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/*
* 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)
#define WALK_LIST2_DELSAFE(n,nn,nxt,list,pos) \
for(nn=HEAD(list); (nxt=nn->next) && (n=SKIP_BACK(typeof(*n),pos,nn)); nn=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_FIRST2(n,pos,list) \
while(n=SKIP_BACK(typeof(*n),pos,HEAD(list)), (n)->pos.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)
static inline _Bool
enlisted(node *n)
{
switch ((!!n->next) + (!!n->prev))
{
case 0: return 0;
case 2: return 1;
case 1: bug("Garbled event list node");
}
bug("Maths is broken. And you should see a new heaven and a new earth: for the first heaven and the first earth had been passed away.");
}
#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 self_link(node *);
void rem_node(node *);
void add_tail_list(list *, list *);
void init_list(list *);
void insert_node(node *, node *);
uint list_length(list *);
#endif
#endif
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