说明
很好的一套链表库, 以 list 的举例说明.
le_prev二级指针, 上一个元素的 next 成员的地址. 此处需要注意的是le_prev是上一个元素的 next 成员的地址,*le_prev是 上一个成员的值, 所以可以通过操作le_prev来操作上一个节点 的 next 成员. TODO
/*
* List definitions.
*/
#define LIST_HEAD(name, type) \
struct name { \
struct type *lh_first; /* first element */ \
}
#define LIST_HEAD_INITIALIZER(head) \
{ NULL }
#define LIST_ENTRY(type) \
struct { \
struct type *le_next; /* next element */ \
struct type **le_prev; /* address of previous next element */ \
}
/*
* List functions.
*/
#define LIST_INIT(head) do { \
(head)->lh_first = NULL; \
} while (/*CONSTCOND*/0)
#define LIST_INSERT_AFTER(listelm, elm, field) do { \
if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
(listelm)->field.le_next->field.le_prev = \
&(elm)->field.le_next; \
(listelm)->field.le_next = (elm); \
(elm)->field.le_prev = &(listelm)->field.le_next; \
} while (/*CONSTCOND*/0)
#define LIST_INSERT_BEFORE(listelm, elm, field) do { \
(elm)->field.le_prev = (listelm)->field.le_prev; \
(elm)->field.le_next = (listelm); \
*(listelm)->field.le_prev = (elm); \
(listelm)->field.le_prev = &(elm)->field.le_next; \
} while (/*CONSTCOND*/0)
#define LIST_INSERT_HEAD(head, elm, field) do { \
if (((elm)->field.le_next = (head)->lh_first) != NULL) \
(head)->lh_first->field.le_prev = &(elm)->field.le_next;\
(head)->lh_first = (elm); \
(elm)->field.le_prev = &(head)->lh_first; \
} while (/*CONSTCOND*/0)
#define LIST_REMOVE(elm, field) do { \
if ((elm)->field.le_next != NULL) \
(elm)->field.le_next->field.le_prev = \
(elm)->field.le_prev; \
*(elm)->field.le_prev = (elm)->field.le_next; \
} while (/*CONSTCOND*/0)
#define LIST_FOREACH(var, head, field) \
for ((var) = ((head)->lh_first); \
(var); \
(var) = ((var)->field.le_next))
#define LIST_FOREACH_SAFE(var, head, field, tvar) \
for ((var) = LIST_FIRST((head)); \
(var) && ((tvar) = LIST_NEXT((var), field), 1); \
(var) = (tvar))
/*
* List access methods.
*/
#define LIST_EMPTY(head) ((head)->lh_first == NULL)
#define LIST_FIRST(head) ((head)->lh_first)
#define LIST_NEXT(elm, field) ((elm)->field.le_next)
使用示例
#include <stdio.h>
#include <stdlib.h>
#include "queue.h"
/**
* 双向链表
*
*/
struct TestListEntry {
int index;
LIST_ENTRY(TestListEntry) entries;
};
static LIST_HEAD(list_head, TestListEntry) list_head;
int main(int argc, char *argv[])
{
int i = 0;
struct TestListEntry *t;
/* 插入元素 */
for (i = 0; i < 5; ++i) {
t = malloc(sizeof(*t));
t->index = i;
LIST_INSERT_HEAD(&list_head, t, entries);
}
/* 遍历链表 */
LIST_FOREACH(t, &list_head, entries) {
printf ("Element: %d\n", t->index);
}
/* 删除链表 */
LIST_FOREACH(t, &list_head, entries) {
printf ("Remode Element: %d\n", t->index);
LIST_REMOVE(t, entries);
}
return 0;
}
