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- #ifndef ENTT_CONTAINER_DENSE_SET_HPP
- #define ENTT_CONTAINER_DENSE_SET_HPP
-
- #include <algorithm>
- #include <cmath>
- #include <cstddef>
- #include <functional>
- #include <iterator>
- #include <limits>
- #include <memory>
- #include <tuple>
- #include <type_traits>
- #include <utility>
- #include <vector>
- #include "../config/config.h"
- #include "../core/compressed_pair.hpp"
- #include "../core/memory.hpp"
- #include "../core/type_traits.hpp"
- #include "fwd.hpp"
-
- namespace entt {
-
- /**
- * @cond TURN_OFF_DOXYGEN
- * Internal details not to be documented.
- */
-
- namespace internal {
-
- template<typename It>
- class dense_set_iterator final {
- template<typename>
- friend class dense_set_iterator;
-
- public:
- using value_type = typename It::value_type::second_type;
- using pointer = const value_type *;
- using reference = const value_type &;
- using difference_type = std::ptrdiff_t;
- using iterator_category = std::random_access_iterator_tag;
-
- dense_set_iterator() ENTT_NOEXCEPT
- : it{} {}
-
- dense_set_iterator(const It iter) ENTT_NOEXCEPT
- : it{iter} {}
-
- template<typename Other, typename = std::enable_if_t<!std::is_same_v<It, Other> && std::is_constructible_v<It, Other>>>
- dense_set_iterator(const dense_set_iterator<Other> &other) ENTT_NOEXCEPT
- : it{other.it} {}
-
- dense_set_iterator &operator++() ENTT_NOEXCEPT {
- return ++it, *this;
- }
-
- dense_set_iterator operator++(int) ENTT_NOEXCEPT {
- dense_set_iterator orig = *this;
- return ++(*this), orig;
- }
-
- dense_set_iterator &operator--() ENTT_NOEXCEPT {
- return --it, *this;
- }
-
- dense_set_iterator operator--(int) ENTT_NOEXCEPT {
- dense_set_iterator orig = *this;
- return operator--(), orig;
- }
-
- dense_set_iterator &operator+=(const difference_type value) ENTT_NOEXCEPT {
- it += value;
- return *this;
- }
-
- dense_set_iterator operator+(const difference_type value) const ENTT_NOEXCEPT {
- dense_set_iterator copy = *this;
- return (copy += value);
- }
-
- dense_set_iterator &operator-=(const difference_type value) ENTT_NOEXCEPT {
- return (*this += -value);
- }
-
- dense_set_iterator operator-(const difference_type value) const ENTT_NOEXCEPT {
- return (*this + -value);
- }
-
- [[nodiscard]] reference operator[](const difference_type value) const ENTT_NOEXCEPT {
- return it[value].second;
- }
-
- [[nodiscard]] pointer operator->() const ENTT_NOEXCEPT {
- return std::addressof(it->second);
- }
-
- [[nodiscard]] reference operator*() const ENTT_NOEXCEPT {
- return *operator->();
- }
-
- template<typename ILhs, typename IRhs>
- friend std::ptrdiff_t operator-(const dense_set_iterator<ILhs> &, const dense_set_iterator<IRhs> &) ENTT_NOEXCEPT;
-
- template<typename ILhs, typename IRhs>
- friend bool operator==(const dense_set_iterator<ILhs> &, const dense_set_iterator<IRhs> &) ENTT_NOEXCEPT;
-
- template<typename ILhs, typename IRhs>
- friend bool operator<(const dense_set_iterator<ILhs> &, const dense_set_iterator<IRhs> &) ENTT_NOEXCEPT;
-
- private:
- It it;
- };
-
- template<typename ILhs, typename IRhs>
- [[nodiscard]] std::ptrdiff_t operator-(const dense_set_iterator<ILhs> &lhs, const dense_set_iterator<IRhs> &rhs) ENTT_NOEXCEPT {
- return lhs.it - rhs.it;
- }
-
- template<typename ILhs, typename IRhs>
