|
|
- #ifndef ENTT_CORE_MEMORY_HPP
- #define ENTT_CORE_MEMORY_HPP
-
- #include <cstddef>
- #include <limits>
- #include <memory>
- #include <tuple>
- #include <type_traits>
- #include <utility>
- #include "../config/config.h"
-
- namespace entt {
-
- /**
- * @brief Unwraps fancy pointers, does nothing otherwise (waiting for C++20).
- * @tparam Type Pointer type.
- * @param ptr Fancy or raw pointer.
- * @return A raw pointer that represents the address of the original pointer.
- */
- template<typename Type>
- [[nodiscard]] constexpr auto to_address(Type &&ptr) ENTT_NOEXCEPT {
- if constexpr(std::is_pointer_v<std::remove_cv_t<std::remove_reference_t<Type>>>) {
- return ptr;
- } else {
- return to_address(std::forward<Type>(ptr).operator->());
- }
- }
-
- /**
- * @brief Utility function to design allocation-aware containers.
- * @tparam Allocator Type of allocator.
- * @param lhs A valid allocator.
- * @param rhs Another valid allocator.
- */
- template<typename Allocator>
- constexpr void propagate_on_container_copy_assignment([[maybe_unused]] Allocator &lhs, [[maybe_unused]] Allocator &rhs) ENTT_NOEXCEPT {
- if constexpr(std::allocator_traits<Allocator>::propagate_on_container_copy_assignment::value) {
- lhs = rhs;
- }
- }
-
- /**
- * @brief Utility function to design allocation-aware containers.
- * @tparam Allocator Type of allocator.
- * @param lhs A valid allocator.
- * @param rhs Another valid allocator.
- */
- template<typename Allocator>
- constexpr void propagate_on_container_move_assignment([[maybe_unused]] Allocator &lhs, [[maybe_unused]] Allocator &rhs) ENTT_NOEXCEPT {
- if constexpr(std::allocator_traits<Allocator>::propagate_on_container_move_assignment::value) {
- lhs = std::move(rhs);
- }
- }
-
- /**
- * @brief Utility function to design allocation-aware containers.
- * @tparam Allocator Type of allocator.
- * @param lhs A valid allocator.
- * @param rhs Another valid allocator.
- */
- template<typename Allocator>
- constexpr void propagate_on_container_swap([[maybe_unused]] Allocator &lhs, [[maybe_unused]] Allocator &rhs) ENTT_NOEXCEPT {
- ENTT_ASSERT(std::allocator_traits<Allocator>::propagate_on_container_swap::value || lhs == rhs, "Cannot swap the containers");
-
- if constexpr(std::allocator_traits<Allocator>::propagate_on_container_swap::value) {
- using std::swap;
- swap(lhs, rhs);
- }
- }
-
- /**
- * @brief Checks whether a value is a power of two or not.
- * @param value A value that may or may not be a power of two.
- * @return True if the value is a power of two, false otherwise.
- */
- [[nodiscard]] inline constexpr bool is_power_of_two(const std::size_t value) ENTT_NOEXCEPT {
- return value && ((value & (value - 1)) == 0);
- }
-
- /**
- * @brief Computes the smallest power of two greater than or equal to a value.
- * @param value The value to use.
- * @return The smallest power of two greater than or equal to the given value.
- */
- [[nodiscard]] inline constexpr std::size_t next_power_of_two(const std::size_t value) ENTT_NOEXCEPT {
- ENTT_ASSERT(value < (std::size_t{1u} << (std::numeric_limits<std::size_t>::digits - 1)), "Numeric limits exceeded");
- std::size_t curr = value - (value != 0u);
-
- for(int next = 1; next < std::numeric_limits<std::size_t>::digits; next = next * 2) {
- curr |= curr >> next;
- }
-
- return ++curr;
- }
-
- /**
- * @brief Fast module utility function (powers of two only).
- * @param value A value for which to calculate the modulus.
- * @param mod _Modulus_, it must be a power of two.
- * @return The common remainder.
