Looping IEnumerable

How do I get a specific index or loop through this data structure?

public class Path<TNode> : IEnumerable<TNode>
{
    public TNode LastStep { get; private set; }
    public Path<TNode> PreviousSteps { get; private set; }
    public double TotalCost { get; private set; }
    private Path(TNode lastStep, Path<TNode> previousSteps, double totalCost)
    {
        LastStep = lastStep;
        PreviousSteps = previousSteps;
        TotalCost = totalCost;
    }
    public Path(TNode start) : this(start, null, 0) { }
    public Path<TNode> AddStep(TNode step, double stepCost)
    {
        return new Path<TNode>(step, this, TotalCost + stepCost);
    }
    public IEnumerator<TNode> GetEnumerator()
    {
        for (Path<TNode> p = this; p != null; p = p.PreviousSteps)
            yield return p.LastStep;
    }
    IEnumerator IEnumerable.GetEnumerator()
    {
        return this.GetEnumerator();
    }

}

It is used as a graph for an A* algorithm. I want to do 2 things with this data structure:

1. Generate a开发者_如何学Python graph (add nodes and their children)
2. Be able to traverse it and find a node and get its specific index like: Path<Vector2> node; then be able to do node[0].

Well you can loop through it just with a foreach loop:

foreach (Vector2 node in path)
{
    ...
}

Admittedly this looks like it will iterate in a reverse order - if you want to reverse it, you could just use LINQ like this:

foreach (Vector2 node in path.Reverse())

You can do that because you've implemented IEnumerable<T>. To be able to access it by index is rather trickier... you won't be able to do that in a particularly efficient way as far as I can tell.

Again, you can use LINQ to fake it - but that will just iterate over the nodes until it reaches the right element:

Vector2 node = path.ElementAt(2); // Or whatever