list.h

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