Quite some time ago (while I was still at uni) I worked on a source-to-   
   source translator implemented using a system called GENTLE (http://   
   gentle.compilertools.net/) which made this job very straightforward.   
   For the lexing and parsing stage it uses lex and yacc, but for tree   
   traversal it has its own rule based language. I see that it has been   
   maintained over the years, so it might still be worthwhile to have a   
   quick look.   
      
   Robby   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)