From 3bf42c6ff3805a0d42bbc661794a95ff31bedc26 Mon Sep 17 00:00:00 2001 From: untodesu Date: Sat, 15 Mar 2025 16:22:09 +0500 Subject: Add whatever I was working on for the last month --- deps/include/entt/entity/sparse_set.hpp | 1068 +++++++++++++++++++++++++++++++ 1 file changed, 1068 insertions(+) create mode 100644 deps/include/entt/entity/sparse_set.hpp (limited to 'deps/include/entt/entity/sparse_set.hpp') diff --git a/deps/include/entt/entity/sparse_set.hpp b/deps/include/entt/entity/sparse_set.hpp new file mode 100644 index 0000000..bea16ae --- /dev/null +++ b/deps/include/entt/entity/sparse_set.hpp @@ -0,0 +1,1068 @@ +#ifndef ENTT_ENTITY_SPARSE_SET_HPP +#define ENTT_ENTITY_SPARSE_SET_HPP + +#include +#include +#include +#include +#include +#include +#include "../config/config.h" +#include "../core/algorithm.hpp" +#include "../core/any.hpp" +#include "../core/bit.hpp" +#include "../core/type_info.hpp" +#include "entity.hpp" +#include "fwd.hpp" + +namespace entt { + +/*! @cond TURN_OFF_DOXYGEN */ +namespace internal { + +template +struct sparse_set_iterator final { + using value_type = typename Container::value_type; + using pointer = typename Container::const_pointer; + using reference = typename Container::const_reference; + using difference_type = typename Container::difference_type; + using iterator_category = std::random_access_iterator_tag; + + constexpr sparse_set_iterator() noexcept + : packed{}, + offset{} {} + + constexpr sparse_set_iterator(const Container &ref, const difference_type idx) noexcept + : packed{&ref}, + offset{idx} {} + + constexpr sparse_set_iterator &operator++() noexcept { + return --offset, *this; + } + + constexpr sparse_set_iterator operator++(int) noexcept { + sparse_set_iterator orig = *this; + return ++(*this), orig; + } + + constexpr sparse_set_iterator &operator--() noexcept { + return ++offset, *this; + } + + constexpr sparse_set_iterator operator--(int) noexcept { + sparse_set_iterator orig = *this; + return operator--(), orig; + } + + constexpr sparse_set_iterator &operator+=(const difference_type value) noexcept { + offset -= value; + return *this; + } + + constexpr sparse_set_iterator operator+(const difference_type value) const noexcept { + sparse_set_iterator copy = *this; + return (copy += value); + } + + constexpr sparse_set_iterator &operator-=(const difference_type value) noexcept { + return (*this += -value); + } + + constexpr sparse_set_iterator operator-(const difference_type value) const noexcept { + return (*this + -value); + } + + [[nodiscard]] constexpr reference operator[](const difference_type value) const noexcept { + return (*packed)[index() - value]; + } + + [[nodiscard]] constexpr pointer operator->() const noexcept { + return std::addressof(operator[](0)); + } + + [[nodiscard]] constexpr reference operator*() const noexcept { + return operator[](0); + } + + [[nodiscard]] constexpr pointer data() const noexcept { + return packed ? packed->data() : nullptr; + } + + [[nodiscard]] constexpr difference_type index() const noexcept { + return offset - 1; + } + +private: + const Container *packed; + difference_type offset; +}; + +template +[[nodiscard]] constexpr std::ptrdiff_t operator-(const sparse_set_iterator &lhs, const sparse_set_iterator &rhs) noexcept { + return rhs.index() - lhs.index(); +} + +template +[[nodiscard]] constexpr bool operator==(const sparse_set_iterator &lhs, const sparse_set_iterator &rhs) noexcept { + return lhs.index() == rhs.index(); +} + +template +[[nodiscard]] constexpr bool operator!=(const sparse_set_iterator &lhs, const sparse_set_iterator &rhs) noexcept { + return !(lhs == rhs); +} + +template +[[nodiscard]] constexpr bool operator<(const sparse_set_iterator &lhs, const sparse_set_iterator &rhs) noexcept { + return lhs.index() > rhs.index(); +} + +template +[[nodiscard]] constexpr bool operator>(const sparse_set_iterator &lhs, const sparse_set_iterator &rhs) noexcept { + return rhs < lhs; +} + +template +[[nodiscard]] constexpr bool operator<=(const sparse_set_iterator &lhs, const sparse_set_iterator &rhs) noexcept { + return !(lhs > rhs); +} + +template +[[nodiscard]] constexpr bool operator>=(const sparse_set_iterator &lhs, const sparse_set_iterator &rhs) noexcept { + return !(lhs < rhs); +} + +} // namespace internal +/*! @endcond */ + +/** + * @brief Sparse set implementation. + * + * Sparse set or packed array or whatever is the name users give it.
