Fontification with a specific function

Fontification with a specific function

[joao]

Hi all,

I'm trying to define a function to find text for fontification. This is
one of the possible elements of `font-lock-keywords'. Looking at the
emacs lisp reference manual (Font Lock Mode/Search-based Fontification),
I see that 

     When FUNCTION is called, it receives one argument, the limit of
     the search.  It should return non-`nil' if it succeeds, and set the
     match data to describe the match that was found.

I don't see where this "match data" is defined. Can anyone point me to
an example, in the emacs sources or in some package, of this usage of
fontification ?

Thanks,

Joao

Re: Fontification with a specific function

[Joakim Hove]

joao17@mailinator.com (joao) writes:


> I don't see where this "match data" is defined. Can anyone point me to
> an example, in the emacs sources or in some package, of this usage of
> fontification ?

<Disclaimer: I have never done this myself>

The match data is some global emacs variable/stack of the last regexp
search results. Let us say you you wanted to fontify the word 'horse'
then function could be like this:

(defun find-horse (p-max)
  ;; OK the regexp is probably far to simple, but it finds
  ;; "horse". Maybe the optional fourth argument COUNT should be
  ;; set??
  (if (re-search-forward " \\(horse\\) " p-max t)   
      t nil))

This function will return t or nil depending on wether the string
horse was found, and if it was found. The match (i.e. horse), and
other information about the match can be found from the functions
match-string, match-beginning , match-data etc, and I guess that is
what the internals of the font-lock code does. Hence, the match data
is automatically set by the (re-search-forward ) function, you don't
have to do that.


Good luck

Joakim

-- 
Joakim Hove
hove AT ift uib no
+47 (55 5)8 27 90
http://www.ift.uib.no/~hove/

Re: Fontification with a specific function

[Oliver Scholz]

Joakim Hove <hove@ift.uib.no> writes:

> joao17@mailinator.com (joao) writes:
>
>
>> I don't see where this "match data" is defined. Can anyone point me to
>> an example, in the emacs sources or in some package, of this usage of
>> fontification ?
>
> <Disclaimer: I have never done this myself>
>
> The match data is some global emacs variable/stack of the last regexp
> search results. Let us say you you wanted to fontify the word 'horse'
> then function could be like this:
>
[function using `re-search-forward'.]

> Hence, the match data is automatically set by the (re-search-forward
> ) function, you don't have to do that.
[...]

Note that you can also set the match-data explicetly with
`set-match-data'.  See (info "(elisp)Entire Match Data").


    Oliver
-- 
24 Vendémiaire an 213 de la Révolution
Liberté, Egalité, Fraternité!

Re: Fontification with a specific function

[joao]

Oliver Scholz <alkibiades@gmx.de> writes:

> Joakim Hove <hove@ift.uib.no> writes:
> [function using `re-search-forward'.]
>
>> Hence, the match data is automatically set by the (re-search-forward
>> ) function, you don't have to do that.

Yes, that's simple enough... but the problem is, my search criteria
here are not purely syntactical, if they were, then I could've used the
other, more usual forms of fontification. Maybe I mix : search with the
regexp functions, then apply my own criteria on top of the match...

> Note that you can also set the match-data explicetly with
> `set-match-data'.  See (info "(elisp)Entire Match Data").

This sounds more promising, I'll look into this.

Thank you, Joakim, Oliver.

Joao