diff options
Diffstat (limited to 'absl/meta')
| -rw-r--r-- | absl/meta/type_traits.h | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/absl/meta/type_traits.h b/absl/meta/type_traits.h index 73a5685b..88af17c3 100644 --- a/absl/meta/type_traits.h +++ b/absl/meta/type_traits.h @@ -36,6 +36,7 @@ #define ABSL_META_TYPE_TRAITS_H_ #include <stddef.h> +#include <functional> #include <type_traits> #include "absl/base/config.h" @@ -349,5 +350,23 @@ using underlying_type_t = typename std::underlying_type<T>::type; template <typename T> using result_of_t = typename std::result_of<T>::type; +namespace type_traits_internal { +template <typename Key, typename = size_t> +struct IsHashable : std::false_type {}; + +template <typename Key> +struct IsHashable<Key, + decltype(std::declval<std::hash<Key>>()(std::declval<Key>()))> + : std::true_type {}; + +template <typename Key> +struct IsHashEnabled + : absl::conjunction<std::is_default_constructible<std::hash<Key>>, + std::is_copy_constructible<std::hash<Key>>, + std::is_destructible<std::hash<Key>>, + std::is_copy_assignable<std::hash<Key>>, + IsHashable<Key>> {}; +} // namespace type_traits_internal + } // namespace absl #endif // ABSL_META_TYPE_TRAITS_H_ |