- [[nodiscard]] bool operator==(const dense_set_iterator<ILhs> &lhs, const dense_set_iterator<IRhs> &rhs) ENTT_NOEXCEPT {
- return lhs.it == rhs.it;
- }
-
- template<typename ILhs, typename IRhs>
- [[nodiscard]] bool operator!=(const dense_set_iterator<ILhs> &lhs, const dense_set_iterator<IRhs> &rhs) ENTT_NOEXCEPT {
- return !(lhs == rhs);
- }
-
- template<typename ILhs, typename IRhs>
- [[nodiscard]] bool operator<(const dense_set_iterator<ILhs> &lhs, const dense_set_iterator<IRhs> &rhs) ENTT_NOEXCEPT {
- return lhs.it < rhs.it;
- }
-
- template<typename ILhs, typename IRhs>
- [[nodiscard]] bool operator>(const dense_set_iterator<ILhs> &lhs, const dense_set_iterator<IRhs> &rhs) ENTT_NOEXCEPT {
- return rhs < lhs;
- }
-
- template<typename ILhs, typename IRhs>
- [[nodiscard]] bool operator<=(const dense_set_iterator<ILhs> &lhs, const dense_set_iterator<IRhs> &rhs) ENTT_NOEXCEPT {
- return !(lhs > rhs);
- }
-
- template<typename ILhs, typename IRhs>
- [[nodiscard]] bool operator>=(const dense_set_iterator<ILhs> &lhs, const dense_set_iterator<IRhs> &rhs) ENTT_NOEXCEPT {
- return !(lhs < rhs);
- }
-
- template<typename It>
- class dense_set_local_iterator final {
- template<typename>
- friend class dense_set_local_iterator;
-
- public:
- using value_type = typename It::value_type::second_type;
- using pointer = const value_type *;
- using reference = const value_type &;
- using difference_type = std::ptrdiff_t;
- using iterator_category = std::forward_iterator_tag;
-
- dense_set_local_iterator() ENTT_NOEXCEPT
- : it{},
- offset{} {}
-
- dense_set_local_iterator(It iter, const std::size_t pos) ENTT_NOEXCEPT
- : it{iter},
- offset{pos} {}
-
- template<typename Other, typename = std::enable_if_t<!std::is_same_v<It, Other> && std::is_constructible_v<It, Other>>>
- dense_set_local_iterator(const dense_set_local_iterator<Other> &other) ENTT_NOEXCEPT
- : it{other.it},
- offset{other.offset} {}
-
- dense_set_local_iterator &operator++() ENTT_NOEXCEPT {
- return offset = it[offset].first, *this;
- }
-
- dense_set_local_iterator operator++(int) ENTT_NOEXCEPT {
- dense_set_local_iterator orig = *this;
- return ++(*this), orig;
- }
-
- [[nodiscard]] pointer operator->() const ENTT_NOEXCEPT {
- return std::addressof(it[offset].second);
- }
-
- [[nodiscard]] reference operator*() const ENTT_NOEXCEPT {
- return *operator->();
- }
-
- [[nodiscard]] std::size_t index() const ENTT_NOEXCEPT {
- return offset;
- }
-
- private:
- It it;
- std::size_t offset;
- };
-
- template<typename ILhs, typename IRhs>
- [[nodiscard]] bool operator==(const dense_set_local_iterator<ILhs> &lhs, const dense_set_local_iterator<IRhs> &rhs) ENTT_NOEXCEPT {
- return lhs.index() == rhs.index();
- }
-
- template<typename ILhs, typename IRhs>
- [[nodiscard]] bool operator!=(const dense_set_local_iterator<ILhs> &lhs, const dense_set_local_iterator<IRhs> &rhs) ENTT_NOEXCEPT {
- return !(lhs == rhs);
- }
-
- } // namespace internal
-
- /**
- * Internal details not to be documented.
- * @endcond
- */
-
- /**
- * @brief Associative container for unique objects of a given type.
- *
- * Internally, elements are organized into buckets. Which bucket an element is
- * placed into depends entirely on its hash. Elements with the same hash code
- * appear in the same bucket.
- *
- * @tparam Type Value type of the associative container.
- * @tparam Hash Type of function to use to hash the values.
