using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using UnityEngine;


public class TestYield : MonoBehaviour
{
    static IEnumerable<int> WithNoYield()
    {
        IList<int> list = new List<int>();
        for (int i = 0; i < 20; i++)
        {
            LogHelper.Log("WithNoYield Quary " + i.ToString());
            if (i > 2)
                list.Add(i);
        }
        return list;
    }

    static IEnumerable<int> WithYield()
    {
        for (int i = 0; i < 20; i++)
        {
            LogHelper.Log("WithYield Quary " + i.ToString());
            if (i > 2)
                yield return i;
        }
    }

    void Start()
    {

        LogHelper.Log("------------------ WithNoYield--------------");
        WithNoYield();

        LogHelper.Log("------------------WithYield--------------");
        // 直接调用yield封装的函数不会被执行，会延迟计算  
        WithYield();
        WithYield();
        WithYield();
        WithYield();
        WithYield();
        WithYield();

        // 执行一次会将控制权从函数里面交出，给外部，如果外部是异步的或者子线程一直循环的被挂起了  
        // 下次再重入该函数，那么该yield函数的调用堆栈状态会被保留，从而接着上次状态继续执行  
        LogHelper.Log("------------------ foreach WithNoYield--------------");
        foreach (int i in WithNoYield())
        {
            LogHelper.Log("Result " + i.ToString());
        }

        // 如果yield迭代器全部执行完了，再重新进来不会保留堆栈信息  
        LogHelper.Log("------------------ foreach WithYield1--------------");
        foreach (int i in WithYield())
        {
            Console.WriteLine("Result " + i.ToString());
            if (i == 10)
            {
                break;
            }
        }

        LogHelper.Log("------------------ foreach WithYield2-------------");
        foreach (int i in WithYield())
        {
            LogHelper.Log("Result " + i.ToString());
        }

        LogHelper.Log("-----------------------------------------");
    }
}