/// <summary>
/// Removes empty Groupings and replaces single element groupings
/// with their child elements.
/// </summary>
/// <returns>This, or if there is only 1 other element, that element
/// with its link to this removed and made to this's parent</returns>
public Rule Simplify(Grouping group)
{
Rule rule;
Rule simplified = null;
// simplify child groups.
for (int i = group.Count - 1; i >= 0; i--)
{
rule = group[i];
if (rule is Grouping)
{
Simplify((Grouping)rule);
}
}
if (group.Count == 1 && group.Quantifier == group[0].Quantifier)
{
simplified = group.RemoveAt(0);
}
else if (group.Count == 0)
{
simplified = new Empty();
}
if (simplified != null)
{
simplified.ProductionName = group.ProductionName;
simplified.IsException = group.IsException;
if (group.Parent != null)
{
group.Parent.Replace(group, simplified);
}
else
{
simplified.Parent = null;
}
return(simplified);
}
return(group);
}
