/// <summary>Returns the stackitems in order from top to bottom.</summary>
public IEnumerator <T> GetEnumerator()
{
for (ImmutableStackCollection <T> p = this; p != null; p = p.Remainder)
{
yield return(p.TopItem);
}
}
/// <summary>Construct a new instance by Push-ing <paramref name="item"/> onto <paramref name="remainder"/>.</summary>
private ImmutableStackCollection(T item, ImmutableStackCollection <T> remainder)
{
TopItem = item;
Remainder = remainder;
}
/// <summary>TODO</summary>
protected ImmutableStackCollection(T topItem, ImmutableStackCollection <T> remainder)
{
TopItem = topItem;
Remainder = remainder;
}