Hi!

On Wed, 08 Mar 2006 00:43:12 +0100, Andreas Fuchs asf@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.