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Implement SFINAE friendly iterator_traits and use that instead.

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This commit is contained in:
David Avedissian 2018-11-07 18:39:25 +00:00
parent e3c28afb61
commit f665a92330
5 changed files with 120 additions and 20 deletions
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47
include/nlohmann/detail/iterators/iterator_traits.hpp Normal file
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#pragma once
#include <iterator> // random_access_iterator_tag
#include <nlohmann/detail/meta/void_t.hpp>
namespace nlohmann
{
namespace detail
{
template <class It, class = void>
struct _iterator_types {};
template <class 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;
};
template <class Iter>
struct iterator_traits : _iterator_types<Iter> {};
template <class T>
struct iterator_traits<T*> {
typedef std::random_access_iterator_tag iterator_category;
typedef T value_type;
typedef ptrdiff_t difference_type;
typedef T* pointer;
typedef T& reference;
};
template <class T>
struct iterator_traits<const T*> {
typedef std::random_access_iterator_tag iterator_category;
typedef T value_type;
typedef ptrdiff_t difference_type;
typedef const T* pointer;
typedef const T& reference;
};
}
}