Re: XKCD/541 compliance, anyone?

[Stefan Monnier <monnier@iro.umontreal.ca>]

> (defvar smiley-regex "[:;x>B][,']?-?[]()PD]"
>   "This regex should match smileys.")

> (defun make-smileys-punctuation (beg end)
>   "Look for smileys between BEG and END position in the buffer, and
>   change their syntax property to punctuation."
>   (goto-char beg)
>   (while (re-search-forward smiley-regex end t)
>     (put-text-property (match-beginning 0) (match-end 0) 'syntax-table '(1))))

You can also use

   (syntax-propertize-rules (smiley-regex (0 ".")))

> (defun enable-smileys-punctuation ()
>   (setq syntax-propertize-function #'make-smileys-punctuation)

Beware: syntax-propertize-function might already be in use, in which
case you should probably use add-function to combine the two.

>   (setq parse-sexp-lookup-properties t))

This is not necessary, it will be set by the syntax-propertize function.

> However, it did not work (in text mode); my make-smileys-punctuation
> seems not even to get called.

Right, syntax-propertization is done lazily, so if nothing calls
syntax-propertize, then that's that.  Usually the main triggers for
syntax-propertize are syntax-ppss and font-lock, but neither is likely
to be used in text-mode.  So you'll probably need to arrange for font-lock to
be enabled *and* for font-lock-keywords-only not to be set to t.

> but then again, not in message mode, for instance.

Probably because font-lock-keywords-only is set to t, so font-lock
doesn't end up calling syntax-ppss.


        Stefan