SiroDiaz / DataStructures

     * @param integer $index the position.

     * @param mixed $data the data to be stored.

     */

    protected function insertEnd($data) {

        $newNode = new SinglyLinkedListNode($data);

        $this->tail->next = &$newNode;

        $newNode->next = &$this->head;

        $this->tail = &$newNode;

    }

    /**

     * Add a new node in the specified index.

    /**

     * {@inheritDoc}

     */

    protected function insertBeginning($data) {

        $newNode = new SinglyLinkedListNode($data);

        if($this->head === null) {

            $this->head = &$newNode;

        } else {

            $newNode->next = $this->head;

            $this->head = &$newNode;

        }

    }

    /**

     * Delete a node in the given position and returns it back.