Entity.hpp

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/*
** EPITECH PROJECT, 2025
** R-Type
** File description:
** Entity.hpp
*/
 
/*
** MIT License
**
** Copyright (c) 2025 Robin Toillon
**
** Permission is hereby granted, free of charge, to any person obtaining
** a copy of this software and associated documentation files (the
** "Software"), to deal in the Software without restriction, including
** without limitation the rights to use, copy, modify, merge, publish,
** distribute, sublicense, and/or sell copies of the Software, and to
** permit persons to whom the Software is furnished to do so, subject to
** the following conditions:
**
** The above copyright notice and this permission notice shall be
** included in all copies or substantial portions of the Software.
**
** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
** EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
** MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
** IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
** CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
** TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
** SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
 
#ifndef RTYPE_ENTITY_HPP_
    #define RTYPE_ENTITY_HPP_
 
    #include <compare>
    #include <cstdint>
    #include <limits>
    #include <functional>
 
namespace rtp::ecs
{
    class Entity {
        public:
            static constexpr std::uint32_t MAX_INDEX =
                            std::numeric_limits<std::uint32_t>::max();
            static constexpr std::uint64_t INDEX_MASK = MAX_INDEX;
            static constexpr std::uint64_t GEN_SHIFT = 32;
 
            constexpr Entity(std::uint32_t index, std::uint32_t generation);
 
            constexpr Entity(void);
 
            [[nodiscard]]
            constexpr std::uint32_t index(void) const;
 
            [[nodiscard]]
            constexpr std::uint32_t generation(void) const;
 
            constexpr auto operator<=>(const Entity &) const = default;
    
            constexpr operator std::uint64_t(void) const noexcept;
 
            [[nodiscard]]
            constexpr bool isNull(void) const noexcept;
 
        private:
            std::uint64_t _id; 
            friend struct std::hash<Entity>;
    };
}
 
namespace std
{
    template <>
    struct hash<rtp::ecs::Entity> {
        size_t operator()(const rtp::ecs::Entity &e) const
        {
            return hash<std::uint64_t>{}(e._id);
        }
    };
}
 
    #include "Entity.inl"
 
namespace rtp::ecs
{
    constexpr Entity NullEntity{};
}
 
#endif /* !RTYPE_ENTITY_HPP_ */