I am building a new system that needs to interact essentially as an SQL backend. We would like to import logical queries into it (e.g. from ApacheSPARQ or Postgres and related things) and want to develop an internal representation (IR) for them. Doing something similar to QGM seems like a good starting point. However, rather than inventing it all from scratch, I'd like to borrow from something that already exists and then extend as needed.
Even if there is no processing code, just data structures, it would be a useful starting point.
So, if there is something open source that I could look at, it would be appreciated.
