Installer copy() assumes wrongly

[Ema4rl]

This is an excerpt from the installer:

class Installer
{
    public static function install()
    {
        self::copy('vendor/kenjis/codeigniter-ss-twig/libraries/Twig.php', 'application/libraries/Twig.php');
    }
}

There has to be a way to pass the path to the install method so that it adjusts depending on the user set-up.

Below is an example of my usual set-up:
-- [CodeIgniter Base]
    -- .app/
      -- v1/
        -- (application files...)
      -- vendor/
        -- (composer vendor libraries...)
    -- .sys/
      -- (system files...)
    -- web/
      -- (public path; contains index.php)