studying the code and adding more comments to understand

it better 🤨🤔

@cs/BinaryTree.php → @cs/BinarySearchTree.php

@@ -1,17 +1,25 @@
 <?php
+namespace julius;
+
 /**
  * Created by PhpStorm.
  * User: Julius Alvarado
  * Date: 8/17/2019
  * Time: 1:17 AM
  */
 
-namespace julius;
 
-class BinaryTree
+class BinarySearchTree
 {
     private $root = null;
-
+
+    /**
+     * Primary Public Function
+     *
+     * Makes an indirect recursive call
+     *
+     * @param $key
+     */
     public function insert($key) {
         $node = new class ($key) {
             public $key;
@@ -32,8 +40,20 @@ public function __construct($key) {
             $this->insertNode($this->root, $node);
         }
     } // END OF: insert()
-
-    private function insertNode($node, $newNode) {
+
+    /**
+     * Private Recursive Helper Function
+     *
+     * We don't operate on the result of recursive call so we don't
+     * return the recursive call.
+     *
+     * The recursive call will just do internal work so nothing has
+     * to be returned
+     *
+     * @param $node
+     * @param $newNode
+     */
+    private function insertNode($node, $newNode): void {
         if($newNode->key < $node->key) {
             if($node->left === null) {
                 $node->left = $newNode;
@@ -51,11 +71,20 @@ private function insertNode($node, $newNode) {
             }
         }
     } // END OF: insertNode()
-
+
+    /**
+     * @return mixed root - can be null or a Node
+     */
     public function getRoot() {
         return $this->root;
     }
-
+
+    /**
+     * Primary Public function
+     *
+     * @param $key
+     * @return bool
+     */
     public function search($key) {
         return $this->searchNode($this->root, $key);
     }
@@ -74,19 +103,40 @@ private function searchNode($node, $key) {
             return true;
         }
     }
-
+
+    /**
+     * Primary Public Function
+     *
+     * @param \Closure $callback
+     */
     public function inOrderTraverse(\Closure $callback) {
         $this->inOrderTraverseNode($this->root, $callback);
     }
-
+
+    /**
+     * Private Recursive Helper Function
+     *
+     * @param $node
+     * @param $callback
+     */
     private function inOrderTraverseNode($node, $callback) {
+        $key = $node->key ?? 'null';
+        echo "\ncurrent key: $key";
+
         if($node !== null) {
             $this->inOrderTraverseNode($node->left, $callback);
-            $callback($node->key);
+            $recurse1 = "point1";
+            $callback($key);
             $this->inOrderTraverseNode($node->right, $callback);
+            $recurse2 = 'point2';
         }
     }
-
+
+    /**
+     * Primary Public Function
+     *
+     * @param \Closure $callback
+     */
     public function preOrderTraverse(\Closure $callback) {
 
     }

@cs/index.php

@@ -6,27 +6,32 @@
  * Time: 1:46 AM
  */
 
-require('BinaryTree.php');
+require('BinarySearchTree.php');
 
-use julius\BinaryTree;
+use julius\BinarySearchTree;
 
 $set1 = [11, 7, 15, 5, 3, 9, 8, 10, 13, 12, 14, 20, 18, 25, 6];
 
-$binaryTree = new BinaryTree();
+$binaryTree = new BinarySearchTree();
 
 foreach($set1 as $v) {
     $binaryTree->insert($v);
 }
 
-echo "\n----------------------------------------------------------------------\n";
+echo "\n----------------------------------------------------------------------------------\n";
 
-$callback = function($value){
+$treeSorted = [];
+$callback = function($value) use (&$treeSorted) {
+    $treeSorted[] = "n<$value>";
     echo " [$value] ";
 };
 
 $binaryTree->inOrderTraverse($callback);
 
-echo "\n----------------------------------------------------------------------\n";
+echo "\n\n";
+var_export($treeSorted);
+
+echo "\n----------------------------------------------------------------------------------\n";