queue.c

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>

#include "queue.h"


Queue* create_queue() {
  Queue* queue = malloc(sizeof(Queue));
  queue->size = 0;
  queue->head = NULL;
  queue->tail = NULL;
  return queue;
}

int front(Queue* queue) {
  assert(!is_empty(queue));
  return queue->head->data;
}

int back(Queue* queue) {
  assert(!is_empty(queue));
  return queue->tail->data;  
}

void enqueue(Queue* queue, int data) {
  QueueNode* node = malloc(sizeof(QueueNode));
  node->data = data;
  node->next = NULL;
  if (is_empty(queue)) {
    queue->head = queue->tail = node;
  } else {
    queue->tail->next = node;
    queue->tail = node;
  }
  queue->size++;
}

int dequeue(Queue* queue) {
  assert(!is_empty(queue));
  int data = front(queue);
  QueueNode* dequeued_node = queue->head;
  queue->head = queue->head->next;
  free(dequeued_node);
  queue->size--;
  return data;
}

void destroy_queue(Queue* queue) {
  QueueNode* current = queue->head;
  while (current) {
    QueueNode* next = current->next;
    free(current);
    current = next;
  }
  free(queue);
}

void print_queue(Queue* queue) {
  QueueNode* current = queue->head;
  while (current) {
    printf("%d ", current->data);
    current = current->next;
  }
  printf("\n");
}

size_t size(Queue* queue) {
  return queue->size;
}

int is_empty(Queue* queue) {
  return queue->size == 0;
}