I haven't tried quex, but I have tried lemon (which can be broken out of
SQLite) and re2c and ragel.
I like ragel and lemon, but the combination supports a push-parser style
from memory, and many tools are inconvenient unless you are prepared to
suck in a whole message before parsing, or let the parser drive a pull
loop, or use a coroutine structure.
Could go all trendy and use a PEG tool like, er,, peg
(http://piumarta.com/software/peg/) (I haven't tried them tho')
James