1 #ifndef CHAIN_H

     2 #define CHAIN_H

     3 

     4 /**

     5  * Defines a generalized "chain of things" behaviour.

     6  *

     7  * The structure of this is a CHAIN_LIST, which contains a number of CHAIN_HEAD items, which then contain a number of

     8  * induvidual items.

     9  */

    10 #include "error.h"

    11 #include <sys/queue.h>

    12 

    13 /**

    14  * The chain header.

    15  */

    16 struct chain_head {

    17     const void *chain;

    18 

    19     void *arg;

    20 

    21     STAILQ_ENTRY(chain_head) node;

    22 };

    23 

    24 /**

    25  * @struct chain_list

    26  *

    27  * The chain list

    28  */

    29 STAILQ_HEAD(chain_list, chain_head);

    30 

    31 /**

    32  * Initialize a `struct chain_list`

    33  */

    34 #define CHAIN_INIT(list_ptr) STAILQ_INIT(list_ptr)

    35 

    36 /**

    37  * Add an item onto the end of a chain_list

    38  */

    39 err_t chain_add (struct chain_list *list, const void *chain, void *arg);

    40 

    41 /**

    42  * Iterate over the contents of a chain_list

    43  *

    44  * struct chain_list *list = ...;

    45  * struct chain_head *head;

    46  * struct foo *foo;

    47  *

    48  *  CHAIN_FOREACH(list, head) {

    49  *      for (foo = head->chain; foo->bar; foo++) {

    50  *          foo->bar(foo, head->arg);

    51  *      }

    52  *  }

    53  */

    54 #define CHAIN_FOREACH(list_ptr, head_ptr) STAILQ_FOREACH(head_ptr, list_ptr, node)

    55 

    56 /**

    57  * Free a chain_list

    58  */

    59 void chain_free (struct chain_list *list);

    60 

    61 #endif