///<summary>
/// Returns the Evaluation at the relative index given. This should be
/// zero or a negative number as a relative reference back up the evaluation
/// stack. Therefore getEvaluation(0) returns the current Evaluation.
///</summary>
public Evaluation getEvaluation(int relativeIndex)
{
Evaluation result = null;
if (relativeIndex <= 0)
{
result = currentEvaluation;
while ((++relativeIndex < 0) && (result != null))
{
result = result.getParent();
}
}
return(result);
}
