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DLList.h
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DLList.h
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#pragma once
#include <iostream>
#include <string>
using namespace std;
template<class T>
class DLList {
public:
struct Node {
Node* prev;
Node* next;
T value;
Node(T v) : prev(nullptr), next(nullptr), value(v) {}
};
DLList() : head(nullptr), tail(nullptr), count(0){}
~DLList() {
clear();
}
const Node* get_head() const {
// implement get_head here
return head;
}
void push_front(T item) {
// implement push_front here
Node* nodeNew = new Node(item);
if (head == nullptr){
head = nodeNew;
tail = nodeNew;
}
else{
nodeNew->next = head;
head->prev = nodeNew;
head = nodeNew;
}
count ++;
}
void push_back(T item) {
// implement push_back here
Node* nodeNew = new Node(item); //new variable
if (head == nullptr){
head = nodeNew;
tail = nodeNew;
}
else {
tail->next = nodeNew;
tail = nodeNew;
}
count++;
}
void insert(T item, int position) {
// implement insert here
//if position invalid
if (position < 0 || position > count){
throw std::out_of_range("Position out of range");
}
Node* nodeNew = new Node(item);
if (position == 0){
if (head == nullptr){
head = nodeNew;
tail = nodeNew;
} else{
nodeNew->next = head;
head->prev = nodeNew;
head = nodeNew;
}
}
else if (position == count){
nodeNew->prev = tail;
tail->next = nodeNew;
tail = nodeNew;
}
else{
Node* current = head;
for (int i = 0; i < position; i++){
if (current == nullptr){
throw std::out_of_range("invalid position");
}
current = current->next;
}
nodeNew->prev = current->prev;
nodeNew->next = current;
current->prev->next = nodeNew;
current->prev = nodeNew;
}
count ++;
}
void pop_front() {
// implement pop_front here
if (head == nullptr){
throw std::length_error("List empty");
}
else if (head == tail){
delete head;
head = nullptr;
tail = nullptr;
}
else{
Node* newHead = head->next;
if (newHead != nullptr){
newHead->prev = nullptr;
delete head;
head = newHead;
}
}
count --;
}
void pop_back() {
// implement pop_back here
if (tail == nullptr){
throw std::length_error("Length of 0");
}
if (head == tail){
delete head;
head = nullptr;
tail = nullptr;
count --;
return;
}
int position = size()-1;
Node* itr = head;
for (int i = 0; i < (position - 1); i++){
itr = itr->next;
}
Node* tmp = tail;
itr->next = nullptr;
delete tmp;
tail = itr;
count --;
}
void remove(int position) {
// implement remove here
if (position >= size()){
throw std::out_of_range("Length exception error");
}
if (position == 0){
Node* tmp = head;
head = head->next;
delete tmp;
}
//if position = size (last)
else if (position == size()-1){
Node* tmp = tail;
tail = tail->prev;
delete tmp;
if (tail != nullptr){
tail->next = nullptr;
}
}
//remove something in the middle
else{
Node* itr = head;
for (int i = 0; i < (position - 1); i++){
itr = itr->next;
}
Node* tmp = itr->next;
itr->next = itr->next->next;
if (itr->next != nullptr){
itr->next->prev = itr;
}
delete tmp;
}
count --;
}
const T& front() const {
// implement front here
if (head == nullptr){
throw std::length_error("List empty");
}
return head->value;
}
const T& back() const {
// implement back here
if (tail == nullptr){
throw std::length_error("List empty");
}
return tail->value;
}
const T& at(int index) const {
// implement at here
if (index < 0 || index >= count){
throw std::out_of_range("Index out of range");
}
Node* current = head;
for (int i = 0; i < index; i++){
current = current->next;
}
return current->value;
}
bool contains(const T& item) const {
// implement contains here
Node* current = head; //starts at first value
while (current != nullptr){
if (current->value == item){
return true;
}
current = current->next;
}
return false;
}
int size() const {
// implement size here
return count;
}
void clear() {
// implement clear here
remove(0);
}
private:
Node* head;
Node* tail;
int count;
};