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/group.hpp | 1057 ++++++++++++++++++++++++++++++++++++ 1 file changed, 1057 insertions(+) create mode 100644 deps/include/entt/entity/group.hpp (limited to 'deps/include/entt/entity/group.hpp') diff --git a/deps/include/entt/entity/group.hpp b/deps/include/entt/entity/group.hpp new file mode 100644 index 0000000..9e6a210 --- /dev/null +++ b/deps/include/entt/entity/group.hpp @@ -0,0 +1,1057 @@ +#ifndef ENTT_ENTITY_GROUP_HPP +#define ENTT_ENTITY_GROUP_HPP + +#include +#include +#include +#include +#include +#include +#include "../config/config.h" +#include "../core/algorithm.hpp" +#include "../core/fwd.hpp" +#include "../core/iterator.hpp" +#include "../core/type_info.hpp" +#include "../core/type_traits.hpp" +#include "entity.hpp" +#include "fwd.hpp" + +namespace entt { + +/*! @cond TURN_OFF_DOXYGEN */ +namespace internal { + +template +class extended_group_iterator; + +template +class extended_group_iterator, get_t> { + template + [[nodiscard]] auto index_to_element([[maybe_unused]] Type &cpool) const { + if constexpr(std::is_void_v) { + return std::make_tuple(); + } else { + return std::forward_as_tuple(cpool.rbegin()[it.index()]); + } + } + +public: + using iterator_type = It; + using value_type = decltype(std::tuple_cat(std::make_tuple(*std::declval()), std::declval().get_as_tuple({})..., std::declval().get_as_tuple({})...)); + using pointer = input_iterator_pointer; + using reference = value_type; + using difference_type = std::ptrdiff_t; + using iterator_category = std::input_iterator_tag; + using iterator_concept = std::forward_iterator_tag; + + constexpr extended_group_iterator() + : it{}, + pools{} {} + + extended_group_iterator(iterator_type from, std::tuple cpools) + : it{from}, + pools{std::move(cpools)} {} + + extended_group_iterator &operator++() noexcept { + return ++it, *this; + } + + extended_group_iterator operator++(int) noexcept { + extended_group_iterator orig = *this; + return ++(*this), orig; + } + + [[nodiscard]] reference operator*() const noexcept { + return std::tuple_cat(std::make_tuple(*it), index_to_element(*std::get(pools))..., std::get(pools)->get_as_tuple(*it)...); + } + + [[nodiscard]] pointer operator->() const noexcept { + return operator*(); + } + + [[nodiscard]] constexpr iterator_type base() const noexcept { + return it; + } + + template + friend constexpr bool operator==(const extended_group_iterator &, const extended_group_iterator &) noexcept; + +private: + It it; + std::tuple pools; +}; + +template +[[nodiscard]] constexpr bool operator==(const extended_group_iterator &lhs, const extended_group_iterator &rhs) noexcept { + return lhs.it == rhs.it; +} + +template +[[nodiscard]] constexpr bool operator!=(const extended_group_iterator &lhs, const extended_group_iterator &rhs) noexcept { + return !(lhs == rhs); +} + +struct group_descriptor { + using size_type = std::size_t; + virtual ~group_descriptor() noexcept = default; + [[nodiscard]] virtual bool owned(const id_type) const noexcept { + return false; + } +}; + +template +class group_handler final: public group_descriptor { + using entity_type = typename Type::entity_type; + + void swap_elements(const std::size_t pos, const entity_type entt) { + for(size_type next{}; next < Owned; ++next) { + pools[next]->swap_elements((*pools[next])[pos], entt); + } + } + + void push_on_construct(const entity_type entt) { + if(std::apply([entt, pos = len](auto *cpool, auto *...other) { return cpool->contains(entt) && !(cpool->index(entt) < pos) && (other->contains(entt) && ...); }, pools) + && std::apply([entt](auto *...cpool) { return (!cpool->contains(entt) && ...); }, filter)) { + swap_elements(len++, entt); + } + } + + void push_on_destroy(const entity_type entt) { + if(std::apply([entt, pos = len](auto *cpool, auto *...other) { return cpool->contains(entt) && !(cpool->index(entt) < pos) && (other->contains(entt) && ...); }, pools) + && std::apply([entt](auto *...cpool) { return (0u + ... + cpool->contains(entt)) == 1u; }, filter)) { + swap_elements(len++, entt); + } + } + + void remove_if(const entity_type entt) { + if(pools[0u]->contains(entt) && (pools[0u]->index(entt) < len)) { + swap_elements(--len, entt); + } + } + + void common_setup() { + // we cannot iterate backwards because we want to leave behind valid entities in case of owned types + for(auto first = pools[0u]->rbegin(), last = first + pools[0u]->size(); first != last; ++first) { + push_on_construct(*first); + } + } + +public: + using common_type = Type; + using size_type = typename Type::size_type; + + template + group_handler(std::tuple ogpool, std::tuple epool) + : pools{std::apply([](auto &&...cpool) { return std::array{&cpool...