- */
- [[nodiscard]] inline constexpr std::size_t fast_mod(const std::size_t value, const std::size_t mod) ENTT_NOEXCEPT {
- ENTT_ASSERT(is_power_of_two(mod), "Value must be a power of two");
- return value & (mod - 1u);
- }
-
- /**
- * @brief Deleter for allocator-aware unique pointers (waiting for C++20).
- * @tparam Args Types of arguments to use to construct the object.
- */
- template<typename Allocator>
- struct allocation_deleter: private Allocator {
- /*! @brief Allocator type. */
- using allocator_type = Allocator;
- /*! @brief Pointer type. */
- using pointer = typename std::allocator_traits<Allocator>::pointer;
-
- /**
- * @brief Inherited constructors.
- * @param alloc The allocator to use.
- */
- allocation_deleter(const allocator_type &alloc)
- : Allocator{alloc} {}
-
- /**
- * @brief Destroys the pointed object and deallocates its memory.
- * @param ptr A valid pointer to an object of the given type.
- */
- void operator()(pointer ptr) {
- using alloc_traits = typename std::allocator_traits<Allocator>;
- alloc_traits::destroy(*this, to_address(ptr));
- alloc_traits::deallocate(*this, ptr, 1u);
- }
- };
-
- /**
- * @brief Allows `std::unique_ptr` to use allocators (waiting for C++20).
- * @tparam Type Type of object to allocate for and to construct.
- * @tparam Allocator Type of allocator used to manage memory and elements.
- * @tparam Args Types of arguments to use to construct the object.
- * @param allocator The allocator to use.
- * @param args Parameters to use to construct the object.
- * @return A properly initialized unique pointer with a custom deleter.
- */
- template<typename Type, typename Allocator, typename... Args>
- auto allocate_unique(Allocator &allocator, Args &&...args) {
- static_assert(!std::is_array_v<Type>, "Array types are not supported");
-
- using alloc_traits = typename std::allocator_traits<Allocator>::template rebind_traits<Type>;
- using allocator_type = typename alloc_traits::allocator_type;
-
- allocator_type alloc{allocator};
- auto ptr = alloc_traits::allocate(alloc, 1u);
-
- ENTT_TRY {
- alloc_traits::construct(alloc, to_address(ptr), std::forward<Args>(args)...);
- }
- ENTT_CATCH {
- alloc_traits::deallocate(alloc, ptr, 1u);
- ENTT_THROW;
- }
-
- return std::unique_ptr<Type, allocation_deleter<allocator_type>>{ptr, alloc};
- }
-
- /**
- * @cond TURN_OFF_DOXYGEN
- * Internal details not to be documented.
- */
-
- namespace internal {
-
- template<typename Type>
- struct uses_allocator_construction {
- template<typename Allocator, typename... Params>
- static constexpr auto args([[maybe_unused]] const Allocator &allocator, Params &&...params) ENTT_NOEXCEPT {
- if constexpr(!std::uses_allocator_v<Type, Allocator> && std::is_constructible_v<Type, Params...>) {
- return std::forward_as_tuple(std::forward<Params>(params)...);
- } else {
- static_assert(std::uses_allocator_v<Type, Allocator>, "Ill-formed request");
-
- if constexpr(std::is_constructible_v<Type, std::allocator_arg_t, const Allocator &, Params...>) {
- return std::tuple<std::allocator_arg_t, const Allocator &, Params &&...>(std::allocator_arg, allocator, std::forward<Params>(params)...);
- } else {
- static_assert(std::is_constructible_v<Type, Params..., const Allocator &>, "Ill-formed request");
- return std::forward_as_tuple(std::forward<Params>(params)..., allocator);
- }
- }
- }
- };
-
- template<typename Type, typename Other>
- struct uses_allocator_construction<std::pair<Type, Other>> {
- using type = std::pair<Type, Other>;
-
- template<typename Allocator, typename First, typename Second>
- static constexpr auto args(const Allocator &allocator, std::piecewise_construct_t, First &&first, Second &&second) ENTT_NOEXCEPT {
- return std::make_tuple(
- std::piecewise_construct,
- std::apply([&allocator](auto &&...curr) { return uses_allocator_construction<Type>::args(allocator, std::forward<decltype(curr)>(curr)...); }, std::forward<First>(first)),
- std::apply([&allocator](auto &&...curr) { return uses_allocator_construction<Other>::args(allocator, std::forward<decltype(curr)>(curr)...); }, std::forward<Second>(second)));
- }
-
- template<typename Allocator>
