Re: latexenc-find-file-coding-system is slow. (was: Your Emacs changes)

[Richard Stallman]

    I guess the re-searching in latexenc-find-file-coding-system needs to
    be improved.

It would be faster to search for the strings "\\inputencoding{" and
"\\usepackage\\[" using search-forward, and each time it finds an
occurrence, do string-match at the beginning of the line to see if the
line is a real match.  It would need to do this loop once for each
string.  Such a loop could easily be 100 times faster than the call to
re-search-forward.

   (while (and (not found) (search-forward string nil t))
     (save-excursion
       (beginning-of-line)
       (if (looking-at entire-regexp)
           (setq found (point))))
     (forward-line 1))

There's another way to speed this up, if there is some rule about
where in the file those constructs should occur.  For instance, if the
rule is that they should occur before the first \foo, and \foo is
commonly found in LaTeX files, it could be faster to search first for
\foo, then use the position of the first \foo as a bound in the other
searches.