PHP Data Structure: Linked List

data-structure-linked-list.php

class LinkedList {
    public $head;

    public function add($data) {
        $new_node = new Node($data);

        if ( is_null( $this->head ) ) {
            $this->head = $new_node;
        } else
        {
            $node = $this->head;

            while (!is_null($node->next))
            {
                $node = $node->next;
            }

            $node->next = $new_node;
        }

        return $new_node;
    }

    public function delete($data) {
        if ( $this->head->data == $data ) {
            $this->head = $this->head->next;
        } else {
            $node = $this->head;

            while( !is_null($node->next) ) {
                if ( $node->next->data == $data ) {
                    $node->next = $node->next->next;
                    break;
                }

                $node = $node->next;
            }
        }
    }
}

class Node {
    public $data;
    public $next;

    public function __construct($data) {
        $this->data = $data;
    }
}