C#递归迭代嵌套属性列表

Question

foreach (TargetObject innerObject1 in complexObject.InnerObjects) { 
    foreach (TargetObject innerObject2 in innerObject1.InnerObjects) { 
        foreach (TargetObject innerObject3 in innerObject2.InnerObjects) { 
           yield return innerObject3;
        } 
        yield return innerObject2;
    } 
    yield return innerObject1;
 }

我该如何递归地做到这一点？我需要将所有嵌套列表中被包含的 TargetObject 实例汇总到一个列表中。下面是一个没有成功的尝试。

 public static IEnumerable<TargetObject> GetRecursively(params TargetObject[] startingObjects) 
    {
        foreach (TargetObject startingObject in startingObjects) 
        {
            foreach (TargetObject innerObject in GetRecursively(startingObject.InnerObjects.ToArray()))
            {
                yield return innerObject;
            }
            yield return startingObject;
        }
    }

- parliament

Answer 1

像这样——返回startingObject，并对InnerObjects中的每个项递归调用：

public static IEnumerable<TargetObject> GetRecursively(TargetObject startingObject) 
{
    yield return startingObject;
    if (startingObject.InnerObjects != null)
        foreach (TargetObject innerObject in startingObject.InnerObjects.ToArray())
            foreach (TargetObject recursiveInner in GetRecursively(innerObject))
                yield return recursiveInner;
}

为了支持将数组作为参数，可以在其周围包装一个foreach：

public static IEnumerable<TargetObject> GetRecursively2(params TargetObject[] startingObjects)
{
    foreach (TargetObject startingObject in startingObjects)
    {
        yield return startingObject;
        if (startingObject.InnerObjects != null)
            foreach (TargetObject innerObject in startingObject.InnerObjects.ToArray())
                foreach (TargetObject recursiveInner in GetRecursively(innerObject))
                    yield return recursiveInner;
    }
}

- McGarnagle

---

值得注意的是，您可以将单个对象传递给params参数，因此数组情况适用于两种情况而无需重载。 - parliament