Peg/leg — recursive-descent parser generators for C (piumarta.com)

While Piumarta's original code is still relevant, I chose to use _why's fork that fixes some bugs and makes the parser reentrant. Take a look: https://github.com/whymirror/greg

Also, take a look at the various forks of greg, including one in use in the OOC compiler Rock: https://github.com/nddrylliog/greg