Recommend C front-end that preserves preprocessor directives

Question

I'd like to start a project that involves transforming C code, but I'd like to include the preprocessor directives. I don't want to reinvent the wheel by writing my own C parser, so does anyone know of a front-end that can parse C preprocessor and C code, and produce an AST that can be used to re-generate (or pretty-print) the original source?

e.g.,:

#define FILENAME "filename"
#include <stdio.h>

FILE *f=0;
...
if (file_is_open) {
#ifdef CAN_OPEN_IT
    f = fopen(FILENAME, "r");
#else
    printf("Unable to open file.\n");
#endif
}

The above code should be parsed into some in-memory representation that can be used to re-generate the source. In other words, it should not be processed as normal C in two phases, first processing the PP directives and then parsing pure C code. Rather it should represent the whole compile-time logic including the preprocessor variables.

Answer 1

Take a look at Clang. (See http://clang.llvm.org/features.html#applications .)