- * @tparam KeyEqual Type of function to use to compare the values for equality.
- * @tparam Allocator Type of allocator used to manage memory and elements.
- */
- template<typename Type, typename Hash, typename KeyEqual, typename Allocator>
- class dense_set {
- static constexpr float default_threshold = 0.875f;
- static constexpr std::size_t minimum_capacity = 8u;
-
- using node_type = std::pair<std::size_t, Type>;
- using alloc_traits = std::allocator_traits<Allocator>;
- static_assert(std::is_same_v<typename alloc_traits::value_type, Type>, "Invalid value type");
- using sparse_container_type = std::vector<std::size_t, typename alloc_traits::template rebind_alloc<std::size_t>>;
- using packed_container_type = std::vector<node_type, typename alloc_traits::template rebind_alloc<node_type>>;
-
- template<typename Other>
- [[nodiscard]] std::size_t value_to_bucket(const Other &value) const ENTT_NOEXCEPT {
- return fast_mod(sparse.second()(value), bucket_count());
- }
-
- template<typename Other>
- [[nodiscard]] auto constrained_find(const Other &value, std::size_t bucket) {
- for(auto it = begin(bucket), last = end(bucket); it != last; ++it) {
- if(packed.second()(*it, value)) {
- return begin() + static_cast<typename iterator::difference_type>(it.index());
- }
- }
-
- return end();
- }
-
- template<typename Other>
- [[nodiscard]] auto constrained_find(const Other &value, std::size_t bucket) const {
- for(auto it = cbegin(bucket), last = cend(bucket); it != last; ++it) {
- if(packed.second()(*it, value)) {
- return cbegin() + static_cast<typename iterator::difference_type>(it.index());
- }
- }
-
- return cend();
- }
-
- template<typename Other>
- [[nodiscard]] auto insert_or_do_nothing(Other &&value) {
- const auto index = value_to_bucket(value);
-
- if(auto it = constrained_find(value, index); it != end()) {
- return std::make_pair(it, false);
- }
-
- packed.first().emplace_back(sparse.first()[index], std::forward<Other>(value));
- sparse.first()[index] = packed.first().size() - 1u;
- rehash_if_required();
-
- return std::make_pair(--end(), true);
- }
-
- void move_and_pop(const std::size_t pos) {
- if(const auto last = size() - 1u; pos != last) {
- packed.first()[pos] = std::move(packed.first().back());
- size_type *curr = sparse.first().data() + value_to_bucket(packed.first().back().second);
- for(; *curr != last; curr = &packed.first()[*curr].first) {}
- *curr = pos;
- }
-
- packed.first().pop_back();
- }
-
- void rehash_if_required() {
- if(size() > (bucket_count() * max_load_factor())) {
- rehash(bucket_count() * 2u);
- }
- }
-
- public:
- /*! @brief Key type of the container. */
- using key_type = Type;
- /*! @brief Value type of the container. */
- using value_type = Type;
- /*! @brief Unsigned integer type. */
- using size_type = std::size_t;
- /*! @brief Type of function to use to hash the elements. */
- using hasher = Hash;
- /*! @brief Type of function to use to compare the elements for equality. */
- using key_equal = KeyEqual;
- /*! @brief Allocator type. */
- using allocator_type = Allocator;
- /*! @brief Random access iterator type. */
- using iterator = internal::dense_set_iterator<typename packed_container_type::iterator>;
- /*! @brief Constant random access iterator type. */
- using const_iterator = internal::dense_set_iterator<typename packed_container_type::const_iterator>;
- /*! @brief Forward iterator type. */
- using local_iterator = internal::dense_set_local_iterator<typename packed_container_type::iterator>;
- /*! @brief Constant forward iterator type. */
- using const_local_iterator = internal::dense_set_local_iterator<typename packed_container_type::const_iterator>;
-
- /*! @brief Default constructor. */
- dense_set()
- : dense_set(minimum_capacity) {}
-
- /**
- * @brief Constructs an empty container with a given allocator.
- * @param allocator The allocator to use.
- */
- explicit dense_set(const allocator_type &allocator)
- : dense_set{minimum_capacity, hasher{}, key_equal{}, allocator} {}
-
- /**
- * @brief Constructs an empty container with a given allocator and user
- * supplied minimal number of buckets.
- * @param bucket_count Minimal number of buckets.
- * @param allocator The allocator to use.
- */
- dense_set(const size_type bucket_count, const allocator_type &allocator)
- : dense_set{bucket_count, hasher{}, key_equal{}, allocator} {}
-
- /**
- * @brief Constructs an empty container with a given allocator, hash
- * function and user supplied minimal number of buckets.
- * @param bucket_count Minimal number of buckets.
- * @param hash Hash function to use.
- * @param allocator The allocator to use.
- */
- dense_set(const size_type bucket_count, const hasher &hash, const allocator_type &allocator)
- : dense_set{bucket_count, hash, key_equal{}, allocator} {}
-
- /**
- * @brief Constructs an empty container with a given allocator, hash
- * function, compare function and user supplied minimal number of buckets.
- * @param bucket_count Minimal number of buckets.
- * @param hash Hash function to use.
- * @param equal Compare function to use.
- * @param allocator The allocator to use.
- */
- explicit dense_set(const size_type bucket_count, const hasher &hash = hasher{}, const key_equal &equal = key_equal{}, const allocator_type &allocator = allocator_type{})
- : sparse{allocator, hash},
- packed{allocator, equal},
- threshold{default_threshold} {
- rehash(bucket_count);
- }
-
- /*! @brief Default copy constructor. */
- dense_set(const dense_set &) = default;
-
- /**
- * @brief Allocator-extended copy constructor.
- * @param other The instance to copy from.
- * @param allocator The allocator to use.
- */
- dense_set(const dense_set &other, const allocator_type &allocator)
- : sparse{std::piecewise_construct, std::forward_as_tuple(other.sparse.first(), allocator), std::forward_as_tuple(other.sparse.second())},
- packed{std::piecewise_construct, std::forward_as_tuple(other.packed.first(), allocator), std::forward_as_tuple(other.packed.second())},
- threshold{other.threshold} {}
-
- /*! @brief Default move constructor. */
- dense_set(dense_set &&) = default;
-
- /**
- * @brief Allocator-extended move constructor.
- * @param other The instance to move from.
- * @param allocator The allocator to use.
- */
- dense_set(dense_set &&other, const allocator_type &allocator)
- : sparse{std::piecewise_construct, std::forward_as_tuple(std::move(other.sparse.first()), allocator), std::forward_as_tuple(std::move(other.sparse.second()))},
- packed{std::piecewise_construct, std::forward_as_tuple(std::move(other.packed.first()), allocator), std::forward_as_tuple(std::move(other.packed.second()))},
- threshold{other.threshold} {}
-
- /**
- * @brief Default copy assignment operator.
- * @return This container.
- */
- dense_set &operator=(const dense_set &) = default;
-
- /**
- * @brief Default move assignment operator.
- * @return This container.
- */
- dense_set &operator=(dense_set &&) = default;
-
- /**
- * @brief Returns the associated allocator.
- * @return The associated allocator.
- */
- [[nodiscard]] constexpr allocator_type get_allocator() const ENTT_NOEXCEPT {
- return sparse.first().get_allocator();
- }
-
- /**
- * @brief Returns an iterator to the beginning.
- *
- * The returned iterator points to the first instance of the internal array.
- * If the array is empty, the returned iterator will be equal to `end()`.
- *
- * @return An iterator to the first instance of the internal array.
- */
- [[nodiscard]] const_iterator cbegin() const ENTT_NOEXCEPT {
- return packed.first().begin();
- }
-
- /*! @copydoc cbegin */
- [[nodiscard]] const_iterator begin() const ENTT_NOEXCEPT {
- return cbegin();
- }
-
- /*! @copydoc begin */
- [[nodiscard]] iterator begin() ENTT_NOEXCEPT {
- return packed.first().begin();
- }
-
- /**
- * @brief Returns an iterator to the end.
- *
- * The returned iterator points to the element following the last instance
- * of the internal array. Attempting to dereference the returned iterator
- * results in undefined behavior.