- static constexpr auto args(const Allocator &allocator) ENTT_NOEXCEPT {
- return uses_allocator_construction<type>::args(allocator, std::piecewise_construct, std::tuple<>{}, std::tuple<>{});
- }
-
- template<typename Allocator, typename First, typename Second>
- static constexpr auto args(const Allocator &allocator, First &&first, Second &&second) ENTT_NOEXCEPT {
- return uses_allocator_construction<type>::args(allocator, std::piecewise_construct, std::forward_as_tuple(std::forward<First>(first)), std::forward_as_tuple(std::forward<Second>(second)));
- }
-
- template<typename Allocator, typename First, typename Second>
- static constexpr auto args(const Allocator &allocator, const std::pair<First, Second> &value) ENTT_NOEXCEPT {
- return uses_allocator_construction<type>::args(allocator, std::piecewise_construct, std::forward_as_tuple(value.first), std::forward_as_tuple(value.second));
- }
-
- template<typename Allocator, typename First, typename Second>
- static constexpr auto args(const Allocator &allocator, std::pair<First, Second> &&value) ENTT_NOEXCEPT {
- return uses_allocator_construction<type>::args(allocator, std::piecewise_construct, std::forward_as_tuple(std::move(value.first)), std::forward_as_tuple(std::move(value.second)));
- }
- };
-
- } // namespace internal
-
- /**
- * Internal details not to be documented.
- * @endcond
- */
-
- /**
- * @brief Uses-allocator construction utility (waiting for C++20).
- *
- * Primarily intended for internal use. Prepares the argument list needed to
- * create an object of a given type by means of uses-allocator construction.
- *
- * @tparam Type Type to return arguments for.
- * @tparam Allocator Type of allocator used to manage memory and elements.
- * @tparam Args Types of arguments to use to construct the object.
- * @param allocator The allocator to use.
- * @param args Parameters to use to construct the object.
- * @return The arguments needed to create an object of the given type.
- */
- template<typename Type, typename Allocator, typename... Args>
- constexpr auto uses_allocator_construction_args(const Allocator &allocator, Args &&...args) ENTT_NOEXCEPT {
- return internal::uses_allocator_construction<Type>::args(allocator, std::forward<Args>(args)...);
- }
-
- /**
- * @brief Uses-allocator construction utility (waiting for C++20).
- *
- * Primarily intended for internal use. Creates an object of a given type by
- * means of uses-allocator construction.
- *
- * @tparam Type Type of object to create.
- * @tparam Allocator Type of allocator used to manage memory and elements.
- * @tparam Args Types of arguments to use to construct the object.
- * @param allocator The allocator to use.
- * @param args Parameters to use to construct the object.
- * @return A newly created object of the given type.
- */
- template<typename Type, typename Allocator, typename... Args>
- constexpr Type make_obj_using_allocator(const Allocator &allocator, Args &&...args) {
- return std::make_from_tuple<Type>(internal::uses_allocator_construction<Type>::args(allocator, std::forward<Args>(args)...));
- }
-
- /**
- * @brief Uses-allocator construction utility (waiting for C++20).
- *
- * Primarily intended for internal use. Creates an object of a given type by
- * means of uses-allocator construction at an uninitialized memory location.
- *
- * @tparam Type Type of object to create.
- * @tparam Allocator Type of allocator used to manage memory and elements.
- * @tparam Args Types of arguments to use to construct the object.
- * @param value Memory location in which to place the object.
- * @param allocator The allocator to use.
- * @param args Parameters to use to construct the object.
- * @return A pointer to the newly created object of the given type.
- */
- template<typename Type, typename Allocator, typename... Args>
- constexpr Type *uninitialized_construct_using_allocator(Type *value, const Allocator &allocator, Args &&...args) {
- return std::apply([&](auto &&...curr) { return new(value) Type(std::forward<decltype(curr)>(curr)...); }, internal::uses_allocator_construction<Type>::args(allocator, std::forward<Args>(args)...));
- }
-
- } // namespace entt
-
- #endif
|