encompass-cs/encompass-cs/EntitySetQuery.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Immutable;

namespace Encompass
{
    public struct EntitySetQuery : IEnumerable<Entity>
    {
        private EntitySetQuery(ComponentManager componentManager, ImmutableArray<Type> includes, ImmutableArray<Type> excludes)
        {
            ComponentManager = componentManager;
            Includes = includes;
            Excludes = excludes;
        }

        internal EntitySetQuery(ComponentManager componentManager)
        {
            ComponentManager = componentManager;
            Includes = ImmutableArray.Create<Type>();
            Excludes = ImmutableArray.Create<Type>();
        }

        private ComponentManager ComponentManager { get; }
        private ImmutableArray<Type> Includes { get; }
        private ImmutableArray<Type> Excludes { get; }

        public EntitySetQuery With<TComponent>() where TComponent : struct, IComponent
        {
            return new EntitySetQuery(ComponentManager, Includes.Add(typeof(TComponent)), Excludes);
        }

        public EntitySetQuery Without<TComponent>() where TComponent : struct, IComponent
        {
            return new EntitySetQuery(ComponentManager, Includes, Excludes.Add(typeof(TComponent)));
        }

        public IEnumerator<Entity> GetEnumerator()
        {
            return ComponentManager.EntitiesWithComponents(Includes).GetEnumerator();
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }
    }
}