xserver

list.h (15170B)

---

 /*
  * 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 _XORG_LIST_H_
 #define _XORG_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 xorg_list').
  *
  *     struct bar {
  *          ...
  *          struct xorg_list list_of_foos;
  *          ...
  *     }
  *
  *     struct foo {
  *          ...
  *          struct xorg_list entry;
  *          ...
  *     }
  *
  * Now we initialize the list head:
  *
  *     struct bar bar;
  *     ...
  *     xorg_list_init(&bar.list_of_foos);
  *
  * Then we create the first element and add it to this list:
  *
  *     struct foo *foo = malloc(...);
  *     ....
  *     xorg_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.
  *      xorg_list_del(&foo->entry);
  *      free(foo);
  *
  * Note: calling xorg_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;
  * xorg_list_for_each_entry(iterator, &bar.list_of_foos, entry) {
  *      if (iterator->something == ...)
  *             ...
  * }
  *
  * Note: You must not call xorg_list_del() on the iterator if you continue the
  * loop. You need to run the safe for-each loop instead:
  *
  * struct foo *iterator, *next;
  * xorg_list_for_each_entry_safe(iterator, next, &bar.list_of_foos, entry) {
  *      if (...)
  *              xorg_list_del(&iterator->entry);
  * }
  *
  */
 
 /**
  * The linkage struct for list nodes. This struct must be part of your
  * to-be-linked struct. struct xorg_list is required for both the head of the
  * list and for each list node.
  *
  * Position and name of the struct xorg_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 xorg_list can be a list
  * head.
  */
 struct xorg_list {
     struct xorg_list *next, *prev;
 };
 
 /**
  * Initialize the list as an empty list.
  *
  * Example:
  * xorg_list_init(&bar->list_of_foos);
  *
  * @param list The list to initialize
  */
 static inline void
 xorg_list_init(struct xorg_list *list)
 {
     list->next = list->prev = list;
 }
 
 static inline void
 __xorg_list_add(struct xorg_list *entry,
                 struct xorg_list *prev, struct xorg_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(...);
  * xorg_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
 xorg_list_add(struct xorg_list *entry, struct xorg_list *head)
 {
     __xorg_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(...);
  * xorg_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
 xorg_list_append(struct xorg_list *entry, struct xorg_list *head)
 {
     __xorg_list_add(entry, head->prev, head);
 }
 
 static inline void
 __xorg_list_del(struct xorg_list *prev, struct xorg_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 xorg_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:
  * xorg_list_del(&foo->entry);
  *
  * @param entry The element to remove.
  */
 static inline void
 xorg_list_del(struct xorg_list *entry)
 {
     __xorg_list_del(entry->prev, entry->next);
     xorg_list_init(entry);
 }
 
 /**
  * Check if the list is empty.
  *
  * Example:
  * xorg_list_is_empty(&bar->list_of_foos);
  *
  * @return True if the list is empty or False if the list contains one or more
  * elements.
  */
 static inline int
 xorg_list_is_empty(struct xorg_list *head)
 {
     return head->next == head;
 }
 
 /**
  * Returns a pointer to the container of this list element.
  *
  * Example:
  * struct foo* f;
  * f = container_of(&foo->entry, struct foo, entry);
  * assert(f == foo);
  *
  * @param ptr Pointer to the struct xorg_list.
  * @param type Data type of the list element.
  * @param member Member name of the struct xorg_list field in the list element.
  * @return A pointer to the data struct containing the list head.
  */
 #ifndef container_of
 #define container_of(ptr, type, member) \
     (type *)((char *)(ptr) - offsetof(type, member))
 #endif
 
 /**
  * Alias of container_of
  */
 #define xorg_list_entry(ptr, type, member) \
     container_of(ptr, type, member)
 
 /**
  * Retrieve the first list entry for the given list pointer.
  *
  * Example:
  * struct foo *first;
  * first = xorg_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 xorg_list field in the list element.
  * @return A pointer to the first list element.
  */
 #define xorg_list_first_entry(ptr, type, member) \
     xorg_list_entry((ptr)->next, type, member)
 
 /**
  * Retrieve the last list entry for the given listpointer.
  *
  * Example:
  * struct foo *first;
  * first = xorg_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 xorg_list field in the list element.
  * @return A pointer to the last list element.
  */
 #define xorg_list_last_entry(ptr, type, member) \
     xorg_list_entry((ptr)->prev, type, member)
 
 #ifdef HAVE_TYPEOF
 #define __container_of(ptr, sample, member)			\
     container_of(ptr, typeof(*sample), member)
 #else
 /* This implementation of __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 __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;
  * xorg_list_for_each_entry(iterator, &bar->list_of_foos, entry) {
  *      [modify iterator]
  * }
  *
  * This macro is not safe for node deletion. Use xorg_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 xorg_list in the list elements.
  *
  */
 #define xorg_list_for_each_entry(pos, head, member)			\
     for (pos = NULL,                                                    \
          pos = __container_of((head)->next, pos, member);		\
 	 &pos->member != (head);					\
 	 pos = __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 xorg_list_for_each_entry for more details.
  */
 #define xorg_list_for_each_entry_safe(pos, tmp, head, member)		\
     for (pos = NULL,                                                    \
          pos = __container_of((head)->next, pos, member),		\
 	 tmp = __container_of(pos->member.next, pos, member);		\
 	 &pos->member != (head);					\
 	 pos = tmp, tmp = __container_of(pos->member.next, tmp, member))
 
 /* NULL-Terminated List Interface
  *
  * The interface below does _not_ use the struct xorg_list as described above.
  * It is mainly for legacy structures that cannot easily be switched to
  * struct xorg_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();
  * 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 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 = nt_list_next(element, next)) { }
  *
  * This macro is not safe for node deletion. Use 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 nt_list_next(_list, _member) \
 	(_list)->_member
 
 /**
  * Iterate through each element in the list.
  *
  * Example:
  * struct foo *iterator;
  * 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 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 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 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(...);
  * nt_list_init(elem, next)
  * 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 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(...);
  * nt_list_init(elem, next)
  * 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 nt_list_insert(_entry, _list, _type, _member)			\
     do {								\
 	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>
  * 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 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 = nt_list_next(__prev, _member);	\
 		    if (__prev->_member)			\
 			__prev->_member = __e->_member;		\
 		}						\
 		nt_list_init(__e, _member);			\
 	} while(0)
 
 /**
  * DO NOT USE THIS.
  * This is a remainder of the xfree86 DDX attempt of having a set of generic
  * list functions. Unfortunately, the xf86OptionRec uses it and we can't
  * easily get rid of it. Do not use for new code.
  */
 typedef struct generic_list_rec {
     void *next;
 } GenericListRec, *GenericListPtr, *glp;
 
 #endif