穿越功能在C＃中的树 [英] Functionally traversing a tree in C#

问题描述

考虑下面的扩展方法在C＃中，遍历：

Consider the following extension method in c#, Traverse:

IEnumerable<T> Traverse<T>( this IEnumerable<T> source, 
                              Func<T, IEnumerable<T>> fnRecurse );

这个方法允许通过一棵树一个递归被T的定义和任何功能使T可返回其。子节点

This method allows one to recurse through a tree as defined by T and whatever function causes T to return its subnodes.

现在考虑以下实现的T：

Now consider the following implementation of T:

class Node
{
  public string Name;
  public List<Node> Children;
}

我的目标是编写最短的功能可能会返回一个IEnumerable $ B包含在这棵树的每个节点的完全合格的路径$ b。是这样的：

My goal is to write the shortest function possible that will return an IEnumerable containing the fully qualified paths for every node in this tree. Something like:

var node = GetParentNode();
return node.Traverse( node => node.Children )
           .Select( node => GetParentName(node) + ":" + node.Name );

显然，加入Parent属性节点使问题微不足道。相反，我想建立一个仿里面我父母不知何故字符串。我不认为这会在C太难+ +，但我看不出如何做到这一点在C＃。任何想法？

Obviously, adding a Parent property to Node makes the problem trivial. Instead I'd like to build my parent strings inside a functor somehow. I don't think this would be too hard in C++ but I don't see how to do it in C#. Any ideas?

推荐答案

我认为，关键是要根本无法通过倒节点类型。相反，通过按下节点，它是合格的路径。例如：

I think the trick is to simply not pass down a Node type. Instead pass down the Node and it's qualified path. For example

var node = GetTheStartNode();
var start = new { Path = node.Name; Node = node };
var paths = 
   start
     .Traverse( x => x.Node.Children.Select(
        c => new { .Path = x.Path + ":" c.Name; .Node=c) )
     .Select(x => x.Path);

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