On Thursday, 8 October 2015 at 14:36:03 UTC, Kagamin wrote:
On Thursday, 8 October 2015 at 13:10:24 UTC, John Colvin wrote:
What you're effectively describing is a trio of iterators
wrapped to give an interface of two linked ranges. popFront
grows the first one and shrinks the second. I'd be interested
to see how to construct that, given a generic range as input.
The C++ example doesn't work with generic iterators, it needs a
specific ability to iterate in both directions, hence a
bidirectional range.
Of course.
The way ranges are used for iteration, they can be seen as
adapters for iterators providing various consistent interfaces
depending on their capabilities. In this example we need a
bidirectional range that can go back and forth, one way to do
it is to provide undo mechanism like undoPopFront and
frontUndoEmpty to allow the range grow back, thus remaining a
range that is a list of items and not an iterator.
I much prefer this second version:
Another way is to provide a reverse range of previously popped
items - this can be seen as iterator or not, more like a range
with history rather than an undoable input range, so maybe the
getter should be `history`.
my question is: How, in practice, does one take a bidirectional
range and make one of these new things? I foresee some
difficulty, but perhaps I'm just not being imaginative enough.
