[boost] cycle_iterator update

From: Neal D. Becker (ndbecker2_at_[hidden])
Date: 2004-04-14 09:11:32

Here is an update to cycle_iterator.  This is based on the original design
by Gennadiy Rozental.  After fairly extensive performance testing I am
getting good results (compared to my old implementation which was
hand-written, not based on boost iterators), after adding operator[].

There are two versions, both give about the same performance in my tests. 
One version, which I prefer, modifies the underlying base iterator for
operations such as increment.  The other implementation never touches the
base iterator, but modifies an integral offset value.

Also included is a Ring container adaptor class, which adapts a container
(e.g., std::vector) to a ring.  Basic operations are there, but more can be
added.

Also a simple test program.