/// <summary>
/// Initializes a new instance of the <see cref="ContextStack{T}" />
/// base on another stack. This is for copy/clone.
/// </summary>
/// <param name="stack">The stack.</param>
public ContextStack(ContextStack <T> stack)
{
_position = stack._position;
_array = new T[stack._array.Length];
stack._array.CopyTo(_array, 0);
}
public Enumerator(ContextStack <T> stack)
{
_stack = stack;
_index = stack._position + 1;
}