I have a problem with creating base class for DoubleLinkedList.
Right now it's giving me this error
/tmp/cc3lORia.o:(.rodata._ZTV24AbstractDoubleLinkedListIiE[_ZTV24AbstractDoubleLinkedListIiE]+0x10): undefined reference to `AbstractDoubleLinkedList::createNewNode(int)' collect2: error: ld returned 1 exit status
I've tried this and that as you can see by commented lines in code, but none of it works.
So how to define abstract template class with abstract method (factory method by the way) and then redefine it in children classes?
/*
* AbstractDoubleLinkedList.hpp
*
* Created on: Mar 2, 2015
* Author: michael
*/
#ifndef ABSTRACTDOUBLELINKEDLIST_H_
#define ABSTRACTDOUBLELINKEDLIST_H_
#include <vector>
using namespace std;
template <class T> class ListNode {
private:
void init();
public:
ListNode();
ListNode(T value);
ListNode *previous;
ListNode *next;
T value;
};
template <class T> void ListNode<T>::init() {
previous = nullptr;
next = nullptr;
}
template <class T> ListNode<T>::ListNode() {
init();
}
template <class T> ListNode<T>::ListNode(T value) {
init();
this->value = value;
}
template <class T> class AbstractDoubleLinkedList {
private:
void pullOutNode(ListNode<T> *node);
protected:
virtual ListNode<T>* createNewNode(T element);
public:
AbstractDoubleLinkedList();
void push_back(T element);
T front();
T back();
void insertBefore(ListNode<T> *node, ListNode<T> *beforeNode);
void insertAfter(ListNode<T> *node, ListNode<T> *afterNode);
void moveNodeAfter(ListNode<T> *node, ListNode<T> *afterNode);
vector<T> toVector();
ListNode<T> *frontNode;
ListNode<T> *backNode;
};
template <class T> void AbstractDoubleLinkedList<T>::push_back(T element) {
ListNode<T>* node = createNewNode(element);
node->previous = backNode;
if (backNode != nullptr) {
backNode->next = node;
node->previous = backNode;
}
else {
frontNode = node;
}
backNode = node;
}
template <class T> void AbstractDoubleLinkedList<T>::pullOutNode(ListNode<T> *node) {
if (node != frontNode) {
node->previous->next = node->next;
}
else {
frontNode = node->next;
}
if (node != backNode) {
node->next->previous = node->previous;
}
else {
backNode = node->previous;
}
}
template <class T> T AbstractDoubleLinkedList<T>::front() {
return frontNode->value;
}
template <class T> T AbstractDoubleLinkedList<T>::back() {
return backNode->value;
}
template <class T> void AbstractDoubleLinkedList<T>::insertAfter(ListNode<T> *node, ListNode<T> *afterNode) {
node->previous = afterNode;
node->next = afterNode->next;
afterNode->next = node;
if (afterNode == backNode) {
backNode = node;
}
}
template <class T> void AbstractDoubleLinkedList<T>::insertBefore(ListNode<T> *node, ListNode<T> *beforeNode) {
node->next = beforeNode;
beforeNode->previous->next = node;
beforeNode->previous = node;
if (beforeNode == frontNode) {
frontNode = node;
}
}
template <class T> void AbstractDoubleLinkedList<T>::moveNodeAfter(ListNode<T> *node, ListNode<T> *afterNode) {
pullOutNode(node);
node->previous = afterNode;
node->next = afterNode->next;
if (node->next == nullptr) {
backNode = node;
}
afterNode->next = node;
}
template <class T> vector<T> AbstractDoubleLinkedList<T>::toVector() {
ListNode<T>* node = frontNode;
vector<int> listAsVector;
bool shouldHaveAnother = (frontNode != nullptr);
while(shouldHaveAnother) {
listAsVector.push_back(node->value);
if (node->next != nullptr)
node = node->next;
else {
shouldHaveAnother = false;
}
}
return listAsVector;
}
template <class T> AbstractDoubleLinkedList<T>::AbstractDoubleLinkedList() {
frontNode = nullptr;
backNode = nullptr;
}
#endif /* ABSTRACTDOUBLELINKEDLIST_HPP_ */
/*
* DoubleLinkedList.hpp
*
* Created on: Feb 26, 2015
* Author: michael
*/
#ifndef DOUBLELINKEDLIST_HPP_
#define DOUBLELINKEDLIST_HPP_
#include "AbstractDoubleLinkedList.hpp"
template <class T> class DoubleLinkedList : public AbstractDoubleLinkedList<T> {
protected:
ListNode<T>* createNewNode(T element) {
return new ListNode<T>(element);
}
public:
~DoubleLinkedList() {
ListNode<T>* node = this->backNode;
bool shouldHaveAnother = (node != nullptr);
while(shouldHaveAnother) {
ListNode<T>* ptr = node->previous;
delete node;
if (ptr != nullptr)
node = ptr;
else {
shouldHaveAnother = false;
}
}
};
};
//template <class T> ListNode<T> DoubleLinkedList<T>::createNewNode(T element) {
// return new ListNode<T>(element);
//}
//template <class T> DoubleLinkedList<T>::~DoubleLinkedList() {
//
// ListNode<T>* node = this->backNode;
// bool shouldHaveAnother = (node != nullptr);
// while(shouldHaveAnother) {
// ListNode<T>* ptr = node->previous;
// delete node;
// if (ptr != nullptr)
// node = ptr;
// else {
// shouldHaveAnother = false;
// }
// }
//}
#endif /* DOUBLELINKEDLIST_HPP_ */
EDIT1: So, there is a question "Why do I need my own container class and why not use list or vector?"
I need a data structure with constant time random access and constant time deletion and insertion. BUT I've already tried std::unordered_set and It's not good enough (while technically it meets the requirements) because of allocations and deallocations of memory (when deleting and inserting)
So I figured another way. I want to use a linked list with one "guard" element and the end. When I need to "delete" element from it I would move it after guard. And to check if list is "empty" I would check if the first element is the guard element. But I need a constant-time random access. This can be achieved by map of pointers to every element.
But to achieve maximum performance I need to also minimize cache misses. And I thinks that std::list would be scattered across the memory, because it is the normal behaviour for it. So I figured that the only way to do so - is to allocate vector> and then use this preallocated nodes to new elements.
So am I wrong somewhere? Can I achieve maximum performance more easier?
