protected function _replace($matches)
    {
        $file = $this->_currentFile;
        if ($matches[1] === '"') {
            // Same directory include
            $file = $this->_findFile($matches[2], dirname($file) . DIRECTORY_SEPARATOR);
        } else {
            // scan all paths
            $file = $this->_findFile($matches[2]);
        }

        // prevent double inclusion
        if (isset($this->_loaded[$file])) {
            return "";
        }
        $this->_loaded[$file] = true;

        $content = file_get_contents($file);
        if ($return = $this->input($file, $content)) {
            return $return . "\n";
        }
        return '';
    }