path: root/lib/typesafe.h

/*
 * Copyright (c) 2016-2019  David Lamparter, for NetDEF, Inc.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#ifndef _FRR_TYPESAFE_H
#define _FRR_TYPESAFE_H

#include <stddef.h>
#include <stdint.h>
#include <stdbool.h>
#include <assert.h>
#include "compiler.h"

/* generic macros for all list-like types */

#define for_each(prefix, head, item)                                           \
	for (item = prefix##_first(head); item;                                \
			item = prefix##_next(head, item))
#define for_each_safe(prefix, head, item)                                      \
	for (typeof(prefix##_next_safe(head, NULL)) prefix##_safe =            \
			prefix##_next_safe(head,                               \
				(item = prefix##_first(head)));                \
		item;                                                          \
		item = prefix##_safe,                                          \
			prefix##_safe = prefix##_next_safe(head, prefix##_safe))
#define for_each_from(prefix, head, item, from)                                \
	for (item = from, from = prefix##_next_safe(head, item);               \
		item;                                                          \
		item = from, from = prefix##_next_safe(head, from))

/* single-linked list, unsorted/arbitrary.
 * can be used as queue with add_tail / pop
 */

/* don't use these structs directly */
struct slist_item {
	struct slist_item *next;
};

struct slist_head {
	struct slist_item *first, **last_next;
	size_t count;
};

static inline void typesafe_list_add(struct slist_head *head,
		struct slist_item **pos, struct slist_item *item)
{
	item->next = *pos;
	*pos = item;
	if (pos == head->last_next)
		head->last_next = &item->next;
	head->count++;
}

/* use as:
 *
 * PREDECL_LIST(namelist)
 * struct name {
 *   struct namelist_item nlitem;
 * }
 * DECLARE_LIST(namelist, struct name, nlitem)
 */
#define PREDECL_LIST(prefix)                                                   \
struct prefix ## _head { struct slist_head sh; };                              \
struct prefix ## _item { struct slist_item si; };

#define INIT_LIST(var) { .sh = { .last_next = &var.sh.first, }, }

#define DECLARE_LIST(prefix, type, field)                                      \
                                                                               \
macro_inline void prefix ## _init(struct prefix##_head *h)                     \
{                                                                              \
	memset(h, 0, sizeof(*h));                                              \
	h->sh.last_next = &h->sh.first;                                        \
}                                                                              \
macro_inline void prefix ## _fini(struct prefix##_head *h)                     \
{                                                                              \
	memset(h, 0, sizeof(*h));                                              \
}                                                                              \
macro_inline void prefix ## _add_head(struct prefix##_head *h, type *item)     \
{                                                                              \
	typesafe_list_add(&h->sh, &h->sh.first, &item->field.si);              \
}                                                                              \
macro_inline void prefix ## _add_tail(struct prefix##_head *h, type *item)     \
{                                                                              \
	typesafe_list_add(&h->sh, h->sh.last_next, &item->field.si);           \
}                                                                              \
macro_inline void prefix ## _add_after(struct prefix##_head *h,                \
		type *after, type *item)                                       \
{                                                                              \
	struct slist_item **nextp;                                             \
	nextp = after ? &after->field.si.next : &h->sh.first;                  \
	typesafe_list_add(&h->sh, nextp, &item->field.si);                     \
}                                                                              \
/* TODO: del_hint */                                                           \
macro_inline void prefix ## _del(struct prefix##_head *h, type *item)          \
{                                                                              \
	struct slist_item **iter = &h->sh.first;                               \
	while (*iter && *iter != &item->field.si)                              \
		iter = &(*iter)->next;                                         \
	if (!*iter)                                                            \
		return;                                                        \
	h->sh.count--;                                                         \
	*iter = item->field.si.next;                                           \
	if (!item->field.si.next)                                              \
		h->sh.last_next = iter;                                        \
}                                                                              \
macro_inline type *prefix ## _pop(struct prefix##_head *h)                     \
{                                                                              \
	struct slist_item *sitem = h->sh.first;                                \
	if (!sitem)                                                            \
		return NULL;                                                   \
	h->sh.count--;                                                         \
	h->sh.first = sitem->next;                                             \
	if (h->sh.first == NULL)                                               \
		h->sh.last_next = &h->sh.first;                                \
	return container_of(sitem, type, field.si);                            \
}                                                                              \
macro_pure type *prefix ## _first(struct prefix##_head *h)                     \
{                                                                              \
	return container_of_null(h->sh.first, type, field.si);                 \
}                                                                              \
macro_pure type *prefix ## _next(struct prefix##_head * h, type *item)         \
{                                                                              \
	struct slist_item *sitem = &item->field.si;                            \
	return container_of_null(sitem->next, type, field.si);                 \
}                                                                              \
macro_pure type *prefix ## _next_safe(struct prefix##_head *h, type *item)     \
{                                                                              \
	struct slist_item *sitem;                                              \
	if (!item)                                                             \
		return NULL;                                                   \
	sitem = &item->field.si;                                               \
	return container_of_null(sitem->next, type, field.si);                 \
}                                                                              \
macro_pure size_t prefix ## _count(struct prefix##_head *h)                    \
{                                                                              \
	return h->sh.count;                                                    \
}                                                                              \
/* ... */

