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 */
13 * Copyright (c) 1991, 1993
14 * The Regents of the University of California. All rights reserved.
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
19 * 1. Redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer.
21 * 2. Redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution.
24 * 3. All advertising materials mentioning features or use of this software
25 * must display the following acknowledgement:
26 * This product includes software developed by the University of
27 * California, Berkeley and its contributors.
28 * 4. Neither the name of the University nor the names of its contributors
29 * may be used to endorse or promote products derived from this software
30 * without specific prior written permission.
32 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
33 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
34 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
35 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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37 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
38 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
39 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
40 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
41 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
44 * @(#)queue.h 8.5 (Berkeley) 8/20/94
45 * $FreeBSD: src/sys/sys/queue.h,v 1.32.2.5 2001/09/30 21:12:54 luigi Exp $
51 #define __offsetof offsetof
54 * This file defines five types of data structures: singly-linked lists,
55 * singly-linked tail queues, lists, tail queues, and circular queues.
57 * A singly-linked list is headed by a single forward pointer. The elements
58 * are singly linked for minimum space and pointer manipulation overhead at
59 * the expense of O(n) removal for arbitrary elements. New elements can be
60 * added to the list after an existing element or at the head of the list.
61 * Elements being removed from the head of the list should use the explicit
62 * macro for this purpose for optimum efficiency. A singly-linked list may
63 * only be traversed in the forward direction. Singly-linked lists are ideal
64 * for applications with large datasets and few or no removals or for
65 * implementing a LIFO queue.
67 * A singly-linked tail queue is headed by a pair of pointers, one to the
68 * head of the list and the other to the tail of the list. The elements are
69 * singly linked for minimum space and pointer manipulation overhead at the
70 * expense of O(n) removal for arbitrary elements. New elements can be added
71 * to the list after an existing element, at the head of the list, or at the
72 * end of the list. Elements being removed from the head of the tail queue
73 * should use the explicit macro for this purpose for optimum efficiency.
74 * A singly-linked tail queue may only be traversed in the forward direction.
75 * Singly-linked tail queues are ideal for applications with large datasets
76 * and few or no removals or for implementing a FIFO queue.
78 * A list is headed by a single forward pointer (or an array of forward
79 * pointers for a hash table header). The elements are doubly linked
80 * so that an arbitrary element can be removed without a need to
81 * traverse the list. New elements can be added to the list before
82 * or after an existing element or at the head of the list. A list
83 * may only be traversed in the forward direction.
85 * A tail queue is headed by a pair of pointers, one to the head of the
86 * list and the other to the tail of the list. The elements are doubly
87 * linked so that an arbitrary element can be removed without a need to
88 * traverse the list. New elements can be added to the list before or
89 * after an existing element, at the head of the list, or at the end of
90 * the list. A tail queue may be traversed in either direction.
92 * A circle queue is headed by a pair of pointers, one to the head of the
93 * list and the other to the tail of the list. The elements are doubly
94 * linked so that an arbitrary element can be removed without a need to
95 * traverse the list. New elements can be added to the list before or after
96 * an existing element, at the head of the list, or at the end of the list.
97 * A circle queue may be traversed in either direction, but has a more
98 * complex end of list detection.
100 * For details on the use of these macros, see the queue(3) manual page.
103 * SLIST LIST STAILQ TAILQ CIRCLEQ
113 * _FOREACH_REVERSE - - - + +
114 * _INSERT_HEAD + + + + +
115 * _INSERT_BEFORE - + - + +
116 * _INSERT_AFTER + + + + +
117 * _INSERT_TAIL - - + + +
118 * _REMOVE_HEAD + - + - -
124 * Singly-linked List definitions.
126 #define SLIST_HEAD(name, type) \
128 struct type *slh_first; /* first element */ \
131 #define SLIST_HEAD_INITIALIZER(head) \
134 #define SLIST_ENTRY(type) \
136 struct type *sle_next; /* next element */ \
140 * Singly-linked List functions.
