ceph/src/boost/libs/config/test/boost_no_cxx17_iterator_traits.ipp

   1 //  Copyright (c) Andrey Semashev 2017.
   2 //  Use, modification and distribution are subject to the
   3 //  Boost Software License, Version 1.0. (See accompanying file
   4 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   5
   6 //  See http://www.boost.org/libs/config for most recent version.
   7
   8 //  MACRO:         BOOST_NO_CXX17_ITERATOR_TRAITS
   9 //  TITLE:         C++17 std::iterator_traits
  10 //  DESCRIPTION:   The compiler does not support SFINAE-friendly std::iterator_traits defined in C++17.
  11
  12 #include <iterator>
  13
  14 namespace boost_no_cxx17_iterator_traits {
  15
  16 struct iterator :
  17     public std::iterator< std::random_access_iterator_tag, char >
  18 {
  19 };
  20
  21 struct non_iterator {};
  22
  23 template< typename T >
  24 struct void_type { typedef void type; };
  25
  26 template< typename Traits, typename Void = void >
  27 struct has_iterator_category
  28 {
  29     enum { value = false };
  30 };
  31
  32 template< typename Traits >
  33 struct has_iterator_category< Traits, typename void_type< typename Traits::iterator_category >::type >
  34 {
  35     enum { value = true };
  36 };
  37
  38 int test()
  39 {
  40     if (!has_iterator_category< std::iterator_traits< boost_no_cxx17_iterator_traits::iterator > >::value)
  41         return 1;
  42
  43     if (has_iterator_category< std::iterator_traits< boost_no_cxx17_iterator_traits::non_iterator > >::value)
  44         return 2;
  45
  46     return 0;
  47 }
  48
  49 }