/*

 * Copyright © 2010 Intel Corporation

 * Copyright © 2010 Francisco Jerez <currojerez@riseup.net>

 *

 * Permission is hereby granted, free of charge, to any person obtaining a

 * copy of this software and associated documentation files (the "Software"),

 * to deal in the Software without restriction, including without limitation

 * the rights to use, copy, modify, merge, publish, distribute, sublicense,

 * and/or sell copies of the Software, and to permit persons to whom the

 * Software is furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice (including the next

 * paragraph) shall be included in all copies or substantial portions of the

 * Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL

 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS

 * IN THE SOFTWARE.

 *

 */

#ifndef _GLVND_LIST_H_

#define _GLVND_LIST_H_

#include <stddef.h> /* offsetof() */

/**

 * @file Classic doubly-link circular list implementation.

 * For real usage examples of the linked list, see the file test/list.c

 *

 * Example:

 * We need to keep a list of struct foo in the parent struct bar, i.e. what

 * we want is something like this.

 *

 *     struct bar {

 *          ...

 *          struct foo *list_of_foos; -----> struct foo {}, struct foo {}, struct foo{}

 *          ...

 *     }

 *

 * We need one list head in bar and a list element in all list_of_foos (both are of

 * data type 'struct glvnd_list').

 *

 *     struct bar {

 *          ...

 *          struct glvnd_list list_of_foos;

 *          ...

 *     }

 *

 *     struct foo {

 *          ...

 *          struct glvnd_list entry;

 *          ...

 *     }

 *

 * Now we initialize the list head:

 *

 *     struct bar bar;

 *     ...

 *     glvnd_list_init(&bar.list_of_foos);

 *

 * Then we create the first element and add it to this list:

 *

 *     struct foo *foo = malloc(...);

 *     ....

 *     glvnd_list_add(&foo->entry, &bar.list_of_foos);

 *

 * Repeat the above for each element you want to add to the list. Deleting

 * works with the element itself.

 *      glvnd_list_del(&foo->entry);

 *      free(foo);

 *

 * Note: calling glvnd_list_del(&bar.list_of_foos) will set bar.list_of_foos to an empty

 * list again.

 *

 * Looping through the list requires a 'struct foo' as iterator and the

 * name of the field the subnodes use.

 *

 * struct foo *iterator;

 * glvnd_list_for_each_entry(iterator, &bar.list_of_foos, entry) {

 *      if (iterator->something == ...)

 *             ...

 * }

 *

 * Note: You must not call glvnd_list_del() on the iterator if you continue the

 * loop. You need to run the safe for-each loop instead:

 *

 * struct foo *iterator, *next;

 * glvnd_list_for_each_entry_safe(iterator, next, &bar.list_of_foos, entry) {

 *      if (...)

 *              glvnd_list_del(&iterator->entry);

 * }

 *

 */

/**

 * The linkage struct for list nodes. This struct must be part of your

 * to-be-linked struct. struct glvnd_list is required for both the head of the

 * list and for each list node.

 *

 * Position and name of the struct glvnd_list field is irrelevant.

 * There are no requirements that elements of a list are of the same type.

 * There are no requirements for a list head, any struct glvnd_list can be a list

 * head.

 */

struct glvnd_list {

    struct glvnd_list *next, *prev;

};

/**

 * Initialize the list as an empty list.

 *

 * Example:

 * glvnd_list_init(&bar->list_of_foos);

 *

 * @param The list to initialized.

 */

static inline void

glvnd_list_init(struct glvnd_list *list)

{

    list->next = list->prev = list;

}

static inline void

__glvnd_list_add(struct glvnd_list *entry,

                struct glvnd_list *prev, struct glvnd_list *next)

{

    next->prev = entry;

    entry->next = next;

    entry->prev = prev;

    prev->next = entry;

}

/**

 * Insert a new element after the given list head. The new element does not

 * need to be initialised as empty list.

 * The list changes from:

 *      head → some element → ...

 * to

 *      head → new element → older element → ...

 *

 * Example:

 * struct foo *newfoo = malloc(...);

 * glvnd_list_add(&newfoo->entry, &bar->list_of_foos);

 *

 * @param entry The new element to prepend to the list.

 * @param head The existing list.

 */

static inline void

glvnd_list_add(struct glvnd_list *entry, struct glvnd_list *head)

{

    __glvnd_list_add(entry, head, head->next);

}

/**

 * Append a new element to the end of the list given with this list head.

 *

 * The list changes from:

 *      head → some element → ... → lastelement

 * to

 *      head → some element → ... → lastelement → new element

 *

 * Example:

 * struct foo *newfoo = malloc(...);

 * glvnd_list_append(&newfoo->entry, &bar->list_of_foos);

 *

 * @param entry The new element to prepend to the list.

 * @param head The existing list.