142 #define SLIST_EMPTY(head) ((head)->slh_first == NULL)
144 #define SLIST_FIRST(head) ((head)->slh_first)
146 #define SLIST_FOREACH(var, head, field) \
147 for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
149 #define SLIST_INIT(head) { \
150 (head)->slh_first = NULL; \
153 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
154 (elm)->field.sle_next = (slistelm)->field.sle_next; \
155 (slistelm)->field.sle_next = (elm); \
158 #define SLIST_INSERT_HEAD(head, elm, field) do { \
159 (elm)->field.sle_next = (head)->slh_first; \
160 (head)->slh_first = (elm); \
163 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
165 #define SLIST_REMOVE_HEAD(head, field) do { \
166 (head)->slh_first = (head)->slh_first->field.sle_next; \
169 #define SLIST_REMOVE(head, elm, type, field) do { \
170 if ((head)->slh_first == (elm)) { \
171 SLIST_REMOVE_HEAD((head), field); \
174 struct type *curelm = (head)->slh_first; \
175 while( curelm->field.sle_next != (elm) ) \
176 curelm = curelm->field.sle_next; \
177 curelm->field.sle_next = \
178 curelm->field.sle_next->field.sle_next; \
183 * Singly-linked Tail queue definitions.
185 #define STAILQ_HEAD(name, type) \
187 struct type *stqh_first;/* first element */ \
188 struct type **stqh_last;/* addr of last next element */ \
191 #define STAILQ_HEAD_INITIALIZER(head) \
192 { NULL, &(head).stqh_first }
194 #define STAILQ_ENTRY(type) \
196 struct type *stqe_next; /* next element */ \
200 * Singly-linked Tail queue functions.
202 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
204 #define STAILQ_INIT(head) do { \
205 (head)->stqh_first = NULL; \
206 (head)->stqh_last = &(head)->stqh_first; \
209 #define STAILQ_FIRST(head) ((head)->stqh_first)
211 #define STAILQ_LAST(head, type, field) \
212 (STAILQ_EMPTY(head) ? \
215 ((char *)((head)->stqh_last) - __offsetof(struct type, field))))
217 #define STAILQ_FOREACH(var, head, field) \
218 for((var) = (head)->stqh_first; (var); (var) = (var)->field.stqe_next)
220 #define STAILQ_INSERT_HEAD(head, elm, field) do { \
221 if (((elm)->field.stqe_next = (head)->stqh_first) == NULL) \
222 (head)->stqh_last = &(elm)->field.stqe_next; \
223 (head)->stqh_first = (elm); \
226 #define STAILQ_INSERT_TAIL(head, elm, field) do { \
227 (elm)->field.stqe_next = NULL; \
228 *(head)->stqh_last = (elm); \
229 (head)->stqh_last = &(elm)->field.stqe_next; \
232 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
233 if (((elm)->field.stqe_next = (tqelm)->field.stqe_next) == NULL)\
234 (head)->stqh_last = &(elm)->field.stqe_next; \
235 (tqelm)->field.stqe_next = (elm); \
238 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
240 #define STAILQ_REMOVE_HEAD(head, field) do { \
241 if (((head)->stqh_first = \
242 (head)->stqh_first->field.stqe_next) == NULL) \
243 (head)->stqh_last = &(head)->stqh_first; \
246 #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do { \
247 if (((head)->stqh_first = (elm)->field.stqe_next) == NULL) \
248 (head)->stqh_last = &(head)->stqh_first; \
251 #define STAILQ_REMOVE(head, elm, type, field) do { \
252 if ((head)->stqh_first == (elm)) { \
253 STAILQ_REMOVE_HEAD(head, field); \
256 struct type *curelm = (head)->stqh_first; \
257 while( curelm->field.stqe_next != (elm) ) \
258 curelm = curelm->field.stqe_next; \
259 if((curelm->field.stqe_next = \
260 curelm->field.stqe_next->field.stqe_next) == NULL) \
261 (head)->stqh_last = &(curelm)->field.stqe_next; \
268 #define LIST_HEAD(name, type) \
270 struct type *lh_first; /* first element */ \
273 #define LIST_HEAD_INITIALIZER(head) \
276 #define LIST_ENTRY(type) \
278 struct type *le_next; /* next element */ \
279 struct type **le_prev; /* address of previous next element */ \
286 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
288 #define LIST_FIRST(head) ((head)->lh_first)
290 #define LIST_FOREACH(var, head, field) \