+ * Two arrays: an _external_ one and an _internal_ one; a _sparse_ one and a + * _packed_ one; one used for direct access through contiguous memory, the other + * one used to get the data through an extra level of indirection.
+ * This type of data structure is widely documented in the literature and on the + * web. This is nothing more than a customized implementation suitable for the + * purpose of the framework. + * + * @note + * Internal data structures arrange elements to maximize performance. There are + * no guarantees that entities are returned in the insertion order when iterate + * a sparse set. Do not make assumption on the order in any case. + * + * @tparam Entity A valid entity type. + * @tparam Allocator Type of allocator used to manage memory and elements. + */ +template +class basic_sparse_set { + using alloc_traits = std::allocator_traits; + static_assert(std::is_same_v, "Invalid value type"); + using sparse_container_type = std::vector>; + using packed_container_type = std::vector; + using traits_type = entt_traits; + + static constexpr auto max_size = static_cast(traits_type::to_entity(null)); + + [[nodiscard]] auto policy_to_head() const noexcept { + return static_cast(max_size * (mode != deletion_policy::swap_only)); + } + + [[nodiscard]] auto sparse_ptr(const Entity entt) const { + const auto pos = static_cast(traits_type::to_entity(entt)); + const auto page = pos / traits_type::page_size; + return (page < sparse.size() && sparse[page]) ? (sparse[page] + fast_mod(pos, traits_type::page_size)) : nullptr; + } + + [[nodiscard]] auto &sparse_ref(const Entity entt) const { + ENTT_ASSERT(sparse_ptr(entt), "Invalid element"); + const auto pos = static_cast(traits_type::to_entity(entt)); + return sparse[pos / traits_type::page_size][fast_mod(pos, traits_type::page_size)]; + } + + [[nodiscard]] auto to_iterator(const Entity entt) const { + return --(end() - index(entt)); + } + + [[nodiscard]] auto &assure_at_least(const Entity entt) { + const auto pos = static_cast(traits_type::to_entity(entt)); + const auto page = pos / traits_type::page_size; + + if(!(page < sparse.size())) { + sparse.resize(page + 1u, nullptr); + } + + if(!sparse[page]) { + constexpr entity_type init = null; + auto page_allocator{packed.get_allocator()}; + sparse[page] = alloc_traits::allocate(page_allocator, traits_type::page_size); + std::uninitialized_fill(sparse[page], sparse[page] + traits_type::page_size, init); + } + + return sparse[page][fast_mod(pos, traits_type::page_size)]; + } + + void release_sparse_pages() { + auto page_allocator{packed.get_allocator()}; + + for(auto &&page: sparse) { + if(page != nullptr) { + std::destroy(page, page + traits_type::page_size); + alloc_traits::deallocate(page_allocator, page, traits_type::page_size); + page = nullptr; + } + } + } + + void swap_at(const std::size_t lhs, const std::size_t rhs) { + auto &from = packed[lhs]; + auto &to = packed[rhs]; + + sparse_ref(from) = traits_type::combine(static_cast(rhs), traits_type::to_integral(from)); + sparse_ref(to) = traits_type::combine(static_cast(lhs), traits_type::to_integral(to)); + + std::swap(from, to); + } + +private: + [[nodiscard]] virtual const void *get_at(const std::size_t) const { + return nullptr; + } + + virtual void swap_or_move([[maybe_unused]] const std::size_t lhs, [[maybe_unused]] const std::size_t rhs) { + ENTT_ASSERT((mode != deletion_policy::swap_only) || ((lhs < head) == (rhs < head)), "Cross swapping is not supported"); + } + +protected: + /*! @brief Random access iterator type. */ + using basic_iterator = internal::sparse_set_iterator; + + /** + * @brief Erases an entity from a sparse set. + * @param it An iterator to the element to pop. + */ + void swap_only(const basic_iterator it) { + ENTT_ASSERT(mode == deletion_policy::swap_only, "Deletion policy mismatch"); + const auto pos = index(*it); + bump(traits_type::next(*it)); + swap_at(pos, head -= (pos < head)); + } + + /** + * @brief Erases an