- *
- * @return An iterator to the element following the last instance of the
- * internal array.
- */
- [[nodiscard]] const_iterator cend() const ENTT_NOEXCEPT {
- return packed.first().end();
- }
-
- /*! @copydoc cend */
- [[nodiscard]] const_iterator end() const ENTT_NOEXCEPT {
- return cend();
- }
-
- /*! @copydoc end */
- [[nodiscard]] iterator end() ENTT_NOEXCEPT {
- return packed.first().end();
- }
-
- /**
- * @brief Checks whether a container is empty.
- * @return True if the container is empty, false otherwise.
- */
- [[nodiscard]] bool empty() const ENTT_NOEXCEPT {
- return packed.first().empty();
- }
-
- /**
- * @brief Returns the number of elements in a container.
- * @return Number of elements in a container.
- */
- [[nodiscard]] size_type size() const ENTT_NOEXCEPT {
- return packed.first().size();
- }
-
- /*! @brief Clears the container. */
- void clear() ENTT_NOEXCEPT {
- sparse.first().clear();
- packed.first().clear();
- rehash(0u);
- }
-
- /**
- * @brief Inserts an element into the container, if it does not exist.
- * @param value An element to insert into the container.
- * @return A pair consisting of an iterator to the inserted element (or to
- * the element that prevented the insertion) and a bool denoting whether the
- * insertion took place.
- */
- std::pair<iterator, bool> insert(const value_type &value) {
- return insert_or_do_nothing(value);
- }
-
- /*! @copydoc insert */
- std::pair<iterator, bool> insert(value_type &&value) {
- return insert_or_do_nothing(std::move(value));
- }
-
- /**
- * @brief Inserts elements into the container, if they do not exist.
- * @tparam It Type of input iterator.
- * @param first An iterator to the first element of the range of elements.
- * @param last An iterator past the last element of the range of elements.
- */
- template<typename It>
- void insert(It first, It last) {
- for(; first != last; ++first) {
- insert(*first);
- }
- }
-
- /**
- * @brief Constructs an element in-place, if it does not exist.
- *
- * The element is also constructed when the container already has the key,
- * in which case the newly constructed object is destroyed immediately.
- *
- * @tparam Args Types of arguments to forward to the constructor of the
- * element.
- * @param args Arguments to forward to the constructor of the element.
- * @return A pair consisting of an iterator to the inserted element (or to
- * the element that prevented the insertion) and a bool denoting whether the
- * insertion took place.
- */
- template<typename... Args>
- std::pair<iterator, bool> emplace(Args &&...args) {
- if constexpr(((sizeof...(Args) == 1u) && ... && std::is_same_v<std::remove_cv_t<std::remove_reference_t<Args>>, value_type>)) {
- return insert_or_do_nothing(std::forward<Args>(args)...);
- } else {
- auto &node = packed.first().emplace_back(std::piecewise_construct, std::make_tuple(packed.first().size()), std::forward_as_tuple(std::forward<Args>(args)...));
- const auto index = value_to_bucket(node.second);
-
- if(auto it = constrained_find(node.second, index); it != end()) {
- packed.first().pop_back();
- return std::make_pair(it, false);
- }
-
- std::swap(node.first, sparse.first()[index]);
- rehash_if_required();
-
- return std::make_pair(--end(), true);
- }
- }
-
- /**
- * @brief Removes an element from a given position.
- * @param pos An iterator to the element to remove.
- * @return An iterator following the removed element.
- */
- iterator erase(const_iterator pos) {
- const auto diff = pos - cbegin();
- erase(*pos);
- return begin() + diff;
- }
-
- /**
- * @brief Removes the given elements from a container.
- * @param first An iterator to the first element of the range of elements.
- * @param last An iterator past the last element of the range of elements.
- * @return An iterator following the last removed element.
- */
- iterator erase(const_iterator first, const_iterator last) {
- const auto dist = first - cbegin();
-
- for(auto from = last - cbegin(); from != dist; --from) {
- erase(packed.first()[from - 1u].second);
- }
-
- return (begin() + dist);
- }
-
- /**
- * @brief Removes the element associated with a given value.
