json/include/nlohmann/detail/iterators/iterator_traits.hpp
2020-06-03 14:20:36 +02:00

52 lines
1.4 KiB
C++

#pragma once
#include <iterator> // random_access_iterator_tag
#include <nlohmann/detail/meta/void_t.hpp>
#include <nlohmann/detail/meta/cpp_future.hpp>
namespace nlohmann
{
namespace detail
{
template<typename It, typename = void>
struct iterator_types {};
template<typename It>
struct iterator_types <
It,
void_t<typename It::difference_type, typename It::value_type, typename It::pointer,
typename It::reference, typename It::iterator_category >>
{
using difference_type = typename It::difference_type;
using value_type = typename It::value_type;
using pointer = typename It::pointer;
using reference = typename It::reference;
using iterator_category = typename It::iterator_category;
};
// This is required as some compilers implement std::iterator_traits in a way that
// doesn't work with SFINAE. See https://github.com/nlohmann/json/issues/1341.
template<typename T, typename = void>
struct iterator_traits
{
};
template<typename T>
struct iterator_traits < T, enable_if_t < !std::is_pointer<T>::value >>
: iterator_types<T>
{
};
template<typename T>
struct iterator_traits<T*, enable_if_t<std::is_object<T>::value>>
{
using iterator_category = std::random_access_iterator_tag;
using value_type = T;
using difference_type = ptrdiff_t;
using pointer = T*;
using reference = T&;
};
} // namespace detail
} // namespace nlohmann