(?i)\b((?:(?:[a-z][\w-]+:)?(?:/{1,3}|[a-z0-9%])|www\d{0,3}[.]|[a-z0-9.\-]+[.][a-z]{2,4}/)(?:[^\s()<>]+|\(([^\s()<>]+|(\([^\s()<>]+\)))*\))+(?:\(([^\s()<>]+|(\([^\s()<>]+\)))*\)|[^\s`!()\[\]{};:'".,<>?«»“”‘’]))
At first glance IP address or URL, embedded in HTML, whatever it is, it's a doozy. I wonder what the performance of it is like.