}; }, ogpool)}, + filter{std::apply([](auto &&...cpool) { return std::array{&cpool...}; }, epool)} { + std::apply([this](auto &...cpool) { ((cpool.on_construct().template connect<&group_handler::push_on_construct>(*this), cpool.on_destroy().template connect<&group_handler::remove_if>(*this)), ...); }, ogpool); + std::apply([this](auto &...cpool) { ((cpool.on_construct().template connect<&group_handler::remove_if>(*this), cpool.on_destroy().template connect<&group_handler::push_on_destroy>(*this)), ...); }, epool); + common_setup(); + } + + [[nodiscard]] bool owned(const id_type hash) const noexcept override { + for(size_type pos{}; pos < Owned; ++pos) { + if(pools[pos]->type().hash() == hash) { + return true; + } + } + + return false; + } + + [[nodiscard]] size_type length() const noexcept { + return len; + } + + template + [[nodiscard]] common_type *storage() const noexcept { + if constexpr(Index < (Owned + Get)) { + return pools[Index]; + } else { + return filter[Index - (Owned + Get)]; + } + } + +private: + std::array pools; + std::array filter; + std::size_t len{}; +}; + +template +class group_handler final: public group_descriptor { + using entity_type = typename Type::entity_type; + + void push_on_construct(const entity_type entt) { + if(!elem.contains(entt) + && std::apply([entt](auto *...cpool) { return (cpool->contains(entt) && ...); }, pools) + && std::apply([entt](auto *...cpool) { return (!cpool->contains(entt) && ...); }, filter)) { + elem.push(entt); + } + } + + void push_on_destroy(const entity_type entt) { + if(!elem.contains(entt) + && std::apply([entt](auto *...cpool) { return (cpool->contains(entt) && ...); }, pools) + && std::apply([entt](auto *...cpool) { return (0u + ... + cpool->contains(entt)) == 1u; }, filter)) { + elem.push(entt); + } + } + + void remove_if(const entity_type entt) { + elem.remove(entt); + } + + void common_setup() { + for(const auto entity: *pools[0u]) { + push_on_construct(entity); + } + } + +public: + using common_type = Type; + + template + group_handler(const Allocator &allocator, std::tuple gpool, std::tuple epool) + : pools{std::apply([](auto &&...cpool) { return std::array{&cpool...}; }, gpool)}, + filter{std::apply([](auto &&...cpool) { return std::array{&cpool...}; }, epool)}, + elem{allocator} { + std::apply([this](auto &...cpool) { ((cpool.on_construct().template connect<&group_handler::push_on_construct>(*this), cpool.on_destroy().template connect<&group_handler::remove_if>(*this)), ...); }, gpool); + std::apply([this](auto &...cpool) { ((cpool.on_construct().template connect<&group_handler::remove_if>(*this), cpool.on_destroy().template connect<&group_handler::push_on_destroy>(*this)), ...); }, epool); + common_setup(); + } + + [[nodiscard]] common_type &handle() noexcept { + return elem; + } + + [[nodiscard]] const common_type &handle() const noexcept { + return elem; + } + + template + [[nodiscard]] common_type *storage() const noexcept { + if constexpr(Index < Get) { + return pools[Index]; + } else { + return filter[Index - Get]; + } + } + +private: + std::array pools; + std::array filter; + common_type elem; +}; + +} // namespace internal +/*! @endcond */ + +/** + * @brief Group. + * + * Primary template isn't defined on purpose. All the specializations give a + * compile-time error, but for a few reasonable cases. + */ +template +class basic_group; + +/** + * @brief Non-owning group. + * + * A non-owning group returns all entities and only the entities that are at + * least in the given storage. Moreover, it's guaranteed that the entity list is + * tightly packed in memory for fast iterations. + * + * @b Important + * + * Iterators aren't invalidated if: + * + * * New elements are added to the storage. + * * The entity currently pointed is modified (for example, elements are added + * or removed from it). + * * The entity currently pointed is destroyed. + * + * In all other cases, modifying the pools iterated by the group in any way + * invalidates all the iterators. + * + * @tparam Get Types of storage _observed_ by the group. + * @tparam Exclude Types of storage used to filter the group. + */ +template +class basic_group, get_t, exclude_t> { + using base_type = std::common_type_t; + using underlying_type = typename base_type::entity_type; + + template + static constexpr std::size_t index_of = type_list_index_v, type_list>; + + template + [[nodiscard]] auto pools_for(std::index_sequence) const noexcept { + using return_type = std::tuple; + return descriptor ? return_type{static_cast(descriptor->template storage())...