No, the real problem is the both C and C++ are context sensitive. (In C compilers, though not C++ ones, 'the lexer hack' is the most common solution) That's fairly hard to parse, although not as bad as some languages. For preprocessing, it's fairly easy to write a C preprocessor, and then look at how your code will look if various options are defined... Actually that would be a really good debugging tool. I should go write that. And then make an emacs mode for it, so that you can type one command at any point, and see how your function/file/whatever will be transformed by the preprocessor.