[range] join() and adaptors::transformed do not play nicely with each other

[Nathan Ridge]

Hello,

For the following code:

#include <vector>
#include <boost/range/adaptor/transformed.hpp>
#include <boost/range/join.hpp>

using boost::adaptors::transformed;
using boost::join;

int add1(int i) { return i + 1; }

int main()
{
std::vector<int> A, B;
auto joined = join(A | transformed(add1), B);
}


I get the following compiler errors:

In file included from ../shared/test/test.cpp:3:0:
../../lib/boost/boost/range/join.hpp: In instantiation of 'boost::range_detail
::joined_type<
const boost::range_detail::transformed_range<int (*)(int), vector<int>

, const vector<int>

../../lib/boost/boost/range/join.hpp:40:7: instantiated from 'boost
::joined_range<
const boost::range_detail::transformed_range<int (*)(int), vector<int>

, const vector<int>
'

../shared/test/test.cpp:13:48: instantiated from here
../../lib/boost/boost/range/join.hpp:34:7: error: no type named 'type' in
'boost::range_detail::demote_iterator_traversal_tag<
boost::detail::iterator_category_with_traversal<
input_iterator_tag, boost::random_access_traversal_tag

, boost::random_access_traversal_tag
'

../../lib/boost/boost/range/join.hpp: In instantiation of 'boost::joined_range<
const boost::range_detail::transformed_range<int (*)(int), vector<int>

, const vector<int>

../shared/test/test.cpp:13:48: instantiated from here
../../lib/boost/boost/range/join.hpp:47:11: error: no type named 'type' in
'boost::range_detail::demote_iterator_traversal_tag<
boost::detail::iterator_category_with_traversal<
input_iterator_tag, boost::random_access_traversal_tag

, boost::random_access_traversal_tag
'

What is going on?

Thanks,
Nate.

[Neil Groves]

Post by Nathan Ridge
../../lib/boost/boost/range/join.hpp:47:11: error: no type named 'type' in
'boost::range_detail::demote_iterator_traversal_tag<
boost::detail::iterator_category_with_traversal<
input_iterator_tag, boost::random_access_traversal_tag

Post by Nathan Ridge
, boost::random_access_traversal_tag
'

What is going on?

My implementation for calculating the minimum traversal is incomplete
because it does not provide template specializations for the
iterator_category_with_traversal class. I need to spend a little more time
looking into the best solution. A quick work-around would be to add the
appropriate specialization. I am concerned that this might be a special-case
of a more general issue with my code. I'll look into this more this week.

Post by Nathan Ridge
Thanks,
Nate.

Thank you for bringing this to my attention.

Regards,
Neil Groves