Inserting a node
When we insert a node, we color it red. This means that the newly inserted node will never change the black height of any ancestor!
However, it could violate another invariant, namely a red node can never have a red parent. Once we fix this invariant violation, we are done! Here's the code to do this:
sealed trait Color case object Red extends Color case object Black extends Color
We know the advantages of sealing a trait. The Color
trait can now be used only in this source file. This helps the compiler check for exhaustive matching. As seen earlier, the List
and BinTree
traits were also sealed.
The case object idiom creates singleton objects, just like List.Nil
and Bintree.Leaf
.
Next, we define our Tree
class:
sealed abstract class ...
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