font-lock-keywords and lines containing comments / quotes

font-lock-keywords and lines containing comments / quotes

[Erik Iverson]

Hello,

I am trying to learn things about font-lock-mode, and am needing help 
understanding the following behavior.  To see what I am confused about, create a 
buffer in emacs-lisp mode (or just use *scratch*) and define the following:

;; syntax highlight lines that start with a "*" in the current buffer
(font-lock-add-keywords nil
			'(("^\\*\\{1\\}.*" . font-lock-keyword-face)))


Now, with the above defined, paste (or type out to see the effect in action) the 
following lines starting with * in the same buffer, which will demonstrate what 
I would like to achieve, and what is going wrong...


* this is highlighted, great!
* so is this, until I type a ; comment
* similiar here, until I type a "quote"


As soon as I type the ; or " characters, the previous part of the line becomes 
"normal" and the comment or quote appears as it should.  I would like for the 
initial part of the line to remain highlighted though.

Obviously I am missing something simple(?) here, but I am having a hard time 
figuring out how the typical major-modes (e.g., emacs-lisp) handle this case. 
Any hints?

Hopefully this was clear! I am using Emacs 23 under Linux.

Best Regards,
Erik Iverson

Re: font-lock-keywords and lines containing comments / quotes

[Tim Visher]

Hi Erik,

On Thu, Feb 25, 2010 at 8:57 PM, Erik Iverson <eriki@ccbr.umn.edu> wrote:
> I am trying to learn things about font-lock-mode, and am needing help
> understanding the following behavior.  To see what I am confused about,
> create a buffer in emacs-lisp mode (or just use *scratch*) and define the
> following:
>
> ;; syntax highlight lines that start with a "*" in the current buffer
> (font-lock-add-keywords nil
>                        '(("^\\*\\{1\\}.*" . font-lock-keyword-face)))
>
>
> Now, with the above defined, paste (or type out to see the effect in action)
> the following lines starting with * in the same buffer, which will
> demonstrate what I would like to achieve, and what is going wrong...
>
>
> * this is highlighted, great!
> * so is this, until I type a ; comment
> * similiar here, until I type a "quote"
>
>
> As soon as I type the ; or " characters, the previous part of the line
> becomes "normal" and the comment or quote appears as it should.  I would
> like for the initial part of the line to remain highlighted though.
>
> Obviously I am missing something simple(?) here, but I am having a hard time
> figuring out how the typical major-modes (e.g., emacs-lisp) handle this
> case. Any hints?
>
> Hopefully this was clear! I am using Emacs 23 under Linux.

I can't say for sure but this smells pretty strongly of a regex
failure.  Lots of stuff in Emacs is keyed off of regexs which can be a
pain because many languages aren't truly regular (take markdown for
instance) and the languages that are would probably be better served
by a state machine.

That being said, have you read the sections in the ELisp reference
manual on Font Lock?  `C-h i m elisp RET m font lock basics RET`
should get you there if you haven't.  That may shed some more light on
the matter for you.

If you have already read that manual, then I'm afraid I probably can't
be of any more service to you.

Good luck!

-- 

In Christ,

Timmy V.

http://burningones.com/
http://five.sentenc.es/ - Spend less time on e-mail

Re: font-lock-keywords and lines containing comments / quotes

[despen]

 On Thu, Feb 25, 2010 at 8:57 PM, Erik Iverson <eriki@ccbr.umn.edu> wrote:
> I am trying to learn things about font-lock-mode, and am needing help
> understanding the following behavior.  To see what I am confused about,
> create a buffer in emacs-lisp mode (or just use *scratch*) and define the
> following:
>
> ;; syntax highlight lines that start with a "*" in the current buffer
> (font-lock-add-keywords nil
>                        '(("^\\*\\{1\\}.*" . font-lock-keyword-face)))
>
>
> Now, with the above defined, paste (or type out to see the effect in action)
> the following lines starting with * in the same buffer, which will
> demonstrate what I would like to achieve, and what is going wrong...
>
>
> * this is highlighted, great!
> * so is this, until I type a ; comment
> * similiar here, until I type a "quote"
>
>
> As soon as I type the ; or " characters, the previous part of the line
> becomes "normal" and the comment or quote appears as it should.  I would
> like for the initial part of the line to remain highlighted though.
>
> Obviously I am missing something simple(?) here, but I am having a hard time
> figuring out how the typical major-modes (e.g., emacs-lisp) handle this
> case. Any hints?

Look at the description of font-lock-defaults.
When you set it, you want to set KEYWORDS-ONLY to t so that
syntax tables (strings and comments) are ignored.

Re: font-lock-keywords and lines containing comments / quotes

[Johan Bockgård]

Erik Iverson <eriki@ccbr.umn.edu> writes:

> ;; syntax highlight lines that start with a "*" in the current buffer
> (font-lock-add-keywords nil
> 			'(("^\\*\\{1\\}.*" . font-lock-keyword-face)))

The \\{1\\} is not useful.

> As soon as I type the ; or " characters, the previous part of the line
> becomes "normal" and the comment or quote appears as it should.  I
> would like for the initial part of the line to remain highlighted
> though.

Use the OVERRIDE element.

    (font-lock-add-keywords
     nil '(("^\\*.*" 0 font-lock-keyword-face keep)))