Guillaume Melquiond
You probably cannot perform the computations on the fly. I guess you have to store your expressions as trees, and then to transform these trees so that the disjunction nodes are at the root.
Yes, that's what I meant. See attached file for an example with std::set_* look-alike functions. They should fit your application.
Guillaume
I have looked at your file, and apart from the lists it looks like what I was trying. The list looks useful I have to look more into that (well for now I have a Group class holding intervals and keywords with vectors). Also like you said in your first comment it looks like I won't be able to only use one tree (priorities). So I need to find a distributive function too. If you have anything on that too I'd gladly take it :) Thank you Guillaume, John