/// <summary>
/// 在执行链路中运行异步方法
/// 比如想在 Where() 中运行异步判断，但是 Where 不支持返回值 Task<bool>，所以可以使用 SelectMany 的重载方法来进行投影，并生成新的带原始数据的对象
/// </summary>
/// <returns></returns>
public static IObservable <int> RunAsyncCodeInPipeline()
{
return(Observable.Range(2, 9)
.SelectMany(x => PrimeGenerator.CheckPrimeAsync(x), (number, isPrime) => new { number, isPrime })
.Where(x => x.isPrime)
.Select(x => x.number));
}
/// <summary>
/// 在链路中中运行异步方法，而且结果顺序输出
/// 使用 Select 和 Concat 代替 SelectMany 就可以顺序输出
/// </summary>
/// <returns></returns>
public static IObservable <int> RunAsyncCodeInPipelineWithOrder()
{
return(Observable.Range(2, 9)
.Select(async x => new { number = x, isPrime = await PrimeGenerator.CheckPrimeAsync(x) })
.Concat()
.Where(x => x.isPrime)
.Select(x => x.number));
}
/// <summary>
/// RunAsyncCodeInPipeline 的 linq 实现，更直观
/// </summary>
/// <returns></returns>
public static IObservable <int> RunAsyncCodeInPipelineByLinq()
{
var resule = from number in Observable.Range(2, 9)
from isPrime in PrimeGenerator.CheckPrimeAsync(number)
where isPrime
select number;
return(resule);
}