Does a standard implementation of a Circular List

问题:

I want to use a circular list.

Short of implementing my own (like this person did) what are my options?

Specifically what I want to do is iterate over a list of objects. When my iterator reaches the end of the list, it should automatically return to the beginning. (Yes, I realize this could be dangerous.)

See Vladimir's definition of a circular_iterator: "A circular_iterator will never be equal with CircularList::end(), thus you can always dereference this iterator."

回答1:

There's no standard circular list.

However, there is a circular buffer in Boost, which might be helpful.

If you don't need anything fancy, you might consider just using a vector and accessing the elements with an index. You can just mod your index with the size of the vector to achieve much the same thing as a circular list.

回答2:

If you want something looking like an iterator you can roll your own, looking something like

template <class baseIter>
class circularIterator {
    private:
        baseIter cur;
        baseIter begin;
        baseIter end;
    public:
        circularIterator(baseIter b, baseIter e, baseIter c=b)
            :cur(i), begin(b), end(e) {}
        baseIter & operator ++(void) {++cur; if(cur == end) {cur = begin;}}
};

(Other iterator operations left as exercise to reader).

回答3:

list<int>::iterator circularNext(list<int> &l, list<int>::iterator &it)
{
    return std::next(it) == l.end() ? l.begin() : std::next(it);
}