protected function processRequire(Iterator $iterator)
    {
        // sort iterator by name
        $iterator = new SortingIterator($iterator, 'strnatcasecmp');

        // Spin through each of the files within the iterator and if their a valid asset they
        // are added to the array of assets for this directory.
        foreach ($iterator as $file)
        {
            if ( ! $file->isFile()) continue;

            $this->add($file->getPathname());
        }

        return $this;
    }