libevent/compat/sys/queue.h

   1 /*      $OpenBSD: queue.h,v 1.16 2000/09/07 19:47:59 art Exp $  */
   2 /*      $NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $       */
   3
   4 /*
   5  * Copyright (c) 1991, 1993
   6  *      The Regents of the University of California.  All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  *      @(#)queue.h     8.5 (Berkeley) 8/20/94
  33  */
  34
  35 #ifndef _SYS_QUEUE_H_
  36 #define _SYS_QUEUE_H_
  37
  38 /*
  39  * This file defines five types of data structures: singly-linked lists,
  40  * lists, simple queues, tail queues, and circular queues.
  41  *
  42  *
  43  * A singly-linked list is headed by a single forward pointer. The elements
  44  * are singly linked for minimum space and pointer manipulation overhead at
  45  * the expense of O(n) removal for arbitrary elements. New elements can be
  46  * added to the list after an existing element or at the head of the list.
  47  * Elements being removed from the head of the list should use the explicit
  48  * macro for this purpose for optimum efficiency. A singly-linked list may
  49  * only be traversed in the forward direction.  Singly-linked lists are ideal
  50  * for applications with large datasets and few or no removals or for
  51  * implementing a LIFO queue.
  52  *
  53  * A list is headed by a single forward pointer (or an array of forward
  54  * pointers for a hash table header). The elements are doubly linked
  55  * so that an arbitrary element can be removed without a need to
  56  * traverse the list. New elements can be added to the list before
  57  * or after an existing element or at the head of the list. A list
  58  * may only be traversed in the forward direction.
  59  *
  60  * A simple queue is headed by a pair of pointers, one the head of the
  61  * list and the other to the tail of the list. The elements are singly
  62  * linked to save space, so elements can only be removed from the
  63  * head of the list. New elements can be added to the list before or after
  64  * an existing element, at the head of the list, or at the end of the
  65  * list. A simple queue may only be traversed in the forward direction.
  66  *
  67  * A tail queue is headed by a pair of pointers, one to the head of the
  68  * list and the other to the tail of the list. The elements are doubly
  69  * linked so that an arbitrary element can be removed without a need to
  70  * traverse the list. New elements can be added to the list before or
  71  * after an existing element, at the head of the list, or at the end of
  72  * the list. A tail queue may be traversed in either direction.
  73  *
  74  * A circle queue is headed by a pair of pointers, one to the head of the
  75  * list and the other to the tail of the list. The elements are doubly
  76  * linked so that an arbitrary element can be removed without a need to
  77  * traverse the list. New elements can be added to the list before or after
  78  * an existing element, at the head of the list, or at the end of the list.
  79  * A circle queue may be traversed in either direction, but has a more
  80  * complex end of list detection.
  81  *
  82  * For details on the use of these macros, see the queue(3) manual page.
  83  */
  84
  85 /*
  86  * Singly-linked List definitions.
  87  */
  88 #define SLIST_HEAD(name, type)                                          \
  89 struct name {                                                           \
  90         struct type *slh_first; /* first element */                     \
  91 }
  92
  93 #define SLIST_HEAD_INITIALIZER(head)                                    \
  94         { NULL }
  95
  96 #ifndef WIN32
  97 #define SLIST_ENTRY(type)                                               \
  98 struct {                                                                \
  99         struct type *sle_next;  /* next element */                      \
 100 }
 101 #endif
 102
 103 /*
 104  * Singly-linked List access methods.
 105  */
 106 #define SLIST_FIRST(head)       ((head)->slh_first)
 107 #define SLIST_END(head)         NULL
 108 #define SLIST_EMPTY(head)       (SLIST_FIRST(head) == SLIST_END(head))
 109 #define SLIST_NEXT(elm, field)  ((elm)->field.sle_next)
 110
 111 #define SLIST_FOREACH(var, head, field)                                 \
 112         for((var) = SLIST_FIRST(head);                                  \
 113             (var) != SLIST_END(head);                                   \
 114             (var) = SLIST_NEXT(var, field))
 115
 116 /*
 117  * Singly-linked List functions.
