Can STL algorithms be used with circular lists?

Question

Creating an STL compliant iterator for your custom list is pretty mundane.

Yet, if the reffered list is a circular one, it seems quite pointless since all STL algorithms are operating on a [first, last) range and in a circular list first = last.

Is there a standard/consice way to overcome this obstacle and have STL algorithms operate on "home made" circular lists ?

I'm supposing defining STL compliant iterators is the first step to this goal, but a solution that would operate on ranges might also be possible.

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I need to implement this for a plethora of "home made" structs. My current solution is to derive from boost::iterator_facade and then create a custom range class (like Rudolph's) and use any algorithm wrapped around range-based execution. Still this has some logical obstacles and would like to see alternatives and or solutions that worked out.

Answer 1

You will need custom iterators, but the solution can still be range-based. One possibility is that begin() could return a specially marked iterator (flag initial=true) so that it knows that it hasn't made the round yet. end() would return an iterator with that flag set to false. Then operator++ would set the flag to false, so that begin() won't be equal to end(). You could use a different marking scheme as well.