On 04/10/2013 04:40 PM, Junio C Hamano wrote:
I have set of items with two attributes, <X,Y>, and would like to keep them in some data structure in such a way that it is efficient to (1) add a new item to the data structure, and (2) pick an item in a specific order. There can be multiple items that share the same value for X, or Y, or both X and Y, and it does not matter in what order items comes out among those that share the same <X,Y>. The type of X is totally ordered. The type of Y also usually is, but Y can take a special value U(nspecified). Now on to the "specific" order I want to pick an item. I'd like to take the item with the largest value of Y in general, and tiebreaking on the value of X which also I prefer to take from larger to smaller. But with a twist. When I am picking an item <X=n,Y=m>, there should be no item remaining in the data store with a value of Y that is smaller than m (duplicates are allowed, so there can still be items with Y=m), and also when I am picking <X=n,Y=m>, there should be no item with Y=Unspecified that has a value of X that is equal or smaller than n.
So X is primary sort and Y is secondary, except Y=Undefined trumps all other values for Y, but never trumps X as primary sort. Can't you just have U be the largest unsigned integer value of the type you choose? For this particular application, I doubt there's any risk of the defined numbers catching up with it. I might have missed something though. This seems a bit too trivial for you to ask for help. -- Andreas Ericsson andreas.ericsson@xxxxxx OP5 AB www.op5.se Tel: +46 8-230225 Fax: +46 8-230231 Considering the successes of the wars on alcohol, poverty, drugs and terror, I think we should give some serious thought to declaring war on peace. -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html