Enumerating Collections that are not inherently IEnumerable?

Question

When you want to recursively enumerate a hierarchical object, selecting some elements based on some criteria, there are numerous examples of techniques like \"flattening\" a

Answer 1

Based on mrydengren's solution:

public static IEnumerable GetRecursively(this IEnumerable collection,
    Func selector,
    Func predicate)
{
    foreach (var item in collection.OfType())
    {
        if(!predicate(item)) continue;

        yield return item;

        IEnumerable children = selector(item).GetRecursively(selector, predicate);
        foreach (var child in children)
        {
            yield return child;
        }
    }
}


var theNodes = treeView1.Nodes.GetRecursively(
    x => x.Nodes,
    n => n.Text.Contains("1")).ToList();

Edit: for BillW