🛠️🐜 Antkeeper superbuild with dependencies included
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561 lines
19 KiB
561 lines
19 KiB
#ifndef ENTT_ENTITY_SNAPSHOT_HPP
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#define ENTT_ENTITY_SNAPSHOT_HPP
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#include <array>
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#include <cstddef>
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#include <iterator>
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#include <tuple>
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#include <type_traits>
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#include <utility>
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#include <vector>
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#include "../config/config.h"
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#include "../container/dense_map.hpp"
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#include "../core/type_traits.hpp"
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#include "component.hpp"
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#include "entity.hpp"
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#include "fwd.hpp"
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#include "registry.hpp"
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namespace entt {
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/**
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* @brief Utility class to create snapshots from a registry.
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*
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* A _snapshot_ can be either a dump of the entire registry or a narrower
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* selection of components of interest.<br/>
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* This type can be used in both cases if provided with a correctly configured
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* output archive.
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*
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* @tparam Entity A valid entity type (see entt_traits for more details).
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*/
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template<typename Entity>
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class basic_snapshot {
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using entity_traits = entt_traits<Entity>;
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template<typename Component, typename Archive, typename It>
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void get(Archive &archive, std::size_t sz, It first, It last) const {
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const auto view = reg->template view<std::add_const_t<Component>>();
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archive(typename entity_traits::entity_type(sz));
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while(first != last) {
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const auto entt = *(first++);
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if(reg->template all_of<Component>(entt)) {
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std::apply(archive, std::tuple_cat(std::make_tuple(entt), view.get(entt)));
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}
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}
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}
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template<typename... Component, typename Archive, typename It, std::size_t... Index>
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void component(Archive &archive, It first, It last, std::index_sequence<Index...>) const {
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std::array<std::size_t, sizeof...(Index)> size{};
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auto begin = first;
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while(begin != last) {
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const auto entt = *(begin++);
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((reg->template all_of<Component>(entt) ? ++size[Index] : 0u), ...);
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}
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(get<Component>(archive, size[Index], first, last), ...);
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}
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public:
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/*! @brief Underlying entity identifier. */
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using entity_type = Entity;
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/**
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* @brief Constructs an instance that is bound to a given registry.
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* @param source A valid reference to a registry.
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*/
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basic_snapshot(const basic_registry<entity_type> &source) ENTT_NOEXCEPT
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: reg{&source} {}
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/*! @brief Default move constructor. */
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basic_snapshot(basic_snapshot &&) ENTT_NOEXCEPT = default;
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/*! @brief Default move assignment operator. @return This snapshot. */
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basic_snapshot &operator=(basic_snapshot &&) ENTT_NOEXCEPT = default;
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/**
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* @brief Puts aside all the entities from the underlying registry.
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*
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* Entities are serialized along with their versions. Destroyed entities are
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* taken in consideration as well by this function.
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*
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* @tparam Archive Type of output archive.
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* @param archive A valid reference to an output archive.
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* @return An object of this type to continue creating the snapshot.
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*/
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template<typename Archive>
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const basic_snapshot &entities(Archive &archive) const {
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const auto sz = reg->size();
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archive(typename entity_traits::entity_type(sz + 1u));
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archive(reg->released());
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for(auto first = reg->data(), last = first + sz; first != last; ++first) {
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archive(*first);
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}
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return *this;
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}
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/**
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* @brief Puts aside the given components.
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*
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* Each instance is serialized together with the entity to which it belongs.
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* Entities are serialized along with their versions.
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*
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* @tparam Component Types of components to serialize.
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* @tparam Archive Type of output archive.
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* @param archive A valid reference to an output archive.
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* @return An object of this type to continue creating the snapshot.
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*/
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template<typename... Component, typename Archive>
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const basic_snapshot &component(Archive &archive) const {
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if constexpr(sizeof...(Component) == 1u) {
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const auto view = reg->template view<const Component...>();
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(component<Component>(archive, view.rbegin(), view.rend()), ...);
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return *this;
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} else {
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(component<Component>(archive), ...);
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return *this;
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}
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}
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/**
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* @brief Puts aside the given components for the entities in a range.
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*
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* Each instance is serialized together with the entity to which it belongs.
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* Entities are serialized along with their versions.
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*
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* @tparam Component Types of components to serialize.
