#ifndef doublychain_
#define doublychain_
#include<iostream>
#include<algorithm>
#include"chainNode.h"

using namespace std;
template<typename T>
class doublychain
{
public:
	      doublychain();
		  ~doublychain();
	void insert(const int theIndex, const T& theElement);
	void erase(int theIndex);
	void output(ostream& out);
protected:
	chainNode<T>*firstNode;
	chainNode<T>*lastNode;
	int listSize;
};
template<typename T>
doublychain<T>::doublychain()
{
	firstNode = lastNode = NULL;
	listSize = 0;
}

template<typename T>
doublychain<T>::~doublychain()
{
	while (firstNode != NULL)
	{
		chainNode<T>*next = firstNode->next;
		delete firstNode; 
		firstNode = next;
	}
	delete firstNode;
}

template<typename T>
void doublychain<T>::insert(const int theIndex, const T& theElement)
{
	if (theIndex == 0)
	{
		firstNode = new chainNode<T>(theElement, firstNode);
		lastNode = firstNode;
		firstNode->pre = NULL;
		lastNode->next = NULL;
	}
	else {
		chainNode<T>*p = firstNode;
		chainNode<T>*q;
		for (int i = 0; i < theIndex -1; ++i)
			p = p->next;
		p->next = new chainNode<T>(theElement, p->next);
		q = p->next;
		q->pre = p;
		if (theIndex ==listSize)
			lastNode = p->next;
	}
	++listSize;
}
template<typename T>
void doublychain<T>::erase(int theIndex)
{
	chainNode<T>*deleteNode;
	chainNode<T>*q;
	if (theIndex = 0)
	{
		deleteNode=firstNode;
		q = firstNode->next;
		firstNode = firstNode->next;
		q->pre = NULL;

	}
	else {
		chainNode<T>*p = firstNode;
		for (int i = 0; i < theIndex - 1; i++)
			p = p->next;
		deleteNode=p->next;
		q = p->next->next;
		p->next = p->next->next;
		q->pre = p;
		if (deleteNode == lastNode)
			lastNode = p;
		
	}
	delete deleteNode;
	--listSize;
}
//對雙向連結串列進行測試
template<typename T>
void doublychain<T>::output(ostream& out)
{
	/*for (chainNode<T>*p = firstNode; p != NULL; p=p->next)
		cout << p->element << " ";*/
	for (chainNode<T>*p = lastNode; p !=NULL; p = p->pre)
		cout << p->element << " ";
}
#endif