 118  */
 119 #define SLIST_INIT(head) {                                              \
 120         SLIST_FIRST(head) = SLIST_END(head);                            \
 121 }
 122
 123 #define SLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
 124         (elm)->field.sle_next = (slistelm)->field.sle_next;             \
 125         (slistelm)->field.sle_next = (elm);                             \
 126 } while (0)
 127
 128 #define SLIST_INSERT_HEAD(head, elm, field) do {                        \
 129         (elm)->field.sle_next = (head)->slh_first;                      \
 130         (head)->slh_first = (elm);                                      \
 131 } while (0)
 132
 133 #define SLIST_REMOVE_HEAD(head, field) do {                             \
 134         (head)->slh_first = (head)->slh_first->field.sle_next;          \
 135 } while (0)
 136
 137 /*
 138  * List definitions.
 139  */
 140 #define LIST_HEAD(name, type)                                           \
 141 struct name {                                                           \
 142         struct type *lh_first;  /* first element */                     \
 143 }
 144
 145 #define LIST_HEAD_INITIALIZER(head)                                     \
 146         { NULL }
 147
 148 #define LIST_ENTRY(type)                                                \
 149 struct {                                                                \
 150         struct type *le_next;   /* next element */                      \
 151         struct type **le_prev;  /* address of previous next element */  \
 152 }
 153
 154 /*
 155  * List access methods
 156  */
 157 #define LIST_FIRST(head)                ((head)->lh_first)
 158 #define LIST_END(head)                  NULL
 159 #define LIST_EMPTY(head)                (LIST_FIRST(head) == LIST_END(head))
 160 #define LIST_NEXT(elm, field)           ((elm)->field.le_next)
 161
 162 #define LIST_FOREACH(var, head, field)                                  \
 163         for((var) = LIST_FIRST(head);                                   \
 164             (var)!= LIST_END(head);                                     \
 165             (var) = LIST_NEXT(var, field))
 166
 167 /*
 168  * List functions.
 169  */
 170 #define LIST_INIT(head) do {                                            \
 171         LIST_FIRST(head) = LIST_END(head);                              \
 172 } while (0)
 173
 174 #define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
 175         if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)  \
 176                 (listelm)->field.le_next->field.le_prev =               \
 177                     &(elm)->field.le_next;                              \
 178         (listelm)->field.le_next = (elm);                               \
 179         (elm)->field.le_prev = &(listelm)->field.le_next;               \
 180 } while (0)
 181
 182 #define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
 183         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 184         (elm)->field.le_next = (listelm);                               \
 185         *(listelm)->field.le_prev = (elm);                              \
 186         (listelm)->field.le_prev = &(elm)->field.le_next;               \
 187 } while (0)
 188
 189 #define LIST_INSERT_HEAD(head, elm, field) do {                         \
 190         if (((elm)->field.le_next = (head)->lh_first) != NULL)          \
 191                 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
 192         (head)->lh_first = (elm);                                       \
 193         (elm)->field.le_prev = &(head)->lh_first;                       \
 194 } while (0)
 195
 196 #define LIST_REMOVE(elm, field) do {                                    \
 197         if ((elm)->field.le_next != NULL)                               \
 198                 (elm)->field.le_next->field.le_prev =                   \
 199                     (elm)->field.le_prev;                               \
 200         *(elm)->field.le_prev = (elm)->field.le_next;                   \
 201 } while (0)
 202
 203 #define LIST_REPLACE(elm, elm2, field) do {                             \
 204         if (((elm2)->field.le_next = (elm)->field.le_next) != NULL)     \
 205                 (elm2)->field.le_next->field.le_prev =                  \
 206                     &(elm2)->field.le_next;                             \
 207         (elm2)->field.le_prev = (elm)->field.le_prev;                   \
 208         *(elm2)->field.le_prev = (elm2);                                \
 209 } while (0)
 210
 211 /*
 212  * Simple queue definitions.
