src/llist.h


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#ifndef foocanberrallistfoo
#define foocanberrallistfoo

/***
  This file is part of libcanberra.

  Copyright 2008 Lennart Poettering

  libcanberra is free software; you can redistribute it and/or modify
  it under the terms of the GNU Lesser General Public License as
  published by the Free Software Foundation, either version 2.1 of the
  License, or (at your option) any later version.

  libcanberra is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with libcanberra. If not, If not, see
  <http://www.gnu.org/licenses/>.
***/

#include "macro.h"

/* Some macros for maintaining doubly linked lists */

/* The head of the linked list. Use this in the structure that shall
 * contain the head of the linked list */
#define CA_LLIST_HEAD(t,name)                                           \
    t *name

/* The pointers in the linked list's items. Use this in the item structure */
#define CA_LLIST_FIELDS(t)                                              \
    t *next, *prev

/* Initialize the list's head */
#define CA_LLIST_HEAD_INIT(t,item)                                      \
    do {                                                                \
        (item) = (t*) NULL; }                                           \
    while(0)

/* Initialize a list item */
#define CA_LLIST_INIT(t,item)                                           \
    do {                                                                \
        t *_item = (item);                                              \
        ca_assert(_item);                                               \
        _item->prev = _item->next = NULL;                               \
    } while(0)

/* Prepend an item to the list */
#define CA_LLIST_PREPEND(t,head,item)                                   \
    do {                                                                \
        t **_head = &(head), *_item = (item);                           \
        ca_assert(_item);                                               \
        if ((_item->next = *_head))                                     \
            _item->next->prev = _item;                                  \
        _item->prev = NULL;                                             \
        *_head = _item;                                                 \
    } while (0)

/* Remove an item from the list */
#define CA_LLIST_REMOVE(t,head,item)                                    \
    do {                                                                \
        t **_head = &(head), *_item = (item);                           \
        ca_assert(_item);                                               \
        if (_item->next)                                                \
            _item->next->prev = _item->prev;                            \
        if (_item->prev)                                                \
            _item->prev->next = _item->next;                            \
        else {                                                          \
            ca_assert(*_head == _item);                                 \
            *_head = _item->next;                                       \
        }                                                               \
        _item->next = _item->prev = NULL;                               \
    } while(0)

/* Find the head of the list */
#define CA_LLIST_FIND_HEAD(t,item,head)                                 \
    do {                                                                \
        t **_head = (head), *_item = (item);                            \
        *_head = _item;                                                 \
        ca_assert(_head);                                               \
        while ((*_head)->prev)                                          \
            *_head = (*_head)->prev;                                    \
    } while (0)

/* Insert an item after another one (a = where, b = what) */
#define CA_LLIST_INSERT_AFTER(t,head,a,b)                               \
    do {                                                                \
        t **_head = &(head), *_a = (a), *_b = (b);                      \
        ca_assert(_b);                                                  \
        if (!_a) {                                                      \
            if ((_b->next = *_head))                                    \
                _b->next->prev = _b;                                    \
            _b->prev = NULL;                                            \
            *_head = _b;                                                \
        } else {                                                        \
            if ((_b->next = _a->next))                                  \
                _b->next->prev = _b;                                    \
            _b->prev = _a;                                              \
            _a->next = _b;                                              \
        }                                                               \
    } while (0)

#endif