Improve BST Implementation by adding essential methods & fixing parent ref. issues

src/Containers-BinarySearchTree-Tests/CTBinarySearchTreeTest.class.st

@@ -48,6 +48,14 @@ CTBinarySearchTreeTest >> testAsArray [
 	self assert: result equals: #(20 30 40 50 70)
 ]
 
+{ #category : 'tests' }
+CTBinarySearchTreeTest >> testAtIfAbsent [
+
+	tree addAll: #(50 30 70).
+	self assert: (tree at: 30 ifAbsent: [ #notFound ]) equals: 30.
+	self assert: (tree at: 99 ifAbsent: [ #notFound ]) equals: #notFound
+]
+
 { #category : 'tests' }
 CTBinarySearchTreeTest >> testBSTValidation [
 
@@ -186,12 +194,13 @@ CTBinarySearchTreeTest >> testEmptyTreeOperations [
 ]
 
 { #category : 'tests' }
-CTBinarySearchTreeTest >> testFindMinMax [
+CTBinarySearchTreeTest >> testFirstLast [
 
 	tree addAll: #(50 30 70 20 80).
-
-	self assert: tree findMin equals: 20.
-	self assert: tree findMax equals: 80
+	self assert: tree first equals: 20.
+	self assert: tree last equals: 80.
+	self assert: CTBinarySearchTree new first isNil.
+	self assert: CTBinarySearchTree new last isNil
 ]
 
 { #category : 'tests' }
@@ -362,16 +371,20 @@ CTBinarySearchTreeTest >> testRemoveNonExistentElement [
 { #category : 'tests' }
 CTBinarySearchTreeTest >> testRemoveRoot [
 	"Root with no children"
+
 	tree add: 50.
 	tree remove: 50.
 	self assert: tree isEmpty.
-	
+
 	"Root with two children"
 	tree clear.
-	tree addAll: #(50 30 70 20 40 60 80).
+	tree addAll: #( 50 30 70 20 40 60 80 ).
 	tree remove: 50.
 	self assert: tree size equals: 6.
 	self deny: (tree includes: 50).
+
+	self assert: (tree includes: 60).
+	self assert: tree root contents equals: 60
 ]
 
 { #category : 'tests' }

src/Containers-BinarySearchTree/CTBSTAbstractNode.class.st

@@ -57,12 +57,24 @@ CTBSTAbstractNode >> findMax [
 	^ self subclassResponsibility
 ]
 
+{ #category : 'searching' }
+CTBSTAbstractNode >> findMaxNode [
+
+	^ self subclassResponsibility
+]
+
 { #category : 'searching' }
 CTBSTAbstractNode >> findMin [
 
 	^ self subclassResponsibility
 ]
 
+{ #category : 'searching' }
+CTBSTAbstractNode >> findMinNode [
+
+		^ self subclassResponsibility
+]
+
 { #category : 'accessing' }
 CTBSTAbstractNode >> height [
 

src/Containers-BinarySearchTree/CTBSTNillNode.class.st → src/Containers-BinarySearchTree/CTBSTNilNode.class.st

@@ -6,14 +6,14 @@ I provide default 'do nothing' behavior for all tree operations, eliminating the
 When elements are added to me, I create and return a new CTBSTNode containing the element, effectively growing the tree.
 "
 Class {
-	#name : 'CTBSTNillNode',
+	#name : 'CTBSTNilNode',
 	#superclass : 'CTBSTAbstractNode',
 	#category : 'Containers-BinarySearchTree',
 	#package : 'Containers-BinarySearchTree'
 }
 
 { #category : 'adding' }
-CTBSTNillNode >> addChild: anObject [
+CTBSTNilNode >> addChild: anObject [
 
 	^ CTBSTNode new
 		contents: anObject;
@@ -22,122 +22,134 @@ CTBSTNillNode >> addChild: anObject [
 ]
 
 { #category : 'accessing' }
-CTBSTNillNode >> contents [
+CTBSTNilNode >> contents [
 
