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Diffstat (limited to 'deps/include/entt/core/compressed_pair.hpp')
| -rw-r--r-- | deps/include/entt/core/compressed_pair.hpp | 272 |
1 files changed, 272 insertions, 0 deletions
diff --git a/deps/include/entt/core/compressed_pair.hpp b/deps/include/entt/core/compressed_pair.hpp new file mode 100644 index 0000000..a10589f --- /dev/null +++ b/deps/include/entt/core/compressed_pair.hpp @@ -0,0 +1,272 @@ +#ifndef ENTT_CORE_COMPRESSED_PAIR_HPP
+#define ENTT_CORE_COMPRESSED_PAIR_HPP
+
+#include <cstddef>
+#include <tuple>
+#include <type_traits>
+#include <utility>
+#include "fwd.hpp"
+#include "type_traits.hpp"
+
+namespace entt {
+
+/*! @cond TURN_OFF_DOXYGEN */
+namespace internal {
+
+template<typename Type, std::size_t, typename = void>
+struct compressed_pair_element {
+ using reference = Type &;
+ using const_reference = const Type &;
+
+ template<typename Dummy = Type, typename = std::enable_if_t<std::is_default_constructible_v<Dummy>>>
+ // NOLINTNEXTLINE(modernize-use-equals-default)
+ constexpr compressed_pair_element() noexcept(std::is_nothrow_default_constructible_v<Type>) {}
+
+ template<typename Arg, typename = std::enable_if_t<!std::is_same_v<std::remove_cv_t<std::remove_reference_t<Arg>>, compressed_pair_element>>>
+ constexpr compressed_pair_element(Arg &&arg) noexcept(std::is_nothrow_constructible_v<Type, Arg>)
+ : value{std::forward<Arg>(arg)} {}
+
+ template<typename... Args, std::size_t... Index>
+ constexpr compressed_pair_element(std::tuple<Args...> args, std::index_sequence<Index...>) noexcept(std::is_nothrow_constructible_v<Type, Args...>)
+ : value{std::forward<Args>(std::get<Index>(args))...} {}
+
+ [[nodiscard]] constexpr reference get() noexcept {
+ return value;
+ }
+
+ [[nodiscard]] constexpr const_reference get() const noexcept {
+ return value;
+ }
+
+private:
+ Type value{};
+};
+
+template<typename Type, std::size_t Tag>
+struct compressed_pair_element<Type, Tag, std::enable_if_t<is_ebco_eligible_v<Type>>>: Type {
+ using reference = Type &;
+ using const_reference = const Type &;
+ using base_type = Type;
+
+ template<typename Dummy = Type, typename = std::enable_if_t<std::is_default_constructible_v<Dummy>>>
+ constexpr compressed_pair_element() noexcept(std::is_nothrow_default_constructible_v<base_type>)
+ : base_type{} {}
+
+ template<typename Arg, typename = std::enable_if_t<!std::is_same_v<std::remove_cv_t<std::remove_reference_t<Arg>>, compressed_pair_element>>>
+ constexpr compressed_pair_element(Arg &&arg) noexcept(std::is_nothrow_constructible_v<base_type, Arg>)
+ : base_type{std::forward<Arg>(arg)} {}
+
+ template<typename... Args, std::size_t... Index>
+ constexpr compressed_pair_element(std::tuple<Args...> args, std::index_sequence<Index...>) noexcept(std::is_nothrow_constructible_v<base_type, Args...>)
+ : base_type{std::forward<Args>(std::get<Index>(args))...} {}
+
+ [[nodiscard]] constexpr reference get() noexcept {
+ return *this;
+ }
+
+ [[nodiscard]] constexpr const_reference get() const noexcept {
+ return *this;
+ }
+};
+
+} // namespace internal
+/*! @endcond */
+
+/**
+ * @brief A compressed pair.
+ *
+ * A pair that exploits the _Empty Base Class Optimization_ (or _EBCO_) to
+ * reduce its final size to a minimum.
