using System.Collections.Generic;

using System.Linq;

​

namespace FSM

{

    public interface IState

    {

        IEnumerable<IState> Transitions { get; }

    }

​

​

    public class Stop : IState

    {

        private Stop(){}

        private static Stop _instance = new Stop();

        private static IState[] _empty = new IState[0];

        public Stop Instance => _instance;

        public IEnumerable<IState> Transitions => _empty;

    }           

​

​

    public class Passthru : IState

    {

        private IState _next;

​

        public IEnumerable<IState> Transitions

        {

            get { if (_next != null) yield return _next; }

        }

    }           

​

    public class Decide : IState

    {

        private IState _yes;

        private IState _no;

​

        public IEnumerable<IState> Transitions

        {

            get 

            { 

                if (_yes != null) yield return _yes; 

                if (_no != null) yield return _no; 

            }

        }

    }           

}

​

​

​