Parses a character string containing an RFC 3986 compliant URL as per NNG.
parse_url(url)A named character vector of length 7, comprising:
scheme - the URL scheme, such as "http" or "inproc" (always lower
case).
userinfo - the username and password (if supplied in the URL
string).
hostname - the name of the host.
port - the port (if not specified, the default port if defined by
the scheme).
path - the path, typically used with HTTP or WebSocket.
query - the query info (typically following ? in the URL).
fragment - used for specifying an anchor, the part after # in a
URL.
Values that cannot be determined are represented by an empty string "".
parse_url("https://user:password@w3.org:8080/type/path?q=info#intro")
#> scheme userinfo hostname port path
#> "https" "user:password" "w3.org" "8080" "/type/path"
#> query fragment
#> "q=info" "intro"
parse_url("tcp://192.168.0.2:5555")
#> scheme userinfo hostname port path
#> "tcp" "" "192.168.0.2" "5555" ""
#> query fragment
#> "" ""