} : return_type{}; + } + +public: + /*! @brief Underlying entity identifier. */ + using entity_type = underlying_type; + /*! @brief Unsigned integer type. */ + using size_type = std::size_t; + /*! @brief Common type among all storage types. */ + using common_type = base_type; + /*! @brief Random access iterator type. */ + using iterator = typename common_type::iterator; + /*! @brief Reverse iterator type. */ + using reverse_iterator = typename common_type::reverse_iterator; + /*! @brief Iterable group type. */ + using iterable = iterable_adaptor, get_t>>; + /*! @brief Group handler type. */ + using handler = internal::group_handler; + + /** + * @brief Group opaque identifier. + * @return Group opaque identifier. + */ + static id_type group_id() noexcept { + return type_hash, get_t...>, exclude_t...>>>::value(); + } + + /*! @brief Default constructor to use to create empty, invalid groups. */ + basic_group() noexcept + : descriptor{} {} + + /** + * @brief Constructs a group from a set of storage classes. + * @param ref A reference to a group handler. + */ + basic_group(handler &ref) noexcept + : descriptor{&ref} {} + + /** + * @brief Returns the leading storage of a group. + * @return The leading storage of the group. + */ + [[nodiscard]] const common_type &handle() const noexcept { + return descriptor->handle(); + } + + /** + * @brief Returns the storage for a given element type, if any. + * @tparam Type Type of element of which to return the storage. + * @return The storage for the given element type. + */ + template + [[nodiscard]] auto *storage() const noexcept { + return storage>(); + } + + /** + * @brief Returns the storage for a given index, if any. + * @tparam Index Index of the storage to return. + * @return The storage for the given index. + */ + template + [[nodiscard]] auto *storage() const noexcept { + using type = type_list_element_t>; + return *this ? static_cast(descriptor->template storage()) : nullptr; + } + + /** + * @brief Returns the number of entities that are part of the group. + * @return Number of entities that are part of the group. + */ + [[nodiscard]] size_type size() const noexcept { + return *this ? handle().size() : size_type{}; + } + + /** + * @brief Returns the number of elements that a group has currently + * allocated space for. + * @return Capacity of the group. + */ + [[nodiscard]] size_type capacity() const noexcept { + return *this ? handle().capacity() : size_type{}; + } + + /*! @brief Requests the removal of unused capacity. */ + void shrink_to_fit() { + if(*this) { + descriptor->handle().shrink_to_fit(); + } + } + + /** + * @brief Checks whether a group is empty. + * @return True if the group is empty, false otherwise. + */ + [[nodiscard]] bool empty() const noexcept { + return !*this || handle().empty(); + } + + /** + * @brief Returns an iterator to the first entity of the group. + * + * If the group is empty, the returned iterator will be equal to `end()`. + * + * @return An iterator to the first entity of the group. + */ + [[nodiscard]] iterator begin() const noexcept { + return *this ? handle().begin() : iterator{}; + } + + /** + * @brief Returns an iterator that is past the last entity of the group. + * @return An iterator to the entity following the last entity of the + * group. + */ + [[nodiscard]] iterator end() const noexcept { + return *this ? handle().end() : iterator{}; + } + + /** + * @brief Returns an iterator to the first entity of the reversed group. + * + * If the group is empty, the returned iterator will be equal to `rend()`. + * + * @return An iterator to the first entity of the reversed group. + */ + [[nodiscard]] reverse_iterator rbegin() const noexcept { + return *this ? handle().rbegin() : reverse_iterator{}; + } + + /** + * @brief Returns an iterator that is past the last entity of the reversed + * group. + * @return An iterator to the entity following the last entity of the + * reversed group. + */ + [[nodiscard]] reverse_iterator rend() const noexcept { + return *this ? handle().rend() : reverse_iterator{}; + } + + /** + * @brief Returns the first entity of the group, if any. + * @return The first entity of the