[thirdparty/systemd.git] / src / basic / list.h

/* SPDX-License-Identifier: LGPL-2.1-or-later */
#pragma once

/* The head of the linked list. Use this in the structure that shall
 * contain the head of the linked list */
#define LIST_HEAD(t,name)                                               \
        t *name

/* The pointers in the linked list's items. Use this in the item structure */
#define LIST_FIELDS(t,name)                                             \
        t *name##_next, *name##_prev

/* Initialize the list's head */
#define LIST_HEAD_INIT(head)                                            \
        do {                                                            \
                (head) = NULL;                                          \
        } while (false)

/* Initialize a list item */
#define LIST_INIT(name,item)                                            \
        do {                                                            \
                typeof(*(item)) *_item = (item);                        \
                assert(_item);                                          \
                _item->name##_prev = _item->name##_next = NULL;         \
        } while (false)

/* Prepend an item to the list */
#define LIST_PREPEND(name,head,item)                                    \
        ({                                                              \
                typeof(*(head)) **_head = &(head), *_item = (item);     \
                assert(_item);                                          \
                if ((_item->name##_next = *_head))                      \
                        _item->name##_next->name##_prev = _item;        \
                _item->name##_prev = NULL;                              \
                *_head = _item;                                         \
                _item;                                                  \
        })

/* Append an item to the list */
#define LIST_APPEND(name,head,item)                                     \
        ({                                                              \
                typeof(*(head)) **_hhead = &(head), *_tail;             \
                _tail = LIST_FIND_TAIL(name, *_hhead);                  \
                LIST_INSERT_AFTER(name, *_hhead, _tail, item);          \
        })

/* Remove an item from the list */
#define LIST_REMOVE(name,head,item)                                     \
        ({                                                              \
                typeof(*(head)) **_head = &(head), *_item = (item);     \
                assert(_item);                                          \
                if (_item->name##_next)                                 \
                        _item->name##_next->name##_prev = _item->name##_prev; \
                if (_item->name##_prev)                                 \
                        _item->name##_prev->name##_next = _item->name##_next; \
                else {                                                  \
                        assert(*_head == _item);                        \
                        *_head = _item->name##_next;                    \
                }                                                       \
                _item->name##_next = _item->name##_prev = NULL;         \
                _item;                                                  \
        })

/* Find the head of the list */
#define LIST_FIND_HEAD(name,item)                                       \
        ({                                                              \
                typeof(*(item)) *_item = (item);                        \
                while (_item && _item->name##_prev)                     \
                        _item = _item->name##_prev;                     \
                _item;                                                  \
        })

/* Find the tail of the list */
#define LIST_FIND_TAIL(name,item)                                       \
        ({                                                              \
                typeof(*(item)) *_item = (item);                        \
                while (_item && _item->name##_next)                     \
                        _item = _item->name##_next;                     \
                _item;                                                  \
        })

/* Insert an item after another one (a = where, b = what) */
#define LIST_INSERT_AFTER(name,head,a,b)                                \
        ({                                                              \
                typeof(*(head)) **_head = &(head), *_a = (a), *_b = (b); \
                assert(_b);                                             \
                if (!_a) {                                              \
                        if ((_b->name##_next = *_head))                 \
                                _b->name##_next->name##_prev = _b;      \
                        _b->name##_prev = NULL;                         \
                        *_head = _b;                                    \
                } else {                                                \
                        if ((_b->name##_next = _a->name##_next))        \
                                _b->name##_next->name##_prev = _b;      \
                        _b->name##_prev = _a;                           \
                        _a->name##_next = _b;                           \
                }                                                       \
                _b;                                                     \
        })

/* Insert an item before another one (a = where, b = what) */
#define LIST_INSERT_BEFORE(name,head,a,b)                               \
        ({                                                              \
                typeof(*(head)) **_head = &(head), *_a = (a), *_b = (b); \
                assert(_b);                                             \
                if (!_a) {                                              \
                        if (!*_head) {                                  \
                                _b->name##_next = NULL;                 \
                                _b->name##_prev = NULL;                 \
                                *_head = _b;                            \
                        } else {                                        \
                                typeof(*(head)) *_tail = (head);        \
                                while (_tail->name##_next)              \
                                        _tail = _tail->name##_next;     \
                                _b->name##_next = NULL;                 \
                                _b->name##_prev = _tail;                \
                                _tail->name##_next = _b;                \
                        }                                               \
                } else {                                                \
                        if ((_b->name##_prev = _a->name##_prev))        \
                                _b->name##_prev->name##_next = _b;      \
                        else                                            \
                                *_head = _b;                            \
                        _b->name##_next = _a;                           \
                        _a->name##_prev = _b;                           \
                }                                                       \
                _b;                                                     \
        })

