/
# allow multiple groups with the same name
(?J)
# protocol user host-ip port path path path querystring fragment
^
#protocol
(?:(?<scheme>[a-zA-Z][a-zA-Z\d+-.]*):)?
(?|
  #slash-slash
  \/\/
  #userinfo
  (?:
     #user
     (?<user>[a-zA-Z\d\-._~\!$&'()*+,;=%]*)
     #password
     (?::(?<pass>[a-zA-Z\d\-._~\!$&'()*+,;=:%]*))?
  @)?
  #host-ip
  (?<host>(?:[a-zA-Z\d-.%]+)|(?:\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})|(?:\[(?:[a-fA-F\d.:]+)\]))?
  #port
  (?::(?<port>\d*))?
  #slash-path
  (?<path>
      (?:\/    [a-zA-Z\d\-._~\!$&'()*+,;=:@%]*   )*
  )

  #slash-path
  |(?<user>)(?<pass>)(?<host>)(?<port>)
   (?<path>\/  [a-zA-Z\d\-._~\!$&'()*+,;=:@%]+(?:\/[a-zA-Z\d\-._~\!$&'()*+,;=:@%]*)*)?

  #path
  |(?<user>)(?<pass>)(?<host>)(?<port>)
   (?<path>    [a-zA-Z\d\-._~\!$&'()*+,;=:@%]+(?:\/[a-zA-Z\d\-._~\!$&'()*+,;=:@%]*)*)

)?
#querystring
(?:\?(?<query>[a-zA-Z\d\-._~\!$&'()*+,;=:@%\/?]*))?
#fragment
(?:\#(?<fragment>[a-zA-Z\d\-._~\!$&'()*+,;=:@%\/?]*))?
$
/x