- * @param value Value of an element to remove.
- * @return Number of elements removed (either 0 or 1).
- */
- size_type erase(const value_type &value) {
- for(size_type *curr = sparse.first().data() + value_to_bucket(value); *curr != (std::numeric_limits<size_type>::max)(); curr = &packed.first()[*curr].first) {
- if(packed.second()(packed.first()[*curr].second, value)) {
- const auto index = *curr;
- *curr = packed.first()[*curr].first;
- move_and_pop(index);
- return 1u;
- }
- }
-
- return 0u;
- }
-
- /**
- * @brief Exchanges the contents with those of a given container.
- * @param other Container to exchange the content with.
- */
- void swap(dense_set &other) {
- using std::swap;
- swap(sparse, other.sparse);
- swap(packed, other.packed);
- swap(threshold, other.threshold);
- }
-
- /**
- * @brief Finds an element with a given value.
- * @param value Value of an element to search for.
- * @return An iterator to an element with the given value. If no such
- * element is found, a past-the-end iterator is returned.
- */
- [[nodiscard]] iterator find(const value_type &value) {
- return constrained_find(value, value_to_bucket(value));
- }
-
- /*! @copydoc find */
- [[nodiscard]] const_iterator find(const value_type &value) const {
- return constrained_find(value, value_to_bucket(value));
- }
-
- /**
- * @brief Finds an element that compares _equivalent_ to a given value.
- * @tparam Other Type of an element to search for.
- * @param value Value of an element to search for.
- * @return An iterator to an element with the given value. If no such
- * element is found, a past-the-end iterator is returned.
- */
- template<typename Other>
- [[nodiscard]] std::enable_if_t<is_transparent_v<hasher> && is_transparent_v<key_equal>, std::conditional_t<false, Other, iterator>>
- find(const Other &value) {
- return constrained_find(value, value_to_bucket(value));
- }
-
- /*! @copydoc find */
- template<typename Other>
- [[nodiscard]] std::enable_if_t<is_transparent_v<hasher> && is_transparent_v<key_equal>, std::conditional_t<false, Other, const_iterator>>
- find(const Other &value) const {
- return constrained_find(value, value_to_bucket(value));
- }
-
- /**
- * @brief Checks if the container contains an element with a given value.
- * @param value Value of an element to search for.
- * @return True if there is such an element, false otherwise.
- */
- [[nodiscard]] bool contains(const value_type &value) const {
- return (find(value) != cend());
- }
-
- /**
- * @brief Checks if the container contains an element that compares
- * _equivalent_ to a given value.
- * @tparam Other Type of an element to search for.
- * @param value Value of an element to search for.
- * @return True if there is such an element, false otherwise.
- */
- template<typename Other>
- [[nodiscard]] std::enable_if_t<is_transparent_v<hasher> && is_transparent_v<key_equal>, std::conditional_t<false, Other, bool>>
- contains(const Other &value) const {
- return (find(value) != cend());
- }
-
- /**
- * @brief Returns an iterator to the beginning of a given bucket.
- * @param index An index of a bucket to access.
- * @return An iterator to the beginning of the given bucket.
- */
- [[nodiscard]] const_local_iterator cbegin(const size_type index) const {
- return {packed.first().begin(), sparse.first()[index]};
- }
-
- /**
- * @brief Returns an iterator to the beginning of a given bucket.
- * @param index An index of a bucket to access.
- * @return An iterator to the beginning of the given bucket.
- */
- [[nodiscard]] const_local_iterator begin(const size_type index) const {
- return cbegin(index);
- }
-
- /**
- * @brief Returns an iterator to the beginning of a given bucket.
- * @param index An index of a bucket to access.
- * @return An iterator to the beginning of the given bucket.
- */
- [[nodiscard]] local_iterator begin(const size_type index) {
- return {packed.first().begin(), sparse.first()[index]};
- }
-
- /**
- * @brief Returns an iterator to the end of a given bucket.
- * @param index An index of a bucket to access.
- * @return An iterator to the end of the given bucket.
