include/linklist.h

   1 /*
   2  * $Logfile: /Freespace2/code/GlobalIncs/LinkList.h $
   3  * $Revision$
   4  * $Date$
   5  * $Author$
   6  *
   7  * Macros to handle doubly linked lists
   8  *
   9  * $Log$
  10  * Revision 1.1  2002/05/03 03:28:12  root
  11  * Initial revision
  12  *
  13  *
  14  * 2     10/07/98 10:52a Dave
  15  * Initial checkin.
  16  *
  17  * 1     10/07/98 10:48a Dave
  18  *
  19  * 5     7/01/97 11:53a Lawrance
  20  * add list_insert_before()
  21  *
  22  * 4     4/15/97 1:27p Lawrance
  23  * added a GET_PREV() macro
  24  *
  25  * 3     2/17/97 5:18p John
  26  * Added a bunch of RCS headers to a bunch of old files that don't have
  27  * them.
  28  *
  29  * $NoKeywords: $
  30  */
  31
  32 #ifndef _LINKLIST_H
  33 #define _LINKLIST_H
  34
  35 // Initializes a list of zero elements
  36 #define list_init( head )                                       \
  37 do {                                                                                            \
  38         (head)->next = (head);                                  \
  39         (head)->prev = (head);                                  \
  40 } while (0)
  41
  42 // Inserts element onto the front of the list
  43 #define list_insert( head, elem )               \
  44 do {                                                                                            \
  45         (elem)->next = (head)->next;                    \
  46         (head)->next->prev = (elem);                    \
  47         (head)->next = (elem);                                  \
  48         (elem)->prev = (head);                                  \
  49 } while (0)
  50
  51 // Inserts new_elem before elem
  52 #define list_insert_before(elem, new_elem)              \
  53 do {                                                                                                                    \
  54         (elem)->prev->next      = (new_elem);                           \
  55         (new_elem)->prev                = (elem)->prev;                 \
  56         (elem)->prev                    = (new_elem);                           \
  57         (new_elem)->next                = (elem);                                       \
  58 } while (0)
  59
  60 // Appends an element on to the tail of the list
  61 #define list_append( head, elem )               \
  62 do      {                                                                                               \
  63         (elem)->prev = (head)->prev;                    \
  64         (elem)->next = (head);                                  \
  65         (head)->prev->next = (elem);                    \
  66         (head)->prev = (elem);                                  \
  67 } while (0)
  68
  69 // Adds list b onto the end of list a
  70 #define list_merge( a, b )                                      \
  71 do {                                                                                            \
  72         (a)->prev->next = (b)->next;                    \
  73         (b)->next->prev = (a)->prev;                    \
  74         (a)->prev = (b)->prev;                                  \
  75         (b)->prev->next = (a);                                  \
  76 } while (0)
  77
  78 // Removes an element from listit's in
  79 #define list_remove( head, elem )               \
  80 do {                                                                                            \
  81         (elem)->prev->next = (elem)->next;      \
  82         (elem)->next->prev = (elem)->prev;      \
  83         (elem)->next = NULL;                                            \
  84         (elem)->prev = NULL;                                            \
  85 } while(0)
  86
  87 #define GET_FIRST(head)         ((head)->next)
  88 #define GET_LAST(head)          ((head)->prev)
  89 #define GET_NEXT(elem)          ((elem)->next)
  90 #define GET_PREV(elem)          ((elem)->prev)
  91 #define END_OF_LIST(head)       (head)
  92 #define NOT_EMPTY(head)         ((head)->next != (head))
  93 #define EMPTY(head)                     ((head)->next == (head))
  94
  95 #endif
  96