How should a clone of the `grep` program highlight matches for Emacs?

How should a clone of the `grep` program highlight matches for Emacs?

[Raffaele Ricciardi]

I am writing an Emacs script as a replacement for the `grep` program 
while executing the `rgrep` command.  Now, I can't make my Emacs script 
highlight the matches in a way that Emacs understands.

After having read the Emacs Lisp file that defines the `rgrep` command 
-- which I am using for my tests -- I guess that the script should 
surround matches with Select Graphic Rendition sequences; and it is 
doing so, like this:

     (princ "\x1b[31m") ; 31 means "red", as hard-coded in `grep.el`
     (princ (match-string-no-properties 0))
     (princ "\x1b[0m"))

These sequences do cause a terminal to highlight the matches, but not 
Emacs (of course, Emacs does highlight matches from `grep`).

What should the script do instead?  Thank you.

Re: How should a clone of the `grep` program highlight matches for Emacs?

[Michael Heerdegen]

Raffaele Ricciardi <rfflrccrd@gmail.com> writes:

> I am writing an Emacs script as a replacement for the `grep` program
> while executing the `rgrep` command.  Now, I can't make my Emacs
> script highlight the matches in a way that Emacs understands.

Do you want to use this script from M-x grep?  I assume "yes".

AFAICT grep.el highlights matches via a grep-mode defined as kind of a
compilation-mode.  The way of highlighting is defined in
`grep-regexp-alist'.  Other things are highlighted via font-lock
keywords.  Of course be sure to bind grep-highlight-matches non-nil.
But in general, grep-mode should be able to highlight as you want it.

My first guess is that might be help to set grep-highlight-matches to
always -- note that this option has a :set custom specification!

If that doesn't help, please show us some code!


Regards,

Michael.

Re: How should a clone of the `grep` program highlight matches for Emacs?

[Raffaele Ricciardi]

On 21/06/15 16:32, Raffaele Ricciardi wrote:
>      (princ "\x1b[31m") ; 31 means "red", as hard-coded in `grep.el`
>      (princ (match-string-no-properties 0))
>      (princ "\x1b[0m"))

This works:

     (princ "\x1b[01;31m")
     (princ (match-string-no-properties 0))
     (princ "\x1b[m")