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type_traits: added type_list_diff[_t]

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This commit is contained in:
Michele Caini
2021-01-15 08:36:22 +01:00
parent f4bd868d6a
commit 446c8df3b4
2 changed files with 31 additions and 0 deletions
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25
src/entt/core/type_traits.hpp
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@@ -290,6 +290,31 @@ template<class List, typename Type>
inline constexpr auto type_list_contains_v = type_list_contains<List, Type>::value;
/*! @brief Primary template isn't defined on purpose. */
template<typename...>
struct type_list_diff;
/**
* @brief Computes the difference between two type lists.
* @tparam Type Types provided by the first type list.
* @tparam Other Types provided by the second type list.
*/
template<typename... Type, typename... Other>
struct type_list_diff<type_list<Type...>, type_list<Other...>> {
/*! @brief A type list that is the difference between the two type lists. */
using type = type_list_cat_t<std::conditional_t<type_list_contains_v<type_list<Other...>, Type>, type_list<>, type_list<Type>>...>;
};
/**
* @brief Helper type.
* @tparam List Type lists between which to compute the difference.
*/
template<typename... List>
using type_list_diff_t = typename type_list_diff<List...>::type;
/**
* @brief A class to use to push around lists of constant values, nothing more.
* @tparam Value Values provided by the value list.

6
test/entt/core/type_traits.cpp
View File

@@ -64,6 +64,12 @@ TEST(TypeTraits, TypeList) {
static_assert(std::is_same_v<entt::type_list_element_t<0u, type>, int>);
static_assert(std::is_same_v<entt::type_list_element_t<1u, type>, char>);
static_assert(std::is_same_v<entt::type_list_element_t<0u, other>, double>);
static_assert(std::is_same_v<entt::type_list_diff_t<entt::type_list<int, char, double>, entt::type_list<float, bool>>, entt::type_list<int, char, double>>);
static_assert(std::is_same_v<entt::type_list_diff_t<entt::type_list<int, char, double>, entt::type_list<int, char, double>>, entt::type_list<>>);
static_assert(std::is_same_v<entt::type_list_diff_t<entt::type_list<int, char, double>, entt::type_list<int, char>>, entt::type_list<double>>);
static_assert(std::is_same_v<entt::type_list_diff_t<entt::type_list<int, char, double>, entt::type_list<char, double>>, entt::type_list<int>>);
static_assert(std::is_same_v<entt::type_list_diff_t<entt::type_list<int, char, double>, entt::type_list<char>>, entt::type_list<int, double>>);
}
TEST(TypeTraits, ValueList) {