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/*
* Copyright (C) 2009 Neverball authors
*
* NEVERBALL is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published
* by the Free Software Foundation; either version 2 of the License,
* or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*/
#include <stdlib.h>
#include <assert.h>
#include "queue.h"
#include "list.h"
struct queue
{
List head;
List tail;
};
Queue queue_new(void)
{
Queue new;
if ((new = malloc(sizeof (*new))))
new->head = new->tail = list_cons(NULL, NULL);
return new;
}
void queue_free(Queue q)
{
assert(queue_empty(q));
free(q->head);
free(q);
}
int queue_empty(Queue q)
{
assert(q);
return q->head == q->tail;
}
void queue_enq(Queue q, void *data)
{
assert(q);
q->tail->data = data;
q->tail->next = list_cons(NULL, NULL);
q->tail = q->tail->next;
}
void *queue_deq(Queue q)
{
void *data = NULL;
if (!queue_empty(q))
{
data = q->head->data;
q->head = list_rest(q->head);
}
return data;
}
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