entity from a sparse set. + * @param it An iterator to the element to pop. + */ + void swap_and_pop(const basic_iterator it) { + ENTT_ASSERT(mode == deletion_policy::swap_and_pop, "Deletion policy mismatch"); + auto &self = sparse_ref(*it); + const auto entt = traits_type::to_entity(self); + sparse_ref(packed.back()) = traits_type::combine(entt, traits_type::to_integral(packed.back())); + packed[static_cast(entt)] = packed.back(); + // unnecessary but it helps to detect nasty bugs + ENTT_ASSERT((packed.back() = null, true), ""); + // lazy self-assignment guard + self = null; + packed.pop_back(); + } + + /** + * @brief Erases an entity from a sparse set. + * @param it An iterator to the element to pop. + */ + void in_place_pop(const basic_iterator it) { + ENTT_ASSERT(mode == deletion_policy::in_place, "Deletion policy mismatch"); + const auto pos = static_cast(traits_type::to_entity(std::exchange(sparse_ref(*it), null))); + packed[pos] = traits_type::combine(static_cast(std::exchange(head, pos)), tombstone); + } + +protected: + /** + * @brief Erases entities from a sparse set. + * @param first An iterator to the first element of the range of entities. + * @param last An iterator past the last element of the range of entities. + */ + virtual void pop(basic_iterator first, basic_iterator last) { + switch(mode) { + case deletion_policy::swap_and_pop: + for(; first != last; ++first) { + swap_and_pop(first); + } + break; + case deletion_policy::in_place: + for(; first != last; ++first) { + in_place_pop(first); + } + break; + case deletion_policy::swap_only: + for(; first != last; ++first) { + swap_only(first); + } + break; + } + } + + /*! @brief Erases all entities of a sparse set. */ + virtual void pop_all() { + switch(mode) { + case deletion_policy::in_place: + if(head != max_size) { + for(auto first = begin(); !(first.index() < 0); ++first) { + if(*first != tombstone) { + sparse_ref(*first) = null; + } + } + break; + } + [[fallthrough]]; + case deletion_policy::swap_only: + case deletion_policy::swap_and_pop: + for(auto first = begin(); !(first.index() < 0); ++first) { + sparse_ref(*first) = null; + } + break; + } + + head = policy_to_head(); + packed.clear(); + } + + /** + * @brief Assigns an entity to a sparse set. + * @param entt A valid identifier. + * @param force_back Force back insertion. + * @return Iterator pointing to the emplaced element. + */ + virtual basic_iterator try_emplace(const Entity entt, const bool force_back, const void * = nullptr) { + ENTT_ASSERT(entt != null && entt != tombstone, "Invalid element"); + auto &elem = assure_at_least(entt); + auto pos = size(); + + switch(mode) { + case deletion_policy::in_place: + if(head != max_size && !force_back) { + pos = head; + ENTT_ASSERT(elem == null, "Slot not available"); + elem = traits_type::combine(static_cast(head), traits_type::to_integral(entt)); + head = static_cast(traits_type::to_entity(std::exchange(packed[pos], entt))); + break; + } + [[fallthrough]]; + case deletion_policy::swap_and_pop: + packed.push_back(entt); + ENTT_ASSERT(elem == null, "Slot not available"); + elem = traits_type::combine(static_cast(packed.size() - 1u), traits_type::to_integral(entt)); + break; + case deletion_policy::swap_only: + if(elem == null) { + packed.push_back(entt); + elem = traits_type::combine(static_cast(packed.size() - 1u), traits_type::to_integral(entt)); + } else { + ENTT_ASSERT(!(static_cast(traits_type::to_entity(elem)) < head), "Slot not available"); + bump(entt); + } + + pos = head++; + swap_at(static_cast(traits_type::to_entity(elem)), pos); + break; + } + + return --(end() - static_cast(pos)); + } + +public: + /*! @brief Allocator type. */ + using allocator_type = Allocator; + /*! @brief Underlying entity identifier. */ + using entity_type = typename traits_type::value_type; + /*! @brief Underlying version type. */ + using version_type = typename traits_type::version_type; + /*! @brief Unsigned integer type. */ + using size_type = std::size_t; + /*! @brief Pointer type to contained entities. */ + using pointer = typename packed_container_type::const_pointer; + /*! @brief Random access iterator type. */ + using iterator = basic_iterator; + /*! @brief