Thorsten Ottosen wrote:
Andrei Alexandrescu skrev:
A design that has a bidirectional iterator walking freely up and down between two limits would be difficult to port to ranges. (If the iterator is random-access, things are trivial.) Ranges can only shrink, they never grow unless assigned from the outside. So when you move one direction it would be difficult to grow one range (shrinking the other is easy). That design would benefit from letting the iterator abstraction exposed.
Couldn't it be done with a special range that stores three iterators? You could introduce SplittableRange, which has four additional primitives:
splitpoint_advance: Move split point one step towards end. Throw/abort/nasal demons if it's already there. splitpoint_retreat: Move split point one step towards begin. See above. front: Return the range between begin and split point. rear: Return the range between split point and end. A special range that stores three iterators would be an implementation possibility. For random-access iterators, you can also use two iterators and an index, and there should be a range adapter that converts any random-access range into a splittable range. Sebastian