Is it important that the processing correctly handle preprocessor directives? Handling #define and #ifxxx can be interesting!

I've several times started work on a Pure Perl C/C++ preprocess parser, but it's a tricky problem even just handling fairly normal code. Handling edge cases in the same way as a range of different C/C++ compilers is just plain nasty. In some cases there isn't well defined behaviour and each compiler's preprocessor may generate different results.