linklist.h

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/*
 * Copyright (C) Volition, Inc. 1999.  All rights reserved.
 *
 * All source code herein is the property of Volition, Inc. You may not sell 
 * or otherwise commercially exploit the source or things you created based on the 
 * source.
 *
*/ 



#ifndef _LINKLIST_H
#define _LINKLIST_H

// Initializes a list of zero elements
#define list_init( head )                                       \
do {                                                                                            \
        (head)->next = (head);                                  \
        (head)->prev = (head);                                  \
} while (0)

// Inserts element onto the front of the list
#define list_insert( head, elem )               \
do {                                                                                            \
        (elem)->next = (head)->next;                    \
        (head)->next->prev = (elem);                    \
        (head)->next = (elem);                                  \
        (elem)->prev = (head);                                  \
} while (0)

// Inserts new_elem before elem
#define list_insert_before(elem, new_elem)              \
do {                                                                                                                    \
        (elem)->prev->next      = (new_elem);                           \
        (new_elem)->prev                = (elem)->prev;                 \
        (elem)->prev                    = (new_elem);                           \
        (new_elem)->next                = (elem);                                       \
} while (0)     

// Appends an element on to the tail of the list
#define list_append( head, elem )               \
do      {                                                                                               \
        (elem)->prev = (head)->prev;                    \
        (elem)->next = (head);                                  \
        (head)->prev->next = (elem);                    \
        (head)->prev = (elem);                                  \
} while (0)

// Adds list b onto the end of list a
#define list_merge( a, b )                                      \
do {                                                                                            \
        (a)->prev->next = (b)->next;                    \
        (b)->next->prev = (a)->prev;                    \
        (a)->prev = (b)->prev;                                  \
        (b)->prev->next = (a);                                  \
} while (0)

// Removes an element from the list
#define list_remove( head, elem )               \
do {                                                                                            \
        (elem)->prev->next = (elem)->next;      \
        (elem)->next->prev = (elem)->prev;      \
        (elem)->next = NULL;                                            \
        (elem)->prev = NULL;                                            \
} while(0)

// Moves elem to be after head
#define list_move_append(head, elem)            \
do {                                                                                            \
        (elem)->prev->next = (elem)->next;                              \
        (elem)->next->prev = (elem)->prev;                              \
        (elem)->prev = (head)->prev;                                    \
        (elem)->next = (head);                                                  \
        (head)->prev->next = (elem);                                    \
        (head)->prev = (elem);                                                  \
} while (0)

#define GET_FIRST(head)         ((head)->next)
#define GET_LAST(head)          ((head)->prev)
#define GET_NEXT(elem)          ((elem)->next)
#define GET_PREV(elem)          ((elem)->prev)
#define END_OF_LIST(head)       (head)
#define NOT_EMPTY(head)         ((head)->next != (head))
#define EMPTY(head)                     ((head)->next == (head))

#endif