SQL code generation from table-free boolean queries?

[Foo Stack]

Given string input such as:
    foo=5 AND a=6 AND date=now OR date='2013/6' AND bar='hello'

I am going to implement:

- boolean understanding (which operator takes precendence)
- spliting off of attributes into my function which computes their table in the SQL database
- piece everything together into an SQL query

However, it came to me that this is probably a very generic thing; and there might be a library for it.

If that's so, can you recommend it?

Thanks!