protected function _filter($regex, $content, $i = 1, $key = '') {
		if (@preg_match($regex, $content, $match) == 1) {
			$result = isset($match[$i]) ? $match[$i] : $match[0];
			if (isset($this->_callback['_all_'])) {
				foreach ($this->_callback['_all_'] as $filter) {
					$result = call_user_func($filter, $result);
				}
			}
			if ($key != '' && isset($this->_callback[$key])) {
				foreach ($this->_callback[$key] as $filter) {
					$result = call_user_func($filter, $result);
				}
			}
			return $result;
		}
		return false;
	}