Constant random access iterator type. */ + using const_iterator = iterator; + /*! @brief Reverse iterator type. */ + using reverse_iterator = std::reverse_iterator; + /*! @brief Constant reverse iterator type. */ + using const_reverse_iterator = std::reverse_iterator; + + /*! @brief Default constructor. */ + basic_sparse_set() + : basic_sparse_set{type_id()} {} + + /** + * @brief Constructs an empty container with a given allocator. + * @param allocator The allocator to use. + */ + explicit basic_sparse_set(const allocator_type &allocator) + : basic_sparse_set{deletion_policy::swap_and_pop, allocator} {} + + /** + * @brief Constructs an empty container with the given policy and allocator. + * @param pol Type of deletion policy. + * @param allocator The allocator to use (possibly default-constructed). + */ + explicit basic_sparse_set(deletion_policy pol, const allocator_type &allocator = {}) + : basic_sparse_set{type_id(), pol, allocator} {} + + /** + * @brief Constructs an empty container with the given value type, policy + * and allocator. + * @param elem Returned value type, if any. + * @param pol Type of deletion policy. + * @param allocator The allocator to use (possibly default-constructed). + */ + explicit basic_sparse_set(const type_info &elem, deletion_policy pol = deletion_policy::swap_and_pop, const allocator_type &allocator = {}) + : sparse{allocator}, + packed{allocator}, + info{&elem}, + mode{pol}, + head{policy_to_head()} { + ENTT_ASSERT(traits_type::version_mask || mode != deletion_policy::in_place, "Policy does not support zero-sized versions"); + } + + /*! @brief Default copy constructor, deleted on purpose. */ + basic_sparse_set(const basic_sparse_set &) = delete; + + /** + * @brief Move constructor. + * @param other The instance to move from. + */ + basic_sparse_set(basic_sparse_set &&other) noexcept + : sparse{std::move(other.sparse)}, + packed{std::move(other.packed)}, + info{other.info}, + mode{other.mode}, + head{std::exchange(other.head, policy_to_head())} {} + + /** + * @brief Allocator-extended move constructor. + * @param other The instance to move from. + * @param allocator The allocator to use. + */ + basic_sparse_set(basic_sparse_set &&other, const allocator_type &allocator) + : sparse{std::move(other.sparse), allocator}, + packed{std::move(other.packed), allocator}, + info{other.info}, + mode{other.mode}, + head{std::exchange(other.head, policy_to_head())} { + ENTT_ASSERT(alloc_traits::is_always_equal::value || get_allocator() == other.get_allocator(), "Copying a sparse set is not allowed"); + } + + /*! @brief Default destructor. */ + virtual ~basic_sparse_set() noexcept { + release_sparse_pages(); + } + + /** + * @brief Default copy assignment operator, deleted on purpose. + * @return This sparse set. + */ + basic_sparse_set &operator=(const basic_sparse_set &) = delete; + + /** + * @brief Move assignment operator. + * @param other The instance to move from. + * @return This sparse set. + */ + basic_sparse_set &operator=(basic_sparse_set &&other) noexcept { + ENTT_ASSERT(alloc_traits::is_always_equal::value || get_allocator() == other.get_allocator(), "Copying a sparse set is not allowed"); + + release_sparse_pages(); + sparse = std::move(other.sparse); + packed = std::move(other.packed); + info = other.info; + mode = other.mode; + head = std::exchange(other.head, policy_to_head()); + return *this; + } + + /** + * @brief Exchanges the contents with those of a given sparse set. + * @param other Sparse set to exchange the content with. + */ + void swap(basic_sparse_set &other) { + using std::swap; + swap(sparse, other.sparse); + swap(packed, other.packed); + swap(info, other.info); + swap(mode, other.mode); + swap(head, other.head); + } + + /** + * @brief Returns the associated allocator. + * @return The associated allocator. + */ + [[nodiscard]] constexpr allocator_type get_allocator() const noexcept { + return packed.get_allocator(); + } + + /** + * @brief Returns the deletion policy of a sparse set. + * @return The deletion policy of the sparse set. + */ + [[nodiscard]] deletion_policy policy() const noexcept { + return mode; + } + + /** + * @brief Returns data on the free list whose meaning depends on the mode. + * @return Free list information that is mode dependent. + */ + [[nodiscard]] size_type free_list() const noexcept { + return head; + } + + /** + * @brief Sets data on the free list whose meaning depends on the mode. + * @param value Free list information that is mode dependent. + */ + void free_list(const size_type value) noexcept { + ENTT_ASSERT((mode == deletion_policy::swap_only) && !