+
+filename :: URL -> Maybe String
+filename url =
+ case parse_result of
+ Nothing -> Nothing
+ Just uri ->
+ let components = split "/" (uriPath uri) in
+ -- Reverse them so that the filename comes first for easier
+ -- pattern-matching.
+ let reverse_components = reverse components in
+ case reverse_components of
+ [] -> Nothing
+ (x:_) -> Just x
+ where
+ parse_result = parseURIReference url
+
+
+
+make_absolute_uri :: URI -> Maybe URI
+make_absolute_uri relative_uri =
+ relativeTo relative_uri base_uri
+ where
+ base_auth = URIAuth { uriUserInfo = "",
+ uriRegName = "lwn.net",
+ uriPort = "" }
+ base_uri = URI { uriScheme = "https:",
+ uriAuthority = Just base_auth,
+ uriPath = "/",
+ uriQuery = "",
+ uriFragment = "" }
+
+
+make_absolute_url :: URL -> Maybe URL
+make_absolute_url relative_url =
+ case parse_result of
+ Nothing -> Nothing
+ Just relative_uri ->
+ let abs_result = make_absolute_uri relative_uri in
+ case abs_result of
+ Nothing -> Nothing
+ Just abs_uri -> Just $ show abs_uri
+ where
+ parse_result = parseURIReference relative_url
+
+-- | Like 'make_absolute_url', except returns its input instead of
+-- 'Nothing' if the absolution fails.
+try_make_absolute_url :: URL -> URL
+try_make_absolute_url url =
+ case make_absolute_url url of
+ Nothing -> url
+ Just abs_url -> abs_url
+