Parsing in prolog

[convi]

Hello guys,
I need some help with prolog code. I need to parse uri strings, in a way that
the predicate :

parsed_uri(URIString, URI).

is true if URIString is then dvided in the composed term :

URI = uri(Scheme, Userinfo, Host, Port, Path, Query, Fragment).

Example :

?- parsed_uri(”

http://disco.unimib.it”,

URI).
URI = uri(http, [], ’disco.unimib.it’, [], [], [], []).

If you guys give me some clues , it would be nice. I know that I have to use some finite state machine
or pushdown automata.