[C++知识库]C++ linkedlist模板实现

#include <iostream>
#include <string>

using namespace std;
template <typename T>   //注意这里没有分号

struct Value
{
	T m_Value;
	Value(){ m_Value=0;}
};

// Value模板具体化（用于处理string类型）
template <>
struct Value <string>
{
	string m_Value;
	Value(){ m_Value.assign("");}
};

// 结点
template <typename T>
struct Node
{
	Node();
	Value<T> m_Value;
	Node<T>* m_Prev;
	Node<T>* m_Next;
};

// 类模板的函数在类外实现，需加上模板参数列表，模板参数
template <typename T>
Node<T>::Node()
{
	m_Prev=nullptr;
	m_Next=nullptr;
}

// 链表
template <typename T>
class LinkedList
{
	private:
		Node<T>* m_Head;
		Node<T>* m_Tail;
		bool m_IsEmpty;
	public:
		LinkedList();
		bool push_back(T val);
		bool push_front(T val);
		bool pop_back();
		bool pop_front();
		bool printList();
};

template <typename T>
LinkedList<T>::LinkedList():
	m_Head(nullptr),
	m_Tail(nullptr),
	m_IsEmpty(true)
	{}

template <typename T>
bool LinkedList<T>::pushback(T val)
{
	Node<T>* node=new Node<T>;
	node->m_Value.m_Value=val;
	if (m_IsEmpty==false)
	{
		m_Tail->m_Next=node;
		node->m_Prev=m_Tail;
		m_Tail=node;
	}
	else
	{
		m_Head = m_Tail = node;
		m_IsEmpty = false;
	}
	return true;
}

template <typename T>
bool LinkedList<T>::pushfront(T val)
{
	Node<T> node=new Node<T>;
	node->m_Value.m_Value=val;
	if (m_IsEmpty==false)
	{
		m_Head->m_Prev = node;
		node->m_Next=m_Head;
		m_Head=node;
	}
	else
	{
		m_Head=m_Tail=node;
		m_IsEmpty = false;
	}
	return true;
}

template <typename T>
bool LinkList<T>::popback()
{
	if (m_IsEmpyt==false)
	{
		Node<T>* delnode = m_Tail;
		m_Tail = m_Tail->m_Prev;

		if(m_Tail==nullptr) 
		{
			m_Head=nullptr;
			m_IsEmpty = true;
		}

		m_Tail->m_Next=nullptr;

		if(delnode)
		{
			delete delNode;
			delNode = nullptr; 
		}
	}
	else
	{
		cout<<"Failed:No element in LinkedList."<<endl;
		return false;
	}
	return true;
}

template <typename T>
bool LinkedList<T> popfront()
{
	if (m_IsEmpty==false)
	{
		Node<T>* delnode=m_Head;
		m_Head=m_Head->m_Next;

		if(m_Head==nullptr)
		{
			m_Tail=nullptr;
			m_IsEmpty=true;
		}

		m_Head->m_Prev = nullptr;
		
		if(delnode)
		{
			delete delnode;
			delnode=nullptr;
		}		
	}
	else
	{
		cout<<"Failed:No element in LinkedList."<<endl;
		return false;
	}
	return true;
}

template <typename T>
bool LinkedList<T>::printList()
{
	Node<T>* node=m_Head;
	while(node)
	{
		cout<<node->m_Value.m_Value<<" ->";
		node=node->m_Next;
	}
	cout<<"nullptr"<<endl;
	return true;
}

void InsertIntData()
{
	LinkedList<int> mylist;
	mylist.push_back(1);
	mylist.push_back(2);
	mylist.push_back(3);
	mylist.printList();
}

void InsertStrData()
{
	LinkedList<string> mylist;
	mylist.push_back('hello');
	mylist.push_back(' ');
	mylist.push_back('world');
	mylist.printList();
}

int main()
{
	InsertIntData();
	InsertStrData();
	return 0;
}