Re: string-match doesn't honor anchor when START is nonzero

[Gerd Moellmann <gerd@gnu.org>]

Jim Meyering <meyering@ascend.com> writes:

> In GNU Emacs 20.5.1 (i686-pc-linux-gnu, X toolkit)
>  of Fri Dec 10 1999 on ixi.eng.ascend.com
> configured using `configure  --prefix=/p/p/emacs-20.5'
> ------------
> 
> The following seems to be at the root of a problem I noticed in Gnus.
> 
> Is it expected that this would evaluate to nil?  (it does)
> 
>   (string-match "^j" " j" 1)
> 
> I expected it to return `1', but the `^' gets in the way.
> The documentation for string-match doesn't address this point
> as far as I could see.
> 

The `^' is a special character in regular expressions, matching
at the beginning of text.

> If returning `nil' is the intended behavior, then there's a bug in
> mail-utils.el (rmail-dont-reply-to) because it seems to expect `1' and
> fails when it gets the `nil'.  The result is that that function removes
> only one of two matching, adjacent addresses.
> 
> This illustrates the problem:
> 
>   (setq rmail-dont-reply-to-names "f.")
>   (load "mail-utils")
>   (rmail-dont-reply-to "b, f1, f2, f3, f4, f5, f6")
> 
>   Return value: "b, f2, f4, f6"
> 

Thanks for the test case.  Does the following patch solve the problem?

Index: mail-utils.el
===================================================================
RCS file: /gd/gnu/cvsroot/emacs/lisp/mail/mail-utils.el,v
retrieving revision 1.44
diff -c -r1.44 mail-utils.el
*** mail-utils.el	1999/08/16 03:14:25	1.44
--- mail-utils.el	2000/01/26 16:06:58
***************
*** 230,254 ****
  	(case-fold-search t)
  	pos epos)
      (while (setq pos (string-match match userids pos))
!       (if (> pos 0) (setq pos (match-beginning 2)))
!       (setq epos
! 	    ;; Delete thru the next comma, plus whitespace after.
! 	    (if (string-match ",[ \t\n]*" userids (match-end 0))
! 		(match-end 0)
! 	      (length userids)))
!       ;; Count the double-quotes since the beginning of the list.
!       ;; Reject this match if it is inside a pair of doublequotes.
!       (let (quote-pos inside-quotes)
! 	(while (and (setq quote-pos (string-match "\"" userids quote-pos))
! 		    (< quote-pos pos))
! 	  (setq quote-pos (1+ quote-pos))
! 	  (setq inside-quotes (not inside-quotes)))
  	(if inside-quotes
  	    ;; Advance to next even-parity quote, and scan from there.
  	    (setq pos (string-match "\"" userids pos))
! 	  (setq userids
! 		(mail-string-delete
! 		 userids pos epos)))))
      ;; get rid of any trailing commas
      (if (setq pos (string-match "[ ,\t\n]*\\'" userids))
  	(setq userids (substring userids 0 pos)))
--- 230,248 ----
  	(case-fold-search t)
  	pos epos)
      (while (setq pos (string-match match userids pos))
!       ;; If there's a match, it starts at the beginning of the string,
!       ;; or with `,'.  We must delete from that position to the
!       ;; end of the user-id which starts at match-beginning 2.
!       (let (inside-quotes quote-pos)
! 	(save-match-data
! 	  (while (and (setq quote-pos (string-match "\"" userids quote-pos))
! 		      (< quote-pos pos))
! 	    (setq quote-pos (1+ quote-pos))
! 	    (setq inside-quotes (not inside-quotes))))
  	(if inside-quotes
  	    ;; Advance to next even-parity quote, and scan from there.
  	    (setq pos (string-match "\"" userids pos))
! 	  (setq userids (replace-match "" nil nil userids)))))
      ;; get rid of any trailing commas
      (if (setq pos (string-match "[ ,\t\n]*\\'" userids))
  	(setq userids (substring userids 0 pos)))
***************
*** 256,261 ****
--- 250,256 ----
      (if (string-match "\\s *" userids)
  	(substring userids (match-end 0))
        userids)))
+ 
  \f
  ;;;###autoload
  (defun mail-fetch-field (field-name &optional last all list)