Implement TreeMap and TreeMapNode with comprehensive test coverage

- Create TreeMap implementation using a self-balancing binary search tree (Red-Black Tree)
- Create TreeMapNode to support TreeMap structure with methods for managing node properties
- Implement put, get, remove, and balancing methods in TreeMap
- Add comprehensive unit tests for TreeMapNode ensuring 100% coverage
- Add extensive test cases for TreeMap including insertion, deletion, balancing, and edge cases
- Ensure proper behavior of TreeMap operations through detailed test scenarios
- Verify usage of TreeMapNode methods within TreeMap implementation

Author: walmir-silva

src/TreeMapNode.php

@@ -4,6 +4,19 @@
 
 namespace KaririCode\DataStructure;
 
+/**
+ * TreeMapNode class.
+ *
+ * This class represents a node in a Red-Black Tree used by TreeMap.
+ * Each node contains a key, a value, a color (red or black), and references to its left, right, and parent nodes.
+ *
+ * @category  Data Structures
+ *
+ * @author    Walmir Silva <walmir.silva@kariricode.org>
+ * @license   MIT
+ *
+ * @see       https://kariricode.org/
+ */
 class TreeMapNode
 {
     public const RED = true;

tests/Map/TreeMapTest.php

@@ -147,7 +147,7 @@ public function testComplexOperations(): void
             [1, 'one'],
             [3, 'three'],
             [6, 'six'],
-            [8, 'eight']
+            [8, 'eight'],
         ];
 
         foreach ($operations as [$key, $value]) {
@@ -297,6 +297,7 @@ private function getRootNode(): ?TreeMapNode
         $reflection = new \ReflectionClass($this->treeMap);
         $rootProperty = $reflection->getProperty('root');
         $rootProperty->setAccessible(true);
+
         return $rootProperty->getValue($this->treeMap);
     }
 
@@ -314,9 +315,10 @@ private function countNodes(): int
     // Recursive method to count nodes in the tree.
     private function countNodesRecursive(?TreeMapNode $node): int
     {
-        if ($node === null) {
+        if (null === $node) {
             return 0;
         }
+
         return 1 + $this->countNodesRecursive($node->left) + $this->countNodesRecursive($node->right);
     }
 
@@ -334,13 +336,13 @@ private function getTreeStructure(): string
     // Recursive method to print the tree structure.
     private function printTree(?TreeMapNode $node, string $prefix = '', bool $isLeft = true): string
     {
-        if ($node === null) {
+        if (null === $node) {
             return '';
         }
 
         $result = $prefix;
 
-        if ($prefix === '') {
+        if ('' === $prefix) {
             $result .= '├── ';
         } else {
             $result .= $isLeft ? '├── ' : '└── ';