private void getElements(IBSTNode currNode, BSTStack stack)
{
// add nodes into stack to use at getEnumerator()
// null nodes not allowed
if (currNode == null)
{
return;
}
if (currNode.isLeaf())
{
// add element to stack
stack.Push(currNode);
}
else
{
// unbox
BSTInternalNode node = (BSTInternalNode)currNode;
// get left node
this.getElements(node.Left, stack);
// add current element to stack
stack.Push(node);
// get right nodes
this.getElements(node.Right, stack);
}
}
/// <summary>
/// Provides implementation so that the items of the list can be accessed by
/// foreach loop iterations.
/// </summary>
/// <returns>A KeyValuePair<int, string> object.</returns>
public IEnumerator <KeyValuePair <int, string> > GetEnumerator()
{
// create a new stack of nodes
BSTStack stack = new BSTStack();
// populate stack, start from root
this.getElements(this._root, stack);
// return values from top element then pop it out
while (!stack.isEmpty())
{
yield return(new KeyValuePair <int, string>(stack.Top.Key, stack.Top.Value));
stack.Pop();
}
}