src/basic/list.h

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 #pragma once
   3
   4 /***
   5   Copyright 2010 Lennart Poettering
   6 ***/
   7
   8 /* The head of the linked list. Use this in the structure that shall
   9  * contain the head of the linked list */
  10 #define LIST_HEAD(t,name)                                               \
  11         t *name
  12
  13 /* The pointers in the linked list's items. Use this in the item structure */
  14 #define LIST_FIELDS(t,name)                                             \
  15         t *name##_next, *name##_prev
  16
  17 /* Initialize the list's head */
  18 #define LIST_HEAD_INIT(head)                                            \
  19         do {                                                            \
  20                 (head) = NULL; }                                        \
  21         while (false)
  22
  23 /* Initialize a list item */
  24 #define LIST_INIT(name,item)                                            \
  25         do {                                                            \
  26                 typeof(*(item)) *_item = (item);                        \
  27                 assert(_item);                                          \
  28                 _item->name##_prev = _item->name##_next = NULL;         \
  29         } while (false)
  30
  31 /* Prepend an item to the list */
  32 #define LIST_PREPEND(name,head,item)                                    \
  33         do {                                                            \
  34                 typeof(*(head)) **_head = &(head), *_item = (item);     \
  35                 assert(_item);                                          \
  36                 if ((_item->name##_next = *_head))                      \
  37                         _item->name##_next->name##_prev = _item;        \
  38                 _item->name##_prev = NULL;                              \
  39                 *_head = _item;                                         \
  40         } while (false)
  41
  42 /* Append an item to the list */
  43 #define LIST_APPEND(name,head,item)                                     \
  44         do {                                                            \
  45                 typeof(*(head)) *_tail;                                 \
  46                 LIST_FIND_TAIL(name,head,_tail);                        \
  47                 LIST_INSERT_AFTER(name,head,_tail,item);                \
  48         } while (false)
  49
  50 /* Remove an item from the list */
  51 #define LIST_REMOVE(name,head,item)                                     \
  52         do {                                                            \
  53                 typeof(*(head)) **_head = &(head), *_item = (item);     \
  54                 assert(_item);                                          \
  55                 if (_item->name##_next)                                 \
  56                         _item->name##_next->name##_prev = _item->name##_prev; \
  57                 if (_item->name##_prev)                                 \
  58                         _item->name##_prev->name##_next = _item->name##_next; \
  59                 else {                                                  \
  60                         assert(*_head == _item);                        \
  61                         *_head = _item->name##_next;                    \
  62                 }                                                       \
  63                 _item->name##_next = _item->name##_prev = NULL;         \
  64         } while (false)
  65
  66 /* Find the head of the list */
  67 #define LIST_FIND_HEAD(name,item,head)                                  \
  68         do {                                                            \
  69                 typeof(*(item)) *_item = (item);                        \
  70                 if (!_item)                                             \
  71                         (head) = NULL;                                  \
  72                 else {                                                  \
  73                         while (_item->name##_prev)                      \
  74                                 _item = _item->name##_prev;             \
  75                         (head) = _item;                                 \
  76                 }                                                       \
  77         } while (false)
  78
  79 /* Find the tail of the list */
  80 #define LIST_FIND_TAIL(name,item,tail)                                  \
  81         do {                                                            \
  82                 typeof(*(item)) *_item = (item);                        \
  83                 if (!_item)                                             \
  84                         (tail) = NULL;                                  \
  85                 else {                                                  \
  86                         while (_item->name##_next)                      \
  87                                 _item = _item->name##_next;             \
  88                         (tail) = _item;                                 \
  89                 }                                                       \
  90         } while (false)
  91
  92 /* Insert an item after another one (a = where, b = what) */
  93 #define LIST_INSERT_AFTER(name,head,a,b)                                \
  94         do {                                                            \
  95                 typeof(*(head)) **_head = &(head), *_a = (a), *_b = (b); \
  96                 assert(_b);                                             \
  97                 if (!_a) {                                              \
  98                         if ((_b->name##_next = *_head))                 \
  99                                 _b->name##_next->name##_prev = _b;      \
 100                         _b->name##_prev = NULL;                         \
 101                         *_head = _b;                                    \
 102                 } else {                                                \
 103                         if ((_b->name##_next = _a->name##_next))        \
 104                                 _b->name##_next->name##_prev = _b;      \
 105                         _b->name##_prev = _a;                           \
 106                         _a->name##_next = _b;                           \
 107                 }                                                       \
 108         } while (false)
 109
 110 /* Insert an item before another one (a = where, b = what) */
 111 #define LIST_INSERT_BEFORE(name,head,a,b)                               \
 112         do {                                                            \
 113                 typeof(*(head)) **_head = &(head), *_a = (a), *_b = (b); \
 114                 assert(_b);                                             \
 115                 if (!_a) {                                              \
 116                         if (!*_head) {                                  \
 117                                 _b->name##_next = NULL;                 \
 118                                 _b->name##_prev = NULL;                 \
 119                                 *_head = _b;                            \
 120                         } else {                                        \
 121                                 typeof(*(head)) *_tail = (head);        \
 122                                 while (_tail->name##_next)              \
 123                                         _tail = _tail->name##_next;     \
 124                                 _b->name##_next = NULL;                 \
 125                                 _b->name##_prev = _tail;                \
 126                                 _tail->name##_next = _b;                \
 127                         }                                               \
 128                 } else {                                                \
 129                         if ((_b->name##_prev = _a->name##_prev))        \
 130                                 _b->name##_prev->name##_next = _b;      \
 131                         else                                            \
 132                                 *_head = _b;                            \
 133                         _b->name##_next = _a;                           \
 134                         _a->name##_prev = _b;                           \
 135                 }                                                       \
 136         } while (false)
 137
 138 #define LIST_JUST_US(name,item)                                         \
 139         (!(item)->name##_prev && !(item)->name##_next)                  \
 140
 141 #define LIST_FOREACH(name,i,head)                                       \
 142         for ((i) = (head); (i); (i) = (i)->name##_next)
 143
 144 #define LIST_FOREACH_SAFE(name,i,n,head)                                \
 145         for ((i) = (head); (i) && (((n) = (i)->name##_next), 1); (i) = (n))
 146
 147 #define LIST_FOREACH_BEFORE(name,i,p)                                   \
 148         for ((i) = (p)->name##_prev; (i); (i) = (i)->name##_prev)
 149
 150 #define LIST_FOREACH_AFTER(name,i,p)                                    \
 151         for ((i) = (p)->name##_next; (i); (i) = (i)->name##_next)
 152
 153 /* Iterate through all the members of the list p is included in, but skip over p */
 154 #define LIST_FOREACH_OTHERS(name,i,p)                                   \
 155         for (({                                                         \
 156                 (i) = (p);                                              \
 157                 while ((i) && (i)->name##_prev)                         \
 158                         (i) = (i)->name##_prev;                         \
 159                 if ((i) == (p))                                         \
 160                         (i) = (p)->name##_next;                         \
 161              });                                                        \
 162              (i);                                                       \
 163              (i) = (i)->name##_next == (p) ? (p)->name##_next : (i)->name##_next)
 164
 165 /* Loop starting from p->next until p->prev.
 166    p can be adjusted meanwhile. */
 167 #define LIST_LOOP_BUT_ONE(name,i,head,p)                                \
 168         for ((i) = (p)->name##_next ? (p)->name##_next : (head);        \
 169              (i) != (p);                                                \
 170              (i) = (i)->name##_next ? (i)->name##_next : (head))
 171
 172 #define LIST_IS_EMPTY(head)                                             \
 173         (!(head))