lib/linklist.h

   1 /* Generic linked list
   2  * Copyright (C) 1997, 2000 Kunihiro Ishiguro
   3  *
   4  * This file is part of GNU Zebra.
   5  *
   6  * GNU Zebra is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the
   8  * Free Software Foundation; either version 2, or (at your option) any
   9  * later version.
  10  *
  11  * GNU Zebra is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with this program; see the file COPYING; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 #ifndef _ZEBRA_LINKLIST_H
  22 #define _ZEBRA_LINKLIST_H
  23
  24 /* listnodes must always contain data to be valid. Adding an empty node
  25  * to a list is invalid
  26  */
  27 struct listnode {
  28         struct listnode *next;
  29         struct listnode *prev;
  30
  31         /* private member, use getdata() to retrieve, do not access directly */
  32         void *data;
  33 };
  34
  35 struct list {
  36         struct listnode *head;
  37         struct listnode *tail;
  38
  39         /* invariant: count is the number of listnodes in the list */
  40         unsigned int count;
  41
  42         /*
  43          * Returns -1 if val1 < val2, 0 if equal?, 1 if val1 > val2.
  44          * Used as definition of sorted for listnode_add_sort
  45          */
  46         int (*cmp)(void *val1, void *val2);
  47
  48         /* callback to free user-owned data when listnode is deleted. supplying
  49          * this callback is very much encouraged!
  50          */
  51         void (*del)(void *val);
  52 };
  53
  54 #define listnextnode(X) ((X) ? ((X)->next) : NULL)
  55 #define listnextnode_unchecked(X) ((X)->next)
  56 #define listhead(X) ((X) ? ((X)->head) : NULL)
  57 #define listhead_unchecked(X) ((X)->head)
  58 #define listtail(X) ((X) ? ((X)->tail) : NULL)
  59 #define listcount(X) ((X)->count)
  60 #define list_isempty(X) ((X)->head == NULL && (X)->tail == NULL)
  61 /* return X->data only if X and X->data are not NULL */
  62 #define listgetdata(X) (assert(X), assert((X)->data != NULL), (X)->data)
  63
  64 /*
  65  * Create a new linked list.
  66  *
  67  * Returns:
  68  *    the created linked list
  69  */
  70 extern struct list *list_new(void);
  71
  72 /*
  73  * Add a new element to the tail of a list.
  74  *
  75  * Runtime is O(1).
  76  *
  77  * list
  78  *    list to operate on
  79  *
  80  * data
  81  *    element to add
  82  */
  83 extern void listnode_add(struct list *list, void *data);
  84
  85 /*
  86  * Add a new element to the beginning of a list.
  87  *
  88  * Runtime is O(1).
  89  *
  90  * list
  91  *    list to operate on
  92  *
  93  * data
  94  *    element to add
  95  */
  96 extern void listnode_add_head(struct list *list, void *data);
  97
  98 /*
  99  * Insert a new element into a list with insertion sort.
 100  *
 101  * If list->cmp is set, this function is used to determine the position to
 102  * insert the new element. If it is not set, this function is equivalent to
 103  * listnode_add.
 104  *
 105  * Runtime is O(N).
 106  *
 107  * list
 108  *    list to operate on
 109  *
 110  * val
 111  *    element to add
 112  */
 113 extern void listnode_add_sort(struct list *list, void *val);
 114
 115 /*
 116  * Insert a new element into a list after another element.
 117  *
 118  * Runtime is O(1).
 119  *
 120  * list
 121  *    list to operate on
 122  *
 123  * pp
 124  *    listnode to insert after
 125  *
 126  * data
 127  *    data to insert
 128  *
 129  * Returns:
 130  *    pointer to newly created listnode that contains the inserted data
 131  */
 132 extern struct listnode *listnode_add_after(struct list *list,
 133                                            struct listnode *pp, void *data);
 134
 135 /*
 136  * Insert a new element into a list before another element.
 137  *
 138  * Runtime is O(1).
 139  *
 140  * list
 141  *    list to operate on
 142  *
 143  * pp
 144  *    listnode to insert before
 145  *
 146  * data
 147  *    data to insert
 148  *
 149  * Returns:
 150  *    pointer to newly created listnode that contains the inserted data
 151  */
 152 extern struct listnode *listnode_add_before(struct list *list,
 153                                             struct listnode *pp, void *data);
 154
 155 /*
 156  * Move a node to the tail of a list.
 157  *
 158  * Runtime is O(1).
 159  *
 160  * list
 161  *    list to operate on
 162  *
 163  * node
 164  *    node to move to tail
 165  */
 166 extern void listnode_move_to_tail(struct list *list, struct listnode *node);
 167
 168 /*
 169  * Delete an element from a list.
 170  *
 171  * Runtime is O(N).
 172  *
 173  * list
 174  *    list to operate on
 175  *
 176  * data
 177  *    data to insert into list
 178  */
 179 extern void listnode_delete(struct list *list, void *data);
 180
 181 /*
 182  * Find the listnode corresponding to an element in a list.