 213  */
 214 #define SIMPLEQ_HEAD(name, type)                                        \
 215 struct name {                                                           \
 216         struct type *sqh_first; /* first element */                     \
 217         struct type **sqh_last; /* addr of last next element */         \
 218 }
 219
 220 #define SIMPLEQ_HEAD_INITIALIZER(head)                                  \
 221         { NULL, &(head).sqh_first }
 222
 223 #define SIMPLEQ_ENTRY(type)                                             \
 224 struct {                                                                \
 225         struct type *sqe_next;  /* next element */                      \
 226 }
 227
 228 /*
 229  * Simple queue access methods.
 230  */
 231 #define SIMPLEQ_FIRST(head)         ((head)->sqh_first)
 232 #define SIMPLEQ_END(head)           NULL
 233 #define SIMPLEQ_EMPTY(head)         (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
 234 #define SIMPLEQ_NEXT(elm, field)    ((elm)->field.sqe_next)
 235
 236 #define SIMPLEQ_FOREACH(var, head, field)                               \
 237         for((var) = SIMPLEQ_FIRST(head);                                \
 238             (var) != SIMPLEQ_END(head);                                 \
 239             (var) = SIMPLEQ_NEXT(var, field))
 240
 241 /*
 242  * Simple queue functions.
 243  */
 244 #define SIMPLEQ_INIT(head) do {                                         \
 245         (head)->sqh_first = NULL;                                       \
 246         (head)->sqh_last = &(head)->sqh_first;                          \
 247 } while (0)
 248
 249 #define SIMPLEQ_INSERT_HEAD(head, elm, field) do {                      \
 250         if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)        \
 251                 (head)->sqh_last = &(elm)->field.sqe_next;              \
 252         (head)->sqh_first = (elm);                                      \
 253 } while (0)
 254
 255 #define SIMPLEQ_INSERT_TAIL(head, elm, field) do {                      \
 256         (elm)->field.sqe_next = NULL;                                   \
 257         *(head)->sqh_last = (elm);                                      \
 258         (head)->sqh_last = &(elm)->field.sqe_next;                      \
 259 } while (0)
 260
 261 #define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {            \
 262         if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
 263                 (head)->sqh_last = &(elm)->field.sqe_next;              \
 264         (listelm)->field.sqe_next = (elm);                              \
 265 } while (0)
 266
 267 #define SIMPLEQ_REMOVE_HEAD(head, elm, field) do {                      \
 268         if (((head)->sqh_first = (elm)->field.sqe_next) == NULL)        \
 269                 (head)->sqh_last = &(head)->sqh_first;                  \
 270 } while (0)
 271
 272 /*
 273  * Tail queue definitions.
 274  */
 275 #define TAILQ_HEAD(name, type)                                          \
 276 struct name {                                                           \
 277         struct type *tqh_first; /* first element */                     \
 278         struct type **tqh_last; /* addr of last next element */         \
 279 }
 280
 281 #define TAILQ_HEAD_INITIALIZER(head)                                    \
 282         { NULL, &(head).tqh_first }
 283
 284 #define TAILQ_ENTRY(type)                                               \
 285 struct {                                                                \
 286         struct type *tqe_next;  /* next element */                      \
 287         struct type **tqe_prev; /* address of previous next element */  \
 288 }
 289
 290 /*
 291  * tail queue access methods
 292  */
 293 #define TAILQ_FIRST(head)               ((head)->tqh_first)
 294 #define TAILQ_END(head)                 NULL
 295 #define TAILQ_NEXT(elm, field)          ((elm)->field.tqe_next)
 296 #define TAILQ_LAST(head, headname)                                      \
 297         (*(((struct headname *)((head)->tqh_last))->tqh_last))
 298 /* XXX */
 299 #define TAILQ_PREV(elm, headname, field)                                \
 300         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 301 #define TAILQ_EMPTY(head)                                               \
 302         (TAILQ_FIRST(head) == TAILQ_END(head))
 303
 304 #define TAILQ_FOREACH(var, head, field)                                 \
 305         for((var) = TAILQ_FIRST(head);                                  \
 306             (var) != TAILQ_END(head);                                   \
 307             (var) = TAILQ_NEXT(var, field))
 308
 309 #define TAILQ_FOREACH_REVERSE(var, head, headname, field)               \
 310         for((var) = TAILQ_LAST(head, headname);                         \
 311             (var) != TAILQ_END(head);                                   \
 312             (var) = TAILQ_PREV(var, headname, field))
 313
 314 /*
 315  * Tail queue functions.
