protected function doHardBreaks($text) {
		if ($this->single_linebreak == true) {
			$expression = '/ {2,}\n|\n{1}/';
		} else {
			$expression = '/ {2,}\n/';
		}

		return preg_replace_callback($expression,
			array(&$this, '_doHardBreaks_callback'), $text);
	}