/* single-linked list, sorted.
 * can be used as priority queue with add / pop
 */

/* don't use these structs directly */
struct ssort_item {
	struct ssort_item *next;
};

struct ssort_head {
	struct ssort_item *first;
	size_t count;
};

/* use as:
 *
 * PREDECL_SORTLIST(namelist)
 * struct name {
 *   struct namelist_item nlitem;
 * }
 * DECLARE_SORTLIST(namelist, struct name, nlitem)
 */
#define _PREDECL_SORTLIST(prefix)                                              \
struct prefix ## _head { struct ssort_head sh; };                              \
struct prefix ## _item { struct ssort_item si; };

#define INIT_SORTLIST_UNIQ(var)		{ }
#define INIT_SORTLIST_NONUNIQ(var)	{ }

#define PREDECL_SORTLIST_UNIQ(prefix)                                          \
	_PREDECL_SORTLIST(prefix)
#define PREDECL_SORTLIST_NONUNIQ(prefix)                                       \
	_PREDECL_SORTLIST(prefix)

#define _DECLARE_SORTLIST(prefix, type, field, cmpfn_nuq, cmpfn_uq)            \
                                                                               \
macro_inline void prefix ## _init(struct prefix##_head *h)                     \
{                                                                              \
	memset(h, 0, sizeof(*h));                                              \
}                                                                              \
macro_inline void prefix ## _fini(struct prefix##_head *h)                     \
{                                                                              \
	memset(h, 0, sizeof(*h));                                              \
}                                                                              \
macro_inline type *prefix ## _add(struct prefix##_head *h, type *item)         \
{                                                                              \
	struct ssort_item **np = &h->sh.first;                                 \
	int c = 1;                                                             \
	while (*np && (c = cmpfn_uq(                                           \
			container_of(*np, type, field.si), item)) < 0)         \
		np = &(*np)->next;                                             \
	if (c == 0)                                                            \
		return container_of(*np, type, field.si);                      \
	item->field.si.next = *np;                                             \
	*np = &item->field.si;                                                 \
	h->sh.count++;                                                         \
	return NULL;                                                           \
}                                                                              \
macro_inline type *prefix ## _find_gteq(struct prefix##_head *h,               \
		const type *item)                                              \
{                                                                              \
	struct ssort_item *sitem = h->sh.first;                                \
	int cmpval = 0;                                                        \
	while (sitem && (cmpval = cmpfn_nuq(                                   \
			container_of(sitem, type, field.si), item) < 0))       \
		sitem = sitem->next;                                           \
	return container_of_null(sitem, type, field.si);                       \
}                                                                              \
macro_inline type *prefix ## _find_lt(struct prefix##_head *h,                 \
		const type *item)                                              \
{                                                                              \
	struct ssort_item *prev = NULL, *sitem = h->sh.first;                  \
	int cmpval = 0;                                                        \
	while (sitem && (cmpval = cmpfn_nuq(                                   \
			container_of(sitem, type, field.si), item) < 0))       \
		sitem = (prev = sitem)->next;                                  \
	return container_of_null(prev, type, field.si);                        \
}                                                                              \
/* TODO: del_hint */                                                           \
macro_inline void prefix ## _del(struct prefix##_head *h, type *item)          \
{                                                                              \
	struct ssort_item **iter = &h->sh.first;                               \
	while (*iter && *iter != &item->field.si)                              \
		iter = &(*iter)->next;                                         \
	if (!*iter)                                                            \
		return;                                                        \
	h->sh.count--;                                                         \
	*iter = item->field.si.next;                                           \
}                                                                              \
macro_inline type *prefix ## _pop(struct prefix##_head *h)                     \
{                                                                              \
	struct ssort_item *sitem = h->sh.first;                                \
	if (!sitem)                                                            \
		return NULL;                                                   \
	h->sh.count--;                                                         \
	h->sh.first = sitem->next;                                             \
	return container_of(sitem, type, field.si);                            \
}                                                                              \
macro_pure type *prefix ## _first(struct prefix##_head *h)                     \
{                                                                              \
	return container_of_null(h->sh.first, type, field.si);                 \
}                                                                              \
macro_pure type *prefix ## _next(struct prefix##_head *h, type *item)          \
{                                                                              \
	struct ssort_item *sitem = &item->field.si;                            \
	return container_of_null(sitem->next, type, field.si);                 \
}                                                                              \
macro_pure type *prefix ## _next_safe(struct prefix##_head *h, type *item)     \
{                                                                              \
	struct ssort_item *sitem;                                              \
	if (!item)                                                             \
		return NULL;                                                   \
	sitem = &item->field.si;                                               \
	return container_of_null(sitem->next, type, field.si);                 \
}                                                                              \
macro_pure size_t prefix ## _count(struct prefix##_head *h)                    \
{                                                                              \
	return h->sh.count;                                                    \
}                                                                              \
/* ... */