#define LIST_JUST_US(name, item)                                        \
        ({                                                              \
                typeof(*(item)) *_item = (item);                        \
                !(_item)->name##_prev && !(_item)->name##_next;         \
        })

/* The type of the iterator 'i' is automatically determined by the type of 'head', and declared in the
 * loop. Hence, do not declare the same variable in the outer scope. Sometimes, we set 'head' through
 * hashmap_get(). In that case, you need to explicitly cast the result. */
#define LIST_FOREACH_WITH_NEXT(name,i,n,head)                           \
        for (typeof(*(head)) *n, *i = (head); i && (n = i->name##_next, true); i = n)

#define LIST_FOREACH(name,i,head)                                       \
        LIST_FOREACH_WITH_NEXT(name, i, UNIQ_T(n, UNIQ), head)

#define _LIST_FOREACH_WITH_PREV(name,i,p,start)                         \
        for (typeof(*(start)) *p, *i = (start); i && (p = i->name##_prev, true); i = p)

#define LIST_FOREACH_BACKWARDS(name,i,start)                            \
        _LIST_FOREACH_WITH_PREV(name, i, UNIQ_T(p, UNIQ), start)

/* Iterate through all the members of the list p is included in, but skip over p */
#define LIST_FOREACH_OTHERS(name,i,p)                                   \
        for (typeof(*(p)) *_p = (p), *i = ({                            \
                                typeof(*_p) *_j = _p;                   \
                                while (_j && _j->name##_prev)           \
                                        _j = _j->name##_prev;           \
                                if (_j == _p)                           \
                                        _j = _p->name##_next;           \
                                _j;                                     \
                        });                                             \
             i;                                                         \
             i = i->name##_next == _p ? _p->name##_next : i->name##_next)

/* Loop starting from p->next until p->prev. p can be adjusted meanwhile. */
#define LIST_LOOP_BUT_ONE(name,i,head,p)                                \
        for (typeof(*(p)) *i = (p)->name##_next ? (p)->name##_next : (head); \
             i != (p);                                                  \
             i = i->name##_next ? i->name##_next : (head))

/* Join two lists tail to head: a->b, c->d to a->b->c->d and de-initialise second list */
#define LIST_JOIN(name,a,b)                                             \
        ({                                                              \
                assert(b);                                              \
                if (!(a))                                               \
                        (a) = (b);                                      \
                else {                                                  \
                        typeof(*(a)) *_head = (b), *_tail;              \
                        _tail = LIST_FIND_TAIL(name, (a));              \
                        _tail->name##_next = _head;                     \
                        _head->name##_prev = _tail;                     \
                }                                                       \
                (b) = NULL;                                             \
                a;                                                      \
        })

#define LIST_POP(name, a)                                               \
        ({                                                              \
                typeof(a)* _a = &(a);                                   \
                typeof(a) _p = *_a;                                     \
                if (_p)                                                 \
                        LIST_REMOVE(name, *_a, _p);                     \
                _p;                                                     \
        })

#define LIST_CLEAR(name, head, free_func)       \
        _LIST_CLEAR(name, head, free_func, UNIQ_T(elem, UNIQ))

/* Clear the list, destroying each element with free_func */
#define _LIST_CLEAR(name, head, free_func, elem)        \
        ({                                              \
                typeof(head) elem;                      \
                while ((elem = LIST_POP(name, head)))   \
                        free_func(elem);                \
                head;                                   \
        })

