Re: Help with iterator helpers

From: rogeeff (rogeeff_at_[hidden])
Date: 2002-01-29 13:05:44

--- In boost_at_y..., "David Abrahams" <david.abrahams_at_r...> wrote:
> 
> ----- Original Message -----
> From: <nbecker_at_f...>
> 
> 
> >     David> You can adapt anything; it doesn't have to be an 
iterator. Your
> iterator has
> >     David> some state data, right? Just adapt that.
> >
> > Depends what you mean by "adapt".  If by "adapt x" you mean "x is 
the
> > first parameter to iterator_adaptor"
> 
> Yes.
> 
> > , then I believe x has to be an
> > iterator.  You can't directly adapt a container, for example.  
You can
> > adapt the container's iterator.
> 
> Trust me, you can. I co-wrote the library, I should know ;^)
> 
> > I guess if you want to adapt the container, you have to do it in 2
> > steps.  First adapt the container's iterator, then make an object 
that
> > uses that adapted iterator.
> 
> Not neccessarily.
> 
> An example of a non-iterator being adapted is 
boost::counting_iterator<int>.
> 
> Ints look enough like iterators that this is maybe not such a good 
example,
> but you could put any kind of data at all in there. Using an 
iterator just
> gets you more convenient defaults for the associated types and 
convenient
> behaviors from default_iterator_policies.
> 
> For your circular buffer, you'd probably want to use the underlying 
iterator
> type as the first parameter, and store the buffer limits in the 
policies
> object.

I have implemented class cycle_iterator based on on 
iterator_adaptors. It is generic class that will work with any 
collection. If it sound interesting I could post the code.

Gennadiy.