[rdtsc]

Another great use of leex and yecc -- a SQL parser from folks at Basho:

https://github.com/basho/riak_ql

Specifically:

https://github.com/basho/riak_ql/blob/develop/src/riak_ql_le...

https://github.com/basho/riak_ql/blob/develop/src/riak_ql_pa...

It is a very concise and well written piece of software.