#define DECLARE_SORTLIST_UNIQ(prefix, type, field, cmpfn)                      \
	_DECLARE_SORTLIST(prefix, type, field, cmpfn, cmpfn)                   \
                                                                               \
macro_inline type *prefix ## _find(const struct prefix##_head *h, const type *item)  \
{                                                                              \
	struct ssort_item *sitem = h->sh.first;                                \
	int cmpval = 0;                                                        \
	while (sitem && (cmpval = cmpfn(                                       \
			container_of(sitem, type, field.si), item) < 0))       \
		sitem = sitem->next;                                           \
	if (!sitem || cmpval > 0)                                              \
		return NULL;                                                   \
	return container_of(sitem, type, field.si);                            \
}                                                                              \
/* ... */

#define DECLARE_SORTLIST_NONUNIQ(prefix, type, field, cmpfn)                   \
macro_inline int _ ## prefix ## _cmp(const type *a, const type *b)             \
{                                                                              \
	int cmpval = cmpfn(a, b);                                              \
	if (cmpval)                                                            \
		return cmpval;                                                 \
	if (a < b)                                                             \
		return -1;                                                     \
	if (a > b)                                                             \
		return 1;                                                      \
	return 0;                                                              \
}                                                                              \
	_DECLARE_SORTLIST(prefix, type, field, cmpfn, _ ## prefix ## _cmp)     \
/* ... */


/* hash, "sorted" by hash value
 */

/* don't use these structs directly */
struct thash_item {
	struct thash_item *next;
	uint32_t hashval;
};

struct thash_head {
	struct thash_item **entries;
	uint32_t count;

	uint8_t tabshift;
	uint8_t minshift, maxshift;
};

#define _HASH_SIZE(tabshift) \
	((1U << (tabshift)) >> 1)
#define HASH_SIZE(head) \
	_HASH_SIZE((head).tabshift)
#define _HASH_KEY(tabshift, val) \
	((val) >> (33 - (tabshift)))
#define HASH_KEY(head, val) \
	_HASH_KEY((head).tabshift, val)
#define HASH_GROW_THRESHOLD(head) \
	((head).count >= HASH_SIZE(head))
#define HASH_SHRINK_THRESHOLD(head) \
	((head).count <= (HASH_SIZE(head) - 1) / 2)

extern void typesafe_hash_grow(struct thash_head *head);
extern void typesafe_hash_shrink(struct thash_head *head);

/* use as:
 *
 * PREDECL_HASH(namelist)
 * struct name {
 *   struct namelist_item nlitem;
 * }
 * DECLARE_HASH(namelist, struct name, nlitem, cmpfunc, hashfunc)
 */
#define PREDECL_HASH(prefix)                                                   \
struct prefix ## _head { struct thash_head hh; };                              \
struct prefix ## _item { struct thash_item hi; };

