protected function set_authority($authority) {
		static $cache;
		if (!$cache) {
			$cache = array();
		}

		if ($authority === null) {
			$this->iuserinfo = null;
			$this->ihost = null;
			$this->port = null;
			return true;
		}
		if (isset($cache[$authority])) {
			list($this->iuserinfo,
				 $this->ihost,
				 $this->port,
				 $return) = $cache[$authority];

			return $return;
		}

		$remaining = $authority;
		if (($iuserinfo_end = strrpos($remaining, '@')) !== false) {
			$iuserinfo = substr($remaining, 0, $iuserinfo_end);
			$remaining = substr($remaining, $iuserinfo_end + 1);
		}
		else {
			$iuserinfo = null;
		}
		if (($port_start = strpos($remaining, ':', strpos($remaining, ']'))) !== false) {
			$port = substr($remaining, $port_start + 1);
			if ($port === false || $port === '') {
				$port = null;
			}
			$remaining = substr($remaining, 0, $port_start);
		}
		else {
			$port = null;
		}

		$return = $this->set_userinfo($iuserinfo) &&
				  $this->set_host($remaining) &&
				  $this->set_port($port);

		$cache[$authority] = array($this->iuserinfo,
								   $this->ihost,
								   $this->port,
								   $return);

		return $return;
	}