double_linked_list.h

/*******************************************************************************
 * DANIEL'S ALGORITHM IMPLEMENTAIONS
 *
 *  /\  |  _   _  ._ o _|_ |_  ._ _   _ 
 * /--\ | (_| (_) |  |  |_ | | | | | _> 
 *         _|                      
 *
 * DOUBLE LINKED-LIST FROM LINUX KERNEL
 *
 * Features:
 * 1. clean
 * 2. data independent
 * 3. data structure contains  next & prev pointer(in list_head struct),
 *    not like linked-list contains data
 *
 * http://en.wikipedia.org/wiki/Double_linked_list
 ******************************************************************************/

#ifndef ALGO_DOUBLE_LINKED_LIST_H__
#define ALGO_DOUBLE_LINKED_LIST_H__

struct list_head {
	struct list_head *next, *prev;
};

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

#define LIST_HEAD(name) \
	struct list_head name = LIST_HEAD_INIT(name)

#define INIT_LIST_HEAD(ptr) do { \
	(ptr)->next = (ptr); (ptr)->prev = (ptr); \
} while (0)

/*
 * Insert a new entry between two known consecutive entries. 
 *
 * This is only for internal list manipulation where we know
 * the prev/next entries already!
 */
static inline void 
list_add_(struct list_head *n,
			      struct list_head *prev,
			      struct list_head *next)
{
	next->prev = n;
	n->next = next;
	n->prev = prev;
	prev->next = n;
}

/*
 * Delete a list entry by making the prev/next entries
 * point to each other.
 *
 * This is only for internal list manipulation where we know
 * the prev/next entries already!
 */
static inline void 
list_del_(struct list_head *prev, struct list_head *next)
{
	next->prev = prev;
	prev->next = next;
}

static inline void 
list_splice_(struct list_head *list, struct list_head *head)
{
	struct list_head *first = list->next;
	struct list_head *last = list->prev;
	struct list_head *at = head->next;

	first->prev = head;
	head->next = first;

	last->next = at;
	at->prev = last;
}

/**
 * list_add - add a new entry
 * @new: new entry to be added
 * @head: list head to add it after
 *
 * Insert a new entry after the specified head.
 * This is good for implementing stacks.
 */
static inline void 
list_add(struct list_head *n, struct list_head *head)
{
	list_add_(n, head, head->next);
}

/**
 * list_add_tail - add a new entry
 * @new: new entry to be added
 * @head: list head to add it before
 *
 * Insert a new entry before the specified head.
 * This is useful for implementing queues.
 */
static inline void 
list_add_tail(struct list_head *n, struct list_head *head)
{
	list_add_(n, head->prev, head);
}

/**
 * list_del - deletes entry from list.
 * @entry: the element to delete from the list.
 * Note: list_empty on entry does not return true after this, the entry is in an undefined state.
 */
static inline void 
list_del(struct list_head *entry)
{
	list_del_(entry->prev, entry->next);
	entry->next = NULL;
	entry->prev = NULL;
}

/**
 * list_del_init - deletes entry from list and reinitialize it.
 * @entry: the element to delete from the list.
 */
static inline void 
list_del_init(struct list_head *entry)
{
	list_del_(entry->prev, entry->next);
	INIT_LIST_HEAD(entry); 
}

/**
 * list_move - delete from one list and add as another's head
 * @list: the entry to move
 * @head: the head that will precede our entry
 */
static inline void 
list_move(struct list_head *list, struct list_head *head)
{
        list_del_(list->prev, list->next);
        list_add(list, head);
}

/**
 * list_move_tail - delete from one list and add as another's tail
 * @list: the entry to move
 * @head: the head that will follow our entry
 */
static inline void 
list_move_tail(struct list_head *list, struct list_head *head)
{
        list_del_(list->prev, list->next);
        list_add_tail(list, head);
}

/**
 * list_empty - tests whether a list is empty
 * @head: the list to test.
 */
static inline int 
list_empty(const struct list_head *head)
{
	return head->next == head;
}

