[boost] Re: std::sort(zip_iterator...) does not compile

From: Anthony Williams (anthony_w.geo_at_[hidden])
Date: 2004-07-22 04:01:43

Gunter Winkler <guwi17_at_[hidden]> writes:

> I tried to use boost::zip_iterator to sort 2 parallel arrays. Unfortunatly
> gcc does not compile the appended example because it can not convert
>
>    boost::detail::iterator_category_with_traversal<std::input_iterator_tag, 
>    boost::random_access_traversal_tag>
>
> to either 
>   std::bidirectional_iterator_tag
> or
>   std::random_access_iterator_tag.
> Thus it cannot dispatch the correct stl::__copy_backward() procedure.
>
> Is sort() not yet supported? 

As Dave already posted, zip_iterator doesn't support return forward or
bidirectional iterators, so std::sort() cannot be used.

What you need is something like my tuple iterator (tupleit.zip from the files
area on the boost yahoo group), which *does* support use with std::sort ---
the iterator category of the tuple iterator is the minimum category of the
supplied iterators.

Anthony
-- 
Anthony Williams
Senior Software Engineer, Beran Instruments Ltd.