2 * Copyright 2001 The OpenLDAP Foundation, Redwood City, California, USA
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted only as authorized by the OpenLDAP
7 * Public License. A copy of this license is available at
8 * http://www.OpenLDAP.org/license.html or in file LICENSE in the
9 * top-level directory of the distribution.
11 /* stolen from FreeBSD for use in OpenLDAP */
14 * Copyright (c) 1991, 1993
15 * The Regents of the University of California. All rights reserved.
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions
20 * 1. Redistributions of source code must retain the above copyright
21 * notice, this list of conditions and the following disclaimer.
22 * 2. Redistributions in binary form must reproduce the above copyright
23 * notice, this list of conditions and the following disclaimer in the
24 * documentation and/or other materials provided with the distribution.
25 * 3. All advertising materials mentioning features or use of this software
26 * must display the following acknowledgement:
27 * This product includes software developed by the University of
28 * California, Berkeley and its contributors.
29 * 4. Neither the name of the University nor the names of its contributors
30 * may be used to endorse or promote products derived from this software
31 * without specific prior written permission.
33 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
34 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
35 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
36 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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38 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
39 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
40 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
41 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
42 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
45 * @(#)queue.h 8.5 (Berkeley) 8/20/94
46 * $FreeBSD: src/sys/sys/queue.h,v 1.32.2.5 2001/09/30 21:12:54 luigi Exp $
53 * This file defines five types of data structures: singly-linked lists,
54 * singly-linked tail queues, lists, tail queues, and circular queues.
56 * A singly-linked list is headed by a single forward pointer. The elements
57 * are singly linked for minimum space and pointer manipulation overhead at
58 * the expense of O(n) removal for arbitrary elements. New elements can be
59 * added to the list after an existing element or at the head of the list.
60 * Elements being removed from the head of the list should use the explicit
61 * macro for this purpose for optimum efficiency. A singly-linked list may
62 * only be traversed in the forward direction. Singly-linked lists are ideal
63 * for applications with large datasets and few or no removals or for
64 * implementing a LIFO queue.
66 * A singly-linked tail queue is headed by a pair of pointers, one to the
67 * head of the list and the other to the tail of the list. The elements are
68 * singly linked for minimum space and pointer manipulation overhead at the
69 * expense of O(n) removal for arbitrary elements. New elements can be added
70 * to the list after an existing element, at the head of the list, or at the
71 * end of the list. Elements being removed from the head of the tail queue
72 * should use the explicit macro for this purpose for optimum efficiency.
73 * A singly-linked tail queue may only be traversed in the forward direction.
74 * Singly-linked tail queues are ideal for applications with large datasets
75 * and few or no removals or for implementing a FIFO queue.
77 * A list is headed by a single forward pointer (or an array of forward
78 * pointers for a hash table header). The elements are doubly linked
79 * so that an arbitrary element can be removed without a need to
80 * traverse the list. New elements can be added to the list before
81 * or after an existing element or at the head of the list. A list
82 * may only be traversed in the forward direction.
84 * A tail queue is headed by a pair of pointers, one to the head of the
85 * list and the other to the tail of the list. The elements are doubly
86 * linked so that an arbitrary element can be removed without a need to
87 * traverse the list. New elements can be added to the list before or
88 * after an existing element, at the head of the list, or at the end of
89 * the list. A tail queue may be traversed in either direction.
91 * A circle queue is headed by a pair of pointers, one to the head of the
92 * list and the other to the tail of the list. The elements are doubly
93 * linked so that an arbitrary element can be removed without a need to
94 * traverse the list. New elements can be added to the list before or after
95 * an existing element, at the head of the list, or at the end of the list.
96 * A circle queue may be traversed in either direction, but has a more
97 * complex end of list detection.
99 * For details on the use of these macros, see the queue(3) manual page.