- */
- [[nodiscard]] const_local_iterator cend([[maybe_unused]] const size_type index) const {
- return {packed.first().begin(), (std::numeric_limits<size_type>::max)()};
- }
-
- /**
- * @brief Returns an iterator to the end of a given bucket.
- * @param index An index of a bucket to access.
- * @return An iterator to the end of the given bucket.
- */
- [[nodiscard]] const_local_iterator end([[maybe_unused]] const size_type index) const {
- return cend(index);
- }
-
- /**
- * @brief Returns an iterator to the end of a given bucket.
- * @param index An index of a bucket to access.
- * @return An iterator to the end of the given bucket.
- */
- [[nodiscard]] local_iterator end([[maybe_unused]] const size_type index) {
- return {packed.first().begin(), (std::numeric_limits<size_type>::max)()};
- }
-
- /**
- * @brief Returns the number of buckets.
- * @return The number of buckets.
- */
- [[nodiscard]] size_type bucket_count() const {
- return sparse.first().size();
- }
-
- /**
- * @brief Returns the maximum number of buckets.
- * @return The maximum number of buckets.
- */
- [[nodiscard]] size_type max_bucket_count() const {
- return sparse.first().max_size();
- }
-
- /**
- * @brief Returns the number of elements in a given bucket.
- * @param index The index of the bucket to examine.
- * @return The number of elements in the given bucket.
- */
- [[nodiscard]] size_type bucket_size(const size_type index) const {
- return static_cast<size_type>(std::distance(begin(index), end(index)));
- }
-
- /**
- * @brief Returns the bucket for a given element.
- * @param value The value of the element to examine.
- * @return The bucket for the given element.
- */
- [[nodiscard]] size_type bucket(const value_type &value) const {
- return value_to_bucket(value);
- }
-
- /**
- * @brief Returns the average number of elements per bucket.
- * @return The average number of elements per bucket.
- */
- [[nodiscard]] float load_factor() const {
- return size() / static_cast<float>(bucket_count());
- }
-
- /**
- * @brief Returns the maximum average number of elements per bucket.
- * @return The maximum average number of elements per bucket.
- */
- [[nodiscard]] float max_load_factor() const {
- return threshold;
- }
-
- /**
- * @brief Sets the desired maximum average number of elements per bucket.
- * @param value A desired maximum average number of elements per bucket.
- */
- void max_load_factor(const float value) {
- ENTT_ASSERT(value > 0.f, "Invalid load factor");
- threshold = value;
- rehash(0u);
- }
-
- /**
- * @brief Reserves at least the specified number of buckets and regenerates
- * the hash table.
- * @param count New number of buckets.
- */
- void rehash(const size_type count) {
- auto value = (std::max)(count, minimum_capacity);
- value = (std::max)(value, static_cast<size_type>(size() / max_load_factor()));
-
- if(const auto sz = next_power_of_two(value); sz != bucket_count()) {
- sparse.first().resize(sz);
- std::fill(sparse.first().begin(), sparse.first().end(), (std::numeric_limits<size_type>::max)());
-
- for(size_type pos{}, last = size(); pos < last; ++pos) {
- const auto index = value_to_bucket(packed.first()[pos].second);
- packed.first()[pos].first = std::exchange(sparse.first()[index], pos);
- }
- }
- }
-
- /**
- * @brief Reserves space for at least the specified number of elements and
- * regenerates the hash table.
- * @param count New number of elements.
- */
- void reserve(const size_type count) {
- packed.first().reserve(count);
- rehash(static_cast<size_type>(std::ceil(count / max_load_factor())));
- }
-
- /**
- * @brief Returns the function used to hash the elements.
- * @return The function used to hash the elements.
- */
- [[nodiscard]] hasher hash_function() const {
- return sparse.second();
- }
-
- /**
- * @brief Returns the function used to compare elements for equality.
- * @return The function used to compare elements for equality.
- */
- [[nodiscard]] key_equal key_eq() const {
- return packed.second();
- }
-
- private:
- compressed_pair<sparse_container_type, hasher> sparse;
- compressed_pair<packed_container_type, key_equal> packed;
- float threshold;
- };
-
- } // namespace entt
-
- #endif
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