#pragma once
/**
 * util/list.h
 * 
 * Double Linked Lists for C
 * 
 * (c) 2016 Harald Christian Joachim Wolff
 * 
 * API (may be implemented with macros!) :
 * 
 * 
 */
 
 typedef struct _list {
	struct _list	*next,
					*prev;
 } list_t;

#define LIST_INIT_STATIC(name)	{ &(name), &(name) }	 

#define LIST(name)	list_t name = LIST_INIT_STATIC(name)
 
static inline void __list_init(list_t *list){
	list->next = list->prev = list;
}

#define list_init(L)	__list_init(L);

static inline void __list_add(list_t *item,list_t *prev,list_t *next) {
	prev->next = item;
	next->prev = item;
	item->next = next;
	item->prev = prev;
};

static inline void list_remove(list_t *item){
	item->prev->next = item->next;
	item->next->prev = item->prev;
	item->prev = item->next = item;
};

static inline void list_append(list_t* item,list_t* head){
	__list_add(item,head->prev,head);
};

static inline void list_insert(list_t* item,list_t* head){
	__list_add(item,head,head->next);
};

static inline list_t* list_next(list_t* item){ return item->next; };
static inline list_t* list_prev(list_t* item){ return item->prev; };

static inline int list_is_empty(list_t *list) {
	return (list->next == list);
};

static inline list_t* list_get(list_t *head,int n){
	if (list_is_empty(head)){
		return 0L;
	};
	while (n--){
		head = head->next;
	};
	return head;
};
static inline list_t* list_fetch_first(list_t *head){
	if (!list_is_empty(head)){
		list_t *f = head->next;
		list_remove(f);
		return f;
	} else {
		return 0L;
	};
};

/**
 * list_entry - get container struct of entry
 * @P:	Pointer to entry
 * @T:	Type of struct
 * @M:	entry member of struct
*/
#define list_entry(P,T,M) 			((T*)(int)(((int)(P)) - (int)(&(((T*)0L)->M))))

#define list_next_entry(P,T,M)		list_entry((P)->next,T,M)
#define list_prev_entry(P,T,M)		list_entry((P)->prev,T,M)

#define list_first_entry(P,T,M)		((P)->next != (P) ? list_entry((P)->next,T,M) : NULL)
#define list_last_entry(P,T,M)		((P)->prev != (P) ? list_entry((P)->prev,T,M) : NULL)

#define for_each_list_entry(pos,list)			for (pos = (list)->next; pos != (list); pos = pos->next)
#define for_each_list_entry_reverse(pos,list)	for (pos = (list)->prev; pos != (list); pos = pos->prev)

#define for_each_list_entry_save(pos,tmp,list)	for (pos = (list)->next, tmp = pos->next; pos != (list); pos = tmp, tmp = pos->next)

static inline int list_count(list_t *head){
	list_t *t;
	int n = 0;
	for_each_list_entry(t,head){
		n++;
	};
	return n;
};