queue.c

#include "queue.h"
#include <stdlib.h>

Queue *CreateQueue()
{
    Queue *q = malloc(sizeof(Queue));

    if (q == NULL)
        return NULL;

    q->head = q->tail = NULL;

    return q;
}

void DestroyQueue(Queue *q)
{
    if (q == NULL)
        return;

    while (Dequeue(q) != NULL)
        ;

    free(q);
}

int IsQueueEmpty(Queue *q)
{
    return (q->tail == NULL && q->head == NULL);
}

void Enqueue(Queue *q, void *data)
{
    Node *node = malloc(sizeof(Node));

    node->data = data;
    node->next = NULL;

    if (q->tail == NULL)
    {
        q->head = q->tail = node;
        return;
    }

    q->tail->next = node;
    q->tail = node;
}

void *Dequeue(Queue *q)
{
    Node *previousHead;
    void *data;

    previousHead = q->head;

    if (previousHead == NULL)
        return NULL;

    q->head = q->head->next;

    if (q->head == NULL)
        q->tail = NULL;

    data = previousHead->data;
    free(previousHead);
    return data;
}
void *Top(Queue *q)
{
    void *data = q->head->data;
    return data;
}