internal static RedBlackNode BalanceLeftDelete(object key, object val, RedBlackNode del, RedBlackNode right)
{
if (del is RedNode)
{
return(MakeRed(key, val, del.Blacken(), right));
}
else if (right is BlackNode)
{
return(RightBalance(key, val, del, right.Redden()));
}
else if (right is RedNode && right.Left is BlackNode)
{
return(MakeRed(right.Left.Key, right.Left.Value,
MakeBlack(key, val, del, right.Left.Left),
RightBalance(right.Key, right.Value, right.Left.Right, right.Right.Redden())));
}
throw new InvalidOperationException("Invariant violation");
}
internal static RedBlackNode BalanceRightDelete(object key, object val, RedBlackNode left, RedBlackNode del)
{
if (del is RedNode)
{
return(MakeRed(key, val, left, del.Blacken()));
}
else if (left is BlackNode)
{
return(LeftBalance(key, val, left.Redden(), del));
}
else if (left is RedNode && left.Right is BlackNode)
{
return(MakeRed(left.Right.Key, left.Right.Value,
LeftBalance(left.Key, left.Value, left.Left.Redden(), left.Right.Left),
MakeBlack(key, val, left.Right.Right, del)));
}
else
{
throw new InvalidOperationException("Invariant violation");
}
}