CoroutineRunner

CoroutineRunner.cs

using System;
using System.Collections.Generic;
using System.Runtime.ExceptionServices;
using System.Threading.Tasks;
using UnityEngine;

namespace Core.Concurrent
{
    public class CoroutineRunner
    {
        private readonly Stack<object> _stack;
        private ExceptionDispatchInfo _exception;

        public CoroutineRunner()
        {
            _stack = new Stack<object>();
        }

        public void Start(System.Collections.IEnumerator enumerator)
        {
            if (enumerator is null) throw new ArgumentNullException(nameof(enumerator));
            if (_stack.Count > 0) throw new ArgumentException(nameof(_stack)); //完了まではこのRunner上ではStartできない

            _exception = null;
            _stack.Push(enumerator);
        }

        /// <summary>
        /// コルーチンを1フレーム回します
        /// 実行するものがない、または実行完了時にfalseを返します
        /// </summary>
        public bool Update()
        {
            if (_stack.Count <= 0) return false;

            var item = _stack.Peek();

            if (!UpdateItem(item))
            {
                _stack.Pop();
            }

            if (_exception != null)
            {
                var ex = _exception;
                _exception = null;
                _stack.Clear();
                ex.Throw();
            }

            return _stack.Count > 0;
        }

        private bool UpdateItem(object item)
        {
            if (item is System.Collections.IEnumerator enumerator)
            {
                return UpdateEnumerator(enumerator);
            }
            else if (item is Task task)
            {
                return CheckTaskComplete(task);
            }
            else if(item is AsyncOperation asyncOp)
            {
                return CheckAsyncOperationComplete(asyncOp);
            }

            throw new InvalidOperationException("stackに積めない型");
        }

        private bool UpdateEnumerator(System.Collections.IEnumerator enumerator)
        {
            bool moveNext = false;
            try
            {
                moveNext = enumerator.MoveNext();
            }
            catch (Exception ex)
            {
                _exception = ExceptionDispatchInfo.Capture(ex);
            }

            if (!moveNext)
            {
                //例外発生時もこちら

                //enumerator.Reset();
                if (enumerator is IDisposable disposable)
                    disposable.Dispose();

                return false;
            }

            var current = enumerator.Current;
            if (current is System.Collections.IEnumerator || current is Task || current is AsyncOperation)
                _stack.Push(current);

            return true;
        }

        private bool CheckTaskComplete(Task task)
        {
            if (task.IsFaulted)
                _exception = ExceptionDispatchInfo.Capture(task.Exception);

            return !task.IsCompleted;
        }

        private bool CheckAsyncOperationComplete(AsyncOperation asyncOp)
        {
            return !asyncOp.isDone;
        }
    }
}