 */

static inline void

glvnd_list_append(struct glvnd_list *entry, struct glvnd_list *head)

{

    __glvnd_list_add(entry, head->prev, head);

}

static inline void

__glvnd_list_del(struct glvnd_list *prev, struct glvnd_list *next)

{

    next->prev = prev;

    prev->next = next;

}

/**

 * Remove the element from the list it is in. Using this function will reset

 * the pointers to/from this element so it is removed from the list. It does

 * NOT free the element itself or manipulate it otherwise.

 *

 * Using glvnd_list_del on a pure list head (like in the example at the top of

 * this file) will NOT remove the first element from

 * the list but rather reset the list as empty list.

 *

 * Example:

 * glvnd_list_del(&foo->entry);

 *

 * @param entry The element to remove.

 */

static inline void

glvnd_list_del(struct glvnd_list *entry)

{

    __glvnd_list_del(entry->prev, entry->next);

    glvnd_list_init(entry);

}

/**

 * Check if the list is empty.

 *

 * Example:

 * glvnd_list_is_empty(&bar->list_of_foos);

 *

 * @return True if the list contains one or more elements or False otherwise.

 */

static inline int

glvnd_list_is_empty(struct glvnd_list *head)

{

    return head->next == head;

}

/**

 * Returns a pointer to the container of this list element.

 *

 * Example:

 * struct foo* f;

 * f = glvnd_container_of(&foo->entry, struct foo, entry);

 * assert(f == foo);

 *

 * @param ptr Pointer to the struct glvnd_list.

 * @param type Data type of the list element.

 * @param member Member name of the struct glvnd_list field in the list element.

 * @return A pointer to the data struct containing the list head.

 */

#ifndef glvnd_container_of

#define glvnd_container_of(ptr, type, member) \

    (type *)((char *)(ptr) - offsetof(type, member))

#endif

/**

 * Alias of glvnd_container_of

 */

#define glvnd_list_entry(ptr, type, member) \

    glvnd_container_of(ptr, type, member)

/**

 * Retrieve the first list entry for the given list pointer.

 *

 * Example:

 * struct foo *first;

 * first = glvnd_list_first_entry(&bar->list_of_foos, struct foo, list_of_foos);

 *

 * @param ptr The list head

 * @param type Data type of the list element to retrieve

 * @param member Member name of the struct glvnd_list field in the list element.

 * @return A pointer to the first list element.

 */

#define glvnd_list_first_entry(ptr, type, member) \

    glvnd_list_entry((ptr)->next, type, member)

/**

 * Retrieve the last list entry for the given listpointer.

 *

 * Example:

 * struct foo *first;

 * first = glvnd_list_last_entry(&bar->list_of_foos, struct foo, list_of_foos);

 *

 * @param ptr The list head

 * @param type Data type of the list element to retrieve

 * @param member Member name of the struct glvnd_list field in the list element.

 * @return A pointer to the last list element.

 */

#define glvnd_list_last_entry(ptr, type, member) \

    glvnd_list_entry((ptr)->prev, type, member)

#ifdef HAVE_TYPEOF

#define __glvnd_container_of(ptr, sample, member)			\

    glvnd_container_of(ptr, typeof(*sample), member)

#else

/* This implementation of __glvnd_container_of has undefined behavior according

 * to the C standard, but it works in many cases.  If your compiler doesn't

 * support typeof() and fails with this implementation, please try a newer

 * compiler.

 */

#define __glvnd_container_of(ptr, sample, member)                            \

    (void *)((char *)(ptr)                                             \

            - ((char *)&(sample)->member - (char *)(sample)))

#endif

/**

 * Loop through the list given by head and set pos to struct in the list.

 *

 * Example:

 * struct foo *iterator;

 * glvnd_list_for_each_entry(iterator, &bar->list_of_foos, entry) {

 *      [modify iterator]

 * }

 *

 * This macro is not safe for node deletion. Use glvnd_list_for_each_entry_safe

 * instead.

 *

 * @param pos Iterator variable of the type of the list elements.

 * @param head List head

 * @param member Member name of the struct glvnd_list in the list elements.

 *

 */

#define glvnd_list_for_each_entry(pos, head, member)				\

    for (pos = __glvnd_container_of((head)->next, pos, member);		\

	 &pos->member != (head);					\

	 pos = __glvnd_container_of(pos->member.next, pos, member))

/**

 * Loop through the list, keeping a backup pointer to the element. This

 * macro allows for the deletion of a list element while looping through the

 * list.

 *

 * See glvnd_list_for_each_entry for more details.

 */

#define glvnd_list_for_each_entry_safe(pos, tmp, head, member)		\

    for (pos = __glvnd_container_of((head)->next, pos, member),		\

	 tmp = __glvnd_container_of(pos->member.next, pos, member);		\

	 &pos->member != (head);					\

	 pos = tmp, tmp = __glvnd_container_of(pos->member.next, tmp, member))

/* NULL-Terminated List Interface

 *

 * The interface below does _not_ use the struct glvnd_list as described above.

 * It is mainly for legacy structures that cannot easily be switched to

 * struct glvnd_list.