+ *
+ * @tparam First The type of the first element that the pair stores.
+ * @tparam Second The type of the second element that the pair stores.
+ */
+template<typename First, typename Second>
+class compressed_pair final
+ : internal::compressed_pair_element<First, 0u>,
+ internal::compressed_pair_element<Second, 1u> {
+ using first_base = internal::compressed_pair_element<First, 0u>;
+ using second_base = internal::compressed_pair_element<Second, 1u>;
+
+public:
+ /*! @brief The type of the first element that the pair stores. */
+ using first_type = First;
+ /*! @brief The type of the second element that the pair stores. */
+ using second_type = Second;
+
+ /**
+ * @brief Default constructor, conditionally enabled.
+ *
+ * This constructor is only available when the types that the pair stores
+ * are both at least default constructible.
+ *
+ * @tparam Dummy Dummy template parameter used for internal purposes.
+ */
+ template<bool Dummy = true, typename = std::enable_if_t<Dummy && std::is_default_constructible_v<first_type> && std::is_default_constructible_v<second_type>>>
+ constexpr compressed_pair() noexcept(std::is_nothrow_default_constructible_v<first_base> && std::is_nothrow_default_constructible_v<second_base>)
+ : first_base{},
+ second_base{} {}
+
+ /**
+ * @brief Copy constructor.
+ * @param other The instance to copy from.
+ */
+ constexpr compressed_pair(const compressed_pair &other) noexcept(std::is_nothrow_copy_constructible_v<first_base> && std::is_nothrow_copy_constructible_v<second_base>) = default;
+
+ /**
+ * @brief Move constructor.
+ * @param other The instance to move from.
+ */
+ constexpr compressed_pair(compressed_pair &&other) noexcept(std::is_nothrow_move_constructible_v<first_base> && std::is_nothrow_move_constructible_v<second_base>) = default;
+
+ /**
+ * @brief Constructs a pair from its values.
+ * @tparam Arg Type of value to use to initialize the first element.
+ * @tparam Other Type of value to use to initialize the second element.
+ * @param arg Value to use to initialize the first element.
+ * @param other Value to use to initialize the second element.
+ */
+ template<typename Arg, typename Other>
+ constexpr compressed_pair(Arg &&arg, Other &&other) noexcept(std::is_nothrow_constructible_v<first_base, Arg> && std::is_nothrow_constructible_v<second_base, Other>)
+ : first_base{std::forward<Arg>(arg)},
+ second_base{std::forward<Other>(other)} {}
+
+ /**
+ * @brief Constructs a pair by forwarding the arguments to its parts.
+ * @tparam Args Types of arguments to use to initialize the first element.
+ * @tparam Other Types of arguments to use to initialize the second element.
+ * @param args Arguments to use to initialize the first element.
+ * @param other Arguments to use to initialize the second element.
+ */
+ template<typename... Args, typename... Other>
+ constexpr compressed_pair(std::piecewise_construct_t, std::tuple<Args...> args, std::tuple<Other...> other) noexcept(std::is_nothrow_constructible_v<first_base, Args...> && std::is_nothrow_constructible_v<second_base, Other...>)
+ : first_base{std::move(args), std::index_sequence_for<Args...>{}},
+ second_base{std::move(other), std::index_sequence_for<Other...>{}} {}
+
+ /*! @brief Default destructor. */
+ ~compressed_pair() noexcept(std::is_nothrow_destructible_v<First> && std::is_nothrow_destructible_v<Second>) = default;
+
+ /**
+ * @brief Copy assignment operator.
+ * @param other The instance to copy from.
+ * @return This compressed pair object.
+ */
+ constexpr compressed_pair &operator=(const compressed_pair &other) noexcept(std::is_nothrow_copy_assignable_v<first_base> && std::is_nothrow_copy_assignable_v<second_base>) = default;
+
+ /**
+ * @brief Move assignment operator.
+ * @param other The instance to move from.
+ * @return This compressed pair object.
