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type_traits: more concepts, less sfinae

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skypjack
2026-02-02 09:34:40 +01:00
parent 0891adb135
commit 7d2321efde
1 changed files with 16 additions and 13 deletions
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29
src/entt/core/type_traits.hpp
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@@ -1,6 +1,7 @@
#ifndef ENTT_CORE_TYPE_TRAITS_HPP
#define ENTT_CORE_TYPE_TRAITS_HPP
#include <concepts>
#include <cstddef>
#include <iterator>
#include <tuple>
@@ -36,12 +37,13 @@ inline constexpr choice_t<N> choice{};
* @brief A type-only `sizeof` wrapper that returns 0 where `sizeof` complains.
* @tparam Type The type of which to return the size.
*/
template<typename Type, typename = void>
template<typename Type>
struct size_of: std::integral_constant<std::size_t, 0u> {};
/*! @copydoc size_of */
template<typename Type>
struct size_of<Type, std::void_t<decltype(sizeof(Type))>>
requires requires { sizeof(Type); }
struct size_of<Type>
// NOLINTNEXTLINE(bugprone-sizeof-expression)
: std::integral_constant<std::size_t, sizeof(Type)> {};
@@ -634,12 +636,13 @@ inline constexpr bool is_applicable_r_v = is_applicable_r<Ret, Func, Args>::valu
* complete, false otherwise.
* @tparam Type The type to test.
*/
template<typename Type, typename = void>
template<typename Type>
struct is_complete: std::false_type {};
/*! @copydoc is_complete */
template<typename Type>
struct is_complete<Type, std::void_t<decltype(sizeof(Type))>>: std::true_type {};
requires requires { sizeof(Type); }
struct is_complete<Type>: std::true_type {};
/**
* @brief Helper variable template.
@@ -653,17 +656,18 @@ inline constexpr bool is_complete_v = is_complete<Type>::value;
* iterator, false otherwise.
* @tparam Type The type to test.
*/
template<typename Type, typename = void>
template<typename Type>
struct is_iterator: std::false_type {};
/*! @cond ENTT_INTERNAL */
namespace internal {
template<typename, typename = void>
template<typename>
struct has_iterator_category: std::false_type {};
template<typename Type>
struct has_iterator_category<Type, std::void_t<typename std::iterator_traits<Type>::iterator_category>>: std::true_type {};
requires requires { typename std::iterator_traits<Type>::iterator_category; }
struct has_iterator_category<Type>: std::true_type {};
} // namespace internal
/*! @endcond */
@@ -671,8 +675,7 @@ struct has_iterator_category<Type, std::void_t<typename std::iterator_traits<Typ
/*! @copydoc is_iterator */
template<typename Type>
requires (!std::is_void_v<std::remove_const_t<std::remove_pointer_t<Type>>>)
struct is_iterator<Type>
: internal::has_iterator_category<Type> {};
struct is_iterator<Type>: internal::has_iterator_category<Type> {};
/**
* @brief Helper variable template.
@@ -687,8 +690,7 @@ inline constexpr bool is_iterator_v = is_iterator<Type>::value;
* @tparam Type The type to test
*/
template<typename Type>
struct is_ebco_eligible
: std::bool_constant<std::is_empty_v<Type> && !std::is_final_v<Type>> {};
struct is_ebco_eligible: std::bool_constant<std::is_empty_v<Type> && !std::is_final_v<Type>> {};
/**
* @brief Helper variable template.
@@ -720,11 +722,12 @@ inline constexpr bool is_transparent_v = is_transparent<Type>::value;
/*! @cond ENTT_INTERNAL */
namespace internal {
template<typename, typename = void>
template<typename>
struct has_tuple_size_value: std::false_type {};
template<typename Type>
struct has_tuple_size_value<Type, std::void_t<decltype(std::tuple_size<const Type>::value)>>: std::true_type {};
requires is_complete_v<std::tuple_size<const Type>>
struct has_tuple_size_value<Type>: std::true_type {};
template<typename>
struct has_value_type: std::false_type {};