src/shared/list.h

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 #pragma once
   4
   5 /***
   6   This file is part of systemd.
   7
   8   Copyright 2010 Lennart Poettering
   9
  10   systemd is free software; you can redistribute it and/or modify it
  11   under the terms of the GNU Lesser General Public License as published by
  12   the Free Software Foundation; either version 2.1 of the License, or
  13   (at your option) any later version.
  14
  15   systemd is distributed in the hope that it will be useful, but
  16   WITHOUT ANY WARRANTY; without even the implied warranty of
  17   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18   Lesser General Public License for more details.
  19
  20   You should have received a copy of the GNU Lesser General Public License
  21   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  22 ***/
  23
  24 /* The head of the linked list. Use this in the structure that shall
  25  * contain the head of the linked list */
  26 #define LIST_HEAD(t,name)                                               \
  27         t *name
  28
  29 /* The pointers in the linked list's items. Use this in the item structure */
  30 #define LIST_FIELDS(t,name)                                             \
  31         t *name##_next, *name##_prev
  32
  33 /* Initialize the list's head */
  34 #define LIST_HEAD_INIT(t,head)                                          \
  35         do {                                                            \
  36                 (head) = NULL; }                                        \
  37         while(false)
  38
  39 /* Initialize a list item */
  40 #define LIST_INIT(t,name,item)                                          \
  41         do {                                                            \
  42                 t *_item = (item);                                      \
  43                 assert(_item);                                          \
  44                 _item->name##_prev = _item->name##_next = NULL;         \
  45         } while(false)
  46
  47 /* Prepend an item to the list */
  48 #define LIST_PREPEND(t,name,head,item)                                  \
  49         do {                                                            \
  50                 t **_head = &(head), *_item = (item);                   \
  51                 assert(_item);                                          \
  52                 if ((_item->name##_next = *_head))                      \
  53                         _item->name##_next->name##_prev = _item;        \
  54                 _item->name##_prev = NULL;                              \
  55                 *_head = _item;                                         \
  56         } while(false)
  57
  58 /* Remove an item from the list */
  59 #define LIST_REMOVE(t,name,head,item)                                   \
  60         do {                                                            \
  61                 t **_head = &(head), *_item = (item);                   \
  62                 assert(_item);                                          \
  63                 if (_item->name##_next)                                 \
  64                         _item->name##_next->name##_prev = _item->name##_prev; \
  65                 if (_item->name##_prev)                                 \
  66                         _item->name##_prev->name##_next = _item->name##_next; \
  67                 else {                                                  \
  68                         assert(*_head == _item);                        \
  69                         *_head = _item->name##_next;                    \
  70                 }                                                       \
  71                 _item->name##_next = _item->name##_prev = NULL;         \
  72         } while(false)
  73
  74 /* Find the head of the list */
  75 #define LIST_FIND_HEAD(t,name,item,head)                                \
  76         do {                                                            \
  77                 t *_item = (item);                                      \
  78                 assert(_item);                                          \
  79                 while (_item->name##_prev)                              \
  80                        _item = _item->name##_prev;                      \
  81                 (head) = _item;                                         \
  82         } while (false)
  83
  84 /* Find the tail of the list */
  85 #define LIST_FIND_TAIL(t,name,item,tail)                                \
  86         do {                                                            \
  87                 t *_item = (item);                                      \
  88                 assert(_item);                                          \
  89                 while (_item->name##_next)                              \
  90                         _item = _item->name##_next;                     \
  91                 (tail) = _item;                                         \
  92         } while (false)
  93
  94 /* Insert an item after another one (a = where, b = what) */
  95 #define LIST_INSERT_AFTER(t,name,head,a,b)                              \
  96         do {                                                            \
  97                 t **_head = &(head), *_a = (a), *_b = (b);              \
  98                 assert(_b);                                             \
  99                 if (!_a) {                                              \
 100                         if ((_b->name##_next = *_head))                 \
 101                                 _b->name##_next->name##_prev = _b;      \
 102                         _b->name##_prev = NULL;                         \
 103                         *_head = _b;                                    \
 104                 } else {                                                \
 105                         if ((_b->name##_next = _a->name##_next))        \
 106                                 _b->name##_next->name##_prev = _b;      \
 107                         _b->name##_prev = _a;                           \
 108                         _a->name##_next = _b;                           \
 109                 }                                                       \
 110         } while(false)
 111
 112 #define LIST_JUST_US(name,item)                                         \
 113         (!(item)->name##_prev && !(item)->name##_next)                  \
 114
 115 #define LIST_FOREACH(name,i,head)                                       \
 116         for ((i) = (head); (i); (i) = (i)->name##_next)
 117
 118 #define LIST_FOREACH_SAFE(name,i,n,head)                                \
 119         for ((i) = (head); (i) && (((n) = (i)->name##_next), 1); (i) = (n))
 120
 121 #define LIST_FOREACH_BEFORE(name,i,p)                                   \
 122         for ((i) = (p)->name##_prev; (i); (i) = (i)->name##_prev)
 123
 124 #define LIST_FOREACH_AFTER(name,i,p)                                    \
 125         for ((i) = (p)->name##_next; (i); (i) = (i)->name##_next)
 126
 127 /* Loop starting from p->next until p->prev.
 128    p can be adjusted meanwhile. */
 129 #define LIST_LOOP_BUT_ONE(name,i,head,p)                                \
 130         for ((i) = (p)->name##_next ? (p)->name##_next : (head);        \
 131              (i) != (p);                                                \
 132              (i) = (i)->name##_next ? (i)->name##_next : (head))