bug#1756: awk-mode: An empty line is not a paragraph separator (should be)

[Alan Mackenzie]

Hi, Teemu!

On Thu, Jan 01, 2009 at 10:27:17AM +0200, Teemu Likonen wrote:
> In awk-mode an empty line is not considered a paragraph separator, only
> lines containing whitespace and "#" character(s) are. After running the
> command "M-x awk-mode" the value of both paragraph-start and
> paragraph-separate are set as follows:

>     "[ \t]*\\(#+\\)[ \t]*$\\|^\f"
>               ^^

> See, at least one # is required. I think better default would be #* so
> that empty lines or lines with only whitespace would be paragraph
> separators too.

Agreed.  Thanks for the report.

> I suggest doing the following change: 
> [ Tweaking the definition of c-comment-prefix-regexp. ]

I'd rather not do it this way, because although c-comment-prefix-regexp
isn't currently used anywhere else, it might be in the future.  A blank
line cannot be a comment prefix in AWK.

> (pike-mode and "other" have a comment prefix regexp which matches a zero
> number of comment prefix characters: \**)

Can you please try the following patch (it might be a few lines offset
from the given line numbers).  It checks whether the comment prefix
matches a blank line, and fixes paragraph-s{tart,eparate} if it doesn't.

#########################################################################

*** orig/cc-styles.el   2009-01-05 11:49:10.753657960 +0000
--- cc-styles.el        2009-01-05 15:29:34.569332408 +0000
***************
*** 512,525 ****
                          (assoc 'other c-comment-prefix-regexp)))
          c-comment-prefix-regexp))
  
!   (let ((comment-line-prefix
!        (concat "[ \t]*\\(" c-current-comment-prefix "\\)[ \t]*")))
  
!     (setq paragraph-start (concat comment-line-prefix
                                  c-paragraph-start
                                  "\\|"
                                  page-delimiter)
!         paragraph-separate (concat comment-line-prefix
                                     c-paragraph-separate
                                     "\\|"
                                     page-delimiter)
--- 512,532 ----
                          (assoc 'other c-comment-prefix-regexp)))
          c-comment-prefix-regexp))
  
!   (let* ((empty-is-prefix (string-match c-current-comment-prefix ""))
!        (nonws-comment-line-prefix
!         (concat "\\(" c-current-comment-prefix "\\)[ \t]*"))
!        (comment-line-prefix (concat "[ \t]*" nonws-comment-line-prefix))
!        (blank-or-comment-line-prefix
!         (concat "[ \t]*"
!                 (if empty-is-prefix "" "\\(")
!                 nonws-comment-line-prefix
!                 (if empty-is-prefix "" "\\)?"))))
  
!     (setq paragraph-start (concat blank-or-comment-line-prefix
                                  c-paragraph-start
                                  "\\|"
                                  page-delimiter)
!         paragraph-separate (concat blank-or-comment-line-prefix
                                     c-paragraph-separate
                                     "\\|"
                                     page-delimiter)

#########################################################################

> There is another and related bug. It is possible to configure the
> comment prefix regexp with the option c-comment-prefix-regexp. But the
> problem is that the option only takes effect when awk-mode is turned on.
> If user later changes indentation style with the command c-set-style
> (bound to C-c .) then it seems that the hard-coded default (#+) takes
> preference over user's c-comment-prefix-regexp settings.

I'll get back to you on this one.

Thanks again for the bug report.

-- 
Alan Mackenzie (Nuremberg, Germany).