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Remove iterator_category

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This commit is contained in:
Victor Zverovich 2020-10-20 16:44:49 -07:00
parent 27fdb4ead2
commit 2a3f4de3f4
1 changed files with 1 additions and 17 deletions
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18
include/fmt/core.h
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@ -1352,32 +1352,16 @@ namespace detail {
// A workaround for gcc 4.8 to make void_t work in a SFINAE context.
template <typename... Ts> struct void_t_impl { using type = void; };
template <typename... Ts>
using void_t = typename detail::void_t_impl<Ts...>::type;
// Detect the iterator category of *any* given type in a SFINAE-friendly way.
// Unfortunately, older implementations of std::iterator_traits are not safe
// for use in a SFINAE-context.
template <typename It, typename Enable = void>
struct iterator_category : std::false_type {};
template <typename T> struct iterator_category<T*> {
using type = std::random_access_iterator_tag;
};
template <typename It>
struct iterator_category<It, void_t<typename It::iterator_category>> {
using type = typename It::iterator_category;
};
template <typename It, typename T, typename Enable = void>
struct is_output_iterator : std::false_type {};
template <typename It, typename T>
struct is_output_iterator<
It, T,
void_t<typename iterator_category<It>::type,
void_t<typename std::iterator_traits<It>::iterator_category,
decltype(*std::declval<It>() = std::declval<T>())>>
: std::true_type {};