Re: [boost] [range]slicing any_range

25 Dec 2013

      On Tue, Dec 24, 2013 at 8:48 PM, Takatoshi Kondo  wrote:
...
...
typedef boost::any_range int_range;
I realized the problem in my code. int_range doesn't support a
reference. It should be
typedef boost::any_range int_range;

If the boost::iterator_facade is passed the template arguments
boost::random_access_traversal_tag as Traversal and no reference type
as Reference, the iterator_category is input_iterator due to a lack of
reference support.

I checked facade_iterator_category.hpp and wrote the following test
code to clarify my understanding.

#include 

struct my_iter:boost::iterator_facade {};
struct my_iter_noref:boost::iterator_facade {};
int main() {
  // has reference
  static_assert(
    std::is_convertible<
      std::iterator_traits::iterator_category,
      std::random_access_iterator_tag
    >::value, "");
  // no reference
  static_assert(
    !std::is_convertible<
      std::iterator_traits::iterator_category,
      std::random_access_iterator_tag
    >::value, "");
  static_assert(
    std::is_convertible<
      std::iterator_traits::iterator_category,
      std::input_iterator_tag
    >::value, "");
}

Takatoshi Kondo