 316  */
 317 #define TAILQ_INIT(head) do {                                           \
 318         (head)->tqh_first = NULL;                                       \
 319         (head)->tqh_last = &(head)->tqh_first;                          \
 320 } while (0)
 321
 322 #define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
 323         if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
 324                 (head)->tqh_first->field.tqe_prev =                     \
 325                     &(elm)->field.tqe_next;                             \
 326         else                                                            \
 327                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 328         (head)->tqh_first = (elm);                                      \
 329         (elm)->field.tqe_prev = &(head)->tqh_first;                     \
 330 } while (0)
 331
 332 #define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
 333         (elm)->field.tqe_next = NULL;                                   \
 334         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 335         *(head)->tqh_last = (elm);                                      \
 336         (head)->tqh_last = &(elm)->field.tqe_next;                      \
 337 } while (0)
 338
 339 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {              \
 340         if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
 341                 (elm)->field.tqe_next->field.tqe_prev =                 \
 342                     &(elm)->field.tqe_next;                             \
 343         else                                                            \
 344                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 345         (listelm)->field.tqe_next = (elm);                              \
 346         (elm)->field.tqe_prev = &(listelm)->field.tqe_next;             \
 347 } while (0)
 348
 349 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
 350         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 351         (elm)->field.tqe_next = (listelm);                              \
 352         *(listelm)->field.tqe_prev = (elm);                             \
 353         (listelm)->field.tqe_prev = &(elm)->field.tqe_next;             \
 354 } while (0)
 355
 356 #define TAILQ_REMOVE(head, elm, field) do {                             \
 357         if (((elm)->field.tqe_next) != NULL)                            \
 358                 (elm)->field.tqe_next->field.tqe_prev =                 \
 359                     (elm)->field.tqe_prev;                              \
 360         else                                                            \
 361                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 362         *(elm)->field.tqe_prev = (elm)->field.tqe_next;                 \
 363 } while (0)
 364
 365 #define TAILQ_REPLACE(head, elm, elm2, field) do {                      \
 366         if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL)   \
 367                 (elm2)->field.tqe_next->field.tqe_prev =                \
 368                     &(elm2)->field.tqe_next;                            \
 369         else                                                            \
 370                 (head)->tqh_last = &(elm2)->field.tqe_next;             \
 371         (elm2)->field.tqe_prev = (elm)->field.tqe_prev;                 \
 372         *(elm2)->field.tqe_prev = (elm2);                               \
 373 } while (0)
 374
 375 /*
 376  * Circular queue definitions.
 377  */
 378 #define CIRCLEQ_HEAD(name, type)                                        \
 379 struct name {                                                           \
 380         struct type *cqh_first;         /* first element */             \
 381         struct type *cqh_last;          /* last element */              \
 382 }
 383
 384 #define CIRCLEQ_HEAD_INITIALIZER(head)                                  \
 385         { CIRCLEQ_END(&head), CIRCLEQ_END(&head) }
 386
 387 #define CIRCLEQ_ENTRY(type)                                             \
 388 struct {                                                                \
 389         struct type *cqe_next;          /* next element */              \
 390         struct type *cqe_prev;          /* previous element */          \
 391 }
 392
 393 /*
 394  * Circular queue access methods
 395  */
 396 #define CIRCLEQ_FIRST(head)             ((head)->cqh_first)
 397 #define CIRCLEQ_LAST(head)              ((head)->cqh_last)
 398 #define CIRCLEQ_END(head)               ((void *)(head))
 399 #define CIRCLEQ_NEXT(elm, field)        ((elm)->field.cqe_next)
 400 #define CIRCLEQ_PREV(elm, field)        ((elm)->field.cqe_prev)
 401 #define CIRCLEQ_EMPTY(head)                                             \
 402         (CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))
 403
 404 #define CIRCLEQ_FOREACH(var, head, field)                               \
 405         for((var) = CIRCLEQ_FIRST(head);                                \
 406             (var) != CIRCLEQ_END(head);                                 \
 407             (var) = CIRCLEQ_NEXT(var, field))
 408
 409 #define CIRCLEQ_FOREACH_REVERSE(var, head, field)                       \
 410         for((var) = CIRCLEQ_LAST(head);                                 \
 411             (var) != CIRCLEQ_END(head);                                 \
 412             (var) = CIRCLEQ_PREV(var, field))
 413
 414 /*
 415  * Circular queue functions.
