Re: Counting SLOC in Emacs

[Marcin Borkowski <mbork@wmi.amu.edu.pl>]

On 2014-11-28, at 15:49, Stefan Monnier wrote:

>>> And don't re-call use-region-p here, in the off-chance that it returns
>>> something else than in the first call.  E.g. you can use (if (and (=
>>> beg (point-min)) (= end (point-max))) "buffer" "region") instead.
>> I don't think it's probable (or even possible), but definitely my
>> solution was not very elegant.  I wonder whether (let)ting
>> (use-region-p) to a temporary variable wouldn't be better.
>
> Yes, it should be passed as an additional argument (you could pass
> `region' or `buffer' as argument, with nil meaning "not interactive,
> just return the count without displaying a message").
>
>> Anyway, thanks for your review!  I will write a blog post about this
>> function (googling for "emacs count sloc" doesn't yield anything
>> useful, let's change it! ;-) ).
>
> Of course, you'll bump into further problems:
>
>      (* foo bar
>       * baz *)
>
> will count as 1 lines, IIUC.  And similarly
>
>      printf ("toto\n"); (* foo bar
>                          * baz *)
>
> will count as 2 lines.  You might want to try something like:

Hm.  Didn't think of this.  (I'm not really accustomed to multi-line
comments, I guess.)

>    (defun count-sloc-region (beg end kind)
>      "Count source lines of code in region (or (narrowed part of)
>    the buffer when no region is active).  SLOC means that empty
>    lines and comment-only lines are not taken into consideration."
>      (interactive
>       (if (use-region-p)
>           (list (region-beginning) (region-end) 'region)
>         (list (point-min) (point-max) 'buffer)))
>      (save-excursion
>        (goto-char beg
>        (let ((count 0))
>          (while (< (point) end)
> 	  (cond
>            ((nth 4 (syntax-ppss)) ;; BOL is already inside a comment.
>             (let ((pos (point)))
>               (goto-char (nth 8 (syntax-ppss)))
>               (forward-comment (point-max))
>               (if (< (point) pos) (goto-char pos)))) ;; Just paranoia.
>            (t (forward-comment (point-max))))
> 	  (setq count (1+ count))
> 	  (forward-line))
>         (when kind
> 	  (message "SLOC in %s: %s." kind count))))))

Wow, thanks!

I'm planning to run a code reading seminar for some ambitious students
at my faculty.  I'm wondering whether it could be a good idea to study
this;).

(In fact, not really - at least not in the beginning - let them learn
some more typical stuff before exposing young minds to Emacs Lisp with
its peculiarities, like `interactive'.  We'll start with Python and JS,
though some Common Lisp is also planned.)

> -- Stefan

Best,

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Faculty of Mathematics and Computer Science
Adam Mickiewicz University