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catboy_engine/include/libcatboy/ecs/ecs.hpp
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#ifndef LIBCATBOY_ECS_ECS_HPP
#define LIBCATBOY_ECS_ECS_HPP
#include "fwd.hpp"
#include "sparseSet.hpp"
#include <concepts>
#include <queue>
#include <stdexcept>
#include <type_traits>
#include <typeindex>
#include <unordered_map>
#include <unordered_set>
#include <vector>
namespace libcatboy {
namespace ecs {
template <std::integral Entity>
class basic_registry {
public:
using entity_type = Entity;
public:
entity_type create_entity() {
if (m_graveyard.empty()) {
entity_type entity = m_entityCounter++;
m_alive.insert(entity);
return entity;
}
entity_type entity = m_graveyard.front();
m_alive.insert(entity);
m_graveyard.pop();
return entity;
}
void erase_entity(entity_type entity) {
if (!m_alive.contains(entity)) return;
m_alive.erase(entity);
for (const auto& [type, set] : m_components) {
set->erase(entity);
}
m_graveyard.push(entity);
}
public:
template <typename T>
void register_component() {
get_set<T>();
}
template <typename T>
void unregister_component() {
auto it = m_components.find(typeid(T));
if (it == m_components.end()) return;
delete reinterpret_cast<sparse_set<T>*>(it->second);
m_components.erase(it);
}
public:
template <typename T>
void insert(entity_type entity, T&& component) {
emplace<std::remove_cvref_t<T>>(entity, std::forward<T>(component));
}
template <typename T, typename... Args>
T& emplace(entity_type entity, Args&&... args) {
if (m_alive.find(entity) == m_alive.end()) throw std::runtime_error("entity is dead");
return get_set<T>().emplace(entity, std::forward<Args>(args)...);
}
public:
template <typename T>
T& at(entity_type entity) {
if (m_alive.find(entity) == m_alive.end()) throw std::runtime_error("entity is dead");
return get_set<T>().at(entity);
}
template <typename T>
const T& at(entity_type entity) const {
if (m_alive.find(entity) == m_alive.end()) throw std::runtime_error("entity is dead");
return get_set<T>().at(entity);
}
public:
template <typename T>
void erase(entity_type entity) {
if (m_alive.find(entity) == m_alive.end()) throw std::runtime_error("entity is dead");
get_set<T>().erase(entity);
}
private:
template <typename T>
sparse_set<T>& get_set() {
auto it = m_components.find(typeid(T));
if (it != m_components.end()) return dynamic_cast<sparse_set<T>&>(*it->second);
sparse_set<T>* set = new sparse_set<T>();
m_components.emplace(typeid(T), set);
return *set;
}
template <typename T>
const sparse_set<T>& get_set() const {
auto it = m_components.find(typeid(T));
if (it != m_components.end()) return dynamic_cast<sparse_set<T>&>(*it->second);
throw std::runtime_error("error");
}
private:
std::unordered_map<std::type_index, isparse_set*> m_components;
std::unordered_set<entity_type> m_alive;
std::queue<entity_type> m_graveyard;
entity_type m_entityCounter = 0;
};
} // namespace ecs
} // namespace libcatboy
#endif // LIBCATBOY_ECS_ECS_HPP