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* @tparam Archive Type of output archive.
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* @tparam It Type of input iterator.
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* @param archive A valid reference to an output archive.
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* @param first An iterator to the first element of the range to serialize.
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* @param last An iterator past the last element of the range to serialize.
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* @return An object of this type to continue creating the snapshot.
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*/
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template<typename... Component, typename Archive, typename It>
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const basic_snapshot &component(Archive &archive, It first, It last) const {
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component<Component...>(archive, first, last, std::index_sequence_for<Component...>{});
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return *this;
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}
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private:
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const basic_registry<entity_type> *reg;
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};
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/**
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* @brief Utility class to restore a snapshot as a whole.
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*
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* A snapshot loader requires that the destination registry be empty and loads
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* all the data at once while keeping intact the identifiers that the entities
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* originally had.<br/>
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* An example of use is the implementation of a save/restore utility.
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*
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* @tparam Entity A valid entity type (see entt_traits for more details).
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*/
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template<typename Entity>
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class basic_snapshot_loader {
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using entity_traits = entt_traits<Entity>;
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template<typename Type, typename Archive>
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void assign(Archive &archive) const {
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typename entity_traits::entity_type length{};
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entity_type entt;
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archive(length);
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if constexpr(ignore_as_empty_v<Type>) {
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while(length--) {
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archive(entt);
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const auto entity = reg->valid(entt) ? entt : reg->create(entt);
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ENTT_ASSERT(entity == entt, "Entity not available for use");
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reg->template emplace<Type>(entt);
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}
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} else {
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Type instance;
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while(length--) {
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archive(entt, instance);
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const auto entity = reg->valid(entt) ? entt : reg->create(entt);
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ENTT_ASSERT(entity == entt, "Entity not available for use");
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reg->template emplace<Type>(entt, std::move(instance));
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}
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}
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}
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public:
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/*! @brief Underlying entity identifier. */
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using entity_type = Entity;
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/**
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* @brief Constructs an instance that is bound to a given registry.
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* @param source A valid reference to a registry.
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*/
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basic_snapshot_loader(basic_registry<entity_type> &source) ENTT_NOEXCEPT
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: reg{&source} {
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// restoring a snapshot as a whole requires a clean registry
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ENTT_ASSERT(reg->empty(), "Registry must be empty");
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}
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/*! @brief Default move constructor. */
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basic_snapshot_loader(basic_snapshot_loader &&) ENTT_NOEXCEPT = default;
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/*! @brief Default move assignment operator. @return This loader. */
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basic_snapshot_loader &operator=(basic_snapshot_loader &&) ENTT_NOEXCEPT = default;
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/**
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* @brief Restores entities that were in use during serialization.
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*
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* This function restores the entities that were in use during serialization
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* and gives them the versions they originally had.
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*
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* @tparam Archive Type of input archive.
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* @param archive A valid reference to an input archive.
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* @return A valid loader to continue restoring data.
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*/
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template<typename Archive>
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const basic_snapshot_loader &entities(Archive &archive) const {
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typename entity_traits::entity_type length{};
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archive(length);
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std::vector<entity_type> all(length);
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for(std::size_t pos{}; pos < length; ++pos) {
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archive(all[pos]);
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}
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reg->assign(++all.cbegin(), all.cend(), all[0u]);
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return *this;
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}
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/**
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* @brief Restores components and assigns them to the right entities.
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*
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* The template parameter list must be exactly the same used during
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* serialization. In the event that the entity to which the component is
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* assigned doesn't exist yet, the loader will take care to create it with
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* the version it originally had.
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*
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* @tparam Component Types of components to restore.
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* @tparam Archive Type of input archive.
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* @param archive A valid reference to an input archive.
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* @return A valid loader to continue restoring data.
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*/
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template<typename... Component, typename Archive>
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const basic_snapshot_loader &component(Archive &archive) const {
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(assign<Component>(archive), ...);
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return *this;
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}
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/**
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* @brief Destroys those entities that have no components.
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*
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* In case all the entities were serialized but only part of the components
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* was saved, it could happen that some of the entities have no components
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* once restored.<br/>
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* This functions helps to identify and destroy those entities.
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*
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* @return A valid loader to continue restoring data.