/**
 * list_splice - join two lists
 * @list: the new list to add.
 * @head: the place to add it in the first list.
 */
static inline void 
list_splice(struct list_head *list, struct list_head *head)
{
	if (!list_empty(list))
		list_splice_(list, head);
}

/**
 * list_splice_init - join two lists and reinitialise the emptied list.
 * @list: the new list to add.
 * @head: the place to add it in the first list.
 *
 * The list at @list is reinitialised
 */
static inline void list_splice_init(struct list_head *list,
				    struct list_head *head)
{
	if (!list_empty(list)) {
		list_splice_(list, head);
		INIT_LIST_HEAD(list);
	}
}

/**
 * list_entry - get the struct for this entry
 * @ptr:	the &struct list_head pointer.
 * @type:	the type of the struct this is embedded in.
 * @member:	the name of the list_struct within the struct.
 */
#ifndef _MSC_VER
#define list_entry(ptr, type, member) \
	(reinterpret_cast<type *>((char *)(ptr)-(char *)(&(reinterpret_cast<type *>(1)->member))+1))
#else
#define list_entry(ptr, ptrtype, member) \
	(reinterpret_cast<ptrtype>((char *)(ptr)-(char *)(&(reinterpret_cast<ptrtype>(1)->member))+1))
#endif


/**
 * list_for_each	-	iterate over a list
 * @pos:	the &struct list_head to use as a loop counter.
 * @head:	the head for your list.
 */
#define list_for_each(pos, head) \
	for (pos = (head)->next; pos != (head); \
        	pos = pos->next)
/**
 * list_for_each_prev	-	iterate over a list backwards
 * @pos:	the &struct list_head to use as a loop counter.
 * @head:	the head for your list.
 */
#define list_for_each_prev(pos, head) \
	for (pos = (head)->prev; pos != (head); \
        	pos = pos->prev)
        	
/**
 * list_for_each_safe	-	iterate over a list safe against removal of list entry
 * @pos:	the &struct list_head to use as a loop counter.
 * @n:		another &struct list_head to use as temporary storage
 * @head:	the head for your list.
 */
#define list_for_each_safe(pos, n, head) \
	for (pos = (head)->next, n = pos->next; pos != (head); \
		pos = n, n = pos->next)

/**
 * list_for_each_entry	-	iterate over list of given type
 * @pos:	the type * to use as a loop counter.
 * @head:	the head for your list.
 * @member:	the name of the list_struct within the struct.
 */
#ifndef _MSC_VER
#define list_for_each_entry(pos, head, member)				\
	for (pos = list_entry((head)->next, typeof(*pos), member);	\
	     &pos->member != (head); 					\
	     pos = list_entry(pos->member.next, typeof(*pos), member))
#else
#define list_for_each_entry(pos, head, member)				\
	for (pos = list_entry((head)->next, typeof(pos), member);	\
	     &pos->member != (head); 					\
	     pos = list_entry(pos->member.next, typeof(pos), member))
#endif
/**
 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
 * @pos:	the type * to use as a loop counter.
 * @n:		another type * to use as temporary storage
 * @head:	the head for your list.
 * @member:	the name of the list_struct within the struct.
 */
#ifndef _MSC_VER
#define list_for_each_entry_safe(pos, n, head, member)			\
	for (pos = list_entry((head)->next, typeof(*pos), member),	\
		n = list_entry(pos->member.next, typeof(*pos), member);	\
	     &pos->member != (head); 					\
	     pos = n, n = list_entry(n->member.next, typeof(*n), member))

#else

template<class T>
struct TypeofHelper
{
	typedef T Type;
};

#define list_for_each_entry_safe(pos, n, head, member)			\
	for (pos = list_entry((head)->next, TypeofHelper<typeof(pos)>::Type, member),	\
		n = list_entry(pos->member.next, TypeofHelper<typeof(pos)>::Type, member);	\
	     &(pos->member) != (head); 					\
	     pos = n, n = list_entry(n->member.next, TypeofHelper<typeof(n)>::Type, member))
#endif

#endif