/* Now include "macro.h", because we want our definition of assert() which the macros above use. We include
 * it down here instead of up top, since macro.h pulls in log.h which in turn needs our own definitions. */
#include "macro.h"
Commit	Line	Data
db9ecf05	1	/* SPDX-License-Identifier: LGPL-2.1-or-later */
c2f1db8f	2	#pragma once
60918275 LP	3
	4	/* The head of the linked list. Use this in the structure that shall
	5	* contain the head of the linked list */
	6	#define LIST_HEAD(t,name) \
034c6ed7	7	t *name
60918275 LP	8
60918275 LP	9	/* The pointers in the linked list's items. Use this in the item structure */
034c6ed7 LP	10	#define LIST_FIELDS(t,name) \
034c6ed7 LP	11	t name##_next, name##_prev
60918275 LP	12
60918275 LP	13	/* Initialize the list's head */
71fda00f	14	#define LIST_HEAD_INIT(head) \
60918275	15	do { \
0d7f7c2f YW	16	(head) = NULL; \
0d7f7c2f YW	17	} while (false)
60918275 LP	18
60918275 LP	19	/* Initialize a list item */
71fda00f	20	#define LIST_INIT(name,item) \
60918275	21	do { \
71fda00f	22	typeof((item)) _item = (item); \
60918275	23	assert(_item); \
034c6ed7	24	_item->name##_prev = _item->name##_next = NULL; \
9ed794a3	25	} while (false)
60918275 LP	26
60918275 LP	27	/* Prepend an item to the list */
71fda00f	28	#define LIST_PREPEND(name,head,item) \
cc232fa0	29	({ \
71fda00f	30	typeof((head)) _head = &(head), _item = (item); \
60918275	31	assert(_item); \
034c6ed7 LP	32	if ((_item->name##_next = *_head)) \
	33	_item->name##_next->name##_prev = _item; \
	34	_item->name##_prev = NULL; \
60918275	35	*_head = _item; \
cc232fa0 DDM	36	_item; \
cc232fa0 DDM	37	})
60918275	38
502f1733 ZJS	39	/* Append an item to the list */
502f1733 ZJS	40	#define LIST_APPEND(name,head,item) \
cc232fa0	41	({ \
30883051	42	typeof((head)) _hhead = &(head), _tail; \
cc232fa0	43	_tail = LIST_FIND_TAIL(name, *_hhead); \
30883051	44	LIST_INSERT_AFTER(name, *_hhead, _tail, item); \
cc232fa0	45	})
502f1733	46
60918275	47	/* Remove an item from the list */
71fda00f	48	#define LIST_REMOVE(name,head,item) \
24a5370b	49	({ \
71fda00f	50	typeof((head)) _head = &(head), _item = (item); \
60918275	51	assert(_item); \
034c6ed7 LP	52	if (_item->name##_next) \
	53	_item->name##_next->name##_prev = _item->name##_prev; \
	54	if (_item->name##_prev) \
	55	_item->name##_prev->name##_next = _item->name##_next; \
60918275 LP	56	else { \
60918275 LP	57	assert(*_head == _item); \
034c6ed7	58	*_head = _item->name##_next; \
60918275	59	} \
034c6ed7	60	_item->name##_next = _item->name##_prev = NULL; \
cc232fa0 DDM	61	_item; \
cc232fa0 DDM	62	})
60918275 LP	63
60918275 LP	64	/* Find the head of the list */
cc232fa0 DDM	65	#define LIST_FIND_HEAD(name,item) \
cc232fa0 DDM	66	({ \
71fda00f	67	typeof((item)) _item = (item); \
cc232fa0 DDM	68	while (_item && _item->name##_prev) \
	69	_item = _item->name##_prev; \
	70	_item; \
	71	})
034c6ed7	72
3b18ae68	73	/* Find the tail of the list */
cc232fa0 DDM	74	#define LIST_FIND_TAIL(name,item) \
cc232fa0 DDM	75	({ \
71fda00f	76	typeof((item)) _item = (item); \
cc232fa0 DDM	77	while (_item && _item->name##_next) \
	78	_item = _item->name##_next; \
	79	_item; \
	80	})
60918275 LP	81
60918275 LP	82	/* Insert an item after another one (a = where, b = what) */
71fda00f	83	#define LIST_INSERT_AFTER(name,head,a,b) \
cc232fa0	84	({ \
71fda00f	85	typeof((head)) _head = &(head), _a = (a), *_b = (b); \
60918275 LP	86	assert(_b); \
60918275 LP	87	if (!_a) { \
034c6ed7 LP	88	if ((_b->name##_next = *_head)) \
	89	_b->name##_next->name##_prev = _b; \
	90	_b->name##_prev = NULL; \
60918275 LP	91	*_head = _b; \
60918275 LP	92	} else { \
034c6ed7 LP	93	if ((_b->name##_next = _a->name##_next)) \
	94	_b->name##_next->name##_prev = _b; \
	95	_b->name##_prev = _a; \
	96	_a->name##_next = _b; \
60918275	97	} \
cc232fa0 DDM	98	_b; \
cc232fa0 DDM	99	})
60918275	100
dbe465c9 AC	101	/* Insert an item before another one (a = where, b = what) */
dbe465c9 AC	102	#define LIST_INSERT_BEFORE(name,head,a,b) \
