TheAlgorithms-C-Plus-Plus/data_structures/queue/queue.cpp

#include "queue.h"
#include <assert.h>
#include <iostream>

using namespace std;

/* Default constructor*/
template <class Kind>
queue<Kind>::queue() {
    queueFront = NULL;
    queueRear = NULL;
    size = 0;
}

/* Destructor */
template <class Kind>
queue<Kind>::~queue() {}

/* Display for testing */
template <class Kind>
void queue<Kind>::display() {
    node<Kind> *current = queueFront;
    cout << "Front --> ";
    while (current != NULL) {
        cout << current->data << "    ";
        current = current->next;
    }
    cout << endl;
    cout << "Size of queue: " << size << endl;
}

/* Determine whether the queue is empty */
template <class Kind>
bool queue<Kind>::isEmptyQueue() {
    return (queueFront == NULL);
}

/* Clear queue */
template <class Kind>
void queue<Kind>::clear() {
    queueFront = NULL;
}

/* Add new item to the queue */
template <class Kind>
void queue<Kind>::enQueue(Kind item) {
    node<Kind> *newNode;
    newNode = new node<Kind>;
    newNode->data = item;
    newNode->next = NULL;
    if (queueFront == NULL) {
        queueFront = newNode;
        queueRear = newNode;
    } else {
        queueRear->next = newNode;
        queueRear = queueRear->next;
    }
    size++;
}

/* Return the top element of the queue */
template <class Kind>
Kind queue<Kind>::front() {
    assert(queueFront != NULL);
    return queueFront->data;
}

/* Remove the element of the queue */
template <class Kind>
void queue<Kind>::deQueue() {
    node<Kind> *temp;
    if (!isEmptyQueue()) {
        temp = queueFront;
        queueFront = queueFront->next;
        delete temp;
        size--;
    } else {
        cout << "Queue is empty !" << endl;
    }
}