Function Uri
( 
uri < uri > &aux (scheme?
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       (and
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        (position
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         :
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         uri)
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        (subseq
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         uri
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         0
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         (position
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          :
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          uri)))) )
parses a uri into an object. If the scheme is registered then the returned object is of that type. otherwise it is a uri structure. Also supports relative uri.