 183  *
 184  * list
 185  *    list to operate on
 186  *
 187  * data
 188  *    data to search for
 189  *
 190  * Returns:
 191  *    pointer to listnode storing the given data if found, NULL otherwise
 192  */
 193 extern struct listnode *listnode_lookup(struct list *list, void *data);
 194
 195 /*
 196  * Retrieve the element at the head of a list.
 197  *
 198  * list
 199  *    list to operate on
 200  *
 201  * Returns:
 202  *    data at head of list, or NULL if list is empty
 203  */
 204 extern void *listnode_head(struct list *list);
 205
 206 /*
 207  * Duplicate a list.
 208  *
 209  * list
 210  *    list to duplicate
 211  *
 212  * Returns:
 213  *    copy of the list
 214  */
 215 extern struct list *list_dup(struct list *l);
 216
 217 /*
 218  * Sort a list in place.
 219  *
 220  * The sorting algorithm used is quicksort. Runtimes are equivalent to those of
 221  * quicksort plus N. The sort is not stable.
 222  *
 223  * For portability reasons, the comparison function takes a pointer to pointer
 224  * to void. This pointer should be dereferenced to get the actual data pointer.
 225  * It is always safe to do this.
 226  *
 227  * list
 228  *    list to sort
 229  *
 230  * cmp
 231  *    comparison function for quicksort. Should return less than, equal to or
 232  *    greater than zero if the first argument is less than, equal to or greater
 233  *    than the second argument.
 234  */
 235 extern void list_sort(struct list *list,
 236                       int (*cmp)(const void **, const void **));
 237
 238 /*
 239  * Delete a list and NULL its pointer.
 240  *
 241  * If non-null, list->del is called with each data element.
 242  *
 243  * plist
 244  *    pointer to list pointer; this will be set to NULL after the list has been
 245  *    deleted
 246  */
 247 extern void list_delete(struct list **plist);
 248
 249 /*
 250  * Delete all nodes from a list without deleting the list itself.
 251  *
 252  * If non-null, list->del is called with each data element.
 253  *
 254  * list
 255  *    list to operate on
 256  */
 257 extern void list_delete_all_node(struct list *list);
 258
 259 /*
 260  * Delete a node from a list.
 261  *
 262  * list->del is not called with the data associated with the node.
 263  *
 264  * Runtime is O(1).
 265  *
 266  * list
 267  *    list to operate on
 268  *
 269  * node
 270  *    the node to delete
 271  */
 272 extern void list_delete_node(struct list *list, struct listnode *node);
 273
 274 /*
 275  * Append a list to an existing list.
 276  *
 277  * Runtime is O(N) where N = listcount(add).
 278  *
 279  * list
 280  *    list to append to
 281  *
 282  * add
 283  *    list to append
 284  */
 285 extern void list_add_list(struct list *list, struct list *add);
 286
 287 /* List iteration macro.
 288  * Usage: for (ALL_LIST_ELEMENTS (...) { ... }
 289  * It is safe to delete the listnode using this macro.
 290  */
 291 #define ALL_LIST_ELEMENTS(list, node, nextnode, data)                          \
 292         (node) = listhead(list), ((data) = NULL);                              \
 293         (node) != NULL                                                         \
 294                 && ((data) = listgetdata(node), (nextnode) = node->next, 1);   \
 295         (node) = (nextnode), ((data) = NULL)
 296
 297 /* read-only list iteration macro.
 298  * Usage: as per ALL_LIST_ELEMENTS, but not safe to delete the listnode Only
 299  * use this macro when it is *immediately obvious* the listnode is not
 300  * deleted in the body of the loop. Does not have forward-reference overhead
 301  * of previous macro.
 302  */
 303 #define ALL_LIST_ELEMENTS_RO(list, node, data)                                 \
 304         (node) = listhead(list), ((data) = NULL);                              \
 305         (node) != NULL && ((data) = listgetdata(node), 1);                     \
 306         (node) = listnextnode(node), ((data) = NULL)
 307
 308 /* these *do not* cleanup list nodes and referenced data, as the functions
 309  * do - these macros simply {de,at}tach a listnode from/to a list.
 310  */
 311
 312 /* List node attach macro.  */
 313 #define LISTNODE_ATTACH(L, N)                                                  \
 314         do {                                                                   \
 315                 (N)->prev = (L)->tail;                                         \
 316                 (N)->next = NULL;                                              \
 317                 if ((L)->head == NULL)                                         \
 318                         (L)->head = (N);                                       \
 319                 else                                                           \
 320                         (L)->tail->next = (N);                                 \
 321                 (L)->tail = (N);                                               \
 322                 (L)->count++;                                                  \
 323         } while (0)
 324
 325 /* List node detach macro.  */
 326 #define LISTNODE_DETACH(L, N)                                                  \
 327         do {                                                                   \
 328                 if ((N)->prev)                                                 \
 329                         (N)->prev->next = (N)->next;                           \
 330                 else                                                           \
 331                         (L)->head = (N)->next;                                 \
 332                 if ((N)->next)                                                 \
 333                         (N)->next->prev = (N)->prev;                           \
 334                 else                                                           \
 335                         (L)->tail = (N)->prev;                                 \
 336                 (L)->count--;                                                  \
 337         } while (0)
 338
 339 #endif /* _ZEBRA_LINKLIST_H */