Subject: bug#6345: css-mode `css-extract-keyword-list' does not actually [PATCH]

From: MON KEY <[email-masked]>
Date: Thu, 3 Jun 2010 14:01:06 -0400

`css-extract-keyword-list' does not actually [PATCH]

In function `css-extract-keyword-list' the search for "Appendix
H. Index" fails e.g. this form:

   (search-backward "Appendix H. Index")

when used to search this the contents of this URL:

 "http://www.w3.org/TR/REC-CSS2/css2.txt"

which is dated: W3C Candidate Recommendation 08 September 2009

Returns this message:

 css-extract-keyword-list: Search failed: "Appendix H. Index"

It appears this function was originally supplied to scrape CSS
keywords as per the commented code in: lisp/textmodes/css-mode.el

,----
| (css-extract-keyword-list
|   '((pseudo . "^ +\\* :\\([^ \n,]+\\)")
|     (at . "^ +\\* @\\([^ \n,]+\\)")
|     (descriptor . "^ +\\* '\\([^ '\n]+\\)' (descriptor)")
|     (media . "^ +\\* '\\([^ '\n]+\\)' media group")
|    (property . "^ +\\* '\\([^ '\n]+\\)',")))
`----

However, W3C has gone behined Stefan's back and changed the Appendix
enumeration without asking his permission first :)

"Appendix H" is now "Appendix I".

Compare the version scraped (presumably):

 (URL `http://www.w3.org/TR/2008/REC-CSS2-20080411/indexlist.html')
 (URL `http://www.w3.org/TR/2008/REC-CSS2-20080411/css2.txt')

with the current version:

 (URL `http://www.w3.org/TR/CSS2/indexlist.html')
 (URL `http://www.w3.org/TR/CSS2/css2.txt')

The following regexp may be more robust and appears to works for
either the older version or the latest version and leaves room for W3C
to continue add appendices J-M:

 (search-backward-regexp "[_━]\\{60,79\\}\xa[[:space:]]+Appendix [A-M]\. Index")

This said, `css-extract-keyword-list' is now borking on regexps in
these conses:

 (css-extract-keyword-list
  '((pseudo . "^ +\\* :\\([^ \n,]+\\)")
    (at . "^ +\\* @\\([^ \n,]+\\)")
    (descriptor . "^ +\\* '\\([^ '\n]+\\)' (descriptor)")
    (media . "^ +\\* '\\([^ '\n]+\\)' media group")
    (property . "^ +\\* '\\([^ '\n]+\\)',")))

and seems to be failing per `url-insert-file-contents' reliance on
`decode-coding-inserted-region' which frobs the asterisks `*' (char
#x2a) into a bullet `•' (char #x2022) -- at least on on my system.

If we substitute occurences of "\\*" with "[*•]" (e.g. "[\x2a\x2022]")
the following regexps now seem to work correctly:

 (pp (css-extract-keyword-list
      '((pseudo . "^ +[\x2a\x2022] :\\([^ \n,]+\\)")
        (at . "^ +[\x2a\x2022] @\\([^ \n,]+\\)")
        (descriptor . "^ +[\x2a\x2022] '\\([^ '\n]+\\)' (descriptor)")
        (media . "^ +[\x2a\x2022] '\\([^ '\n]+\\)' media group")
        (property . "^ +[\x2a\x2022] '\\([^ '\n]+\\)',")))
     (current-buffer))

Following diffed against Bazaar revision 100231

;;; ==============================

*** ediff3753M5g	2010-06-03 09:43:04.000000000 -0400
--- lisp/textmodes/css-mode.el	2010-06-03 09:42:43.000000000 -0400
***************
*** 41,49 ****

  (defun css-extract-keyword-list (res)
    (with-temp-buffer
!     (url-insert-file-contents "http://www.w3.org/TR/REC-CSS2/css2.txt")
      (goto-char (point-max))
!     (search-backward "Appendix H. Index")
      (forward-line)
      (delete-region (point-min) (point))
      (let ((result nil)
--- 41,49 ----

  (defun css-extract-keyword-list (res)
    (with-temp-buffer
!     (url-insert-file-contents
"http://www.w3.org/TR/2008/REC-CSS2-20080411/css2.txt")
      (goto-char (point-max))
!     (search-backward-regexp "[_━]\\{60,79\\}\xa[[:space:]]+Appendix
[A-M]\. Index")
      (forward-line)
      (delete-region (point-min) (point))
      (let ((result nil)
***************
*** 115,125 ****

  ;; Extraction was done with:
  ;; (css-extract-keyword-list
! ;;  '((pseudo . "^ +\\* :\\([^ \n,]+\\)")
! ;;    (at . "^ +\\* @\\([^ \n,]+\\)")
! ;;    (descriptor . "^ +\\* '\\([^ '\n]+\\)' (descriptor)")
! ;;    (media . "^ +\\* '\\([^ '\n]+\\)' media group")
! ;;    (property . "^ +\\* '\\([^ '\n]+\\)',")))

  (defconst css-pseudo-ids
    '("active" "after" "before" "first" "first-child" "first-letter"
"first-line"
--- 115,125 ----

  ;; Extraction was done with:
  ;; (css-extract-keyword-list
! ;;      '((pseudo . "^ +[\x2a\x2022] :\\([^ \n,]+\\)")
! ;;        (at . "^ +[\x2a\x2022] @\\([^ \n,]+\\)")
! ;;        (descriptor . "^ +[\x2a\x2022] '\\([^ '\n]+\\)' (descriptor)")
! ;;        (media . "^ +[\x2a\x2022] '\\([^ '\n]+\\)' media group")
! ;;        (property . "^ +[\x2a\x2022] '\\([^ '\n]+\\)',")))

  (defconst css-pseudo-ids
    '("active" "after" "before" "first" "first-child" "first-letter"
"first-line"