双向循环链表中结点类，链表类的定义与实现。

template<class T> class DouListNode   
{   
    T data;   
    DouListNode<T>* link;   
    DouListNode<T>* prior;   
    public:   
        DouListNode():link(NULL),prior(NULL){}   
        DouListNode(T value):link(NULL),prior(NULL),data(value){}   
        ~DouListNode(){};   
        void SetLink(DouListNode<T>* next);   
        void SetPrior(DouListNode<T>* pre);   
        DouListNode<T>* GetLink();   
        DouListNode<T>* GetPrior();   
        T& GetData();   
};   
template<class T>   
void DouListNode<T>::SetLink(DouListNode<T>* next)   
{   
    link=next;   
}   
template<class T>   
void DouListNode<T>::SetPrior(DouListNode<T>* pre)   
{   
    prior=pre;   
}   
template<class T>   
DouListNode<T>* DouListNode<T>::GetLink()   
{   
    return link;   
}   
template<class T>   
DouListNode<T>* DouListNode<T>::GetPrior()   
{   
    return prior;   
}   
template<class T>   
T& DouListNode<T>::GetData()   
{   
    return data;   
}   
  
template<class T> class DouList   
{   
    DouListNode<T>* head;   
    DouListNode<T>* tail;   
    DouListNode<T>* cur;   
    public:   
        DouList();   
        ~DouList(){};   
        bool AddTail(T value);   
        bool AddHead(T value);   
        void RemoveThis(bool direction);   
        void RemoveAll();   
        void SetBegin();   
        int GetCount();   
        void TowardCur();   
        void BackCur();   
        DouListNode<T>* GetCur();   
        DouListNode<T>* GetHead();   
        DouListNode<T>* GetTail();   
        void InsertAfter(T value);   
        bool IsEmpty();   
        T GetNext();   
        T GetPrior();   
};   
template<class T>   
DouList<T>::DouList()   
{   
    head=tail=new DouListNode<T>;   
    cur=NULL;   
    head->SetLink(head);   
    head->SetPrior(tail);   
}   
template<class T>   
bool DouList<T>::AddTail(T value)   
{   
    DouListNode<T>* add=new DouListNode<T>(value);   
    tail->SetLink(add);   
    add->SetPrior(tail);   
    tail=tail->GetLink();   
    tail->SetLink(head);   
    head->SetPrior(add);   
    if(tail!=NULL)   
    {   
        return true;   
    }   
    else  
        return false;   
}  
template<class T>
bool DouList<T>::AddHead(T value)
{
	DouListNode<T>* add=new DouListNode<T>(value);
	add->SetPrior(head);
	add->SetLink(head->GetLink());
	head->GetLink()->SetPrior(add);
	head->SetLink(add);
	if(tail==head)
	{
		tail=head->GetLink();
	}
	if(add!=NULL)
	{
		return true;
	}
	else
		return false;
}
template<class T>
void DouList<T>::RemoveThis(bool direction)
{
	if(cur==head)
	{
		if(direction==0)
			cur=cur->GetLink();
		if(direction==1)
			cur=cur->GetPrior();
	}
	DouListNode<T>* preCur=NULL;
	DouListNode<T>* nextCur=NULL;
	preCur=cur->GetPrior();
	nextCur=cur->GetLink();
	preCur->SetLink(cur->GetLink());
	nextCur->SetPrior(cur->GetPrior());
	if(direction==0)
		cur=nextCur;
	if(direction==1)
		cur=preCur;

}
template<class T>
void DouList<T>::RemoveAll()
{
	SetBegin();
	int length=GetCount();
	for(int i=0;i<length;i++)
	{
		RemoveThis(0);
	}
	cur=head;
}
template<class T>
void DouList<T>::SetBegin()
{
	cur=head;
}
template<class T>
int DouList<T>::GetCount()
{
	int num=0;
	DouListNode<T>* here=cur;
	while(cur->GetLink()!=here)
	{
		cur=cur->GetLink();
		++num;
	}
	cur=cur->GetLink();
	return num;
}
template<class T>
void DouList<T>::TowardCur()
{
	cur=cur->GetLink();
}
template<class T>
void  DouList<T>::BackCur()
{
	cur=cur->GetPrior();
}
template<class T>
DouListNode<T>* DouList<T>::GetCur()
{
	return cur;
}
template<class T>
DouListNode<T>* DouList<T>::GetHead()
{
	return head;
}
template<class T>
DouListNode<T>* DouList<T>::GetTail()
{
	return tai;
}
template<class T>
bool DouList<T>::IsEmpty()
{
	return head->GetLink()==head;
}
template<class T>
void DouList<T>::InsertAfter(T value)
{
	DouListNode<T>* add=new DouListNode<T>(value);
	DouListNode<T>* nextCur=cur->GetLink();
	cur->SetLink(add);
	add->SetLink(nextCur);
	nextCur->SetPrior(add);
	add->SetPrior(cur);
	if(cur==tail)
	{
		tail=cur->GetLink();
	}
}
template<class T>
T DouList<T>::GetNext()
{
	if(cur==head)
		cur=cur->GetLink();
	T num=cur->GetData();
	cur=cur->GetLink();
	return num;
}
template<class T>
T DouList<T>::GetPrior()
{
	if(cur==head)
		cur=cur->GetPrior();
	T num=cur->GetData();
	cur=cur->GetPrior();
	return num;
}