tree.cs

sealed class Dumper
{
  static public string Dump(Node root) {
      return Dump(root, new List<bool>{});
  }

  // isLastPath - for every node in the current path, is it the last child? 
  static internal string Dump(Node n, List<bool> isLastPath) {
      string bar = "¦";
    string junction = "+";
    string line = "-";
    string turn = "+";
    
    string result = "";
    int depth = (isLastPath.Count);

    // ascii-art nodes
    if (depth > 0) {
      bool nodeIsLastChild = isLastPath.Last();
      
      // leave out leaf node
      IEnumerable<bool> ancestorsAreLast = isLastPath.Take(isLastPath.Count-1);   
    
        // draw lines for parents
      foreach(bool isLast in ancestorsAreLast) {
        if (isLast) {
          result += "  ";
        }
        else {
            result += bar + " ";
        }
      }
      
      // draw lines for child
      if (nodeIsLastChild) {
        result += turn + line;
      }
      else {
        result += junction + line;
      }
    }
    
    // draw text node
    result += n.Text + "\n";
    
    int num = n.Children.Count;
    int j = 0;
    foreach(Node child in n.Children) {
        List<bool> newPath = new List<bool>();
      newPath.AddRange(isLastPath);
      newPath.Add( j == num-1 );
      
      result += Dump(child, newPath);
      j++;
    }
    
    return result;
  }
}