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133 | #include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/queue.h>
//定义包含tailq的结构体
struct entry {
int data; //用户数据部分
TAILQ_ENTRY(entry) entries; //Tail queue，这个必须要定义
};
#if 0
//下面是TAILQ_ENTRY宏源码，
#define TAILQ_ENTRY(type) \
struct {\
struct type *tqe_next; /* next element */\
struct type **tqe_prev; /* address of previous next element */\
}
//在匿名结果体里，加了两个struct type类型的指针
//展开struct entry就是
struct entry {
int data;
struct{
struct entry *tqe_next;
struct entry **tqe_prev;
} entries;
};
#endif
//定义tailq的头结构体
TAILQ_HEAD(tailhead, entry);
#if 0
//下面是TAILQ_HEAD宏源码，
#define TAILQ_HEAD(name, type) \
struct name { \
struct type *tqh_first; /* first element */ \
struct type **tqh_last; /* addr of last next element */ \
}
//展开就是
struct tailhead {
struct entry *tqh_first;
struct entry **tqh_last;
};
#endif
int main(void)
{
struct tailhead head; //定义tailq头部
struct entry *n1, *n2, *n3, *np; //定义4个节点指针
int i;
//初始化头部,这里传进去的是指针
TAILQ_INIT(&head);
#if 0
//TAILQ_INIT宏源码
#define TAILQ_INIT(head) do {\
TAILQ_FIRST((head)) = NULL;\
(head)->tqh_last = &TAILQ_FIRST((head));\
} while (0)
//TAILQ_FIRS源码
#define TAILQ_FIRST(head) ((head)->tqh_first)
//展开后的初始化源码
do{
heap->tqh_first = NULL; //tqh_first值赋值为空
heap->tqh_last = &heap->tqh_first; //tqh_last值赋值为tqh_first的地址，
//注意是tqh_first这个变量的地址，
//而不是tqh_first指向的节点的地址
}while()
//初始化完变量值 __________
// tqh_first |NULL |
// tqh_last |&tqh_first|
// ——————————
#endif
n1 = malloc(sizeof(struct entry));
TAILQ_INSERT_HEAD(&head, n1, entries);
#if 0
//TAILQ_INSERT_HEAD宏源码
#define TAILQ_INSERT_HEAD(head, elm, field) do { \
if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
TAILQ_FIRST((head))->field.tqe_prev = \
&TAILQ_NEXT((elm), field); \
else \
(head)->tqh_last = &TAILQ_NEXT((elm), field); \
TAILQ_FIRST((head)) = (elm); \
(elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
} while (0)
//TAILQ_NEXT源码
#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
//展开后的源码
do {
//将头节点的下一节点作为elm的下一个节点
elm->entries.tqe_next = head.tqh_first;
if(elm->entries.tqe_next != NULL) //如果elm的下一节点不为空
{
//将之前的一个节点的prev指向elm的next
head->tqh_first->entries.tqe_prev =&elm->entries.tqe_next;
}
else //elm下一节点为空，即队列就一个节点
{
head->tqh_last = &elm->entries.tqe_next; //尾指针包含elm的tqe_next的地址
}
head->tqh_first = elm; //新节点为头节点之后的第一个节点
elm->entries.tqe_prev = &head->tqh_first; //elm的pre指针包含头节点tqh_first的地址
} while (0)
#endif
n1 = malloc(sizeof(struct entry));
TAILQ_INSERT_TAIL(&head, n1, entries);
n2 = malloc(sizeof(struct entry));
TAILQ_INSERT_AFTER(&head, n1, n2, entries);
n3 = malloc(sizeof(struct entry));
TAILQ_INSERT_BEFORE(n2, n3, entries);
TAILQ_REMOVE(&head, n2, entries);
free(n2);
i = 0;
TAILQ_FOREACH(np, &head, entries)
np->data = i++;
TAILQ_FOREACH_REVERSE(np, &head, tailhead, entries)
printf("%i\n", np->data);
n1 = TAILQ_FIRST(&head);
while (n1 != NULL) {
n2 = TAILQ_NEXT(n1, entries);
free(n1);
n1 = n2;
}
TAILQ_INIT(&head);
exit(EXIT_SUCCESS);
}
|
