XML schema for non-XML file?

Hi!

I would like to extract informations  from non-xml text file and put it 
in xml format.

Instead of doing a program for each type of text file I have, I would 
like to use a "schema like" file specifying the
structure of my non-xml text file for retriving from it the informations 
that I will put in xml.

Have you heard of projects/technologie/etc that do this?

Can I achieve my goal by using XSLT or other xml related technology?

Thanks a lot!

Yaneric Roussel