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TODO: Test logging.
author:
   stack

 URI Generic Syntax                August 1998
 B.

 URI Generic Syntax                August 1998
 B. Parsing a URI Reference with a Regular Expression
 As described in Section 4.3, the generic URI syntax is not sufficient
 to disambiguate the components of some forms of URI.  Since the
 "greedy algorithm" described in that section is identical to the
 disambiguation method used by POSIX regular expressions, it is
 natural and commonplace to use a regular expression for parsing the
 potential four components and fragment identifier of a URI reference.
 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
  as $.  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 = 
 $7 = 
 $8 = #Related
 $9 = Related
 where  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
 

Below differs from the rfc regex in that it has java escaping of regex characters and we allow a URI made of a fragment only (Added extra group so indexing is off by one after scheme).