102 * SLIST LIST STAILQ TAILQ CIRCLEQ
112 * _FOREACH_REVERSE - - - + +
113 * _INSERT_HEAD + + + + +
114 * _INSERT_BEFORE - + - + +
115 * _INSERT_AFTER + + + + +
116 * _INSERT_TAIL - - + + +
117 * _REMOVE_HEAD + - + - -
122 * see queue(3) for instructions on how to use
125 /* The latest set of Windows headers defines SLIST_ENTRY in WINNT.H */
131 * Singly-linked List definitions.
133 #define SLIST_HEAD(name, type) \
135 struct type *slh_first; /* first element */ \
138 #define SLIST_HEAD_INITIALIZER(head) \
141 #define SLIST_ENTRY(type) \
143 struct type *sle_next; /* next element */ \
147 * Singly-linked List functions.
149 #define SLIST_EMPTY(head) ((head)->slh_first == NULL)
151 #define SLIST_FIRST(head) ((head)->slh_first)
153 #define SLIST_FOREACH(var, head, field) \
154 for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
156 #define SLIST_INIT(head) { \
157 (head)->slh_first = NULL; \
160 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
161 (elm)->field.sle_next = (slistelm)->field.sle_next; \
162 (slistelm)->field.sle_next = (elm); \
165 #define SLIST_INSERT_HEAD(head, elm, field) do { \
166 (elm)->field.sle_next = (head)->slh_first; \
167 (head)->slh_first = (elm); \
170 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
172 #define SLIST_REMOVE_HEAD(head, field) do { \
173 (head)->slh_first = (head)->slh_first->field.sle_next; \
176 #define SLIST_REMOVE(head, elm, type, field) do { \
177 if ((head)->slh_first == (elm)) { \
178 SLIST_REMOVE_HEAD((head), field); \
181 struct type *curelm = (head)->slh_first; \
182 while( curelm->field.sle_next != (elm) ) \
183 curelm = curelm->field.sle_next; \
184 curelm->field.sle_next = \
185 curelm->field.sle_next->field.sle_next; \
190 * Singly-linked Tail queue definitions.
192 #define STAILQ_HEAD(name, type) \
194 struct type *stqh_first;/* first element */ \
195 struct type **stqh_last;/* addr of last next element */ \
198 #define STAILQ_HEAD_INITIALIZER(head) \
199 { NULL, &(head).stqh_first }
201 #define STAILQ_ENTRY(type) \
203 struct type *stqe_next; /* next element */ \
207 * Singly-linked Tail queue functions.
209 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
211 #define STAILQ_INIT(head) do { \
212 (head)->stqh_first = NULL; \
213 (head)->stqh_last = &(head)->stqh_first; \
216 #define STAILQ_FIRST(head) ((head)->stqh_first)
218 #define STAILQ_LAST(head, type, field) \
219 (STAILQ_EMPTY(head) ? \
222 ((char *)((head)->stqh_last) - offsetof(struct type, field))))
224 #define STAILQ_FOREACH(var, head, field) \
225 for((var) = (head)->stqh_first; (var); (var) = (var)->field.stqe_next)
227 #define STAILQ_INSERT_HEAD(head, elm, field) do { \
228 if (((elm)->field.stqe_next = (head)->stqh_first) == NULL) \
229 (head)->stqh_last = &(elm)->field.stqe_next; \
230 (head)->stqh_first = (elm); \
233 #define STAILQ_INSERT_TAIL(head, elm, field) do { \
234 (elm)->field.stqe_next = NULL; \
235 *(head)->stqh_last = (elm); \
236 (head)->stqh_last = &(elm)->field.stqe_next; \
239 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
240 if (((elm)->field.stqe_next = (tqelm)->field.stqe_next) == NULL)\
241 (head)->stqh_last = &(elm)->field.stqe_next; \
242 (tqelm)->field.stqe_next = (elm); \
245 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
247 #define STAILQ_REMOVE_HEAD(head, field) do { \
248 if (((head)->stqh_first = \
249 (head)->stqh_first->field.stqe_next) == NULL) \
250 (head)->stqh_last = &(head)->stqh_first; \
253 #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do { \
254 if (((head)->stqh_first = (elm)->field.stqe_next) == NULL) \
255 (head)->stqh_last = &(head)->stqh_first; \
258 #define STAILQ_REMOVE(head, elm, type, field) do { \
259 if ((head)->stqh_first == (elm)) { \
260 STAILQ_REMOVE_HEAD(head, field); \
263 struct type *curelm = (head)->stqh_first; \
264 while( curelm->field.stqe_next != (elm) ) \
265 curelm = curelm->field.stqe_next; \
266 if((curelm->field.stqe_next = \
267 curelm->field.stqe_next->field.stqe_next) == NULL) \
268 (head)->stqh_last = &(curelm)->field.stqe_next; \
275 #define LIST_HEAD(name, type) \
277 struct type *lh_first; /* first element */ \
280 #define LIST_HEAD_INITIALIZER(head) \
