Queue with Template

Description

Please modify class Queue’s declaration and definition so as to finish the test from main.cpp…

Attention: please use template you have learned in the class to finish this assignment

Here is my answer:

//queue.h:
template<typename T>
class Queue {
  public:
    Queue() {
        front_node = NULL;
        back_node = NULL;
        node_num = 0;
    }

    Queue(const Queue & another) {
        Node* temp = another.front_node;
        node_num = 0;
        front_node = back_node = NULL;
        for (int i = 0; i < another.node_num; ++i) {
            push(temp->element);
            temp = temp->next;
        }
    }

    ~Queue() {
        while (node_num) {
            pop();
        }
    }

    bool empty() {return node_num == 0;}

    int size() {return node_num;}

    T front() const {
        if (front_node)
            return front_node->element;
    }

    T back() const {
        if (back_node)
            return back_node->element;
    }

    void push(T element) {
        if (front_node == NULL) {
            front_node = new Node(element);
            back_node = front_node;
            node_num++;
        } else {
            Node* current = new Node(element);
            back_node->next = current;
            back_node = current;
            node_num++;
        }
    }

    void pop() {
        if (front_node) {
            Node* temp = front_node;
            front_node = front_node->next;
            delete temp;
            node_num--;
            if (node_num == 0)
                back_node = NULL;
        }
    }

    void swap(Queue & queue) {
        Node* temp = this->front_node;
        this->front_node = queue.front_node;
        queue.front_node = temp;
        temp = this->back_node;
        this->back_node = queue.back_node;
        queue.back_node = temp;
        int size = this->node_num;
        this->node_num = queue.node_num;
        queue.node_num = size;
    }

  private:
    struct Node {
      T element;
      Node* next;
      Node(T ele, Node* n = NULL) {
        element = ele;
        next = n;
      }
    };
    Node* front_node;
    Node* back_node;
    int node_num;
};

//test.cpp:
#include <iostream>
#include "Queue.h"
#include <string>
#include <sstream>

using namespace std;

class Job {
    public:
        explicit Job(int pri = 0) {
            id = number++;
            priority = pri;
        }
        string toString() {
            stringstream ss;
            ss << "[" << id << ":" << priority << "]";
            return ss.str();
        }
    private:
        static int number;
        int id;
        int priority;
};

int Job::number = 0;

template<class T>
void print(Queue<T> queue) {
    while (!queue.empty()) {
        cout << queue.front() << " ";
        queue.pop();
    }
    cout << endl;
}

int main() {
    // test case 1: integer..
    Queue<int> que;
    int m, n;
    cin >> m >> n;
    for (int i = 0; i < m; i++) que.push(i + 0.01);
    for (int i = 0; i < n; i++) que.pop();
    if (!que.empty()) {
        cout << que.front() << endl;
        cout << que.back() << endl;
    }
    cout << "The size is: " << que.size() << endl;
    if (que.empty()) cout << "The queue is empty!" << endl;
    else cout << "The queue is NOT empty!" << endl;

    // test case 2: double..
    Queue<double> que1;
    cin >> m >> n;
    for (int i = 0; i < m; i++) que1.push(i + 0.01);
    for (int i = 0; i < n; i++) que1.pop();
    if (!que1.empty()) {
        cout << que1.front() << endl;
        cout << que1.back() << endl;
    }
    cout << "The size is: " << que1.size() << endl;
    if (que1.empty()) cout << "The queue is empty!" << endl;
    else cout << "The queue is NOT empty!" << endl;

    // test case 3: user defined class..
    Queue<Job> que2;
    cin >> m >> n;
    for (int i = 0; i < m; i++) que2.push(Job(i));
    for (int i = 0; i < n; i++) que2.pop();

    if (!que2.empty()) {
        cout << que2.front().toString() << endl;
        cout << que2.back().toString() << endl;
    }
    cout << "The size is: " << que2.size() << endl;
    if (que2.empty()) cout << "The queue is empty!" << endl;
    else cout << "The queue is NOT empty!" << endl;

    // test case 4: swap function..
    Queue<int> que3, que4;
    for (int i = 0; i < m; i++) que3.push(i);
    for (int i = 0; i < n; i++) que4.push(m - i);
    cout << "Before Swap...." << endl;
    print(que3);
    print(que4);

    que3.swap(que4);
    cout << "After Swap...." << endl;
    cout << endl;
    print(que3);
    print(que4);
}