 *

 * This interface is for structs like

 *      struct foo {

 *          [...]

 *          struct foo *next;

 *           [...]

 *      };

 *

 * The position and field name of "next" are arbitrary.

 */

/**

 * Init the element as null-terminated list.

 *

 * Example:

 * struct foo *list = malloc();

 * glvnd_nt_list_init(list, next);

 *

 * @param list The list element that will be the start of the list

 * @param member Member name of the field pointing to next struct

 */

#define glvnd_nt_list_init(_list, _member) \

	(_list)->_member = NULL

/**

 * Returns the next element in the list or NULL on termination.

 *

 * Example:

 * struct foo *element = list;

 * while ((element = glvnd_nt_list_next(element, next)) { }

 *

 * This macro is not safe for node deletion. Use glvnd_nt_list_for_each_entry_safe

 * instead.

 *

 * @param list The list or current element.

 * @param member Member name of the field pointing to next struct.

 */

#define glvnd_nt_list_next(_list, _member) \

	(_list)->_member

/**

 * Iterate through each element in the list.

 *

 * Example:

 * struct foo *iterator;

 * glvnd_nt_list_for_each_entry(iterator, list, next) {

 *      [modify iterator]

 * }

 *

 * @param entry Assigned to the current list element

 * @param list The list to iterate through.

 * @param member Member name of the field pointing to next struct.

 */

#define glvnd_nt_list_for_each_entry(_entry, _list, _member)			\

	for (_entry = _list; _entry; _entry = (_entry)->_member)

/**

 * Iterate through each element in the list, keeping a backup pointer to the

 * element. This macro allows for the deletion of a list element while

 * looping through the list.

 *

 * See glvnd_nt_list_for_each_entry for more details.

 *

 * @param entry Assigned to the current list element

 * @param tmp The pointer to the next element

 * @param list The list to iterate through.

 * @param member Member name of the field pointing to next struct.

 */

#define glvnd_nt_list_for_each_entry_safe(_entry, _tmp, _list, _member)	\

	for (_entry = _list, _tmp = (_entry) ? (_entry)->_member : NULL;\

		_entry;							\

		_entry = _tmp, _tmp = (_tmp) ? (_tmp)->_member: NULL)

/**

 * Append the element to the end of the list. This macro may be used to

 * merge two lists.

 *

 * Example:

 * struct foo *elem = malloc(...);

 * glvnd_nt_list_init(elem, next)

 * glvnd_nt_list_append(elem, list, struct foo, next);

 *

 * Resulting list order:

 * list_item_0 -> list_item_1 -> ... -> elem_item_0 -> elem_item_1 ...

 *

 * @param entry An entry (or list) to append to the list

 * @param list The list to append to. This list must be a valid list, not

 * NULL.

 * @param type The list type

 * @param member Member name of the field pointing to next struct

 */

#define glvnd_nt_list_append(_entry, _list, _type, _member)		        \

    do {								\

	_type *__iterator = _list;					\

	while (__iterator->_member) { __iterator = __iterator->_member;}\

	__iterator->_member = _entry;					\

    } while (0)

/**

 * Insert the element at the next position in the list. This macro may be

 * used to insert a list into a list.

 *

 * struct foo *elem = malloc(...);

 * glvnd_nt_list_init(elem, next)

 * glvnd_nt_list_insert(elem, list, struct foo, next);

 *

 * Resulting list order:

 * list_item_0 -> elem_item_0 -> elem_item_1 ... -> list_item_1 -> ...

 *

 * @param entry An entry (or list) to append to the list

 * @param list The list to insert to. This list must be a valid list, not

 * NULL.

 * @param type The list type

 * @param member Member name of the field pointing to next struct

 */

#define glvnd_nt_list_insert(_entry, _list, _type, _member)			\

    do {								\

	glvnd_nt_list_append((_list)->_member, _entry, _type, _member);	\

	(_list)->_member = _entry;					\

    } while (0)

/**

 * Delete the entry from the list by iterating through the list and

 * removing any reference from the list to the entry.

 *

 * Example:

 * struct foo *elem = <assign to right element>

 * glvnd_nt_list_del(elem, list, struct foo, next);

 *

 * @param entry The entry to delete from the list. entry is always

 * re-initialized as a null-terminated list.

 * @param list The list containing the entry, set to the new list without

 * the removed entry.

 * @param type The list type

 * @param member Member name of the field pointing to the next entry

 */

#define glvnd_nt_list_del(_entry, _list, _type, _member)		\

	do {							\

		_type *__e = _entry;				\

		if (__e == NULL || _list == NULL) break;        \

		if ((_list) == __e) {				\

		    _list = __e->_member;			\

		} else {					\

		    _type *__prev = _list;			\

		    while (__prev->_member && __prev->_member != __e)	\

			__prev = glvnd_nt_list_next(__prev, _member);	\

		    if (__prev->_member)			\

			__prev->_member = __e->_member;		\

		}						\

		glvnd_nt_list_init(__e, _member);			\

	} while(0)

#endif