blake2-ppc db22f2627d std: Implement .rposition() on double-ended iterators with known size
This is a generalization of the vector .rposition() method, to all
double-ended iterators that have the ExactSizeHint trait.

This resolves the slight asymmetry around `position` and `rposition`

* position from front is `vec.iter().position()`
* position from the back was, `vec.rposition()` is now `vec.iter().rposition()`

Additionally, other indexed sequences (only `extra::ringbuf` I think),
will have the same method available once it implements ExactSizeHint.
2013-08-30 20:06:26 +02:00
..
2013-08-03 22:48:02 -04:00