Re: latexenc-find-file-coding-system is slow.

[Lute Kamstra <Lute.Kamstra.lists@xs4all.nl>]

[For some reason, I didn't see your message on emacs-devel.]

Arne Jørgensen <arne@arnested.dk> writes:

> Lute Kamstra <Lute.Kamstra.lists@xs4all.nl> writes:
>
>> I guess the re-searching in latexenc-find-file-coding-system needs to
>> be improved.
>
> I have made a try at speeding up the search for input encoding.

Thanks.

> What is does now is search for "inputenc" with `search-forward' until
> the first match also matches (with `looking-at') an
> \inputencoding{...} or \usepackage[...]{inputenc} (that is not inside
> a comment).

That should speed things up.

> For now I have not added a limit for how far to search for this
> because I still see no way to decide this for all common cases. And
> then I would like to hear if the change has any effect on the speed as
> it is.

It's probably fast enough now.

> I limitied the search for a TeX-master/tex-main-file in the local
> variables section though. The limit is borrowed from
> `hack-local-variables'.

That should work.

[...]

I think there a some minor problems with the details of the
implementation:

> Index: lisp/international/latexenc.el
> ===================================================================
> RCS file: /cvsroot/emacs/emacs/lisp/international/latexenc.el,v
> retrieving revision 1.3
> diff -u -p -r1.3 latexenc.el
> --- lisp/international/latexenc.el	1 May 2005 11:01:49 -0000	1.3
> +++ lisp/international/latexenc.el	4 May 2005 18:12:23 -0000
> @@ -120,24 +120,33 @@ coding system names is determined from `
>        (save-excursion
>          ;; try to find the coding system in this file
>          (goto-char (point-min))
> -        (if (or
> -             (re-search-forward "^[^%\n]*\\\\inputencoding{\\(.*\\)}" nil t)
> -             (re-search-forward "^[^%\n]*\\\\usepackage\\[\\(.*\\)\\]{inputenc}" nil t))
> -            (let* ((match (match-string 1))
> -                   (sym (intern match)))
> -              (when (latexenc-inputenc-to-coding-system match)
> -                (setq sym (latexenc-inputenc-to-coding-system match))
> -                (when (coding-system-p sym)
> -		  sym
> -                  (if (and (require 'code-pages nil t) (coding-system-p sym))
> -                      sym
> -                    'undecided))))
> +	(if (catch 'cs
> +	      (let ((case-fold-search nil))
> +		(while (search-forward "inputenc" nil t)
> +		  (goto-char (match-beginning 0))
> +		  (beginning-of-line)
> +		  (if (or (looking-at "[^%\n]*\\\\usepackage\\[\\(.*\\)\\]{\\(.*,\\)?inputenc\\(,.*\\)?}")

That also matches something like:

\usepackage[opt]{package} % don't use {package,inputenc}

> +			  (looking-at "[^%\n]*\\\\inputencoding{\\(.*\\)}"))
> +		      (throw 'cs (match-string 1))

Why throw (match-string 1) instead of t?

> +		    (goto-char (match-end 0))))))
> +	    (let* ((match (match-string 1))
> +		   (sym (intern match)))
> +	      (when (latexenc-inputenc-to-coding-system match)
> +		(setq sym (latexenc-inputenc-to-coding-system match)))
> +	      (when (coding-system-p sym)
> +		sym
> +		(if (and (require 'code-pages nil t) (coding-system-p sym))
> +		    sym
> +		  'undecided)))
>            ;; else try to find it in the master/main file
> -          (let (latexenc-main-file)
> +          (let (latexenc-main-file
> +		bound)
>              ;; is there a TeX-master or tex-main-file in the local variable section
>              (unless latexenc-dont-use-TeX-master-flag
>                (goto-char (point-max))
> -              (when (re-search-backward "^%+ *\\(TeX-master\\|tex-main-file\\): *\"\\(.+\\)\"" nil t)
> +	      (search-backward "\n\^L" (max (- (point-max) 3000) (point-min)) 'move)
> +	      (setq bound (search-forward "Local Variables:" nil t))
> +              (when (re-search-forward "^%+ *\\(TeX-master\\|tex-main-file\\): *\"\\(.+\\)\"" nil t)
>                  (let ((file (concat (file-name-directory (nth 1 arg-list)) (match-string 2))))
>                    (if (file-exists-p file)
>                        (setq latexenc-main-file file)

You don't seem to use the variable bound.

Could you also write a ChangeLog entry for your patch?

Lute.