/* vim: set ts=4 sw=4 ai:
 * tq.c -- tail queue implementation derived from NetBSD's queue.h
 */

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

struct tqh *tq_new(void)
{
	struct tqh *hd;

	hd = malloc(sizeof(*hd));
	if (hd != NULL)
		tq_init(hd);

	return hd;
}

struct tqe *tq_elem_new(void *data)
{
	struct tqe *e;

	e = malloc(sizeof(*e));
	if (e != NULL)
		e->data = data;

	return e;
}

void tq_insert_head(struct tqh *hd, struct tqe *e)
{
	if ((e->next = hd->first) != NULL)
		hd->first->pprev = &e->next;
	else
		hd->last = &e->next;
	hd->first = e;
	e->pprev = &hd->first;
}

void tq_insert_tail(struct tqh *hd, struct tqe *e)
{
	e->next = NULL;
	e->pprev = hd->last;
	*hd->last = e;
	hd->last = &e->next;
}

void tq_insert_after(struct tqh *hd, struct tqe *e, struct tqe *n)
{
	if ((n->next = e->next) != NULL)
		n->next->pprev = &n->next;
	else
		hd->last = &n->next;
	e->next = n;
	n->pprev = &e->next;
}

void tq_insert_before(struct tqh *hd, struct tqe *e, struct tqe *n)
{
	n->pprev = e->pprev;
	n->next = e;
	*e->pprev = n;
	e->pprev = &n->next;
	if (hd->first == e)
		hd->first = n;
}

void tq_remove(struct tqh *hd, struct tqe *e)
{
	if ((e->next) != NULL)
		e->next->pprev = e->pprev;
	else
		hd->last = e->pprev;
	*e->pprev = e->next;
}

void tq_replace(struct tqh *hd, struct tqe *e, struct tqe *n)
{
	if ((n->next = e->next) != NULL)
		n->next->pprev = &n->next;
	else
		hd->last = &n->next;
	n->pprev = e->pprev;
	*n->pprev = n;
}

void tq_concat(struct tqh *hd1, struct tqh *hd2)
{
	if (hd2->first != NULL) {
		*hd1->last = hd2->first;
		hd2->first->pprev = hd1->last;
		hd1->last = hd2->last;
		hd2->first = NULL;
		hd2->last = &hd2->first;
	}
}

void tq_cleanup(struct tqh *hd, void (*func)(void *))
{
	struct tqe *e, *t;

	tq_foreach_safe(e, hd, t) {
		tq_remove(hd, e);
		if (func)
			func(e->data);
		free(e);
	}
}

struct tqe *tq_find_from_data(struct tqh *hd, const void *data, int (*cmp)(const void *, const void *))
{
	struct tqe *e;

	if (hd && !tq_empty(hd))
		tq_foreach(e, hd)
			if (e->data && cmp(e->data, data) == 0)
				return e;

	return NULL;
}