Re: Make ietf-drums-remove-comments() robust against broken header

[TSUCHIYA Masatoshi <tsuchiya@namazu.org>]

>> On Fri, 31 Oct 2008 08:33:52 +0900
>> yamaoka@jpl.org (Katsumi Yamaoka) said as follows:

>>    References: (") <200810150047.AA17342@mailhost.example.net>
>> which AFAICS is allowed.

>The patch makes the function remove not only the odd comment but
>also things following it.  You meant it has to behave like the
>following, didn't you?

>(ietf-drums-remove-comments "(\") <200810150047.AA17342@mailhost.example.net>")
> => " <200810150047.AA17342@mailhost.example.net>"

>Ok.  It is below.  Anyway I believe we need to fix the function
>whatever the way, or we cannot view messages having such odd comments.

>TSUCHIYA-san, WDYT?

I checked http://www.ietf.org/rfc/rfc2822.txt, and noticed that
double-quote is always allowed as texts of comments.

FWS             =       ([*WSP CRLF] 1*WSP) /   ; Folding white space
                        obs-FWS

ctext           =       NO-WS-CTL /     ; Non white space controls
                        %d33-39 /       ; The rest of the US-ASCII
                        %d42-91 /       ;  characters not including "(",
                        %d93-126        ;  ")", or "\"

ccontent        =       ctext / quoted-pair / comment

comment         =       "(" *([FWS] ccontent) [FWS] ")"

CFWS            =       *([FWS] comment) (([FWS] comment) / FWS)

Therefore, I think that your solution can be simplified as follows.

(defun ietf-drums-remove-comments (string)
  "Remove comments from STRING."
  (with-temp-buffer
    (let (c)
      (ietf-drums-init string)
      (while (not (eobp))
	(setq c (char-after))
	(cond
	 ((eq c ?\")
	  (forward-sexp 1))
	 ((eq c ?\()
	  (delete-region
	   (point)
	   (condition-case nil
	       (with-syntax-table (copy-syntax-table ietf-drums-syntax-table)
		 (modify-syntax-entry ?\" "w")
		 (forward-sexp 1)
		 (point))
	     (error (point-max)))))
	 (t
	  (forward-char 1))))
      (buffer-string))))

-- 
TSUCHIYA Masatoshi