+ */
+ constexpr compressed_pair &operator=(compressed_pair &&other) noexcept(std::is_nothrow_move_assignable_v<first_base> && std::is_nothrow_move_assignable_v<second_base>) = default;
+
+ /**
+ * @brief Returns the first element that a pair stores.
+ * @return The first element that a pair stores.
+ */
+ [[nodiscard]] constexpr first_type &first() noexcept {
+ return static_cast<first_base &>(*this).get();
+ }
+
+ /*! @copydoc first */
+ [[nodiscard]] constexpr const first_type &first() const noexcept {
+ return static_cast<const first_base &>(*this).get();
+ }
+
+ /**
+ * @brief Returns the second element that a pair stores.
+ * @return The second element that a pair stores.
+ */
+ [[nodiscard]] constexpr second_type &second() noexcept {
+ return static_cast<second_base &>(*this).get();
+ }
+
+ /*! @copydoc second */
+ [[nodiscard]] constexpr const second_type &second() const noexcept {
+ return static_cast<const second_base &>(*this).get();
+ }
+
+ /**
+ * @brief Swaps two compressed pair objects.
+ * @param other The compressed pair to swap with.
+ */
+ constexpr void swap(compressed_pair &other) noexcept(std::is_nothrow_swappable_v<first_type> && std::is_nothrow_swappable_v<second_type>) {
+ using std::swap;
+ swap(first(), other.first());
+ swap(second(), other.second());
+ }
+
+ /**
+ * @brief Extracts an element from the compressed pair.
+ * @tparam Index An integer value that is either 0 or 1.
+ * @return Returns a reference to the first element if `Index` is 0 and a
+ * reference to the second element if `Index` is 1.
+ */
+ template<std::size_t Index>
+ [[nodiscard]] constexpr decltype(auto) get() noexcept {
+ if constexpr(Index == 0u) {
+ return first();
+ } else {
+ static_assert(Index == 1u, "Index out of bounds");
+ return second();
+ }
+ }
+
+ /*! @copydoc get */
+ template<std::size_t Index>
+ [[nodiscard]] constexpr decltype(auto) get() const noexcept {
+ if constexpr(Index == 0u) {
+ return first();
+ } else {
+ static_assert(Index == 1u, "Index out of bounds");
+ return second();
+ }
+ }
+};
+
+/**
+ * @brief Deduction guide.
+ * @tparam Type Type of value to use to initialize the first element.
+ * @tparam Other Type of value to use to initialize the second element.
+ */
+template<typename Type, typename Other>
+compressed_pair(Type &&, Other &&) -> compressed_pair<std::decay_t<Type>, std::decay_t<Other>>;
+
+/**
+ * @brief Swaps two compressed pair objects.
+ * @tparam First The type of the first element that the pairs store.
+ * @tparam Second The type of the second element that the pairs store.
+ * @param lhs A valid compressed pair object.
+ * @param rhs A valid compressed pair object.
+ */
+template<typename First, typename Second>
+inline constexpr void swap(compressed_pair<First, Second> &lhs, compressed_pair<First, Second> &rhs) {
+ lhs.swap(rhs);
+}
+
+} // namespace entt
+
+namespace std {
+
+/**
+ * @brief `std::tuple_size` specialization for `compressed_pair`s.
+ * @tparam First The type of the first element that the pair stores.
+ * @tparam Second The type of the second element that the pair stores.
+ */
+template<typename First, typename Second>
+struct tuple_size<entt::compressed_pair<First, Second>>: integral_constant<size_t, 2u> {};
+
+/**
+ * @brief `std::tuple_element` specialization for `compressed_pair`s.
+ * @tparam Index The index of the type to return.
+ * @tparam First The type of the first element that the pair stores.
+ * @tparam Second The type of the second element that the pair stores.
+ */
+template<size_t Index, typename First, typename Second>
+struct tuple_element<Index, entt::compressed_pair<First, Second>>: conditional<Index == 0u, First, Second> {
+ static_assert(Index < 2u, "Index out of bounds");
+};
+
+} // namespace std
+
+#endif
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