(value > packed.size()), "Invalid value"); + head = value; + } + + /** + * @brief Increases the capacity of a sparse set. + * + * If the new capacity is greater than the current capacity, new storage is + * allocated, otherwise the method does nothing. + * + * @param cap Desired capacity. + */ + virtual void reserve(const size_type cap) { + packed.reserve(cap); + } + + /** + * @brief Returns the number of elements that a sparse set has currently + * allocated space for. + * @return Capacity of the sparse set. + */ + [[nodiscard]] virtual size_type capacity() const noexcept { + return packed.capacity(); + } + + /*! @brief Requests the removal of unused capacity. */ + virtual void shrink_to_fit() { + packed.shrink_to_fit(); + } + + /** + * @brief Returns the extent of a sparse set. + * + * The extent of a sparse set is also the size of the internal sparse array. + * There is no guarantee that the internal packed array has the same size. + * Usually the size of the internal sparse array is equal or greater than + * the one of the internal packed array. + * + * @return Extent of the sparse set. + */ + [[nodiscard]] size_type extent() const noexcept { + return sparse.size() * traits_type::page_size; + } + + /** + * @brief Returns the number of elements in a sparse set. + * + * The number of elements is also the size of the internal packed array. + * There is no guarantee that the internal sparse array has the same size. + * Usually the size of the internal sparse array is equal or greater than + * the one of the internal packed array. + * + * @return Number of elements. + */ + [[nodiscard]] size_type size() const noexcept { + return packed.size(); + } + + /** + * @brief Checks whether a sparse set is empty. + * @return True if the sparse set is empty, false otherwise. + */ + [[nodiscard]] bool empty() const noexcept { + return packed.empty(); + } + + /** + * @brief Checks whether a sparse set is fully packed. + * @return True if the sparse set is fully packed, false otherwise. + */ + [[nodiscard]] bool contiguous() const noexcept { + return (mode != deletion_policy::in_place) || (head == max_size); + } + + /** + * @brief Direct access to the internal packed array. + * @return A pointer to the internal packed array. + */ + [[nodiscard]] pointer data() const noexcept { + return packed.data(); + } + + /** + * @brief Returns an iterator to the beginning. + * + * If the sparse set is empty, the returned iterator will be equal to + * `end()`. + * + * @return An iterator to the first entity of the sparse set. + */ + [[nodiscard]] iterator begin() const noexcept { + const auto pos = static_cast(packed.size()); + return iterator{packed, pos}; + } + + /*! @copydoc begin */ + [[nodiscard]] const_iterator cbegin() const noexcept { + return begin(); + } + + /** + * @brief Returns an iterator to the end. + * @return An iterator to the element following the last entity of a sparse + * set. + */ + [[nodiscard]] iterator end() const noexcept { + return iterator{packed, {}}; + } + + /*! @copydoc end */ + [[nodiscard]] const_iterator cend() const noexcept { + return end(); + } + + /** + * @brief Returns a reverse iterator to the beginning. + * + * If the sparse set is empty, the returned iterator will be equal to + * `rend()`. + * + * @return An iterator to the first entity of the reversed internal packed + * array. + */ + [[nodiscard]] reverse_iterator rbegin() const noexcept { + return std::make_reverse_iterator(end()); + } + + /*! @copydoc rbegin */ + [[nodiscard]] const_reverse_iterator crbegin() const noexcept { + return rbegin(); + } + + /** + * @brief Returns a reverse iterator to the end. + * @return An iterator to the element following the last entity of the + * reversed sparse set. + */ + [[nodiscard]] reverse_iterator