(2011.07.19) 单链表.cpp -- 最基本的单链表C++

// 单链表.cpp -- 最基本的单链表C++

// Singly-linked list node
template <class Elem> class Link
{
	public:
		Elem element;			// value for this node
		Link *next;				// pointer to next node in list
		Link(const Elem& elemval, Link* nextval = NULL)
		{ element = elemval; next = nextval;}
		Link (Link* nextval = NULL)
		{ next = nextval;}
};

// Linked list implementation
template <class Elem> class LList: public Link<Elem>
{
	private:
		Link <Elem>* head;		// Pointer to list header
		Link <Elem>* tail;		// Pointer to last Elem in list
		Link <Elem>* fence;		// Last element on left side
		int leftcnt;			// Size of left partition
		int rightcnt;			// Size of right partition
		void init()				// Intialization routine
		{
		fence = tail = head = new Link <Elem>;
		leftcnt = rightcnt = 0;
		}
		void removeall()		// return nodes to free store
		{
		while(head != NULL)
			{
			fence = head;
			head = head -> next;
			delete fence;
			}
		}
	public:
		LList(int size = DefaultListSize) { init();}
		~LList()	{removeall();}	// Destructor
		void clear()	{removeall(); init();}
		bool insert(const Elem&);
		bool append(const elem&);
		bool remove(Elem&);
		void setStart()
		{	fence = head; rightcnt += leftcnt; leftcnt = 0; }
		void setEnd()
		{   fence = tail; leftcnt += rightcnt; rightcnt = 0;}
		void prev();
		void next();
		{
			if (fence != tail)	// don't move fence if right empty
			{
				fence = fence -> next;
				rightcnt--;
				leftcnt++;
			}
		}
		int leftLength()const {return leftcnt;}
		int rightLength()const {return rightcnt;}
		bool setPos(int pos);
		bool getValue(Elem& it) const
		{
			if {rightLength() == 0) return false;
			// 当带了表结头，要先指向下一个元素取值。
			// 如果带了表结头后，取值不是还是0,1,2,3...所以就要看具体的功能来写
			it = fence -> next -> element;	
			return true;
		}	
		void print() const;
};

template <class Elem>	// Insert at front of right partition
bool LList <Elem>::insert(const Elem& item)
	{
	fence -> next = new Link <Elem> (item, fence -> next);
	if (tail == fence) tail = fence -> next;		// new tail
	rightcnt++;
	return true;
	}

template <class Elem>	// Append Elem to end of the list
bool LList <Elem>::append(const Elem& item)
	{
	tail = tail -> next = new Link<Elem>(item, NULL);
	rightcnt++;
	return true;
	}

// Remove and return first Elem in right partition
template <class Elem> bool LList<Elem>::remove(Elem& it)
	{
	if (fence -> next == NULL) return false;	// Empty right
	it = fence -> next -> element;				// Remember value
	Link<Elem>* ltemp = fence -> next;			// Remember link node
	fence -> next = ltemp -> next;				// Remove from list
	if (tail == ltemp) tail = fence;			// Reset tail
	delete ltemp;
	rightcnt--;
	return true;
	}

// Move fence one step left; no change if left is empty
template <class Elem> void LList<Elem>::setPos(int pos)
	{
	if ((pos < 0) || (pos > rightcnt + leftcnt)) return false;
	fence = head;
	for (int i = 0; i < pos; i++) fence = fence -> next;
	return true;
	}

// Set the size of left partition to pos 
template <class Elem> bool LList<Elem>::setPos(int pos)
	{
	if ((pos < 0) || (pos > rightcnt + leftcnt)) return false;
	fence = head;
	for(int = 0; i < pos; i++) fence = fence -> next;
	return true;
	}

template <class elem> void LList<Elem>::print() const
	{
	Link<Elem>* temp = head;
	cout << " < ";
	while(temp != fence)
		{
		cout << temp -> next -> element << " ";
		temp = temp -> next;
		}
	cout << " | ";
	while(temp -> next != NULL)
		{
		cout << temp -> next -> element << " ";
		temp = temp -> next;
		}
	cout << ">\n";
	}