doubleLinkedList.cpp

struct DoubleLinkedListNode: Node {
  DoubleLinkedListNode() {
    next = NULL;
    prev = NULL;
  }

  DoubleLinkedListNode(int value, DoubleLinkedListNode *nextNode, DoubleLinkedListNode *prevNode);

  DoubleLinkedListNode *next;
  DoubleLinkedListNode *prev;
};

DoubleLinkedListNode::DoubleLinkedListNode(int value, DoubleLinkedListNode *nextNode, DoubleLinkedListNode *prevNode) {
  next = nextNode;
  prev = prevNode;
  data = value;
}

class DoubleLinkedList {
 public:
  DoubleLinkedListNode *head = NULL;

  DoubleLinkedList() { }

  void insertFront(int value);

  void deleteFront();

  bool isEmpty();
};

bool DoubleLinkedList::isEmpty() {
  return (head == NULL);
}

void DoubleLinkedList::insertFront(int value) {
  DoubleLinkedListNode *node = new DoubleLinkedListNode(value, head, NULL);
  head = node;
  if (head->next != NULL) { head->next->prev = head; }
}

void DoubleLinkedList::deleteFront() {
  DoubleLinkedListNode *tmp = head->next;
  if (tmp != NULL) { tmp->prev = NULL; }
  delete head;
  head = tmp;
}