#define INIT_HASH(var)	{ }

#define DECLARE_HASH(prefix, type, field, cmpfn, hashfn)                       \
                                                                               \
macro_inline void prefix ## _init(struct prefix##_head *h)                     \
{                                                                              \
	memset(h, 0, sizeof(*h));                                              \
}                                                                              \
macro_inline void prefix ## _fini(struct prefix##_head *h)                     \
{                                                                              \
	assert(h->hh.count == 0);                                              \
	h->hh.minshift = 0;                                                    \
	typesafe_hash_shrink(&h->hh);                                          \
	memset(h, 0, sizeof(*h));                                              \
}                                                                              \
macro_inline type *prefix ## _add(struct prefix##_head *h, type *item)         \
{                                                                              \
	h->hh.count++;                                                         \
	if (!h->hh.tabshift || HASH_GROW_THRESHOLD(h->hh))                     \
		typesafe_hash_grow(&h->hh);                                    \
                                                                               \
	uint32_t hval = hashfn(item), hbits = HASH_KEY(h->hh, hval);           \
	item->field.hi.hashval = hval;                                         \
	struct thash_item **np = &h->hh.entries[hbits];                        \
	while (*np && (*np)->hashval < hval)                                   \
		np = &(*np)->next;                                             \
	if (*np && cmpfn(container_of(*np, type, field.hi), item) == 0) {      \
		h->hh.count--;                                                 \
		return container_of(*np, type, field.hi);                      \
	}                                                                      \
	item->field.hi.next = *np;                                             \
	*np = &item->field.hi;                                                 \
	return NULL;                                                           \
}                                                                              \
macro_inline type *prefix ## _find(const struct prefix##_head *h, const type *item)  \
{                                                                              \
	if (!h->hh.tabshift)                                                   \
		return NULL;                                                   \
	uint32_t hval = hashfn(item), hbits = HASH_KEY(h->hh, hval);           \
	struct thash_item *hitem = h->hh.entries[hbits];                       \
	while (hitem && hitem->hashval < hval)                                 \
		hitem = hitem->next;                                           \
	while (hitem && hitem->hashval == hval) {                              \
		if (!cmpfn(container_of(hitem, type, field.hi), item))         \
			return container_of(hitem, type, field.hi);            \
		hitem = hitem->next;                                           \
	}                                                                      \
	return NULL;                                                           \
}                                                                              \
macro_inline void prefix ## _del(struct prefix##_head *h, type *item)          \
{                                                                              \
	if (!h->hh.tabshift)                                                   \
		return;                                                        \
	uint32_t hval = item->field.hi.hashval, hbits = HASH_KEY(h->hh, hval); \
	struct thash_item **np = &h->hh.entries[hbits];                        \
	while (*np && (*np)->hashval < hval)                                   \
		np = &(*np)->next;                                             \
	while (*np && *np != &item->field.hi && (*np)->hashval == hval)        \
		np = &(*np)->next;                                             \
	if (*np != &item->field.hi)                                            \
		return;                                                        \
	*np = item->field.hi.next;                                             \
	item->field.hi.next = NULL;                                            \
	h->hh.count--;                                                         \
	if (HASH_SHRINK_THRESHOLD(h->hh))                                      \
		typesafe_hash_shrink(&h->hh);                                  \
}                                                                              \
macro_inline type *prefix ## _pop(struct prefix##_head *h)                     \
{                                                                              \
	uint32_t i;                                                            \
	for (i = 0; i < HASH_SIZE(h->hh); i++)                                 \
		if (h->hh.entries[i]) {                                        \
			struct thash_item *hitem = h->hh.entries[i];           \
			h->hh.entries[i] = hitem->next;                        \
			h->hh.count--;                                         \
			hitem->next = NULL;                                    \
			if (HASH_SHRINK_THRESHOLD(h->hh))                      \
				typesafe_hash_shrink(&h->hh);                  \
			return container_of(hitem, type, field.hi);            \
		}                                                              \
	return NULL;                                                           \
}                                                                              \
macro_pure type *prefix ## _first(struct prefix##_head *h)                     \
{                                                                              \
	uint32_t i;                                                            \
	for (i = 0; i < HASH_SIZE(h->hh); i++)                                 \
		if (h->hh.entries[i])                                          \
			return container_of(h->hh.entries[i], type, field.hi); \
	return NULL;                                                           \
}                                                                              \
macro_pure type *prefix ## _next(struct prefix##_head *h, type *item)          \
{                                                                              \
	struct thash_item *hitem = &item->field.hi;                            \
	if (hitem->next)                                                       \
		return container_of(hitem->next, type, field.hi);              \
	uint32_t i = HASH_KEY(h->hh, hitem->hashval) + 1;                      \
        for (; i < HASH_SIZE(h->hh); i++)                                      \
		if (h->hh.entries[i])                                          \
			return container_of(h->hh.entries[i], type, field.hi); \
	return NULL;                                                           \
}                                                                              \
macro_pure type *prefix ## _next_safe(struct prefix##_head *h, type *item)     \
{                                                                              \
	if (!item)                                                             \
		return NULL;                                                   \
	return prefix ## _next(h, item);                                       \
}                                                                              \
macro_pure size_t prefix ## _count(struct prefix##_head *h)                    \
{                                                                              \
	return h->hh.count;                                                    \
}                                                                              \
/* ... */

/* skiplist, sorted.
 * can be used as priority queue with add / pop
 */

/* don't use these structs directly */
#define SKIPLIST_MAXDEPTH	16
#define SKIPLIST_EMBED		4
#define SKIPLIST_OVERFLOW	(SKIPLIST_EMBED - 1)

struct sskip_item {
	struct sskip_item *next[SKIPLIST_EMBED];
};

struct sskip_overflow {
	struct sskip_item *next[SKIPLIST_MAXDEPTH - SKIPLIST_OVERFLOW];
};

struct sskip_head {
	struct sskip_item hitem;
	struct sskip_item *overflow[SKIPLIST_MAXDEPTH - SKIPLIST_OVERFLOW];
	size_t count;
};

/* use as:
 *
 * PREDECL_SKIPLIST(namelist)
 * struct name {
 *   struct namelist_item nlitem;
 * }
 * DECLARE_SKIPLIST(namelist, struct name, nlitem, cmpfunc)
 */
#define _PREDECL_SKIPLIST(prefix)                                              \
struct prefix ## _head { struct sskip_head sh; };                              \
struct prefix ## _item { struct sskip_item si; };

#define INIT_SKIPLIST_UNIQ(var)		{ }
#define INIT_SKIPLIST_NONUNIQ(var)	{ }

#define _DECLARE_SKIPLIST(prefix, type, field, cmpfn_nuq, cmpfn_uq)            \
                                                                               \
macro_inline void prefix ## _init(struct prefix##_head *h)                     \
{                                                                              \
	memset(h, 0, sizeof(*h));                                              \
	h->sh.hitem.next[SKIPLIST_OVERFLOW] = (struct sskip_item *)            \
		((uintptr_t)h->sh.overflow | 1);                               \
}                                                                              \
macro_inline void prefix ## _fini(struct prefix##_head *h)                     \
{                                                                              \
	memset(h, 0, sizeof(*h));                                              \
}                                                                              \
macro_inline type *prefix ## _add(struct prefix##_head *h, type *item)         \
{                                                                              \
	struct sskip_item *si;                                                 \
	si = typesafe_skiplist_add(&h->sh, &item->field.si, cmpfn_uq);         \
	return container_of_null(si, type, field.si);                          \
}                                                                              \
macro_inline type *prefix ## _find_gteq(struct prefix##_head *h,               \
		const type *item)                                              \
{                                                                              \
	struct sskip_item *sitem = typesafe_skiplist_find_gteq(&h->sh,         \
			&item->field.si, cmpfn_nuq);                           \
	return container_of_null(sitem, type, field.si);                       \
}                                                                              \
macro_inline type *prefix ## _find_lt(struct prefix##_head *h,                 \
		const type *item)                                              \
{                                                                              \
	struct sskip_item *sitem = typesafe_skiplist_find_lt(&h->sh,           \
			&item->field.si, cmpfn_nuq);                           \
	return container_of_null(sitem, type, field.si);                       \
}                                                                              \
macro_inline void prefix ## _del(struct prefix##_head *h, type *item)          \
{                                                                              \
	typesafe_skiplist_del(&h->sh, &item->field.si, cmpfn_uq);              \
}                                                                              \
macro_inline type *prefix ## _pop(struct prefix##_head *h)                     \
{                                                                              \
	struct sskip_item *sitem = h->sh.hitem.next[0];                        \
	if (!sitem)                                                            \
		return NULL;                                                   \
	typesafe_skiplist_del(&h->sh, sitem, cmpfn_uq);                        \
	return container_of(sitem, type, field.si);                            \
}                                                                              \
macro_pure type *prefix ## _first(struct prefix##_head *h)                     \
{                                                                              \
	struct sskip_item *first = h->sh.hitem.next[0];                        \
	return container_of_null(first, type, field.si);                       \
}                                                                              \
macro_pure type *prefix ## _next(struct prefix##_head *h, type *item)          \
{                                                                              \
	struct sskip_item *next = item->field.si.next[0];                      \
	return container_of_null(next, type, field.si);                        \
}                                                                              \
macro_pure type *prefix ## _next_safe(struct prefix##_head *h, type *item)     \
{                                                                              \
	struct sskip_item *next;                                               \
	next = item ? item->field.si.next[0] : NULL;                           \
	return container_of_null(next, type, field.si);                        \
}                                                                              \
macro_pure size_t prefix ## _count(struct prefix##_head *h)                    \
{                                                                              \
	return h->sh.count;                                                    \
}                                                                              \
/* ... */

#define PREDECL_SKIPLIST_UNIQ(prefix)                                          \
	_PREDECL_SKIPLIST(prefix)
#define DECLARE_SKIPLIST_UNIQ(prefix, type, field, cmpfn)                      \
                                                                               \
macro_inline int prefix ## __cmp(const struct sskip_item *a,                   \
		const struct sskip_item *b)                                    \
{                                                                              \
	return cmpfn(container_of(a, type, field.si),                          \
			container_of(b, type, field.si));                      \
}                                                                              \
macro_inline type *prefix ## _find(const struct prefix##_head *h, const type *item)  \
{                                                                              \
	struct sskip_item *sitem = typesafe_skiplist_find(&h->sh,              \
			&item->field.si, &prefix ## __cmp);                    \
	return container_of_null(sitem, type, field.si);                       \
}                                                                              \
                                                                               \
_DECLARE_SKIPLIST(prefix, type, field,                                         \
		prefix ## __cmp, prefix ## __cmp)                              \
/* ... */

#define PREDECL_SKIPLIST_NONUNIQ(prefix)                                       \
	_PREDECL_SKIPLIST(prefix)
#define DECLARE_SKIPLIST_NONUNIQ(prefix, type, field, cmpfn)                   \
                                                                               \
macro_inline int prefix ## __cmp(const struct sskip_item *a,                   \
		const struct sskip_item *b)                                    \
{                                                                              \
	return cmpfn(container_of(a, type, field.si),                          \
			container_of(b, type, field.si));                      \
}                                                                              \
macro_inline int prefix ## __cmp_uq(const struct sskip_item *a,                \
		const struct sskip_item *b)                                    \
{                                                                              \
	int cmpval = cmpfn(container_of(a, type, field.si),                    \
			container_of(b, type, field.si));                      \
	if (cmpval)                                                            \
		return cmpval;                                                 \
	if (a < b)                                                             \
		return -1;                                                     \
	if (a > b)                                                             \
		return 1;                                                      \
	return 0;                                                              \
}                                                                              \
                                                                               \
_DECLARE_SKIPLIST(prefix, type, field,                                         \
		prefix ## __cmp, prefix ## __cmp_uq)                           \
/* ... */


extern struct sskip_item *typesafe_skiplist_add(struct sskip_head *head,
		struct sskip_item *item, int (*cmpfn)(
			const struct sskip_item *a,
			const struct sskip_item *b));
extern struct sskip_item *typesafe_skiplist_find(struct sskip_head *head,
		const struct sskip_item *item, int (*cmpfn)(
			const struct sskip_item *a,
			const struct sskip_item *b));
extern struct sskip_item *typesafe_skiplist_find_gteq(struct sskip_head *head,
		const struct sskip_item *item, int (*cmpfn)(
			const struct sskip_item *a,
			const struct sskip_item *b));
extern struct sskip_item *typesafe_skiplist_find_lt(struct sskip_head *head,
		const struct sskip_item *item, int (*cmpfn)(
			const struct sskip_item *a,
			const struct sskip_item *b));
extern void typesafe_skiplist_del(struct sskip_head *head,
		struct sskip_item *item, int (*cmpfn)(
			const struct sskip_item *a,
			const struct sskip_item *b));

/* this needs to stay at the end because both files include each other.
 * the resolved order is typesafe.h before typerb.h
 */
#include "typerb.h"

#endif /* _FRR_TYPESAFE_H */