Re: changing visuals of code in emacs

[Andrei Alexandrescu <SeeWebsiteForEmail@erdani.org>]

Pascal J. Bourguignon wrote:
> Andrei Alexandrescu <SeeWebsiteForEmail@erdani.org> writes:
> 
>> Pascal J. Bourguignon wrote:
>>> Andrei Alexandrescu <SeeWebsiteForEmail@erdani.org> writes:
>>>
>>>> Hello,
>>>>
>>>>
>>>> I'd like to change code visuals for the D programming language as
>>>> follows. I'd like the construct:
>>>>
>>>> Symbol!(balanced_parens)
>>>>
>>>> to be visualized as:
>>>>
>>>> Symbol«balanced_parens»
>>>>
>>>> The chevrons should appear electrically when I type the closing
>>>> ")". Note that balanced_parens could in turn nested use of "!()", as
>>>> in A!(B!(C)), and they should all be paired using chevrons. The
>>>> underlying file should not contain the chevrons, just the ASCII
>>>> representation using "!(" and ")".
>>>>
>>>> I haven't done much elisp programming beyond the common .emacs
>>>> configuration tricks, so I don't know where to start. A few searches
>>>> suggested that overlays may be what I'm looking for... any ideas and
>>>> pointers? Thank you.
>>> If you didn't ask for recursion, this could have be done with
>>> font-locking.
>>> (font-lock-add-keywords nil
>>>   '(("\\(!(\\)[^()]*\\()\\)"      0 (progn
>>>          (compose-region (match-beginning 1) (match-end 1) ?« 'decompose-region)
>>>          (compose-region (match-beginning 2) (match-end 2) ?» 'decompose-region)
>>>          nil))))
>>> But since this uses regular expressions, it won't work for recursive
>>> !(...).
>>> You can still use compose-region, but you'll have to implement the
>>> parsing yourself.  Perhaps this could be hooked on the code doing the
>>> parenthesis balancing?
>> I think I'd be happy with a nonrecursive region to get my feet
>> wet. How do I use your font-lock-add-keywords code? I added it to both
>> my .emacs and my d-mode.el file, to no avail.
> 
> You could run it from a d-mode-hook if it exists, ensuring that
> font-lock-mode is enabled.
> 
> (add-hook 'd-mode-hook 
>           (lambda () 
>             (font-lock-add-keywords nil
>               '(("\\(!(\\)[^()]*\\()\\)"      0 (progn
>                      (compose-region (match-beginning 1) (match-end 1) ?« 'decompose-region)
>                      (compose-region (match-beginning 2) (match-end 2) ?» 'decompose-region)
>                      nil))))
>             (font-lock-mode 1)))
> 

Thanks! I got that working. It ought to get me started.

Regards,

Andrei