Question

我们说我有两个班级：

public Foo
{
   public List<Foo> Childs { get; set; }
   public Bar BarObj { get; set; }
   public int Level { get; set; }
}

public Bar
{
   public List<Foo> Childs { get; set; }
}

现在我想从“Foo”对象的集合中获取嵌套级别

我目前的工作方法如下：

int currentLevel = 0;
public void ApplyNestingLevel(List<Foo> list)
{
    foreach(var item in list)
    {
        item.Level = currentLevel;
        if(item.Childs.Count > 0 || item.BarObj.Childs.Count > 0)
        {
            currentLevel++;
        }
        ApplyNestingLevel(item.Childs);
        ApplyNestingLevel(item.BarObj.Childs);
    }
}

我怎么能让这更“优雅/简单”？

Answer 1

存储对父项的引用，并使Level属性递归。

我在下面的代码示例中添加了一个示例和一些其他设计建议。希望这可以帮助。仅供参考，这与“四人帮”的Composite Pattern设计完全相同，对于那些认真考虑OOP的人来说，这应该是必读的。

DoFactory .NET Composite Pattern

Design Patterns: Elements of Reusable Object-Oriented Software, on Amazon.com

    public class Foo
    {

        public Foo(Foo parent = default(Foo))
        { 
            this.parent = parent;
            this.children = new List<Foo>();
        }

        private readonly Foo parent;
        private readonly List<Foo> children;

        public int Level { get { return ReferenceEquals(parent,null) ? 0 : parent.Level + 1; } }

        // don't expose the actual list... see below for why
        public IEnumerable<Foo> Children { get { foreach(Foo child in this.children) yield return child; } }

        //  instead of exposing the child object list
        //  declare an explicit method with any parameters 
        //  necessary.  this allows you to enforce the invariant 
        //  condition that all objects in a children collection
        //  will have their parent reference set to their 
        //  actual parent
        public void AddChild()
        {
            Foo newChild = new Foo(parent:this);
            this.children.Add(newChild);
        }

        //  if you need the ability to remove items as well, 
        //  you can expose a remove method too.  Just make 
        //  sure that you validate expected preconditions
        public int RemoveChild(Foo childToRemove)
        { 
            if(ReferenceEquals(childToRemove,null)) throw new ArgumentNullException("childToRemove");
            if(!ReferenceEquals(this,childToRemove.parent)) throw new ArgumentException("The object cannot be removed because the current object is not the correct parent.","childToRemove"); 
            return children.RemoveAll((Foo existentChild) => existentChild.Equals(childToRemove));
        }


    }

Answer 2

public void ApplyNestingLevel(Foo f)
{
    ApplyNestingLevel(f, 0);
}


public void ApplyNestingLevel(Foo f, int level)
{
    if(f == null) { return; }
    f.Level = level
    if(f.Childs != null) {
        foreach(Foo child in f.Childs)
        {
            ApplyNestingLevel(child, level + 1);
        }
    }
    if(f.BarObj != null && f.BarObj.Childs != null) {
        foreach(Foo child in f.BarObj.Childs)
        {
            ApplyNestingLevel(child, level + 1);
        }
    }
}

C＃get nesting Tree of Tree

2 个答案: