cpp
复制代码
#pragma once
#include<assert.h>
#include<iostream>
using namespace std;
namespace aqc
{
template<class T>
struct list_node
{
list_node* _next;
list_node* _prev;
T _data;
list_node(const T& x=T())//加const防止权限放大，用引用减少拷贝
:_next(nullptr)
,_prev(nullptr)
,_data(x)
{}
};
template<class T,class Ref,class Ptr>
struct __list_iterator
{
typedef list_node<T> node;
typedef __list_iterator<T, Ref, Ptr> self;
node* _node;
__list_iterator(node* tmp)//BUG--函数名报错
:_node(tmp)
{}
Ref operator*()//返回值引用或const引用，不能构成重载，不好办了
//，因此传第二个模板参数，在创建迭代器时确定返回的是什么
{
return _node->_data;
}
Ptr operator->()//同上，有T*和const T*
{
return &(_node->_data);
}
self& operator++()
{
this->_node = _node->_next;
return *this;
}
self operator++(int)
{
self tmp(*this);//生成默认浅拷贝构造
_node = _node -> _next;
return tmp;
}
self& operator--()
{
_node = _node->_prev;
return *this;
}
self operator--(int)
{
self tmp(_node);//显示构造
_node = _node->_prev;
return tmp;
}
bool operator!=(const self& x)const
{
return _node != x._node;
}
bool operator==(const self& x)
{
return _node == x._node;
}
};
template<class Iterator,class Ref,class Ptr>
struct ReverseIterator
{
typedef ReverseIterator<Iterator, Ref, Ptr> self;
Iterator _cur;
ReverseIterator(Iterator it)
:_cur(it)
{}
Ref operator*()//为了保持对称的形态，rbegin对end，rend对begin，解引用时要调整一下
{
Iterator tmp=_cur;
--tmp;
return *tmp;
}
Ptr operator->()
{
return &(_cur._node->_data);
}
self& operator++()
{
--_cur;
return *this;
}
self operator++(int)
{
self tmp = *this;
--_cur;
return tmp;
}
self operator--()
{
++_cur;
return *this;
}
bool operator!=(const self& x)const
{
return _cur != x._cur;
}
};
template<class T>
class list
{
typedef list_node<T> node;
public:
typedef __list_iterator<T, T&, T*> iterator;
typedef __list_iterator<T, const T&, const T*> const_iterator;
typedef ReverseIterator< iterator, T&, T*> reverse_iterator;
typedef ReverseIterator<const_iterator, const T&, const T*> const_reverse_iterator;
iterator begin()
{
return iterator(_head->_next);
}
const_iterator begin()const//不论普通链表还是const链表都可使用const迭代器
{
return const_iterator(_head->_next);
}
iterator end()
{
return iterator(_head);
}
const_iterator end()const
{
return const_iterator(_head);
}
reverse_iterator rbegin()
{
return reverse_iterator(end());
}
reverse_iterator rend()
{
return reverse_iterator(begin());
}
void empty_init()
{
_head = new node;
_head->_next = _head;
_head->_prev = _head;
}
list()
{
empty_init();
}
template<class Iterator >
list(Iterator first, Iterator last)
{
empty_init();
while (first != last)
{
push_back(*first);
first++;
}
}
void swap(list<T>& lt)
{
std::swap(_head, lt._head);
}
list(list<T>& lt)
{
empty_init();
list<T> tmp(lt.begin(), lt.end());
swap(tmp);
}
list<int>& operator=(list<T> lt)
{
swap(lt);
return *this;
}
void print()
{
for (auto e : *this)
{
cout << e << " ";
}
cout << endl;
}
void clear()
{
iterator it = begin();
while (it != end())
{
erase(it++);//it++最终it加一，返回it没加一时的临时变量
}
}
~list()
{
clear();
delete _head;
}
void push_back(const T& x)
{
insert(end(), x);
}
void push_front(const T& x)
{
insert(begin(), x);
}
void pop_back()
{
erase(--end());
}
void erase(iterator pos)
{
node* prev = pos._node->_prev;
node* next = pos._node->_next;
prev->_next = next;
next->_prev = prev;
delete pos._node;
}
void insert(iterator pos, const T& x)
{
node* prev = pos._node->_prev;
node* pcur = pos._node;
node* new_node = new node(x);
prev->_next = new_node;
new_node->_prev = prev;
new_node->_next = pcur;
pcur->_prev = new_node;
}
private:
node* _head;
};
}