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added type_list_size and type_list_size_v

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This commit is contained in:
Michele Caini
2019-08-22 17:59:15 +02:00
parent b8b1e6ba62
commit 94136531a5
2 changed files with 25 additions and 11 deletions
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32
src/entt/core/type_traits.hpp
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@@ -10,15 +10,32 @@
namespace entt {
/*! @brief A class to use to push around lists of types, nothing more. */
template<typename...>
struct type_list {};
/*! @brief Primary template isn't defined on purpose. */
template<typename>
struct type_list_size;
/**
* @brief A class to use to push around lists of types, nothing more.
* @tparam Type Types provided by the given type list.
* @brief Compile-time number of elements in a type list.
* @tparam Type Types provided by the type list.
*/
template<typename... Type>
struct type_list {
/*! @brief Unsigned integer type. */
static constexpr auto size = sizeof...(Type);
};
struct type_list_size<type_list<Type...>>
: std::integral_constant<std::size_t, sizeof...(Type)>
{};
/**
* @brief Helper variable template.
* @tparam List Type list.
*/
template<class List>
constexpr auto type_list_size_v = type_list_size<List>::value;
/*! @brief Primary template isn't defined on purpose. */
@@ -145,9 +162,6 @@ struct is_named_type<Type, std::void_t<named_type_traits_t<std::decay_t<Type>>>>
/**
* @brief Helper variable template.
*
* True if a given type has a name, false otherwise.
*
* @tparam Type Potentially named type.
*/
template<class Type>

4
test/entt/core/type_traits.cpp
View File

@@ -5,8 +5,8 @@ TEST(TypeList, Functionalities) {
using type = entt::type_list<int, char>;
using other = entt::type_list<double>;
ASSERT_EQ((type::size), (decltype(type::size){2}));
ASSERT_EQ((other::size), (decltype(other::size){1}));
ASSERT_EQ(entt::type_list_size_v<type>, 2u);
ASSERT_EQ(entt::type_list_size_v<other>, 1u);
ASSERT_TRUE((std::is_same_v<entt::type_list_cat_t<type, other, type, other>, entt::type_list<int, char, double, int, char, double>>));
ASSERT_TRUE((std::is_same_v<entt::type_list_cat_t<type, other>, entt::type_list<int, char, double>>));
ASSERT_TRUE((std::is_same_v<entt::type_list_cat_t<type, type>, entt::type_list<int, char, int, char>>));