group if one exists, the null entity + * otherwise. + */ + [[nodiscard]] entity_type front() const noexcept { + const auto it = begin(); + return it != end() ? *it : null; + } + + /** + * @brief Returns the last entity of the group, if any. + * @return The last entity of the group if one exists, the null entity + * otherwise. + */ + [[nodiscard]] entity_type back() const noexcept { + const auto it = rbegin(); + return it != rend() ? *it : null; + } + + /** + * @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]] iterator find(const entity_type entt) const noexcept { + return *this ? handle().find(entt) : iterator{}; + } + + /** + * @brief Returns the identifier that occupies the given position. + * @param pos Position of the element to return. + * @return The identifier that occupies the given position. + */ + [[nodiscard]] entity_type operator[](const size_type pos) const { + return begin()[pos]; + } + + /** + * @brief Checks if a group is properly initialized. + * @return True if the group is properly initialized, false otherwise. + */ + [[nodiscard]] explicit operator bool() const noexcept { + return descriptor != nullptr; + } + + /** + * @brief Checks if a group contains an entity. + * @param entt A valid identifier. + * @return True if the group contains the given entity, false otherwise. + */ + [[nodiscard]] bool contains(const entity_type entt) const noexcept { + return *this && handle().contains(entt); + } + + /** + * @brief Returns the elements assigned to the given entity. + * @tparam Type Type of the element to get. + * @tparam Other Other types of elements to get. + * @param entt A valid identifier. + * @return The elements assigned to the entity. + */ + template + [[nodiscard]] decltype(auto) get(const entity_type entt) const { + return get, index_of...>(entt); + } + + /** + * @brief Returns the elements assigned to the given entity. + * @tparam Index Indexes of the elements to get. + * @param entt A valid identifier. + * @return The elements assigned to the entity. + */ + template + [[nodiscard]] decltype(auto) get(const entity_type entt) const { + const auto cpools = pools_for(std::index_sequence_for{}); + + if constexpr(sizeof...(Index) == 0) { + return std::apply([entt](auto *...curr) { return std::tuple_cat(curr->get_as_tuple(entt)...); }, cpools); + } else if constexpr(sizeof...(Index) == 1) { + return (std::get(cpools)->get(entt), ...); + } else { + return std::tuple_cat(std::get(cpools)->get_as_tuple(entt)...); + } + } + + /** + * @brief Iterates entities and elements and applies the given function + * object to them. + * + * The function object is invoked for each entity. It is provided with the + * entity itself and a set of references to non-empty elements. The + * _constness_ of the elements is as requested.
+ * The signature of the function must be equivalent to one of the following + * forms: + * + * @code{.cpp} + * void(const entity_type, Type &...); + * void(Type &...); + * @endcode + * + * @note + * Empty types aren't explicitly instantiated and therefore they are never + * returned during iterations. + * + * @tparam Func Type of the function object to invoke. + * @param func A valid function object. + */ + template + void each(Func func) const { + for(const auto entt: *this) { + if constexpr(is_applicable_v{}, std::declval().get({})))>) { + std::apply(func, std::tuple_cat(std::make_tuple(entt), get(entt))); + } else { + std::apply(func, get(entt)); + } + } + } + + /** + * @brief Returns an iterable object to use to _visit_ a group. + * + * The iterable object returns tuples that contain the current entity and a + * set of references to its non-empty elements. The _constness_ of the + * elements is as requested. + * + * @note + * Empty types aren't explicitly instantiated and therefore they are never + * returned during iterations. + * + * @return An iterable object to use to _visit_ the group. + */ + [[nodiscard]] iterable each() const noexcept { + const auto cpools = pools_for(std::index_sequence_for{}); + return iterable{{begin(), cpools}, {end(), cpools}}; + } + + /** + * @brief Sort a group 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 one of the following: + * + * @code{.cpp} + * bool(std::tuple, std::tuple); + * bool(const Type &..., const Type &...); + * bool(const Entity, const Entity); + * @endcode + * + * Where `Type` are such that they are iterated by the group.
