UnityECS/LocalPackages/com.nimin.tinyecs/Runtime/Entity.cs

using System;
using GameCore.LowLevel;
using Unity.Collections.LowLevel.Unsafe;

namespace GameCore.TinyECS
{
    public readonly struct Entity<TEnum> : IEquatable<Entity<TEnum>> where TEnum : unmanaged, IConvertible
    {
        public readonly TEnum type;
        public readonly int index;
        public readonly int generation;

        public Entity(TEnum type, int index, int generation)
        {
            this.type = type;
            this.index = index;
            this.generation = generation;
        }

        public override string ToString() => $"Entity<{type}>({index},{generation})";
        public bool Equals(Entity<TEnum> other) => type.Equals(other.type) && index == other.index && generation == other.generation;
        public override bool Equals(object obj) => obj is Entity<TEnum> other && Equals(other);
        public override int GetHashCode() => LowLevelUtility.HashCombine(UnsafeUtility.EnumToInt(type), index, generation);
        public static bool operator ==(Entity<TEnum> lhs, Entity<TEnum> rhs) => lhs.Equals(rhs);
        public static bool operator !=(Entity<TEnum> lhs, Entity<TEnum> rhs) => !(lhs == rhs);

    }
}