src/Autoloader.php
public static function findPSR4($ns, $class_name, $path)
    {
        $class = str_replace($ns, "", $class_name);
        $class_file = str_replace('\\', DIRECTORY_SEPARATOR, $class) . '.php';

        $class_path = $path . DIRECTORY_SEPARATOR . $class_file;
        if (file_exists($class_path))
            return $class_path;

        return null;
    }
public static function findPSR4($ns, $class_name, $path)
    {
        $class = str_replace($ns, "", $class_name);
        $class_file = str_replace('\\', DIRECTORY_SEPARATOR, $class) . '.php';

        $class_path = $path . DIRECTORY_SEPARATOR . $class_file;
        if (file_exists($class_path))
            return $class_path;

        return null;
    }
Look up file according to PSR4 standard:
http://www.php-fig.org/psr/psr-4/

@param $ns string The namespace of the class
@param $class_name string The class to locatae
@param $path string The path where the namespace classes are located
@return string The path to the class file. Null when not found