Data Structures and Algorithms in Java[1].pdf - Fulvio Frisone

Class BinarySearchTree uses location-aware entries (see Section 8.4.2). Thus,
its update methods inform any moved BSTEntry objects of their new positions.
We also use several simple auxiliary methods for accessing and testing data, such as
checkKey, which checks if a key is valid (albeit using a fairly simple rule in this
case). We also use an instance variable, actionPos, which stores the position
where the most recent search, insertion, or removal ended. This instance variable is
not necessary to the implementation of a binary search tree, but is useful to classes
that will extend BinarySearchTree (see Code Fragments 10.7, 10.8, 10.10, and
10.11) to identify the position where the previous search, insertion, or removal has
taken place. Position action Pos has the intended meaning provided it is used
right after executing the method find, insert, or remove.
Code Fragment 10.3: Class BinarySearchTree.
(Continues in Code Fragment 10.4.)
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