Re: font-lock regexp for complementary keywords

[David Combs]

In article <mailman.4451.1153844221.9609.help-gnu-emacs@gnu.org>,
Kevin Rodgers  <ihs_4664@yahoo.com> wrote:
>Dieter Wilhelm wrote:
>> Hi
>> 
>> I'd like to fontify Ansys keywords.  The solver accepts unique short
>> forms of the command keywords, the rest is ignored.  For example the
>> uniqe part of `/filname' is `/fil' and I'd like to fontify
>> 
>> /fil and
>> /filn and
>> /filna and
>> /filnam and
>> /filname and
>> 
>> as well.  The only idea I got so far is to do it in 5 separate
>> font-lock statements:
>> 
>> \\(/fil\\) 1 font-lock...
>> /fil\\(n\\) 1 fon...
>> /filn\\(a\\) 1 ...
>> /filna\\(m\\) 1 ...
>> /filnam\\(e\\) 1 ...
>
>Why are you grouping and highlighting either "/fil" or the last letter?
>
>> Very ugly and inefficient, isn't it?
>> Originally I thought that something like this
>> 
>> /fil\\(n\\|na\\|nam\\|name\\)
>> 
>> would work but rexexp-bulider doesn't show any matches for the
>> complementing alternatives.
>
>"/fil\\(n\\(a\\(me?\\)?\\)?\\)?\\>" 0 font-lock...

A really-stupid question:

That last line -- were it not elisp but eg postscript (or reverse polish),
I'd at least understand the syntax:  font-lock would (likely) take at least 
two args (would get stacked) and then font-lock (op) would would run.

But this *is* elisp, so just what is that expression?  It clearly
must be some part of a bigger expression, form, whatever.  Perhaps
you could show an example?

Thanks!

David