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  * This file is a modified copy of queue.h from a BSD system:
  40  * we only need tail queues here.
  41  *
  42  * A tail queue is headed by a pair of pointers, one to the head of the
  43  * list and the other to the tail of the list. The elements are doubly
  44  * linked so that an arbitrary element can be removed without a need to
  45  * traverse the list. New elements can be added to the list before or
  46  * after an existing element, at the head of the list, or at the end of
  47  * the list. A tail queue may be traversed in either direction.
  48  */
  49
  50 /*
  51  * Tail queue definitions.
  52  */
  53 #define SM_TAILQ_HEAD(name, type)                                       \
  54 struct name {                                                           \
  55         struct type *tqh_first; /* first element */                     \
  56         struct type **tqh_last; /* addr of last next element */         \
  57 }
  58
  59 #define SM_TAILQ_HEAD_INITIALIZER(head)                                 \
  60         { NULL, &(head).tqh_first }
  61
  62 #define SM_TAILQ_ENTRY(type)                                            \
  63 struct {                                                                \
  64         struct type *tqe_next;  /* next element */                      \
  65         struct type **tqe_prev; /* address of previous next element */  \
  66 }
  67
  68 /*
  69  * tail queue access methods
  70  */
  71 #define SM_TAILQ_FIRST(head)            ((head)->tqh_first)
  72 #define SM_TAILQ_END(head)              NULL
  73 #define SM_TAILQ_NEXT(elm, field)       ((elm)->field.tqe_next)
  74 #define SM_TAILQ_LAST(head, headname)                                   \
  75         (*(((struct headname *)((head)->tqh_last))->tqh_last))
  76 /* XXX */
  77 #define SM_TAILQ_PREV(elm, headname, field)                             \
  78         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
  79 #define SM_TAILQ_EMPTY(head)                                            \
  80         (SM_TAILQ_FIRST(head) == SM_TAILQ_END(head))
  81
  82 #define SM_TAILQ_FOREACH(var, head, field)                              \
  83         for((var) = SM_TAILQ_FIRST(head);                               \
  84             (var) != SM_TAILQ_END(head);                                \
  85             (var) = SM_TAILQ_NEXT(var, field))
  86
  87 #define SM_TAILQ_FOREACH_REVERSE(var, head, headname, field)            \
  88         for((var) = SM_TAILQ_LAST(head, headname);                      \
  89             (var) != SM_TAILQ_END(head);                                \
  90             (var) = SM_TAILQ_PREV(var, headname, field))
  91
  92 /*
  93  * Tail queue functions.
  94  */
  95 #define SM_TAILQ_INIT(head) do {                                        \
  96         (head)->tqh_first = NULL;                                       \
  97         (head)->tqh_last = &(head)->tqh_first;                          \
  98 } while (0)
  99
 100 #define SM_TAILQ_INSERT_HEAD(head, elm, field) do {                     \
 101         if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
 102                 (head)->tqh_first->field.tqe_prev =                     \
 103                     &(elm)->field.tqe_next;                             \
 104         else                                                            \
 105                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 106         (head)->tqh_first = (elm);                                      \
 107         (elm)->field.tqe_prev = &(head)->tqh_first;                     \
 108 } while (0)
 109
 110 #define SM_TAILQ_INSERT_TAIL(head, elm, field) do {                     \
 111         (elm)->field.tqe_next = NULL;                                   \
 112         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 113         *(head)->tqh_last = (elm);                                      \
 114         (head)->tqh_last = &(elm)->field.tqe_next;                      \
 115 } while (0)
 116
 117 #define SM_TAILQ_INSERT_AFTER(head, listelm, elm, field) do {           \
 118         if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
 119                 (elm)->field.tqe_next->field.tqe_prev =                 \
 120                     &(elm)->field.tqe_next;                             \
 121         else                                                            \
 122                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 123         (listelm)->field.tqe_next = (elm);                              \
 124         (elm)->field.tqe_prev = &(listelm)->field.tqe_next;             \
 125 } while (0)
 126
 127 #define SM_TAILQ_INSERT_BEFORE(listelm, elm, field) do {                \
 128         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 129         (elm)->field.tqe_next = (listelm);                              \
 130         *(listelm)->field.tqe_prev = (elm);                             \
 131         (listelm)->field.tqe_prev = &(elm)->field.tqe_next;             \
 132 } while (0)
 133
 134 #define SM_TAILQ_REMOVE(head, elm, field) do {                          \
 135         if (((elm)->field.tqe_next) != NULL)                            \
 136                 (elm)->field.tqe_next->field.tqe_prev =                 \
 137                     (elm)->field.tqe_prev;                              \
 138         else                                                            \
 139                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 140         *(elm)->field.tqe_prev = (elm)->field.tqe_next;                 \
 141 } while (0)
 142
 143 #define SM_TAILQ_REPLACE(head, elm, elm2, field) do {                   \
 144         if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL)   \
 145                 (elm2)->field.tqe_next->field.tqe_prev =                \
 146                     &(elm2)->field.tqe_next;                            \
 147         else                                                            \
 148                 (head)->tqh_last = &(elm2)->field.tqe_next;             \
 149         (elm2)->field.tqe_prev = (elm)->field.tqe_prev;                 \
 150         *(elm2)->field.tqe_prev = (elm2);                               \
 151 } while (0)
 152
 153 #endif  /* !SM_TAILQ_H_ */