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// Copyright (c) Andrey Semashev 2017.
// Use, modification and distribution are subject to the
// Boost Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
// See http://www.boost.org/libs/config for most recent version.
// MACRO: BOOST_NO_CXX17_ITERATOR_TRAITS
// TITLE: C++17 std::iterator_traits
// DESCRIPTION: The compiler does not support SFINAE-friendly std::iterator_traits defined in C++17.
#include <iterator>
namespace boost_no_cxx17_iterator_traits {
struct iterator
{
typedef std::random_access_iterator_tag iterator_category;
typedef char value_type;
typedef std::ptrdiff_t difference_type;
typedef char* pointer;
typedef char& reference;
reference operator*()const;
iterator operator++();
};
struct non_iterator {};
template< typename T >
struct void_type { typedef void type; };
template< typename Traits, typename Void = void >
struct has_iterator_category
{
enum { value = false };
};
template< typename Traits >
struct has_iterator_category< Traits, typename void_type< typename Traits::iterator_category >::type >
{
enum { value = true };
};
int test()
{
static_assert(has_iterator_category< std::iterator_traits< boost_no_cxx17_iterator_traits::iterator > >::value, "has_iterator_category failed");
static_assert(!has_iterator_category< std::iterator_traits< boost_no_cxx17_iterator_traits::non_iterator > >::value, "has_iterator_category negative check failed");
return 0;
}
}
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