+ * 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 Type Optional type of element to compare. + * @tparam Other Other optional types of elements to compare. + * @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) { + sort, index_of...>(std::move(compare), std::move(algo), std::forward(args)...); + } + + /** + * @brief Sort a group according to the given comparison function. + * + * @sa sort + * + * @tparam Index Optional indexes of elements to compare. + * @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) { + if(*this) { + if constexpr(sizeof...(Index) == 0) { + static_assert(std::is_invocable_v, "Invalid comparison function"); + descriptor->handle().sort(std::move(compare), std::move(algo), std::forward(args)...); + } else { + auto comp = [&compare, cpools = pools_for(std::index_sequence_for{})](const entity_type lhs, const entity_type rhs) { + if constexpr(sizeof...(Index) == 1) { + return compare((std::get(cpools)->get(lhs), ...), (std::get(cpools)->get(rhs), ...)); + } else { + return compare(std::forward_as_tuple(std::get(cpools)->get(lhs)...), std::forward_as_tuple(std::get(cpools)->get(rhs)...)); + } + }; + + descriptor->handle().sort(std::move(comp), std::move(algo), std::forward(args)...); + } + } + } + + /** + * @brief Sort entities according to their order in a range. + * + * The shared pool of entities and thus its order is affected by the changes + * to each and every pool that it tracks. + * + * @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 sort_as(It first, It last) const { + if(*this) { + descriptor->handle().sort_as(first, last); + } + } + +private: + handler *descriptor; +}; + +/** + * @brief Owning group. + * + * Owning groups returns all entities and only the entities that are at + * least in the given storage. Moreover: + * + * * It's guaranteed that the entity list is tightly packed in memory for fast + * iterations. + * * It's guaranteed that all elements in the owned storage are tightly packed + * in memory for even faster iterations and to allow direct access. + * * They stay true to the order of the owned storage and all instances have the + * same order in memory. + * + * The more types of storage are owned, the faster it is to iterate a group. + * + * @b Important + * + * Iterators aren't invalidated if: + * + * * New elements are added to the storage. + * * The entity currently pointed is modified (for example, elements are added + * or removed from it). + * * The entity currently pointed is destroyed. + * + * In all other cases, modifying the pools iterated by the group in any way + * invalidates all the iterators. + * + * @tparam Owned Types of storage _owned_ by the group. + * @tparam Get Types of storage _observed_ by the group. + * @tparam Exclude Types of storage used to filter the group. + */ +template +class basic_group, get_t, exclude_t> { + static_assert(((Owned::storage_policy != deletion_policy::in_place) && ...), "Groups do not support in-place delete"); + + using base_type = std::common_type_t; + using underlying_type = typename base_type::entity_type; + + template + static constexpr std::size_t index_of = type_list_index_v, type_list>; + + template + [[nodiscard]] auto pools_for(std::index_sequence, std::index_sequence) const noexcept { + using return_type = std::tuple; + return descriptor ? return_type{static_cast(descriptor->template storage())..., static_cast(descriptor->template storage())...} : return_type{}; + } + +public: + /*! @brief Underlying entity identifier. */ + using entity_type = underlying_type; + /*! @brief Unsigned integer type. */ + using size_type = std::size_t; + /*! @brief Common type among all storage types. */ + using common_type = base_type; + /*! @brief Random access iterator type. */ + using iterator = typename common_type::iterator; + /*! @brief Reverse iterator type. */ + using reverse_iterator = typename common_type::reverse_iterator; + /*! @brief Iterable group type. */ + using iterable = iterable_adaptor, get_t>>; + /*! @brief Group handler type. */ + using handler = internal::group_handler; + + /** + * @brief Group opaque identifier. + * @return Group opaque identifier. + */ + static id_type group_id() noexcept { + return type_hash...>, get_t...>, exclude_t...