doublelist.c

练习.................................................

#include "string.h"
#include "memory.h"
#include "assert.h"

typedef struct LIST_NODE_TAG
{
    int key;
    struct LIST_NODE_TAG * pre;
    struct LIST_NODE_TAG *next;
}LIST_NODE_STRU;

#define LIST_SIZE                 10

#define NULL_PTR                0

/*链表头的前趋和后继都是头节点本身*/
#define LIST_HEAD_INIT (name) \
    LIST_NODE_STRU name = { 0xffffffff,&(name), &(name) } 

/*遍历链表*/
#define list_traver_each(head, pos) \
	for (pos = head->next; pos != head; pos = pos->next)

/*加入新节点*/
void __list_add(LIST_NODE_STRU * node, LIST_NODE_STRU * pre,  LIST_NODE_STRU * next);

/*删除节点*/
void __list_delete(LIST_NODE_STRU * pre,  LIST_NODE_STRU * next);

/*在头接点后加入节点*/
void _list_add_after_head(LIST_NODE_STRU * head, LIST_NODE_STRU * node);


void __list_add(LIST_NODE_STRU * node, LIST_NODE_STRU * pre,  LIST_NODE_STRU * next)
{
    pre->next     = node;
    node->pre    = pre;
    node->next  = next;
    next->pre     = node;
}

void __list_delete(LIST_NODE_STRU * pre,  LIST_NODE_STRU * next)
{
    pre->next = next;
    next->pre = pre;
}

void _list_add_after_head(LIST_NODE_STRU * head, LIST_NODE_STRU * node)
{
    /*如果链表为空将加入的第一个元素作为尾部节点*/
    if (_list_empty(head))
    {
        head->pre =node ;
        node->next = head;
    }
    
    __list_add(node, head, head->next);
    return;
}

void _list_delete_ex(LIST_NODE_STRU * head, LIST_NODE_STRU * node)
{
    /*如果删除的是尾部节点*/
    if (node->next == head)
    {
        head->pre = node->pre;
        node->pre->next = head;
    }
    /*中间节点*/
    else
    {
        __list_delete(node->pre, node->next);
    }
    
    free(node);
    return;
}

int _list_empty(LIST_NODE_STRU * head)
{
    return head->next == head;
}

int main(void)
{
    int i;
    LIST_NODE_STRU * node          = NULL_PTR;
    struct LIST_NODE_TAG * pos   = NULL_PTR;
    struct LIST_NODE_TAG header;

    header.pre =  &header;
    header.next = &header;

    for (i = 0; i < LIST_SIZE; i++)
    {
        node = (LIST_NODE_STRU*)malloc(sizeof(LIST_NODE_STRU));
        assert(node);
        node->key = i;
        printf("-%d",i);
        _list_add_after_head(&header, node);
    }

    printf("\r\n>>\r\n");
    list_traver_each((&header), pos)
    {
        printf("-%d", pos->key);
    }
    
    list_traver_each((&header), pos)
    {
        _list_delete_ex(&header, pos);
    }

    if (!_list_empty(&header))
    {
        printf("\r\n some error");
    }
    
    return 0;
}