 416  */
 417 #define CIRCLEQ_INIT(head) do {                                         \
 418         (head)->cqh_first = CIRCLEQ_END(head);                          \
 419         (head)->cqh_last = CIRCLEQ_END(head);                           \
 420 } while (0)
 421
 422 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {            \
 423         (elm)->field.cqe_next = (listelm)->field.cqe_next;              \
 424         (elm)->field.cqe_prev = (listelm);                              \
 425         if ((listelm)->field.cqe_next == CIRCLEQ_END(head))             \
 426                 (head)->cqh_last = (elm);                               \
 427         else                                                            \
 428                 (listelm)->field.cqe_next->field.cqe_prev = (elm);      \
 429         (listelm)->field.cqe_next = (elm);                              \
 430 } while (0)
 431
 432 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {           \
 433         (elm)->field.cqe_next = (listelm);                              \
 434         (elm)->field.cqe_prev = (listelm)->field.cqe_prev;              \
 435         if ((listelm)->field.cqe_prev == CIRCLEQ_END(head))             \
 436                 (head)->cqh_first = (elm);                              \
 437         else                                                            \
 438                 (listelm)->field.cqe_prev->field.cqe_next = (elm);      \
 439         (listelm)->field.cqe_prev = (elm);                              \
 440 } while (0)
 441
 442 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do {                      \
 443         (elm)->field.cqe_next = (head)->cqh_first;                      \
 444         (elm)->field.cqe_prev = CIRCLEQ_END(head);                      \
 445         if ((head)->cqh_last == CIRCLEQ_END(head))                      \
 446                 (head)->cqh_last = (elm);                               \
 447         else                                                            \
 448                 (head)->cqh_first->field.cqe_prev = (elm);              \
 449         (head)->cqh_first = (elm);                                      \
 450 } while (0)
 451
 452 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do {                      \
 453         (elm)->field.cqe_next = CIRCLEQ_END(head);                      \
 454         (elm)->field.cqe_prev = (head)->cqh_last;                       \
 455         if ((head)->cqh_first == CIRCLEQ_END(head))                     \
 456                 (head)->cqh_first = (elm);                              \
 457         else                                                            \
 458                 (head)->cqh_last->field.cqe_next = (elm);               \
 459         (head)->cqh_last = (elm);                                       \
 460 } while (0)
 461
 462 #define CIRCLEQ_REMOVE(head, elm, field) do {                           \
 463         if ((elm)->field.cqe_next == CIRCLEQ_END(head))                 \
 464                 (head)->cqh_last = (elm)->field.cqe_prev;               \
 465         else                                                            \
 466                 (elm)->field.cqe_next->field.cqe_prev =                 \
 467                     (elm)->field.cqe_prev;                              \
 468         if ((elm)->field.cqe_prev == CIRCLEQ_END(head))                 \
 469                 (head)->cqh_first = (elm)->field.cqe_next;              \
 470         else                                                            \
 471                 (elm)->field.cqe_prev->field.cqe_next =                 \
 472                     (elm)->field.cqe_next;                              \
 473 } while (0)
 474
 475 #define CIRCLEQ_REPLACE(head, elm, elm2, field) do {                    \
 476         if (((elm2)->field.cqe_next = (elm)->field.cqe_next) ==         \
 477             CIRCLEQ_END(head))                                          \
 478                 (head).cqh_last = (elm2);                               \
 479         else                                                            \
 480                 (elm2)->field.cqe_next->field.cqe_prev = (elm2);        \
 481         if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) ==         \
 482             CIRCLEQ_END(head))                                          \
 483                 (head).cqh_first = (elm2);                              \
 484         else                                                            \
 485                 (elm2)->field.cqe_prev->field.cqe_next = (elm2);        \
 486 } while (0)
 487
 488 #endif  /* !_SYS_QUEUE_H_ */