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/* Standard C */
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
/* Project */
#include "util.h"
typedef int T;
struct queue_item {
struct queue_item *next;
T data;
};
struct queue {
struct queue_item *head, *tail;
};
void
queue_init(struct queue *queue)
{
queue->head = NULL;
}
void
queue_put(struct queue *queue, T data)
{
struct queue_item *new_item;
if ( (new_item = malloc(sizeof(*new_item))) != NULL ) {
struct queue_item *tmp = queue->tail;
new_item->data = data;
new_item->next = NULL;
queue->tail = new_item;
if ( queue->head == NULL )
queue->head = queue->tail;
else
tmp->next = queue->tail;
}
else
ERROR("out of memory");
}
bool
queue_get(struct queue *queue, T *data)
{
if ( queue->head != NULL ) {
struct queue_item *next = queue->head->next;
if ( data != NULL ) {
*data = queue->head->data;
}
free(queue->head);
queue->head = next;
return true;
}
else
return false;
}
bool
queue_empty(struct queue *queue)
{
return queue->head == NULL;
}
void
queue_free(struct queue *queue)
{
struct queue_item *item, *next;
for ( item = queue->head; item; item = next ) {
next = item->next;
free(item);
}
}
int
main()
{
struct queue queue[1];
queue_init(queue);
for ( int i = 0; i != 10; ++i )
queue_put(queue, i);
while ( !queue_empty(queue) ) {
int i;
if ( queue_get(queue, &i) )
printf("%d\n", i);
else
ERROR("this shouldn't happen!");
}
queue_free(queue);
return EXIT_SUCCESS;
}
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