Writing code to find/replace html

Hi,

I'm not sure if this is the right place to ask, but here goes...
I have a bunch of html docs that I need to do find/replaces on, but the
find/replaces are substantially more advanced than what is offered on
Dreamweaver MX. Does anyone know what language I could use (like an
object-oriented language) to manipulate and rewrite html code? Writing a
quick function seems much easier than cutting and pasting thousands of
lines.....

Thanks,
Aaron