>>>::value(); + } + + /*! @brief Default constructor to use to create empty, invalid groups. */ + basic_group() noexcept + : descriptor{} {} + + /** + * @brief Constructs a group from a set of storage classes. + * @param ref A reference to a group handler. + */ + basic_group(handler &ref) noexcept + : descriptor{&ref} {} + + /** + * @brief Returns the leading storage of a group. + * @return The leading storage of the group. + */ + [[nodiscard]] const common_type &handle() const noexcept { + return *storage<0>(); + } + + /** + * @brief Returns the storage for a given element type, if any. + * @tparam Type Type of element of which to return the storage. + * @return The storage for the given element type. + */ + template + [[nodiscard]] auto *storage() const noexcept { + return storage>(); + } + + /** + * @brief Returns the storage for a given index, if any. + * @tparam Index Index of the storage to return. + * @return The storage for the given index. + */ + template + [[nodiscard]] auto *storage() const noexcept { + using type = type_list_element_t>; + return *this ? static_cast(descriptor->template storage()) : nullptr; + } + + /** + * @brief Returns the number of entities that that are part of the group. + * @return Number of entities that that are part of the group. + */ + [[nodiscard]] size_type size() const noexcept { + return *this ? descriptor->length() : size_type{}; + } + + /** + * @brief Checks whether a group is empty. + * @return True if the group is empty, false otherwise. + */ + [[nodiscard]] bool empty() const noexcept { + return !*this || !descriptor->length(); + } + + /** + * @brief Returns an iterator to the first entity of the group. + * + * If the group is empty, the returned iterator will be equal to `end()`. + * + * @return An iterator to the first entity of the group. + */ + [[nodiscard]] iterator begin() const noexcept { + return *this ? (handle().end() - descriptor->length()) : iterator{}; + } + + /** + * @brief Returns an iterator that is past the last entity of the group. + * @return An iterator to the entity following the last entity of the + * group. + */ + [[nodiscard]] iterator end() const noexcept { + return *this ? handle().end() : iterator{}; + } + + /** + * @brief Returns an iterator to the first entity of the reversed group. + * + * If the group is empty, the returned iterator will be equal to `rend()`. + * + * @return An iterator to the first entity of the reversed group. + */ + [[nodiscard]] reverse_iterator rbegin() const noexcept { + return *this ? handle().rbegin() : reverse_iterator{}; + } + + /** + * @brief Returns an iterator that is past the last entity of the reversed + * group. + * @return An iterator to the entity following the last entity of the + * reversed group. + */ + [[nodiscard]] reverse_iterator rend() const noexcept { + return *this ? (handle().rbegin() + descriptor->length()) : reverse_iterator{}; + } + + /** + * @brief Returns the first entity of the group, if any. + * @return The first entity of the group if one exists, the null entity + * otherwise. + */ + [[nodiscard]] entity_type front() const noexcept { + const auto it = begin(); + return it != end() ? *it : null; + } + + /** + * @brief Returns the last entity of the group, if any. + * @return The last entity of the group if one exists, the null entity + * otherwise. + */ + [[nodiscard]] entity_type back() const noexcept { + const auto it = rbegin(); + return it != rend() ? *it : null; + } + + /** + * @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]] iterator find(const entity_type entt) const noexcept { + const auto it = *this ? handle().find(entt) : iterator{}; + return it >= begin() ? it : iterator{}; + } + + /** + * @brief Returns the identifier that occupies the given position. + * @param pos Position of the element to return. + * @return The identifier that occupies the given position. + */ + [[nodiscard]] entity_type operator[](const size_type pos) const { + return begin()[pos]; + } + + /** + * @brief Checks if a group is properly initialized. + * @return True if the group is properly initialized, false otherwise. + */ + [[nodiscard]] explicit operator bool() const noexcept { + return descriptor != nullptr; + } + + /** + * @brief Checks if a group contains an entity. + * @param entt A valid identifier. + * @return True if the group contains the given entity, false otherwise. + */ + [[nodiscard]] bool contains(const entity_type entt) const noexcept { + return *this && handle().contains(entt) && (handle().index(entt) < (descriptor->length())); + } + + /** + * @brief Returns the elements assigned to the given entity. + * @tparam Type Type of the element to get. + * @tparam Other Other types of elements to get. + * @param entt A valid identifier. + * @return The elements assigned to the entity. + */ + template + [[nodiscard]] decltype(auto) get(const entity_type entt) const { + return get, index_of...