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*/
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const basic_snapshot_loader &orphans() const {
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reg->each([this](const auto entt) {
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if(reg->orphan(entt)) {
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reg->release(entt);
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}
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});
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return *this;
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}
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private:
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basic_registry<entity_type> *reg;
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};
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/**
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* @brief Utility class for _continuous loading_.
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*
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* A _continuous loader_ is designed to load data from a source registry to a
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* (possibly) non-empty destination. The loader can accommodate in a registry
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* more than one snapshot in a sort of _continuous loading_ that updates the
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* destination one step at a time.<br/>
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* Identifiers that entities originally had are not transferred to the target.
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* Instead, the loader maps remote identifiers to local ones while restoring a
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* snapshot.<br/>
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* An example of use is the implementation of a client-server applications with
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* the requirement of transferring somehow parts of the representation side to
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* side.
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*
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* @tparam Entity A valid entity type (see entt_traits for more details).
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*/
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template<typename Entity>
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class basic_continuous_loader {
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using entity_traits = entt_traits<Entity>;
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void destroy(Entity entt) {
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if(const auto it = remloc.find(entt); it == remloc.cend()) {
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const auto local = reg->create();
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remloc.emplace(entt, std::make_pair(local, true));
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reg->destroy(local);
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}
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}
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void restore(Entity entt) {
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const auto it = remloc.find(entt);
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if(it == remloc.cend()) {
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const auto local = reg->create();
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remloc.emplace(entt, std::make_pair(local, true));
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} else {
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if(!reg->valid(remloc[entt].first)) {
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remloc[entt].first = reg->create();
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}
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// set the dirty flag
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remloc[entt].second = true;
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}
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}
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template<typename Container>
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auto update(int, Container &container) -> decltype(typename Container::mapped_type{}, void()) {
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// map like container
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Container other;
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for(auto &&pair: container) {
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using first_type = std::remove_const_t<typename std::decay_t<decltype(pair)>::first_type>;
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using second_type = typename std::decay_t<decltype(pair)>::second_type;
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if constexpr(std::is_same_v<first_type, entity_type> && std::is_same_v<second_type, entity_type>) {
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other.emplace(map(pair.first), map(pair.second));
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} else if constexpr(std::is_same_v<first_type, entity_type>) {
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other.emplace(map(pair.first), std::move(pair.second));
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} else {
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static_assert(std::is_same_v<second_type, entity_type>, "Neither the key nor the value are of entity type");
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other.emplace(std::move(pair.first), map(pair.second));
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}
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}
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using std::swap;
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swap(container, other);
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}
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template<typename Container>
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auto update(char, Container &container) -> decltype(typename Container::value_type{}, void()) {
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// vector like container
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static_assert(std::is_same_v<typename Container::value_type, entity_type>, "Invalid value type");
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for(auto &&entt: container) {
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entt = map(entt);
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}
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}
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template<typename Other, typename Type, typename Member>
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void update([[maybe_unused]] Other &instance, [[maybe_unused]] Member Type::*member) {
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if constexpr(!std::is_same_v<Other, Type>) {
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return;
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} else if constexpr(std::is_same_v<Member, entity_type>) {
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instance.*member = map(instance.*member);
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} else {
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// maybe a container? let's try...
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update(0, instance.*member);
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}
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}
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template<typename Component>
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void remove_if_exists() {
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for(auto &&ref: remloc) {
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const auto local = ref.second.first;
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if(reg->valid(local)) {
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reg->template remove<Component>(local);
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}
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}
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}
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template<typename Other, typename Archive, typename... Type, typename... Member>
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void assign(Archive &archive, [[maybe_unused]] Member Type::*...member) {
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typename entity_traits::entity_type length{};
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entity_type entt;
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archive(length);
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if constexpr(ignore_as_empty_v<Other>) {
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while(length--) {
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archive(entt);
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restore(entt);
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reg->template emplace_or_replace<Other>(map(entt));
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}
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} else {
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Other instance;
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while(length--) {
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archive(entt, instance);
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(update(instance, member), ...);
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restore(entt);
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reg->template emplace_or_replace<Other>(map(entt), std::move(instance));
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}
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}
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}
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public:
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/*! @brief Underlying entity identifier. */
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using entity_type = Entity;
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/**
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* @brief Constructs an instance that is bound to a given registry.
