchange.com/q/301067/"
}

Tested also

https://example.com/wp-json/wpse/v1/post_by_permalink/aHR0cHM6Ly93b3JkcHJlc3Muc3RhY2tleGNoYW5nZS5jb20vcXVlc3Rpb25zLzMwMTA2Ny9yZWdpc3Rlci1yZXN0LXJvdXRlLXJlZ2V4LW9wdGlvbi1mb3ItYmFzZTY0LW9yLWFsdGVybmF0ZS8zMDEwNzY=

that gave:

{
path: "https://wordpress.stackexchange.com/questions/301067/register-rest-route-regex-option-for-base64-or-alternate/301076"
}

Tested further:

https://example.com/wp-json/wpse/v1/post_by_permalink/dGVzdC90ZXN0LzM1NzM0Ly0=

with output:

{
path: "test/test/35734/-"
}