It maps ok with bidirectional/random access. If an iterator has a given iterator category, the range will preserve it. I have used it in code, and it's quite powerful.
Don't you need a current position, start and an end for bidirectional iteration? Forward "ranges" just get a current position and an end.
In my view, bidirectional means that the begin() iterator from the range can move both ways, and that it still has an end() of the range. Best, John -- John Torjo, Contributing editor, C/C++ Users Journal -- "Win32 GUI Generics" -- generics & GUI do mix, after all -- http://www.torjo.com/win32gui/ -- v1.5 - tooltips at your fingertips (work for menus too!) + bitmap buttons (work for MessageBox too!) + tab dialogs, hyper links, lite html