IPv6regex

(
	((?=(?>.*?::)(?!.*::)))
	(::)?
	([0-9a-f]{1,4}::?){0,5}|([0-9a-f]{1,4}:){6}
)
(
	\2([0-9a-f]{1,4}(::?|$)){0,2}
	|(
		(25[0-5]|(2[0-4]|1[0-9]|[1-9])?[0-9])(\.|$)
	){4}
	|[0-9a-f]{1,4}:[0-9a-f]{1,4}
)
(?<![^:]:)
(?<!\.)


	static void r2() {
		String s = "(((?=(?>.*?::)(?!.*::)))(::)?([a]{1,3}::?){0,5}|([a]{4}:){6})";
		Pattern p = Pattern.compile(s);
		String[] datas = { "a:a::", "::a:a:", "a::a:",
				"::aaa:aaa:aaa:aaa:aaa:", "::aaaa:aaaa:aaaa:aaaa:aaaa:aaaa:" };
		for (String data : datas) {
			Matcher m = p.matcher(data);
			while (m.find()) {
				for (int i = 0; i <= m.groupCount(); i++) {
					System.out.printf("%s [%s]\n", i, m.group(i));
				}
			}
			System.out.println("######");
		}
	}