Parsing Perl well enough to do a good job of syntax highlighting is hard
. The ony program I've seen that seems to get it right all the time is perltidy
. It's 20,000 lines of Perl, most of which aren't concerned with syntax highlighting. But that gives a sense of the scale of the problem.
So, let's say you had a special tag, <perl_code> has been suggested here, that would run the tag contents through
perltidy --html. The highlighting is implemented with a CSS stylesheet, which could be incorporated into the standard site CSS. To turn off the highlighting, or to implement your own style, just add a custom stylesheet.
Of course, it would still be a significant load on the server(s).