291 for((var) = (head)->lh_first; (var); (var) = (var)->field.le_next)
293 #define LIST_INIT(head) do { \
294 (head)->lh_first = NULL; \
297 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
298 if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
299 (listelm)->field.le_next->field.le_prev = \
300 &(elm)->field.le_next; \
301 (listelm)->field.le_next = (elm); \
302 (elm)->field.le_prev = &(listelm)->field.le_next; \
305 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
306 (elm)->field.le_prev = (listelm)->field.le_prev; \
307 (elm)->field.le_next = (listelm); \
308 *(listelm)->field.le_prev = (elm); \
309 (listelm)->field.le_prev = &(elm)->field.le_next; \
312 #define LIST_INSERT_HEAD(head, elm, field) do { \
313 if (((elm)->field.le_next = (head)->lh_first) != NULL) \
314 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
315 (head)->lh_first = (elm); \
316 (elm)->field.le_prev = &(head)->lh_first; \
319 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
321 #define LIST_REMOVE(elm, field) do { \
322 if ((elm)->field.le_next != NULL) \
323 (elm)->field.le_next->field.le_prev = \
324 (elm)->field.le_prev; \
325 *(elm)->field.le_prev = (elm)->field.le_next; \
329 * Tail queue definitions.
331 #define TAILQ_HEAD(name, type) \
333 struct type *tqh_first; /* first element */ \
334 struct type **tqh_last; /* addr of last next element */ \
337 #define TAILQ_HEAD_INITIALIZER(head) \
338 { NULL, &(head).tqh_first }
340 #define TAILQ_ENTRY(type) \
342 struct type *tqe_next; /* next element */ \
343 struct type **tqe_prev; /* address of previous next element */ \
347 * Tail queue functions.
349 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
351 #define TAILQ_FOREACH(var, head, field) \
352 for (var = TAILQ_FIRST(head); var; var = TAILQ_NEXT(var, field))
354 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
355 for ((var) = TAILQ_LAST((head), headname); \
357 (var) = TAILQ_PREV((var), headname, field))
359 #define TAILQ_FIRST(head) ((head)->tqh_first)
361 #define TAILQ_LAST(head, headname) \
362 (*(((struct headname *)((head)->tqh_last))->tqh_last))
364 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
366 #define TAILQ_PREV(elm, headname, field) \
367 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
369 #define TAILQ_INIT(head) do { \
370 (head)->tqh_first = NULL; \
371 (head)->tqh_last = &(head)->tqh_first; \
374 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
375 if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
376 (head)->tqh_first->field.tqe_prev = \
377 &(elm)->field.tqe_next; \
379 (head)->tqh_last = &(elm)->field.tqe_next; \
380 (head)->tqh_first = (elm); \
381 (elm)->field.tqe_prev = &(head)->tqh_first; \
384 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
385 (elm)->field.tqe_next = NULL; \
386 (elm)->field.tqe_prev = (head)->tqh_last; \
387 *(head)->tqh_last = (elm); \
388 (head)->tqh_last = &(elm)->field.tqe_next; \
391 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
392 if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
393 (elm)->field.tqe_next->field.tqe_prev = \
394 &(elm)->field.tqe_next; \
396 (head)->tqh_last = &(elm)->field.tqe_next; \
397 (listelm)->field.tqe_next = (elm); \
398 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
401 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
402 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
403 (elm)->field.tqe_next = (listelm); \
404 *(listelm)->field.tqe_prev = (elm); \
405 (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
408 #define TAILQ_REMOVE(head, elm, field) do { \
409 if (((elm)->field.tqe_next) != NULL) \
410 (elm)->field.tqe_next->field.tqe_prev = \
411 (elm)->field.tqe_prev; \
413 (head)->tqh_last = (elm)->field.tqe_prev; \
414 *(elm)->field.tqe_prev = (elm)->field.tqe_next; \
418 * Circular queue definitions.