rend() const noexcept { + return std::make_reverse_iterator(begin()); + } + + /*! @copydoc rend */ + [[nodiscard]] const_reverse_iterator crend() const noexcept { + return rend(); + } + + /** + * @brief Finds an entity. + * @param entt A valid identifier. + * @return An iterator to the given entity if it's found, past the end + * iterator otherwise. + */ + [[nodiscard]] const_iterator find(const entity_type entt) const noexcept { + return contains(entt) ? to_iterator(entt) : end(); + } + + /** + * @brief Checks if a sparse set contains an entity. + * @param entt A valid identifier. + * @return True if the sparse set contains the entity, false otherwise. + */ + [[nodiscard]] bool contains(const entity_type entt) const noexcept { + const auto elem = sparse_ptr(entt); + constexpr auto cap = traits_type::entity_mask; + constexpr auto mask = traits_type::to_integral(null) & ~cap; + // testing versions permits to avoid accessing the packed array + return elem && (((mask & traits_type::to_integral(entt)) ^ traits_type::to_integral(*elem)) < cap); + } + + /** + * @brief Returns the contained version for an identifier. + * @param entt A valid identifier. + * @return The version for the given identifier if present, the tombstone + * version otherwise. + */ + [[nodiscard]] version_type current(const entity_type entt) const noexcept { + const auto elem = sparse_ptr(entt); + constexpr auto fallback = traits_type::to_version(tombstone); + return elem ? traits_type::to_version(*elem) : fallback; + } + + /** + * @brief Returns the position of an entity in a sparse set. + * + * @warning + * Attempting to get the position of an entity that doesn't belong to the + * sparse set results in undefined behavior. + * + * @param entt A valid identifier. + * @return The position of the entity in the sparse set. + */ + [[nodiscard]] size_type index(const entity_type entt) const noexcept { + ENTT_ASSERT(contains(entt), "Set does not contain entity"); + return static_cast(traits_type::to_entity(sparse_ref(entt))); + } + + /** + * @brief Returns the entity at specified location. + * @param pos The position for which to return the entity. + * @return The entity at specified location. + */ + [[nodiscard]] entity_type operator[](const size_type pos) const noexcept { + ENTT_ASSERT(pos < packed.size(), "Index out of bounds"); + return packed[pos]; + } + + /** + * @brief Returns the element assigned to an entity, if any. + * + * @warning + * Attempting to use an entity that doesn't belong to the sparse set results + * in undefined behavior. + * + * @param entt A valid identifier. + * @return An opaque pointer to the element assigned to the entity, if any. + */ + [[nodiscard]] const void *value(const entity_type entt) const noexcept { + return get_at(index(entt)); + } + + /*! @copydoc value */ + [[nodiscard]] void *value(const entity_type entt) noexcept { + return const_cast(std::as_const(*this).value(entt)); + } + + /** + * @brief Assigns an entity to a sparse set. + * + * @warning + * Attempting to assign an entity that already belongs to the sparse set + * results in undefined behavior. + * + * @param entt A valid identifier. + * @param elem Optional opaque element to forward to mixins, if any. + * @return Iterator pointing to the emplaced element in case of success, the + * `end()` iterator otherwise. + */ + iterator push(const entity_type entt, const void *elem = nullptr) { + return try_emplace(entt, false, elem); + } + + /** + * @brief Assigns one or more entities to a sparse set. + * + * @warning + * Attempting to assign an entity that already belongs to the sparse set + * results in undefined behavior. + * + * @tparam It Type of input iterator. + * @param first An iterator to the first element of the range of entities. + * @param last An iterator past the last element of the range of entities. + * @return Iterator pointing to the first element inserted in case of + * success, the `end()` iterator otherwise. + */ + template + iterator push(It first, It last) { + auto curr = end(); + + for(; first != last; ++first) { + curr = try_emplace(*first, true); + } + + return curr; + } + + /** + * @brief Bump the version number of an entity. + * + * @warning + * Attempting to bump the version of an entity that doesn't belong to the + * sparse set results in undefined behavior. + * + * @param entt A valid identifier. + * @return The version of the given identifier. + */ + version_type bump(const entity_type entt) { + auto &elem = sparse_ref(entt); + ENTT_ASSERT(entt != null && elem != tombstone, "Cannot set the required version"); + elem = traits_type::combine(traits_type::to_integral(elem), traits_type::to_integral(entt)); + packed[static_cast(traits_type::to_entity(elem))] = entt; + return traits_type::to_version(entt); + } + + /** + * @brief Erases an entity from a sparse set. + * + * @warning + * Attempting to erase an entity that doesn't belong to the sparse set + * results in undefined behavior. + * + * @param entt A valid identifier. + */ + void erase(const entity_type entt) { + const auto it = to_iterator(entt); + pop(it, it + 1u); + } + + /** + * @brief Erases entities from a set. + * + * @sa erase + * + * @tparam It Type of input iterator. + * @param first An iterator to the first element of the range of entities. + * @param last An iterator past the last element of the range of entities. + */ + template + void erase(It first, It last) { + if constexpr(std::is_same_v) { + pop(first, last); + } else { + for(; first != last; ++first) { + erase(*first); + } + } + } + + /** + * @brief Removes an entity from a sparse set if it exists. + * @param entt A valid identifier. + * @return True if the entity is actually removed, false otherwise. + */ + bool remove(const entity_type entt) { + return contains(entt) && (erase(entt), true); + } + + /** + * @brief Removes entities from a sparse set if they exist. + * @tparam It Type of input iterator. + * @param first An iterator to the first element of the range of entities. + * @param last An iterator past the last element of the range of entities. + * @return The number of entities actually removed. + */ + template + size_type remove(It first, It last) { + size_type count{}; + + if constexpr(std::is_same_v) { + while(first != last) { + while(first != last && !contains(*first)) { + ++first; + } + + const auto it = first; + + while(first != last && contains(*first)) { + ++first; + } + + count += std::distance(it, first); + erase(it, first); + } + } else { + for(; first != last; ++first) { + count += remove(*first); + } + } + + return count; + } + + /*! @brief Removes all tombstones from a sparse set. */ + void compact() { + if(mode == deletion_policy::in_place) { + size_type from = packed.size(); + size_type pos = std::exchange(head, max_size); + + for(; from && packed[from - 1u] == tombstone; --from) {} + + while(pos != max_size) { + if(const auto to = std::exchange(pos, static_cast(traits_type::to_entity(packed[pos]))); to < from) { + --from; + swap_or_move(from, to); + + packed[to] = packed[from]; + const auto elem = static_cast(to); + sparse_ref(packed[to]) = traits_type::combine(elem, traits_type::to_integral(packed[to])); + + for(; from && packed[from - 1u] == tombstone; --from) {} + } + } + + packed.erase(packed.begin() + from, packed.end()); + } + } + + /** + * @brief Swaps two entities in a sparse set. + * + * For what it's worth, this function affects both the internal sparse array + * and the internal packed array. Users should not care of that anyway. + * + * @warning + * Attempting to swap entities that don't belong to the sparse set results + * in undefined behavior. + * + * @param lhs A valid identifier. + * @param rhs A valid identifier. + */ + void swap_elements(const entity_type lhs, const entity_type rhs) { + const auto from = index(lhs); + const auto to = index(rhs); + + // basic no-leak guarantee if swapping throws + swap_or_move(from, to); + swap_at(from, to); + } + + /** + * @brief Sort the first count elements according to the given comparison + * function. + * + * The comparison function object must return `true` if the first element + * is _less_ than the second one, `false` otherwise. The signature of the + * comparison function should be equivalent to the following: + * + * @code{.cpp} + * bool(const Entity, const Entity); + * @endcode + * + * Moreover, the comparison function object shall induce a + * _strict