/* * BIRD Library -- Linked Lists * * (c) 1998 Martin Mares <mj@ucw.cz> * * Can be freely distributed and used under the terms of the GNU GPL. */ #ifndef _BIRD_LISTS_H_ #define _BIRD_LISTS_H_ /* * I admit the list structure is very tricky and also somewhat awkward, * but it's both efficient and easy to manipulate once one understands the * basic trick: The list head always contains two synthetic nodes which are * always present in the list: the head and the tail. But as the `next' * entry of the tail and the `prev' entry of the head are both NULL, the * nodes can overlap each other: * * head head_node.next * null head_node.prev tail_node.next * tail tail_node.prev */ typedef struct node { struct node *next, *prev; } node; typedef union list { /* In fact two overlayed nodes */ struct { /* Head node */ struct node head_node; void *head_padding; }; struct { /* Tail node */ void *tail_padding; struct node tail_node; }; struct { /* Split to separate pointers */ struct node *head; struct node *null; struct node *tail; }; } list; #define NODE (node *) #define HEAD(list) ((void *)((list).head)) #define TAIL(list) ((void *)((list).tail)) #define NODE_NEXT(n) ((void *)((NODE (n))->next)) #define NODE_VALID(n) ((NODE (n))->next) #define WALK_LIST(n,list) for(n=HEAD(list); NODE_VALID(n); n=NODE_NEXT(n)) #define WALK_LIST2(n,nn,list,pos) \ for(nn=(list).head; NODE_VALID(nn) && (n=SKIP_BACK(typeof(*n),pos,nn)); nn=nn->next) #define WALK_LIST_DELSAFE(n,nxt,list) \ for(n=HEAD(list); nxt=NODE_NEXT(n); n=(void *) nxt) /* WALK_LIST_FIRST supposes that called code removes each processed node */ #define WALK_LIST_FIRST(n,list) \ while(n=HEAD(list), (NODE (n))->next) #define WALK_LIST_BACKWARDS(n,list) for(n=TAIL(list);(NODE (n))->prev; \ n=(void *)((NODE (n))->prev)) #define WALK_LIST_BACKWARDS_DELSAFE(n,prv,list) \ for(n=TAIL(list); prv=(void *)((NODE (n))->prev); n=(void *) prv) #define EMPTY_LIST(list) (!(list).head->next) #ifndef _BIRD_LISTS_C_ #define LIST_INLINE static inline #include "lib/lists.c" #undef LIST_INLINE #else /* _BIRD_LISTS_C_ */ #define LIST_INLINE void add_tail(list *, node *); void add_head(list *, node *); void rem_node(node *); void add_tail_list(list *, list *); void init_list(list *); void insert_node(node *, node *); #endif #endif