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* @param source A valid reference to a registry.
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*/
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basic_continuous_loader(basic_registry<entity_type> &source) ENTT_NOEXCEPT
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: reg{&source} {}
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/*! @brief Default move constructor. */
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basic_continuous_loader(basic_continuous_loader &&) = default;
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/*! @brief Default move assignment operator. @return This loader. */
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basic_continuous_loader &operator=(basic_continuous_loader &&) = default;
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/**
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* @brief Restores entities that were in use during serialization.
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*
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* This function restores the entities that were in use during serialization
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* and creates local counterparts for them if required.
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*
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* @tparam Archive Type of input archive.
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* @param archive A valid reference to an input archive.
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* @return A non-const reference to this loader.
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*/
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template<typename Archive>
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basic_continuous_loader &entities(Archive &archive) {
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typename entity_traits::entity_type length{};
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entity_type entt{};
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archive(length);
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// discards the head of the list of destroyed entities
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archive(entt);
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for(std::size_t pos{}, last = length - 1u; pos < last; ++pos) {
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archive(entt);
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if(const auto entity = entity_traits::to_entity(entt); entity == pos) {
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restore(entt);
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} else {
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destroy(entt);
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}
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}
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return *this;
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}
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/**
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* @brief Restores components and assigns them to the right entities.
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*
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* The template parameter list must be exactly the same used during
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* serialization. In the event that the entity to which the component is
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* assigned doesn't exist yet, the loader will take care to create a local
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* counterpart for it.<br/>
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* Members can be either data members of type entity_type or containers of
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* entities. In both cases, the loader will visit them and update the
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* entities by replacing each one with its local counterpart.
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*
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* @tparam Component Type of component to restore.
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* @tparam Archive Type of input archive.
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* @tparam Type Types of components to update with local counterparts.
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* @tparam Member Types of members to update with their local counterparts.
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* @param archive A valid reference to an input archive.
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* @param member Members to update with their local counterparts.
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* @return A non-const reference to this loader.
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*/
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template<typename... Component, typename Archive, typename... Type, typename... Member>
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basic_continuous_loader &component(Archive &archive, Member Type::*...member) {
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(remove_if_exists<Component>(), ...);
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(assign<Component>(archive, member...), ...);
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return *this;
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}
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/**
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* @brief Helps to purge entities that no longer have a conterpart.
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*
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* Users should invoke this member function after restoring each snapshot,
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* unless they know exactly what they are doing.
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*
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* @return A non-const reference to this loader.
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*/
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basic_continuous_loader &shrink() {
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auto it = remloc.begin();
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while(it != remloc.cend()) {
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const auto local = it->second.first;
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bool &dirty = it->second.second;
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if(dirty) {
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dirty = false;
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++it;
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} else {
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if(reg->valid(local)) {
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reg->destroy(local);
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}
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it = remloc.erase(it);
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}
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}
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return *this;
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}
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/**
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* @brief Destroys those entities that have no components.
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*
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* In case all the entities were serialized but only part of the components
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* was saved, it could happen that some of the entities have no components
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* once restored.<br/>
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* This functions helps to identify and destroy those entities.
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*
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* @return A non-const reference to this loader.
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*/
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basic_continuous_loader &orphans() {
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reg->each([this](const auto entt) {
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if(reg->orphan(entt)) {
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reg->release(entt);
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}
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});
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return *this;
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}
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/**
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* @brief Tests if a loader knows about a given entity.
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* @param entt A valid identifier.
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* @return True if `entity` is managed by the loader, false otherwise.
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*/
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[[nodiscard]] bool contains(entity_type entt) const ENTT_NOEXCEPT {
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return (remloc.find(entt) != remloc.cend());
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}
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/**
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* @brief Returns the identifier to which an entity refers.
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* @param entt A valid identifier.
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* @return The local identifier if any, the null entity otherwise.
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*/
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[[nodiscard]] entity_type map(entity_type entt) const ENTT_NOEXCEPT {
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const auto it = remloc.find(entt);
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entity_type other = null;
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if(it != remloc.cend()) {
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other = it->second.first;
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}
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return other;
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}
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private:
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dense_map<entity_type, std::pair<entity_type, bool>> remloc;
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basic_registry<entity_type> *reg;
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};
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} // namespace entt
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#endif
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