EntityID.hpp

Go to the documentation of this file.

//
//  CeresEngine - A game development framework
//
//  Created by Rogiel Sulzbach.
//  Copyright (c) 2018-2022 Rogiel Sulzbach. All rights reserved.
//
 
#pragma once
 
#include "CeresEngine/DataTypes.hpp"
#include "CeresEngine/Macros.hpp"
 
#include "CeresEngine/Foundation/Hash.hpp"
#include "CeresEngine/Foundation/Container/Map.hpp"
#include "CeresEngine/Foundation/Container/Vector.hpp"
 
#include <cstdint>
#include <iosfwd>
 
namespace CeresEngine {
 
    using EntityIndex = UInt32;
    using EntityVersion = UInt32;
 
    struct CE_SCRIPT_EXPORT() EntityID final {
        CE_SCRIPT_EXPORT(readonly = true)
        EntityIndex index = 0;
 
        CE_SCRIPT_EXPORT(readonly = true)
        EntityVersion version = 0;
 
        CE_SCRIPT_EXPORT()
        inline EntityID() noexcept = default;
 
        CE_SCRIPT_EXPORT()
        EntityID(const EntityID& other) noexcept = default;
 
        EntityID& operator=(const EntityID& other) noexcept = default;
 
        CE_SCRIPT_EXPORT(readonly = true)
        inline EntityID(const EntityIndex index, const EntityVersion version) noexcept : index(index), version(version) {}
 
    public: // Operators
        friend inline constexpr bool operator==(const EntityID& a, const EntityID& b) noexcept { return a.index == b.index && a.version == b.version; }
 
        friend inline constexpr bool operator!=(const EntityID& a, const EntityID& b) noexcept { return a.index != b.index || a.version != b.version; }
 
        friend std::ostream& operator<<(std::ostream& os, const EntityID& entityID);
    };
 
    class EntityIDAllocator {
    private:
        HashMap<EntityIndex, EntityVersion> mEntityVersions;
 
        EntityIndex mNextEntityIndex = 0;
 
        Vector<EntityID> mFreeList;
 
    public:
        [[nodiscard]] EntityID allocate() noexcept;
 
        [[nodiscard]] Vector<EntityID> allocate(EntityIndex n) noexcept;
 
        void release(EntityID entityID) noexcept;
 
        [[nodiscard]] EntityVersion getLatestVersion(EntityIndex index) const noexcept;
    };
 
} // namespace CeresEngine
 
template<> struct std::hash<CeresEngine::EntityID> {
    size_t operator()(const CeresEngine::EntityID& entityID) const { return CeresEngine::hash(entityID.index, entityID.version); }
};