protected type N: TreeNode[K, E]
# The `root` node of the tree (null if tree is empty)
- protected var root: nullable N protected writable = null
+ protected var root: nullable N = null is protected writable
# Display the tree in a gaphical windows
# Graphviz with a working -Txlib is expected
class TreeNode[K: Comparable, E]
# TreeNode type
- type SELF: TreeNode[K, E]
+ type N: TreeNode[K, E]
# `key` for this node
var key: K
var value: E
# Direct parent of this node (null if the node is root)
- var parent: nullable SELF writable = null
+ var parent: nullable N = null is writable
- redef fun to_s do return "\{{value}\}"
+ redef fun to_s do return "\{{value or else ""}\}"
# Return dot representation of this node
# Used for debugging by `AbstractTree::show_dot`