ring list?

[Uqbar]

Hi all!
I need to implement a ring list that should be much like a STL list (doubly linked) with the plus of having the two ends linked each other.
In this way, rlist.begin-- == rlist.end and rlist.end++ == rlist.begin (or any other similar condition).
As far as I know there's no STL/Boost implementation and I'd like not to implement my solution by adding if()s to the existing STL list<>.
Any hint?

[kbw]

You can create your own utility library with its own namespace and add it there. You wouldn't normally expect to modify a standard library.

[jsmith]

Why don't you just create a circular_iterator?