Libcondset
This library provides a class representing sets of predicates and data
...The class also has a compact binary format, making this class best suited to sending conditions over the network or saving them in files.
It is a small library providing one C++ class. It can be used as a dynamic library, a static library, or just a header and an object file.
This library has been tested for the formats portability and has been tested on Ubuntu 11.04, Ubuntu 10.04, and Mac OSX 10.7. It should work on most, if not all UNIX/POSIX based operating systems that can run GCC.
If you want to add anything to the code, just drop me a line in the discussion and I'll give you write access.