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(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 /* Remove an item from the list */
  59 #define LIST_REMOVE(name,head,item)                                     \
  60         do {                                                            \
  61                 typeof(*(head)) **_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(name,item,head)                                  \
  76         do {                                                            \
  77                 typeof(*(item)) *_item = (item);                        \
  78                 if (!_item)                                             \
  79                         (head) = NULL;                                  \
  80                 else {                                                  \
  81                         while (_item->name##_prev)                      \
  82                                 _item = _item->name##_prev;             \
  83                         (head) = _item;                                 \
  84                 }                                                       \
  85         } while (false)
  86
  87 /* Find the tail of the list */
  88 #define LIST_FIND_TAIL(name,item,tail)                                  \
  89         do {                                                            \
  90                 typeof(*(item)) *_item = (item);                        \
  91                 if (!_item)                                             \
  92                         (tail) = NULL;                                  \
  93                 else {                                                  \
  94                         while (_item->name##_next)                      \
  95                                 _item = _item->name##_next;             \
  96                         (tail) = _item;                                 \
  97                 }                                                       \
  98         } while (false)
  99
 100 /* Insert an item after another one (a = where, b = what) */
 101 #define LIST_INSERT_AFTER(name,head,a,b)                                \
 102         do {                                                            \
 103                 typeof(*(head)) **_head = &(head), *_a = (a), *_b = (b); \
 104                 assert(_b);                                             \
 105                 if (!_a) {                                              \
 106                         if ((_b->name##_next = *_head))                 \
 107                                 _b->name##_next->name##_prev = _b;      \
 108                         _b->name##_prev = NULL;                         \
 109                         *_head = _b;                                    \
 110                 } else {                                                \
 111                         if ((_b->name##_next = _a->name##_next))        \
 112                                 _b->name##_next->name##_prev = _b;      \
 113                         _b->name##_prev = _a;                           \
 114                         _a->name##_next = _b;                           \
 115                 }                                                       \
 116         } while(false)
 117
 118 #define LIST_JUST_US(name,item)                                         \
 119         (!(item)->name##_prev && !(item)->name##_next)                  \
 120
 121 #define LIST_FOREACH(name,i,head)                                       \
 122         for ((i) = (head); (i); (i) = (i)->name##_next)
 123
 124 #define LIST_FOREACH_SAFE(name,i,n,head)                                \
 125         for ((i) = (head); (i) && (((n) = (i)->name##_next), 1); (i) = (n))
 126
 127 #define LIST_FOREACH_BEFORE(name,i,p)                                   \
 128         for ((i) = (p)->name##_prev; (i); (i) = (i)->name##_prev)
 129
 130 #define LIST_FOREACH_AFTER(name,i,p)                                    \
 131         for ((i) = (p)->name##_next; (i); (i) = (i)->name##_next)
 132
 133 /* Loop starting from p->next until p->prev.
 134    p can be adjusted meanwhile. */
 135 #define LIST_LOOP_BUT_ONE(name,i,head,p)                                \
 136         for ((i) = (p)->name##_next ? (p)->name##_next : (head);        \
 137              (i) != (p);                                                \
 138              (i) = (i)->name##_next ? (i)->name##_next : (head))