Re: which-func, imenu, AUCTeX

[Greg Bognar]

Hi Arash,

Thanks!  Meanwhile, I also tried to write a simple function, using
`tex-current-defun-name' from `tex-mode.el' as the starting point:

----------8<----------8<----------8<----------8<----------8<----------
  (defun my-latex-current-heading-name ()
    "Return the name of the LaTeX section/paragraph/chapter at point, or nil.
  To be used by which-func to display heading name in the modeline."
    (save-excursion
      (when (re-search-backward
                   "^\\\\\\(sub\\)*\\(section\\|paragraph\\|chapter\\)" nil t)
        (goto-char (search-forward "{" nil t))
        (buffer-substring-no-properties (point)
                                        (1- (search-forward "}" nil t))))))
----------8<----------8<----------8<----------8<----------8<----------

When I tested both of them, strange and wondrous things started to happen :)

Both seem to work well when I use `add-log-current-defun-function'

   (setq add-log-current-defun-function #'my-latex-current-heading-name)

   (setq add-log-current-defun-function #'TeX-which-func-defun-name)

But when I use either 

   (setq which-func-functions #'TeX-which-func-defun-name)

   (setq which-func-functions #'my-latex-current-heading-name)

they don't seem to work well.  In particular, remember that line in the preamble
of my test file:

   \titlespacing\section{0pt}{2\bigskipamount}{\parskip}

They give me section{0pt} in the modeline when I'm before the first \section,
which they shouldn't (since neither does this when set to
`add-log-current-defun-function').

Perhaps this has something to do with `which-func-functions'?  Again, both
functions work with `add-log-current-defun-function'.

In addition, your function (but I think mine not, at least so far) sometimes
generates an error with my test file:

  Error running timer `which-func-update': (error "Error in which-func-update: 
(scan-error \"Containing expression ends prematurely\" 1088 1089)")

The buffer positions which are indicated are in this line:

  \bibpunct[:~]{(}{)}{,}{a}{}{,}

specifically, the error points to one of the }{ on this line. 

In any case, I'm happy with using `add-log-current-defun-function'.  I will also
try to modify the function(s) to pick up on beamer \frametitle's too.

All the best,
Greg

-------------------------------------------------------------------------------
On Fri 18 Oct 2024 at 14:07 Arash Esbati wrote:
> 
> Hi Greg,
> 
> Greg Bognar <greg.bognar@startmail.com> writes:
> 
> > Thanks for the (always) helpful explanation and pointers!
> 
> You're welcome.
> 
> > So (since I'm not very competent in elisp) are you suggesting that one
> > way to get what I want would be to write a function (perhaps starting
> > from `TeX-current-defun-name') that returns only what I want and than
> > set the `which-func-functions' variable to this function, like below
> > with `add-log-current-defun-function'?
> 
> Yes, that would be one solution.  The function can look like this:
> 
> --8<---------------cut here---------------start------------->8---
> (defun TeX-which-func-defun-name ()
>   "Return the name of the TeX section/paragraph/chapter at point, or nil."
>   (save-excursion
>     (let (s1 e1)
>       ;; If we are now precisely at the beginning of a sectioning
>       ;; command, move forward and make sure `re-search-backward'
>       ;;  finds this one rather than the previous one:
>       (or (eobp) (progn
>                    (when (looking-at-p "\\\\")
>                      (forward-char))
>                    (unless (eolp)
>                      (forward-sexp))))
>       ;; Search backward for sectioning command.  If
>       ;; `LaTeX-section-label' is buffer-local, assume that a style
>       ;; has changed the value and recalculate the string.  Otherwise
>       ;; take the standard one:
>       (when (re-search-backward
>              (concat
>               ;; Consider only top-level macros
>               "^"
>               (when (eq major-mode 'docTeX-mode) "%")
>               "[ \t]*"
>               (if (local-variable-p 'LaTeX-section-label)
>                   (concat "\\\\"
>                           (regexp-opt
>                            (remove "part" (mapcar #'car LaTeX-section-label)))
>                           "\\*?")
>                 "\\\\\\(sub\\)*\\(section\\|paragraph\\|chapter\\)\\*?"))
>              nil t)
>         ;; Skip over the sectioning command, incl. the *:
>         (goto-char (match-end 0))
>         ;; Skip over the optional argument, if any:
>         (when (looking-at-p "[ \t]*\\[")
>           (forward-sexp))
>         ;; Skip over any chars until the mandatory argument:
>         (skip-chars-forward "^{")
>         ;; Remember the points for the mandatory argument:
>         (setq s1 (point))
>         (setq e1 (progn (forward-sexp)
>                         (point)))
>         ;; Now pick the content:
>         (buffer-substring-no-properties (1+ s1) (1- e1))))))
> --8<---------------cut here---------------end--------------->8---
> 
> Then you do this in your init file:
> 
> (setq which-func-functions #'TeX-which-func-defun-name)
> 
> Do you want to give it a roll?
> 
> Best, Arash