front-end tools for preprocessor / macro expansion

[Henrik Sorensen]

For the PL/I front-end project (pl1gcc.sourceforge.net), I am just about to 
begin to add  a preprocessor expansion step, and was wondering what other 
front-end do.

My initial thoughts were to create a completely separate program that just do 
the preprocessing and passes the output to the compiler.

Some background info regarding the PL/I preprocessor.

The PL/I processor language is more of a real text pre-processor that anything 
else, eg it is possible to define functions and have declared variables of 
data type either numeric or character based, and control statements includes 
for-loops, if-then constructs and goto statements.


any thoughts, hints is much appreciated.

Henrik