cc232fa0	103	({ \
dbe465c9 AC	104	typeof((head)) _head = &(head), _a = (a), *_b = (b); \
	105	assert(_b); \
	106	if (!_a) { \
	107	if (!*_head) { \
	108	_b->name##_next = NULL; \
	109	_b->name##_prev = NULL; \
	110	*_head = _b; \
	111	} else { \
	112	typeof((head)) _tail = (head); \
	113	while (_tail->name##_next) \
	114	_tail = _tail->name##_next; \
	115	_b->name##_next = NULL; \
	116	_b->name##_prev = _tail; \
	117	_tail->name##_next = _b; \
	118	} \
	119	} else { \
	120	if ((_b->name##_prev = _a->name##_prev)) \
	121	_b->name##_prev->name##_next = _b; \
5076f421 MO	122	else \
5076f421 MO	123	*_head = _b; \
dbe465c9 AC	124	_b->name##_next = _a; \
	125	_a->name##_prev = _b; \
	126	} \
cc232fa0 DDM	127	_b; \
cc232fa0 DDM	128	})
dbe465c9	129
24a5370b YW	130	#define LIST_JUST_US(name, item) \
	131	({ \
	132	typeof((item)) _item = (item); \
	133	!(_item)->name##_prev && !(_item)->name##_next; \
	134	})
6210e7fc	135
03677889 YW	136	/* The type of the iterator 'i' is automatically determined by the type of 'head', and declared in the
	137	* loop. Hence, do not declare the same variable in the outer scope. Sometimes, we set 'head' through
	138	* hashmap_get(). In that case, you need to explicitly cast the result. */
80a226b2 YW	139	#define LIST_FOREACH_WITH_NEXT(name,i,n,head) \
	140	for (typeof((head)) n, *i = (head); i && (n = i->name##_next, true); i = n)
	141
034c6ed7	142	#define LIST_FOREACH(name,i,head) \
80a226b2	143	LIST_FOREACH_WITH_NEXT(name, i, UNIQ_T(n, UNIQ), head)
60918275	144
80a226b2 YW	145	#define _LIST_FOREACH_WITH_PREV(name,i,p,start) \
80a226b2 YW	146	for (typeof((start)) p, *i = (start); i && (p = i->name##_prev, true); i = p)
60918275	147
80a226b2 YW	148	#define LIST_FOREACH_BACKWARDS(name,i,start) \
80a226b2 YW	149	_LIST_FOREACH_WITH_PREV(name, i, UNIQ_T(p, UNIQ), start)
2bc8ca0c	150
7663df37 LP	151	/* Iterate through all the members of the list p is included in, but skip over p */
7663df37 LP	152	#define LIST_FOREACH_OTHERS(name,i,p) \
03677889 YW	153	for (typeof((p)) _p = (p), *i = ({ \
	154	typeof(_p) _j = _p; \
	155	while (_j && _j->name##_prev) \
	156	_j = _j->name##_prev; \
	157	if (_j == _p) \
	158	_j = _p->name##_next; \
	159	_j; \
	160	}); \
	161	i; \
	162	i = i->name##_next == _p ? _p->name##_next : i->name##_next)
	163
	164	/* Loop starting from p->next until p->prev. p can be adjusted meanwhile. */
2bc8ca0c	165	#define LIST_LOOP_BUT_ONE(name,i,head,p) \
03677889 YW	166	for (typeof((p)) i = (p)->name##_next ? (p)->name##_next : (head); \
	167	i != (p); \
	168	i = i->name##_next ? i->name##_next : (head))
40a57716	169
5511d8c1 LB	170	/* Join two lists tail to head: a->b, c->d to a->b->c->d and de-initialise second list */
5511d8c1 LB	171	#define LIST_JOIN(name,a,b) \
cc232fa0	172	({ \
5511d8c1 LB	173	assert(b); \
	174	if (!(a)) \
	175	(a) = (b); \
	176	else { \
	177	typeof((a)) _head = (b), *_tail; \
cc232fa0	178	_tail = LIST_FIND_TAIL(name, (a)); \
5511d8c1 LB	179	_tail->name##_next = _head; \
	180	_head->name##_prev = _tail; \
	181	} \
	182	(b) = NULL; \
cc232fa0 DDM	183	a; \
cc232fa0 DDM	184	})
55cb63bf LP	185
	186	#define LIST_POP(name, a) \
	187	({ \
	188	typeof(a)* _a = &(a); \
	189	typeof(a) _p = *_a; \
	190	if (_p) \
	191	LIST_REMOVE(name, *_a, _p); \
	192	_p; \
	193	})
7c7a9138	194
d327b775 DT	195	#define LIST_CLEAR(name, head, free_func) \
	196	_LIST_CLEAR(name, head, free_func, UNIQ_T(elem, UNIQ))
	197
fcdd21ec	198	/* Clear the list, destroying each element with free_func */
d327b775 DT	199	#define _LIST_CLEAR(name, head, free_func, elem) \
	200	({ \
	201	typeof(head) elem; \
	202	while ((elem = LIST_POP(name, head))) \
	203	free_func(elem); \
	204	head; \
	205	})
	206
7c7a9138 DDM	207	/* Now include "macro.h", because we want our definition of assert() which the macros above use. We include
	208	* it down here instead of up top, since macro.h pulls in log.h which in turn needs our own definitions. */
	209	#include "macro.h"