src/basic/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(head)                                            \
  35         do {                                                            \
  36                 (head) = NULL; }                                        \
  37         while(false)
  38
  39 /* Initialize a list item */
  40 #define LIST_INIT(name,item)                                            \
  41         do {                                                            \
  42                 typeof(*(item)) *_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(name,head,item)                                    \
  49         do {                                                            \
  50                 typeof(*(head)) **_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 /* Append an item to the list */
  59 #define LIST_APPEND(name,head,item)                                     \
  60         do {                                                            \
  61                 typeof(*(head)) *_tail;                                 \
  62                 LIST_FIND_TAIL(name,head,_tail);                        \
  63                 LIST_INSERT_AFTER(name,head,_tail,item);                \
  64         } while(false)
  65
  66 /* Remove an item from the list */
  67 #define LIST_REMOVE(name,head,item)                                     \
  68         do {                                                            \
  69                 typeof(*(head)) **_head = &(head), *_item = (item);     \
  70                 assert(_item);                                          \
  71                 if (_item->name##_next)                                 \
  72                         _item->name##_next->name##_prev = _item->name##_prev; \
  73                 if (_item->name##_prev)                                 \
  74                         _item->name##_prev->name##_next = _item->name##_next; \
  75                 else {                                                  \
  76                         assert(*_head == _item);                        \
  77                         *_head = _item->name##_next;                    \
  78                 }                                                       \
  79                 _item->name##_next = _item->name##_prev = NULL;         \
  80         } while(false)
  81
  82 /* Find the head of the list */
  83 #define LIST_FIND_HEAD(name,item,head)                                  \
  84         do {                                                            \
  85                 typeof(*(item)) *_item = (item);                        \
  86                 if (!_item)                                             \
  87                         (head) = NULL;                                  \
  88                 else {                                                  \
  89                         while (_item->name##_prev)                      \
  90                                 _item = _item->name##_prev;             \
  91                         (head) = _item;                                 \
  92                 }                                                       \
  93         } while (false)
  94
  95 /* Find the tail of the list */
  96 #define LIST_FIND_TAIL(name,item,tail)                                  \
  97         do {                                                            \
  98                 typeof(*(item)) *_item = (item);                        \
  99                 if (!_item)                                             \
 100                         (tail) = NULL;                                  \
 101                 else {                                                  \
 102                         while (_item->name##_next)                      \
 103                                 _item = _item->name##_next;             \
 104                         (tail) = _item;                                 \
 105                 }                                                       \
 106         } while (false)
 107
 108 /* Insert an item after another one (a = where, b = what) */
 109 #define LIST_INSERT_AFTER(name,head,a,b)                                \
 110         do {                                                            \
 111                 typeof(*(head)) **_head = &(head), *_a = (a), *_b = (b); \
 112                 assert(_b);                                             \
 113                 if (!_a) {                                              \
 114                         if ((_b->name##_next = *_head))                 \
 115                                 _b->name##_next->name##_prev = _b;      \
 116                         _b->name##_prev = NULL;                         \
 117                         *_head = _b;                                    \
 118                 } else {                                                \
 119                         if ((_b->name##_next = _a->name##_next))        \
 120                                 _b->name##_next->name##_prev = _b;      \
 121                         _b->name##_prev = _a;                           \
 122                         _a->name##_next = _b;                           \
 123                 }                                                       \
 124         } while(false)
 125
 126 #define LIST_JUST_US(name,item)                                         \
 127         (!(item)->name##_prev && !(item)->name##_next)                  \
 128
 129 #define LIST_FOREACH(name,i,head)                                       \
 130         for ((i) = (head); (i); (i) = (i)->name##_next)
 131
 132 #define LIST_FOREACH_SAFE(name,i,n,head)                                \
 133         for ((i) = (head); (i) && (((n) = (i)->name##_next), 1); (i) = (n))
 134
 135 #define LIST_FOREACH_BEFORE(name,i,p)                                   \
 136         for ((i) = (p)->name##_prev; (i); (i) = (i)->name##_prev)
 137
 138 #define LIST_FOREACH_AFTER(name,i,p)                                    \
 139         for ((i) = (p)->name##_next; (i); (i) = (i)->name##_next)
 140
 141 /* Iterate through all the members of the list p is included in, but skip over p */
 142 #define LIST_FOREACH_OTHERS(name,i,p)                                   \
 143         for (({                                                         \
 144                 (i) = (p);                                              \
 145                 while ((i) && (i)->name##_prev)                         \
 146                         (i) = (i)->name##_prev;                         \
 147                 if ((i) == (p))                                         \
 148                         (i) = (p)->name##_next;                         \
 149              });                                                        \
 150              (i);                                                       \
 151              (i) = (i)->name##_next == (p) ? (p)->name##_next : (i)->name##_next)
 152
 153 /* Loop starting from p->next until p->prev.
 154    p can be adjusted meanwhile. */
 155 #define LIST_LOOP_BUT_ONE(name,i,head,p)                                \
 156         for ((i) = (p)->name##_next ? (p)->name##_next : (head);        \
 157              (i) != (p);                                                \
 158              (i) = (i)->name##_next ? (i)->name##_next : (head))