weak ordering_ on the values. + * + * The sort function object must offer a member function template + * `operator()` that accepts three arguments: + * + * * An iterator to the first element of the range to sort. + * * An iterator past the last element of the range to sort. + * * A comparison function to use to compare the elements. + * + * @tparam Compare Type of comparison function object. + * @tparam Sort Type of sort function object. + * @tparam Args Types of arguments to forward to the sort function object. + * @param length Number of elements to sort. + * @param compare A valid comparison function object. + * @param algo A valid sort function object. + * @param args Arguments to forward to the sort function object, if any. + */ + template + void sort_n(const size_type length, Compare compare, Sort algo = Sort{}, Args &&...args) { + ENTT_ASSERT((mode != deletion_policy::in_place) || (head == max_size), "Sorting with tombstones not allowed"); + ENTT_ASSERT(!(length > packed.size()), "Length exceeds the number of elements"); + + algo(packed.rend() - length, packed.rend(), std::move(compare), std::forward(args)...); + + for(size_type pos{}; pos < length; ++pos) { + auto curr = pos; + auto next = index(packed[curr]); + + while(curr != next) { + const auto idx = index(packed[next]); + const auto entt = packed[curr]; + + swap_or_move(next, idx); + const auto elem = static_cast(curr); + sparse_ref(entt) = traits_type::combine(elem, traits_type::to_integral(packed[curr])); + curr = std::exchange(next, idx); + } + } + } + + /** + * @brief Sort all elements according to the given comparison function. + * + * @sa sort_n + * + * @tparam Compare Type of comparison function object. + * @tparam Sort Type of sort function object. + * @tparam Args Types of arguments to forward to the sort function object. + * @param compare A valid comparison function object. + * @param algo A valid sort function object. + * @param args Arguments to forward to the sort function object, if any. + */ + template + void sort(Compare compare, Sort algo = Sort{}, Args &&...args) { + const size_type len = (mode == deletion_policy::swap_only) ? head : packed.size(); + sort_n(len, std::move(compare), std::move(algo), std::forward(args)...); + } + + /** + * @brief Sort entities according to their order in a range. + * + * Entities that are part of both the sparse set and the range are ordered + * internally according to the order they have in the range.
+ * All other entities goes to the end of the sparse set and there are no + * guarantees on their order. + * + * @tparam It Type of input iterator. + * @param first An iterator to the first element of the range of entities. + * @param last An iterator past the last element of the range of entities. + * @return An iterator past the last of the elements actually shared. + */ + template + iterator sort_as(It first, It last) { + ENTT_ASSERT((mode != deletion_policy::in_place) || (head == max_size), "Sorting with tombstones not allowed"); + const size_type len = (mode == deletion_policy::swap_only) ? head : packed.size(); + auto it = end() - static_cast(len); + + for(const auto other = end(); (it != other) && (first != last); ++first) { + if(const auto curr = *first; contains(curr)) { + if(const auto entt = *it; entt != curr) { + // basic no-leak guarantee (with invalid state) if swapping throws + swap_elements(entt, curr); + } + + ++it; + } + } + + return it; + } + + /*! @brief Clears a sparse set. */ + void clear() { + pop_all(); + // sanity check to avoid subtle issues due to storage classes + ENTT_ASSERT((compact(), size()) == 0u, "Non-empty set"); + head = policy_to_head(); + packed.clear(); + } + + /** + * @brief Returned value type, if any. + * @return Returned value type, if any. + */ + [[nodiscard]] const type_info &type() const noexcept { + return *info; + } + + /*! @brief Forwards variables to derived classes, if any. */ + // NOLINTNEXTLINE(performance-unnecessary-value-param) + virtual void bind(any) noexcept {} + +private: + sparse_container_type sparse; + packed_container_type packed; + const type_info *info; + deletion_policy mode; + size_type head; +}; + +} // namespace entt + +#endif -- cgit