contrib/sendmail/include/sm/tailq.h

   1 /*      $OpenBSD: queue.h,v 1.30 2005/10/25 06:37:47 otto 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 SM_TAILQ_H_
  36 #define SM_TAILQ_H_
  37
  38 /*
  39  * $Id: tailq.h,v 1.3 2012/01/21 00:12:14 ashish Exp $
  40  *
  41  * This file is a modified copy of queue.h from a BSD system:
  42  * we only need tail queues here.
  43  * We do not use queue.h directly because there is a conflict with
  44  * some versions of that file on some OSs.
  45  *
  46  * A tail queue is headed by a pair of pointers, one to the head of the
  47  * list and the other to the tail of the list. The elements are doubly
  48  * linked so that an arbitrary element can be removed without a need to
  49  * traverse the list. New elements can be added to the list before or
  50  * after an existing element, at the head of the list, or at the end of
  51  * the list. A tail queue may be traversed in either direction.
  52  */
  53
  54 /*
  55  * Tail queue definitions.
  56  */
  57 #define SM_TAILQ_HEAD(name, type)                                       \
  58 struct name {                                                           \
  59         struct type *tqh_first; /* first element */                     \
  60         struct type **tqh_last; /* addr of last next element */         \
  61 }
  62
  63 #define SM_TAILQ_HEAD_INITIALIZER(head)                                 \
  64         { NULL, &(head).tqh_first }
  65
  66 #define SM_TAILQ_ENTRY(type)                                            \
  67 struct {                                                                \
  68         struct type *tqe_next;  /* next element */                      \
  69         struct type **tqe_prev; /* address of previous next element */  \
  70 }
  71
  72 /*
  73  * tail queue access methods
  74  */
  75 #define SM_TAILQ_FIRST(head)            ((head)->tqh_first)
  76 #define SM_TAILQ_END(head)              NULL
  77 #define SM_TAILQ_NEXT(elm, field)       ((elm)->field.tqe_next)
  78 #define SM_TAILQ_LAST(head, headname)                                   \
  79         (*(((struct headname *)((head)->tqh_last))->tqh_last))
  80 /* XXX */
  81 #define SM_TAILQ_PREV(elm, headname, field)                             \
  82         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
  83 #define SM_TAILQ_EMPTY(head)                                            \
  84         (SM_TAILQ_FIRST(head) == SM_TAILQ_END(head))
  85
  86 #define SM_TAILQ_FOREACH(var, head, field)                              \
  87         for((var) = SM_TAILQ_FIRST(head);                               \
  88             (var) != SM_TAILQ_END(head);                                \
  89             (var) = SM_TAILQ_NEXT(var, field))
  90
  91 #define SM_TAILQ_FOREACH_REVERSE(var, head, headname, field)            \
  92         for((var) = SM_TAILQ_LAST(head, headname);                      \
  93             (var) != SM_TAILQ_END(head);                                \
  94             (var) = SM_TAILQ_PREV(var, headname, field))
  95
  96 /*
  97  * Tail queue functions.
  98  */
  99 #define SM_TAILQ_INIT(head) do {                                        \
 100         (head)->tqh_first = NULL;                                       \
 101         (head)->tqh_last = &(head)->tqh_first;                          \
 102 } while (0)
 103
 104 #define SM_TAILQ_INSERT_HEAD(head, elm, field) do {                     \
 105         if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
 106                 (head)->tqh_first->field.tqe_prev =                     \
 107                     &(elm)->field.tqe_next;                             \
 108         else                                                            \
 109                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 110         (head)->tqh_first = (elm);                                      \
 111         (elm)->field.tqe_prev = &(head)->tqh_first;                     \
 112 } while (0)
 113
 114 #define SM_TAILQ_INSERT_TAIL(head, elm, field) do {                     \
 115         (elm)->field.tqe_next = NULL;                                   \
 116         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 117         *(head)->tqh_last = (elm);                                      \
 118         (head)->tqh_last = &(elm)->field.tqe_next;                      \
 119 } while (0)
 120
 121 #define SM_TAILQ_INSERT_AFTER(head, listelm, elm, field) do {           \
 122         if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
 123                 (elm)->field.tqe_next->field.tqe_prev =                 \
 124                     &(elm)->field.tqe_next;                             \
 125         else                                                            \
 126                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 127         (listelm)->field.tqe_next = (elm);                              \
 128         (elm)->field.tqe_prev = &(listelm)->field.tqe_next;             \
 129 } while (0)
 130
 131 #define SM_TAILQ_INSERT_BEFORE(listelm, elm, field) do {                \
 132         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 133         (elm)->field.tqe_next = (listelm);                              \
 134         *(listelm)->field.tqe_prev = (elm);                             \
 135         (listelm)->field.tqe_prev = &(elm)->field.tqe_next;             \
 136 } while (0)
 137
 138 #define SM_TAILQ_REMOVE(head, elm, field) do {                          \
 139         if (((elm)->field.tqe_next) != NULL)                            \
 140                 (elm)->field.tqe_next->field.tqe_prev =                 \
 141                     (elm)->field.tqe_prev;                              \
 142         else                                                            \
 143                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 144         *(elm)->field.tqe_prev = (elm)->field.tqe_next;                 \
 145 } while (0)
 146
 147 #define SM_TAILQ_REPLACE(head, elm, elm2, field) do {                   \
 148         if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL)   \
 149                 (elm2)->field.tqe_next->field.tqe_prev =                \
 150                     &(elm2)->field.tqe_next;                            \
 151         else                                                            \
 152                 (head)->tqh_last = &(elm2)->field.tqe_next;             \
 153         (elm2)->field.tqe_prev = (elm)->field.tqe_prev;                 \
 154         *(elm2)->field.tqe_prev = (elm2);                               \
 155 } while (0)
 156
 157 #endif  /* !SM_TAILQ_H_ */