283 #define LIST_ENTRY(type) \
285 struct type *le_next; /* next element */ \
286 struct type **le_prev; /* address of previous next element */ \
293 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
295 #define LIST_FIRST(head) ((head)->lh_first)
297 #define LIST_FOREACH(var, head, field) \
298 for((var) = (head)->lh_first; (var); (var) = (var)->field.le_next)
300 #define LIST_INIT(head) do { \
301 (head)->lh_first = NULL; \
304 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
305 if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
306 (listelm)->field.le_next->field.le_prev = \
307 &(elm)->field.le_next; \
308 (listelm)->field.le_next = (elm); \
309 (elm)->field.le_prev = &(listelm)->field.le_next; \
312 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
313 (elm)->field.le_prev = (listelm)->field.le_prev; \
314 (elm)->field.le_next = (listelm); \
315 *(listelm)->field.le_prev = (elm); \
316 (listelm)->field.le_prev = &(elm)->field.le_next; \
319 #define LIST_INSERT_HEAD(head, elm, field) do { \
320 if (((elm)->field.le_next = (head)->lh_first) != NULL) \
321 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
322 (head)->lh_first = (elm); \
323 (elm)->field.le_prev = &(head)->lh_first; \
326 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
328 #define LIST_REMOVE(elm, field) do { \
329 if ((elm)->field.le_next != NULL) \
330 (elm)->field.le_next->field.le_prev = \
331 (elm)->field.le_prev; \
332 *(elm)->field.le_prev = (elm)->field.le_next; \
336 * Tail queue definitions.
338 #define TAILQ_HEAD(name, type) \
340 struct type *tqh_first; /* first element */ \
341 struct type **tqh_last; /* addr of last next element */ \
344 #define TAILQ_HEAD_INITIALIZER(head) \
345 { NULL, &(head).tqh_first }
347 #define TAILQ_ENTRY(type) \
349 struct type *tqe_next; /* next element */ \
350 struct type **tqe_prev; /* address of previous next element */ \
354 * Tail queue functions.
356 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
358 #define TAILQ_FOREACH(var, head, field) \
359 for (var = TAILQ_FIRST(head); var; var = TAILQ_NEXT(var, field))
361 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
362 for ((var) = TAILQ_LAST((head), headname); \
364 (var) = TAILQ_PREV((var), headname, field))
366 #define TAILQ_FIRST(head) ((head)->tqh_first)
368 #define TAILQ_LAST(head, headname) \
369 (*(((struct headname *)((head)->tqh_last))->tqh_last))
371 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
373 #define TAILQ_PREV(elm, headname, field) \
374 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
376 #define TAILQ_INIT(head) do { \
377 (head)->tqh_first = NULL; \
378 (head)->tqh_last = &(head)->tqh_first; \
381 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
382 if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
383 (head)->tqh_first->field.tqe_prev = \
384 &(elm)->field.tqe_next; \
386 (head)->tqh_last = &(elm)->field.tqe_next; \
387 (head)->tqh_first = (elm); \
388 (elm)->field.tqe_prev = &(head)->tqh_first; \
391 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
392 (elm)->field.tqe_next = NULL; \
393 (elm)->field.tqe_prev = (head)->tqh_last; \
394 *(head)->tqh_last = (elm); \
395 (head)->tqh_last = &(elm)->field.tqe_next; \
398 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
399 if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
400 (elm)->field.tqe_next->field.tqe_prev = \
401 &(elm)->field.tqe_next; \
403 (head)->tqh_last = &(elm)->field.tqe_next; \
404 (listelm)->field.tqe_next = (elm); \
405 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
408 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
409 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
410 (elm)->field.tqe_next = (listelm); \
411 *(listelm)->field.tqe_prev = (elm); \
412 (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
415 #define TAILQ_REMOVE(head, elm, field) do { \
416 if (((elm)->field.tqe_next) != NULL) \
417 (elm)->field.tqe_next->field.tqe_prev = \
418 (elm)->field.tqe_prev; \
420 (head)->tqh_last = (elm)->field.tqe_prev; \
421 *(elm)->field.tqe_prev = (elm)->field.tqe_next; \
425 * Circular queue definitions.