>(entt); + } + + /** + * @brief Returns the elements assigned to the given entity. + * @tparam Index Indexes of the elements to get. + * @param entt A valid identifier. + * @return The elements assigned to the entity. + */ + template + [[nodiscard]] decltype(auto) get(const entity_type entt) const { + const auto cpools = pools_for(std::index_sequence_for{}, std::index_sequence_for{}); + + if constexpr(sizeof...(Index) == 0) { + return std::apply([entt](auto *...curr) { return std::tuple_cat(curr->get_as_tuple(entt)...); }, cpools); + } else if constexpr(sizeof...(Index) == 1) { + return (std::get(cpools)->get(entt), ...); + } else { + return std::tuple_cat(std::get(cpools)->get_as_tuple(entt)...); + } + } + + /** + * @brief Iterates entities and elements and applies the given function + * object to them. + * + * The function object is invoked for each entity. It is provided with the + * entity itself and a set of references to non-empty elements. The + * _constness_ of the elements is as requested.
+ * The signature of the function must be equivalent to one of the following + * forms: + * + * @code{.cpp} + * void(const entity_type, Type &...); + * void(Type &...); + * @endcode + * + * @note + * Empty types aren't explicitly instantiated and therefore they are never + * returned during iterations. + * + * @tparam Func Type of the function object to invoke. + * @param func A valid function object. + */ + template + void each(Func func) const { + for(auto args: each()) { + if constexpr(is_applicable_v{}, std::declval().get({})))>) { + std::apply(func, args); + } else { + std::apply([&func](auto, auto &&...less) { func(std::forward(less)...); }, args); + } + } + } + + /** + * @brief Returns an iterable object to use to _visit_ a group. + * + * The iterable object returns tuples that contain the current entity and a + * set of references to its non-empty elements. The _constness_ of the + * elements is as requested. + * + * @note + * Empty types aren't explicitly instantiated and therefore they are never + * returned during iterations. + * + * @return An iterable object to use to _visit_ the group. + */ + [[nodiscard]] iterable each() const noexcept { + const auto cpools = pools_for(std::index_sequence_for{}, std::index_sequence_for{}); + return iterable{{begin(), cpools}, {end(), cpools}}; + } + + /** + * @brief Sort a group 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 one of the following: + * + * @code{.cpp} + * bool(std::tuple, std::tuple); + * bool(const Type &, const Type &); + * bool(const Entity, const Entity); + * @endcode + * + * Where `Type` are either owned types or not but still such that they are + * iterated by the group.
+ * 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 Type Optional type of element to compare. + * @tparam Other Other optional types of elements to compare. + * @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 { + sort, index_of...>(std::move(compare), std::move(algo), std::forward(args)...); + } + + /** + * @brief Sort a group according to the given comparison function. + * + * @sa sort + * + * @tparam Index Optional indexes of elements to compare. + * @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 { + const auto cpools = pools_for(std::index_sequence_for{}, std::index_sequence_for{}); + + if constexpr(sizeof...(Index) == 0) { + static_assert(std::is_invocable_v, "Invalid comparison function"); + storage<0>()->sort_n(descriptor->length(), std::move(compare), std::move(algo), std::forward(args)...); + } else { + auto comp = [&compare, &cpools](const entity_type lhs, const entity_type rhs) { + if constexpr(sizeof...(Index) == 1) { + return compare((std::get(cpools)->get(lhs), ...), (std::get(cpools)->get(rhs), ...)); + } else { + return compare(std::forward_as_tuple(std::get(cpools)->get(lhs)...), std::forward_as_tuple(std::get(cpools)->get(rhs)...)); + } + }; + + storage<0>()->sort_n(descriptor->length(), std::move(comp), std::move(algo), std::forward(args)...); + } + + auto cb = [this](auto *head, auto *...other) { + for(auto next = descriptor->length(); next; --next) { + const auto pos = next - 1; + [[maybe_unused]] const auto entt = head->data()[pos]; + (other->swap_elements(other->data()[pos], entt), ...); + } + }; + + std::apply(cb, cpools); + } + +private: + handler *descriptor; +}; + +} // namespace entt + +#endif -- cgit