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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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