 	^ nil
 ]
 
 { #category : 'accessing' }
-CTBSTNillNode >> contents: anObject [
+CTBSTNilNode >> contents: anObject [
 
 	"Do nothing for nil node"
 ]
 
 { #category : 'enumerating' }
-CTBSTNillNode >> elementsFrom: min to: max into: aCollection [
+CTBSTNilNode >> elementsFrom: min to: max into: aCollection [
 
 	"Do nothing for nill node"
 ]
 
 { #category : 'enumerating' }
-CTBSTNillNode >> elementsGreaterThan: anObject into: aCollection [
+CTBSTNilNode >> elementsGreaterThan: anObject into: aCollection [
 
 	"Do nothing for nill node"
 ]
 
 { #category : 'enumerating' }
-CTBSTNillNode >> elementsLessThan: anObject into: aCollection [
+CTBSTNilNode >> elementsLessThan: anObject into: aCollection [
 
 	"Do nothing for nill node"
 ]
 
 { #category : 'searching' }
-CTBSTNillNode >> findMax [
+CTBSTNilNode >> findMax [
 
 	^ nil
 ]
 
 { #category : 'searching' }
-CTBSTNillNode >> findMin [
+CTBSTNilNode >> findMaxNode [
+
+	^ self
+]
+
+{ #category : 'searching' }
+CTBSTNilNode >> findMin [
 
 	^ nil
 ]
 
+{ #category : 'searching' }
+CTBSTNilNode >> findMinNode [
+
+	^ self
+]
+
 { #category : 'accessing' }
-CTBSTNillNode >> height [
+CTBSTNilNode >> height [
 
 	^ 0
 ]
 
 { #category : 'enumerating' }
-CTBSTNillNode >> inOrderDo: aBlock [
+CTBSTNilNode >> inOrderDo: aBlock [
 
 	"Do nothing for nil node"
 ]
 
 { #category : 'testing' }
-CTBSTNillNode >> isEmpty [
+CTBSTNilNode >> isEmpty [
 
 	^ true
 ]
 
 { #category : 'testing' }
-CTBSTNillNode >> isLeaf [
+CTBSTNilNode >> isLeaf [
 
 	^ false
 ]
 
 { #category : 'enumerating' }
-CTBSTNillNode >> postOrderDo: aBlock [
+CTBSTNilNode >> postOrderDo: aBlock [
 
 	"Do nothing for nill node"
 ]
 
 { #category : 'enumerating' }
-CTBSTNillNode >> preOrderDo: aBlock [
+CTBSTNilNode >> preOrderDo: aBlock [
 
 	"Do nothing for nill node"
 ]
 
 { #category : 'searching' }
-CTBSTNillNode >> predecessorOf: anObject [
+CTBSTNilNode >> predecessorOf: anObject [
 
 	^ nil
 ]
 
 { #category : 'removing' }
-CTBSTNillNode >> removeValue: anObject [
+CTBSTNilNode >> removeValue: anObject [
 
 	"Element not found - return self unchanged"
 	^ self
 ]
 
 { #category : 'accessing' }
-CTBSTNillNode >> search: anObject [
+CTBSTNilNode >> search: anObject [
 
 	^ nil
 ]
 
 { #category : 'accessing' }
-CTBSTNillNode >> size [
+CTBSTNilNode >> size [
 
 	^ 0
 ]
 
 { #category : 'searching' }
-CTBSTNillNode >> successorOf: anObject [
+CTBSTNilNode >> successorOf: anObject [
 
 	^ nil
 ]
 
 { #category : 'testing' }
-CTBSTNillNode >> validateBSTProperty [
+CTBSTNilNode >> validateBSTProperty [
 
 	^ true
 ]
 
 { #category : 'private' }
-CTBSTNillNode >> validateBSTPropertyWithMin: min max: max [
+CTBSTNilNode >> validateBSTPropertyWithMin: min max: max [
 
 	^ true
 ]