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type traits: added member_class and member_class_t

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This commit is contained in:
Michele Caini
2020-02-17 08:18:58 +01:00
parent 688d435d8e
commit 09f36e32f7
2 changed files with 44 additions and 0 deletions
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32
src/entt/core/type_traits.hpp
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@@ -3,6 +3,7 @@
#include <cstddef>
#include <utility>
#include <type_traits>
#include "../config/config.h"
#include "../core/hashed_string.hpp"
@@ -169,6 +170,37 @@ template<class Type>
constexpr auto is_equality_comparable_v = is_equality_comparable<Type>::value;
/**
* @brief Extracts the class of a non-static member object or function.
* @tparam Member A pointer to a non-static member object or function.
*/
template<typename Member>
class member_class {
static_assert(std::is_member_pointer_v<Member>);
template<typename Class, typename Ret, typename... Args>
static Class * clazz(Ret(Class:: *)(Args...));
template<typename Class, typename Ret, typename... Args>
static Class * clazz(Ret(Class:: *)(Args...) const);
template<typename Class, typename Type>
static Class * clazz(Type Class:: *);
public:
/*! @brief The class of the given non-static member object or function. */
using type = std::remove_pointer_t<decltype(clazz(std::declval<Member>()))>;
};
/**
* @brief Helper type.
* @tparam Member A pointer to a non-static member object or function.
*/
template<typename Member>
using member_class_t = typename member_class<Member>::type;
}

12
test/entt/core/type_traits.cpp
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@@ -22,3 +22,15 @@ TEST(IsEqualityComparable, Functionalities) {
ASSERT_TRUE(entt::is_equality_comparable_v<int>);
ASSERT_FALSE(entt::is_equality_comparable_v<void>);
}
TEST(MemberClass, Functionalities) {
struct clazz {
char foo(int) { return {}; }
int bar(double, float) const { return {}; }
bool quux;
};
ASSERT_TRUE((std::is_same_v<clazz, entt::member_class_t<decltype(&clazz::foo)>>));
ASSERT_TRUE((std::is_same_v<clazz, entt::member_class_t<decltype(&clazz::bar)>>));
ASSERT_TRUE((std::is_same_v<clazz, entt::member_class_t<decltype(&clazz::quux)>>));
}