雙鏈表【參照redis鏈表結構】

參照了Redis裏面的雙鏈表結構，能夠說是徹底複製粘貼，redis的雙鏈表仍是寫的很通俗易懂的，沒有什麼花裏胡哨的東西，可是redis還有個iter迭代器的結構來遍歷鏈表。我這裏就沒有實現了，只是實現了雙鏈表的基本操做

redis雙鏈表結構有以下特色

1. 多態：能夠儲存多種數據類型
2. 雙端
3. 無環：也就是說head->pre==NULL tail->next=NULL
4. 帶有長度計數器
5. 有頭指針和尾指針

實現

注意，這裏的鏈表有一個迭代器結構，方便遍歷鏈表

#include<iostream>
#include<stdlib.h>
using namespace std;


#define START_HEAD 0
#define START_TAIL 1

struct listNode{
	listNode* prev;
	listNode* next;
	int value;  //能夠是void  void*類型 實現多態鏈表 
};

struct list{
	listNode* head;
	listNode* tail;
	int len;
}; 

//迭代器模式 
typedef struct listIter {
    listNode *next;
    int direction; //遍歷方向 
};


//建立迭代器 
listIter *listGetIterator(list *myList, int direction)
{
    listIter *iter = (listIter*)malloc(sizeof(listIter));
    
    if (direction == START_HEAD)
        iter->next = myList->head;
    else
        iter->next = myList->tail;
    iter->direction = direction;
    return iter;
}
/* Release the iterator memory */
void listReleaseIterator(listIter *iter) {
    free(iter);
}

//將迭代器指向開頭節點 
void listRewind(list *myList, listIter *li) {
    li->next = myList->head;
    li->direction = START_HEAD;
}
//迭代器指向尾部節點 
void listRewindTail(list *myList, listIter *li) {
    li->next = myList->tail;
    li->direction = START_TAIL;
}


//用迭代器遍歷下一個節點 
listNode *listNext(listIter *iter)
{
    listNode *current = iter->next;

    if (current != NULL) {
        if (iter->direction == START_HEAD)
            iter->next = current->next;
        else
            iter->next = current->prev;
    }
    return current;
}




//初始化鏈表 
list* listCreate(){
	list* myList;
	myList = (list*)malloc(sizeof(list)); 
	myList->head = myList->tail=NULL;
	myList->len=0;
	return myList; 
} 

//移除鏈表元素 
void listEmpty(list* list){
	int len = 0;
	listNode* current,*next;
	current = list->head;
	while(len--){
		next = current->next;
		free(current);
		current = next;
	}
	list->head=list->tail=NULL;
	list->len=0;
} 

void listRelease(list* list){
	listEmpty(list);
	free(list); 
	list = NULL;
}

//頭插 
list* listAddNodeHead(list* list,int val){
	listNode* node = (listNode*)malloc(sizeof(listNode));
	node->value = val;
	if(list->len==0){
		list->head = list->tail=node;
		node->prev=node->next=NULL;
	}else{
		node->prev = NULL;
		
		node->next = list->head;
		list->head->prev = node; 
		
		list->head = node;
	}
	list->len++;
	return list; 
}
//尾插
list* listAddNodeTail(list* myList,int val){
	listNode* node = (listNode*)malloc(sizeof(listNode));
	node->value = val;
	if(myList->len==0){
		myList->head = myList->tail = node;
		node->prev=node->next=NULL; 
	}else{
		node->prev = myList->tail;
		myList->tail->next = node;
		
		node->next=NULL;
		
		myList->tail = node;
	}
	myList->len++;
	return myList;
} 

//插入到指定節點前面或後面 
list* listInsertNode(list* list,listNode* old_node,int val,bool after){
	listNode* node = (listNode*)malloc(sizeof(listNode));
	node->value = val;
	if(after){
		
		node->prev = old_node;
		node->next = old_node->next; 
		if(list->tail==old_node){
			list->tail = node;	
		}
	}else{
		
		node->next = old_node;
		node->prev = old_node->prev;
		if(list->head==old_node){
			list->head = node;
		}	
	}
	
	if(node->prev!=NULL){
		node->prev->next = node;
	}
	if(node->next!=NULL){
		node->next->prev = node;
	}
	list->len++;
	return list;
}

//刪除指定節點 
void listDelNode(list* list,listNode* node){
	if(node->prev)
		node->prev->next = node->next; 
	else //是頭節點 
		list->head = node->next;
	
	if(node->next) //若是不是尾節點
		node->next->prev = node->prev;
	else
		list->tail = node->prev; 
	free(node);
	node = NULL;
	list->len--;
} 

//鏈表的複製
list* listCopy(list* old_list){
	
	list* new_list = listCreate();
		
	listNode* node;
	listIter iter;
	listRewind(old_list,&iter); //指向開頭節點  
	while((node=listNext(&iter))!=NULL){
		listAddNodeTail(new_list,node->value);
	} 
	//listRelease(old_list);
	return new_list;
} 

//根據值查找節點 
listNode* listSearchKey(list* myList,int val){
	listNode* node;
	listIter iter;
	listRewind(myList,&iter);
	
	
	
	while((node=listNext(&iter))!=NULL && node->value!=val)
		;
		
	if(node)
		return node;
	else
		return NULL; 
}

//根據索引查找節點 支持倒排序索引 
listNode* listIndex(list* list,int index){
	listNode* node;
	
	if(index<0){
		index = (-index)-1;
		node = list->tail;
		while(index-- && node) node =node->prev; 
	}
	else{
		node = list->head;
		while(index-- && node) node = node->next; 
	}
	return node;
} 
 
//second鏈接到first
list* listJoin(list* first,list* second){
	if(second->head)
		second->head->prev = first->tail;
	
	if(first->tail)
		first->tail->next = second->head;
	else //first鏈表是空的
		first->head = second->head;
	
	
	if(second->tail)
		first->tail = second->tail;
	
	
	first->len +=second->len;
	
	second->head = second->tail = NULL;
	second->len = 0;
	
	return first;	
}

#define dlist_for_each(pos, head) \
	for (pos = (head)->next; pos != NULL; pos = pos->next)
 
#define dlist_reverse_for_each(pos, head)  \
	for (pos = (head)->next; pos!=NULL; pos = pos->next)

void Show_Int_List(list* myList){
	listNode* node;
	dlist_for_each(node,myList->head){
		cout<<node->value<<endl;
	}
		
} 


int main(){
	
	list* myList1 = listCreate();
	for(int i=1;i<=5;i++)
		listAddNodeTail(myList1,i);
	Show_Int_List(myList1);
	cout<<endl;
	
	list* myList2 = listCreate();
	for(int i=6;i<=10;i++)
		listAddNodeTail(myList2,i);
	Show_Int_List(myList2);
	cout<<endl;
	
	listJoin(myList1,myList2);
	Show_Int_List(myList1);
	cout<<endl;
	
	cout<<listIndex(myList1,-2)->value<<endl;
	cout<<endl;
	
	list* myList3=NULL;
	myList3 = listCopy(myList1);
	listAddNodeHead(myList3,99);
	listDelNode(myList3,listSearchKey(myList3,10));
	Show_Int_List(myList3);
	cout<<endl;
	cout<<"len:"<<myList3->len<<endl;
	
	
	
	return 0;
}