# From http://www.ietf.org/rfc/rfc2396.txt
# RegEx for URI

The following line is the regular expression for breaking-down a URI
   reference into its components.

      ^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?
       12            3  4          5       6  7        8 9

   The numbers in the second line above are only to assist
   readability;
   they indicate the reference points for each subexpression (i.e.,
   each
   paired parenthesis).  We refer to the value matched for
   subexpression
   <n> as $<n>.  For example, matching the above expression to

      http://www.ics.uci.edu/pub/ietf/uri/#Related

   results in the following subexpression matches:

      $1 = http:
      $2 = http
      $3 = //www.ics.uci.edu
      $4 = www.ics.uci.edu
      $5 = /pub/ietf/uri/
      $6 = <undefined>
      $7 = <undefined>
      $8 = #Related
      $9 = Related

   where <undefined> indicates that the component is not present, as
   is
   the case for the query component in the above example.  Therefore,
   we
   can determine the value of the four components and fragment as

      scheme    = $2
      authority = $4
      path      = $5
      query     = $7
      fragment  = $9