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type_traits: further refine is_equality_comparable[_v] to avoid specializations

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This commit is contained in:
Michele Caini
2023-10-31 14:08:38 +01:00
parent 273035ff49
commit 206d2f623d
1 changed files with 12 additions and 11 deletions
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23
src/entt/core/type_traits.hpp
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@@ -3,7 +3,6 @@
#include <cstddef>
#include <iterator>
#include <optional>
#include <tuple>
#include <type_traits>
#include <utility>
@@ -786,23 +785,30 @@ template<typename>
template<typename Type>
[[nodiscard]] constexpr auto maybe_equality_comparable(int) -> decltype(std::declval<Type>() == std::declval<Type>()) {
return true;
}
template<typename Type>
[[nodiscard]] constexpr auto dispatch_is_equality_comparable() {
if constexpr(has_tuple_size_value<Type>::value) {
return unpack_maybe_equality_comparable<Type>(std::make_index_sequence<std::tuple_size<Type>::value>{});
return maybe_equality_comparable<Type>(0) && unpack_maybe_equality_comparable<Type>(std::make_index_sequence<std::tuple_size<Type>::value>{});
} else if constexpr(has_value_type<Type>::value) {
if constexpr(is_iterator_v<Type> || std::is_same_v<typename Type::value_type, Type>) {
return true;
return maybe_equality_comparable<Type>(0);
} else if constexpr(is_equality_comparable<typename Type::value_type>::value) {
return maybe_equality_comparable<Type>(0);
} else {
return is_equality_comparable<typename Type::value_type>::value;
return false;
}
} else {
return true;
return maybe_equality_comparable<Type>(0);
}
}
} // namespace internal
template<typename Type>
struct is_equality_comparable: std::bool_constant<internal::maybe_equality_comparable<Type>(0)> {};
struct is_equality_comparable: std::bool_constant<internal::dispatch_is_equality_comparable<Type>()> {};
/**
* Internal details not to be documented.
@@ -813,11 +819,6 @@ struct is_equality_comparable: std::bool_constant<internal::maybe_equality_compa
template<typename Type, auto N>
struct is_equality_comparable<Type[N]>: std::false_type {};
/*! @copydoc is_equality_comparable */
template<typename Type>
// std::optional has a non sfinae-friendly comparison operator :(
struct is_equality_comparable<std::optional<Type>>: is_equality_comparable<typename std::optional<Type>::value_type> {};
/**
* @brief Helper variable template.
* @tparam Type The type to test.