entity.cs

using System;
using System.Collections.Generic;

namespace ECS
{
    public sealed class Entity
    {
        // A unique ID representing the Entity. Will not be reused if
        // the entity is deleted.
        public long UniqueID { get; internal set; }

        // The entity's components mapped to their type.
        private Dictionary<Type, IComponent> components;

        internal Entity(int id)
        {
            UniqueID = id;
        }

        public T GetComponent<T>() where T:IComponent
        {
            if (components.ContainsKey(typeof(T)))
            {
                return (T)components[typeof(T)];
            }
            return default(T);
        }

        public void AddComponent<T>(T component) where T:IComponent
        {
            if (!components.ContainsKey(typeof(T)))
            {
                components[typeof(T)] = component;
            }
        }
    }
}