427 #define CIRCLEQ_HEAD(name, type) \
429 struct type *cqh_first; /* first element */ \
430 struct type *cqh_last; /* last element */ \
433 #define CIRCLEQ_ENTRY(type) \
435 struct type *cqe_next; /* next element */ \
436 struct type *cqe_prev; /* previous element */ \
440 * Circular queue functions.
442 #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head))
444 #define CIRCLEQ_FIRST(head) ((head)->cqh_first)
446 #define CIRCLEQ_FOREACH(var, head, field) \
447 for((var) = (head)->cqh_first; \
448 (var) != (void *)(head); \
449 (var) = (var)->field.cqe_next)
451 #define CIRCLEQ_FOREACH_REVERSE(var, head, field) \
452 for((var) = (head)->cqh_last; \
453 (var) != (void *)(head); \
454 (var) = (var)->field.cqe_prev)
456 #define CIRCLEQ_INIT(head) do { \
457 (head)->cqh_first = (void *)(head); \
458 (head)->cqh_last = (void *)(head); \
461 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
462 (elm)->field.cqe_next = (listelm)->field.cqe_next; \
463 (elm)->field.cqe_prev = (listelm); \
464 if ((listelm)->field.cqe_next == (void *)(head)) \
465 (head)->cqh_last = (elm); \
467 (listelm)->field.cqe_next->field.cqe_prev = (elm); \
468 (listelm)->field.cqe_next = (elm); \
471 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \
472 (elm)->field.cqe_next = (listelm); \
473 (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \
474 if ((listelm)->field.cqe_prev == (void *)(head)) \
475 (head)->cqh_first = (elm); \
477 (listelm)->field.cqe_prev->field.cqe_next = (elm); \
478 (listelm)->field.cqe_prev = (elm); \
481 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \
482 (elm)->field.cqe_next = (head)->cqh_first; \
483 (elm)->field.cqe_prev = (void *)(head); \
484 if ((head)->cqh_last == (void *)(head)) \
485 (head)->cqh_last = (elm); \
487 (head)->cqh_first->field.cqe_prev = (elm); \
488 (head)->cqh_first = (elm); \
491 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \
492 (elm)->field.cqe_next = (void *)(head); \
493 (elm)->field.cqe_prev = (head)->cqh_last; \
494 if ((head)->cqh_first == (void *)(head)) \
495 (head)->cqh_first = (elm); \
497 (head)->cqh_last->field.cqe_next = (elm); \
498 (head)->cqh_last = (elm); \
501 #define CIRCLEQ_LAST(head) ((head)->cqh_last)
503 #define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next)
505 #define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev)
507 #define CIRCLEQ_REMOVE(head, elm, field) do { \
508 if ((elm)->field.cqe_next == (void *)(head)) \
509 (head)->cqh_last = (elm)->field.cqe_prev; \
511 (elm)->field.cqe_next->field.cqe_prev = \
512 (elm)->field.cqe_prev; \
513 if ((elm)->field.cqe_prev == (void *)(head)) \
514 (head)->cqh_first = (elm)->field.cqe_next; \
516 (elm)->field.cqe_prev->field.cqe_next = \
517 (elm)->field.cqe_next; \
520 #endif /* !_SYS_QUEUE_H_ */