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
|
/*
* Copyright (c) 2008, 2009 Nicira Networks.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <config.h>
#include "list.h"
#include <assert.h>
/* Initializes 'list' as an empty list. */
void
list_init(struct list *list)
{
list->next = list->prev = list;
}
/* Inserts 'elem' just before 'before'. */
void
list_insert(struct list *before, struct list *elem)
{
elem->prev = before->prev;
elem->next = before;
before->prev->next = elem;
before->prev = elem;
}
/* Removes elements 'first' though 'last' (exclusive) from their current list,
then inserts them just before 'before'. */
void
list_splice(struct list *before, struct list *first, struct list *last)
{
if (first == last)
return;
last = last->prev;
/* Cleanly remove 'first'...'last' from its current list. */
first->prev->next = last->next;
last->next->prev = first->prev;
/* Splice 'first'...'last' into new list. */
first->prev = before->prev;
last->next = before;
before->prev->next = first;
before->prev = last;
}
/* Inserts 'elem' at the beginning of 'list', so that it becomes the front in
'list'. */
void
list_push_front(struct list *list, struct list *elem)
{
list_insert(list->next, elem);
}
/* Inserts 'elem' at the end of 'list', so that it becomes the back in
* 'list'. */
void
list_push_back(struct list *list, struct list *elem)
{
list_insert(list, elem);
}
/* Puts 'elem' in the position currently occupied by 'position'.
* Afterward, 'position' is not part of a list. */
void
list_replace(struct list *element, const struct list *position)
{
element->next = position->next;
element->next->prev = element;
element->prev = position->prev;
element->prev->next = element;
}
/* Adjusts pointers around 'list' to compensate for 'list' having been moved
* around in memory (e.g. as a consequence of realloc()). */
void
list_moved(struct list *list)
{
list->prev->next = list->next->prev = list;
}
/* Removes 'elem' from its list and returns the element that followed it.
Undefined behavior if 'elem' is not in a list. */
struct list *
list_remove(struct list *elem)
{
elem->prev->next = elem->next;
elem->next->prev = elem->prev;
return elem->next;
}
/* Removes the front element from 'list' and returns it. Undefined behavior if
'list' is empty before removal. */
struct list *
list_pop_front(struct list *list)
{
struct list *front = list->next;
list_remove(front);
return front;
}
/* Removes the back element from 'list' and returns it.
Undefined behavior if 'list' is empty before removal. */
struct list *
list_pop_back(struct list *list)
{
struct list *back = list->prev;
list_remove(back);
return back;
}
/* Returns the front element in 'list'.
Undefined behavior if 'list' is empty. */
struct list *
list_front(struct list *list)
{
assert(!list_is_empty(list));
return list->next;
}
/* Returns the back element in 'list'.
Undefined behavior if 'list' is empty. */
struct list *
list_back(struct list *list)
{
assert(!list_is_empty(list));
return list->prev;
}
/* Returns the number of elements in 'list'.
Runs in O(n) in the number of elements. */
size_t
list_size(const struct list *list)
{
const struct list *e;
size_t cnt = 0;
for (e = list->next; e != list; e = e->next)
cnt++;
return cnt;
}
/* Returns true if 'list' is empty, false otherwise. */
bool
list_is_empty(const struct list *list)
{
return list->next == list;
}
|