420 #define CIRCLEQ_HEAD(name, type) \
422 struct type *cqh_first; /* first element */ \
423 struct type *cqh_last; /* last element */ \
426 #define CIRCLEQ_ENTRY(type) \
428 struct type *cqe_next; /* next element */ \
429 struct type *cqe_prev; /* previous element */ \
433 * Circular queue functions.
435 #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head))
437 #define CIRCLEQ_FIRST(head) ((head)->cqh_first)
439 #define CIRCLEQ_FOREACH(var, head, field) \
440 for((var) = (head)->cqh_first; \
441 (var) != (void *)(head); \
442 (var) = (var)->field.cqe_next)
444 #define CIRCLEQ_FOREACH_REVERSE(var, head, field) \
445 for((var) = (head)->cqh_last; \
446 (var) != (void *)(head); \
447 (var) = (var)->field.cqe_prev)
449 #define CIRCLEQ_INIT(head) do { \
450 (head)->cqh_first = (void *)(head); \
451 (head)->cqh_last = (void *)(head); \
454 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
455 (elm)->field.cqe_next = (listelm)->field.cqe_next; \
456 (elm)->field.cqe_prev = (listelm); \
457 if ((listelm)->field.cqe_next == (void *)(head)) \
458 (head)->cqh_last = (elm); \
460 (listelm)->field.cqe_next->field.cqe_prev = (elm); \
461 (listelm)->field.cqe_next = (elm); \
464 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \
465 (elm)->field.cqe_next = (listelm); \
466 (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \
467 if ((listelm)->field.cqe_prev == (void *)(head)) \
468 (head)->cqh_first = (elm); \
470 (listelm)->field.cqe_prev->field.cqe_next = (elm); \
471 (listelm)->field.cqe_prev = (elm); \
474 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \
475 (elm)->field.cqe_next = (head)->cqh_first; \
476 (elm)->field.cqe_prev = (void *)(head); \
477 if ((head)->cqh_last == (void *)(head)) \
478 (head)->cqh_last = (elm); \
480 (head)->cqh_first->field.cqe_prev = (elm); \
481 (head)->cqh_first = (elm); \
484 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \
485 (elm)->field.cqe_next = (void *)(head); \
486 (elm)->field.cqe_prev = (head)->cqh_last; \
487 if ((head)->cqh_first == (void *)(head)) \
488 (head)->cqh_first = (elm); \
490 (head)->cqh_last->field.cqe_next = (elm); \
491 (head)->cqh_last = (elm); \
494 #define CIRCLEQ_LAST(head) ((head)->cqh_last)
496 #define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next)
498 #define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev)
500 #define CIRCLEQ_REMOVE(head, elm, field) do { \
501 if ((elm)->field.cqe_next == (void *)(head)) \
502 (head)->cqh_last = (elm)->field.cqe_prev; \
504 (elm)->field.cqe_next->field.cqe_prev = \
505 (elm)->field.cqe_prev; \
506 if ((elm)->field.cqe_prev == (void *)(head)) \
507 (head)->cqh_first = (elm)->field.cqe_next; \
509 (elm)->field.cqe_prev->field.cqe_next = \
510 (elm)->field.cqe_next; \
513 #endif /* !_SYS_QUEUE_H_ */