Hi!
On Wed, 08 Mar 2006 00:43:12 +0100, Andreas Fuchs <asf(a)boinkor.net> wrote:
> I would like to teach cl-irc about the goodness of external-formats,
> and because irc doesn't let users specify which external format to
> use, I need something as flexible as flexi-streams (-:
>
> So, once I've read an irc command (as a "line" of latin-1
> characters), I'd like to convert it to text that looks the least
> insane, which is why my code tries several external-formats in a row
> and returns as soon as it found one that doesn't throw an error:
>
> (defun try-decode-line (line external-formats)
> (loop for external-format in external-formats
> for decoded = nil
> for error = nil
> do (multiple-value-setq (decoded error)
> (ignore-errors
> (flexi-streams:with-input-from-sequence (in line)
> (setf (flexi-streams:flexi-stream-external-format in)
> external-format)
> (read-line in))))
> do (format t "~&tried ~s: ~S~% error: ~A~%" external-format decoded
> error)
> if decoded
> do (return decoded)))
If LINE is a string you want this:
(defun try-decode-line (line external-formats)
(loop for external-format in external-formats
for decoded = nil
for error = nil
do (multiple-value-setq (decoded error)
(ignore-errors
(with-input-from-string (in line)
(let ((flexi (flexi-streams:make-flexi-stream in :external-format external-format)))
(read-line flexi)))))
do (format t "~&tried ~s: ~S~% error: ~A~%" external-format decoded
error)
if decoded
do (return decoded)))
But actually I think you want LINE to be a sequence of octets, so this
is what you want:
(defun try-decode-line (line external-formats)
(loop for external-format in external-formats
for decoded = nil
for error = nil
do (multiple-value-setq (decoded error)
(ignore-errors
(flexi-streams:with-input-from-sequence (in line)
(let ((flexi (flexi-streams:make-flexi-stream in :external-format external-format)))
(read-line flexi)))))
do (format t "~&tried ~s: ~S~% error: ~A~%" external-format decoded
error)
if decoded
do (return decoded)))
Result:
CL-USER 11 > (try-decode-line '(228 246 252) '((:utf-8 :eol-style :lf)
(:latin-1 :eol-style :lf)))
tried (:UTF-8 :EOL-STYLE :LF): NIL
error: Unexpected value #xF6 in UTF-8 sequence.
tried (:LATIN-1 :EOL-STYLE :LF): "äöü"
error: T
"äöü"
But you'll need version 0.5.3 to see that because there was a typo in
the code which generated the error messages.
> Hrmpf! Am I abusing flexi-streams too much or is that a bug? How
> should one read externally-formatted data from an in-memory stream,
> anyway?
You forgot that you have to create a flexi stream first - in-memory
streams happen to be provided by the same library but they're
something different. Use MAKE-FLEXI-STREAM to turn them into
flexi streams.
> And are string-backed in-memory streams even allowed?
No. CL already has WITH-INPUT-FROM-STRING... :)
> Thanks for your time and for developing flexi-streams. In return, I
> hope to be able to buy you a beverage of your choice in Hamburg (-:
Nice. Looking forward to seeing you there!
Cheers,
Edi.
