summaryrefslogtreecommitdiff
path: root/include/list.h
blob: 11de7c561020009805665bf25099a8f7407d52c8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
/*
 * 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 The list to initialized.
 */
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 contains one or more elements or False otherwise.
 */
static inline Bool
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 = __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 = __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