目录
前言
一.deque的常用接口
二.deque的原理
2.1 vector与list的优缺点
最后发现，二者可以说是互补的表现
2.2 deque的原理
三.反向迭代器
四.全部代码
//ReverseIterator.h
#pragma once
template<class Iterator, class Ref, class Ptr>
struct ReverseIterator
{
typedef ReverseIterator<Iterator, Ref,Ptr> Self;
Iterator cur;//创建正向迭代器类对象
ReverseIterator(Iterator it)//通过正向迭代器对象构造并初始化对象
:cur(it)
{}
Self& operator++()
{
--cur;//调用正向迭代器的--接口
return *this;
}
Self& operator--()
{
++cur;//调用正向迭代器的++接口
return *this;
}
Ref operator*()
{
Iterator tmp = cur;//因为反向迭代器对称的特性，后面需要前置--，而解引用不需要迭代器移动，所有用临时对象来搞
--tmp;
return *tmp;
}
Ptr operator->()
{
return &(operator*());//->实际上是两个，这里只需要返回解引用后的地址即可 例如*返回AA，那么&AA就是AA*了
}
bool operator!=(const Self& s)
{
return cur != s.cur;
}
};//list.h
#pragma once
#include <assert.h>
#include"ReverseIterator.h"
namespace lj
{
template <class T>
struct ListNode
{
ListNode<T>* _next;
ListNode<T>* _prev;
T _Data;
//构造初始化 利用匿名对象调用该类型的构造函数
ListNode<T>(const T& x = T())
{
_next = nullptr;
_prev = nullptr;
_Data = x;
}
};
template <class T,class Ref,class Ptr>
struct _list_iterator
{
typedef ListNode<T> Node;
typedef _list_iterator<T,Ref,Ptr> self;
Node* _node;
//构造函数
_list_iterator(Node* node)
{
_node = node;
}
//前置++
self& operator++()
{
//不再是单纯的自加1，而是指向下一位置
_node = _node->_next;
return *this;
}
//后置++
self operator++(int)
{
self tmp(*this);
_node = _node->_next;
return tmp;
}
//前置--
self& operator--()
{
_node = _node->_prev;
return *this;
}
//前置--
self operator--(int)
{
//拷贝一份--前的数据
self tmp(*this);
_node = _node->_prev;
return tmp;
}
//解引用
Ref operator*()
{
return _node->_Data;
}
//指针与指针的对比！=
bool operator!=(const self& x)
{
return _node != x._node;
}
//指针与指针的对比==
bool operator==(const self& x)
{
return _node == x._node;
}
Ptr operator->()
{
return &_node->_data;
}
};
template <class T>
class list
{
typedef ListNode<T> Node;
public:
typedef _list_iterator<T,T&,T*> iterator;
typedef _list_iterator<T,const T&,T*> const_iterator;
typedef ReverseIterator<iterator, T&, T*> reverse_iterator;
typedef ReverseIterator<const_iterator, const T&, const T*> const_reverse_iterator;
reverse_iterator rbegin()
{
return reverse_iterator(end());//把正向迭代器传输过去
}
reverse_iterator rend()
{
return reverse_iterator(begin());//把正向迭代器传输过去
}
//构造函数
list()
{
init();
}
void init()
{
_head = new Node;//创建带头节点
_head->_next = _head;//构成双向循序
_head->_prev = _head;
}
//尾插
void push_back(const T& x)
{
insert(end(), x);
先创建新节点
//Node* newnode = new Node(x);
先找到尾节点
//Node* tail = _head->_prev;
开始链接
//tail->_next = newnode;
//newnode->_prev = tail;
//newnode->_next = _head;
//_head->_prev = newnode;
}
//指向第一个有效节点
iterator begin()
{ //单参数隐式类型转换
//return iterator(_head->_next);
return _head->_next;
}
const_iterator begin()const
{ //单参数隐式类型转换
//return iterator(_head->_next);
return _head->_next;
}
//指向头节点：哨兵位
iterator end()
{
//return iterator(_head);
return _head;
}
//指向头节点：哨兵位
const_iterator end()const
{
//return iterator(_head);
return _head;
}
//插入
iterator insert(iterator pos,const T& x)
{
//创建插入节点
Node* newnode = new Node(x);
//记录插入位置
Node* node = pos._node;
Node* nodeprev = node->_prev;
nodeprev->_next = newnode;
newnode->_prev = nodeprev;
newnode->_next = node;
node->_prev = newnode;
//return iterator(newnode);
return newnode;
}
//头插
void push_front(const T& x)
{
insert(begin(), x);
}
//erase 删除
iterator erase(iterator pos)
{
//记录位置
Node* node = pos._node;
Node* nodenext = node->_next;
Node* nodeprev = node->_prev;
//开始链接
nodeprev->_next = nodenext;
nodenext->_prev = nodeprev;
delete node;
return nodenext;
}
//pop_back 尾删
void pop_back()
{
erase(--end());
}
//pop_front 头删
void pop_front()
{
erase(begin());
}
//clear 清理
void clear()
{
iterator it = begin();
while (it != end())
{
it = erase(it);
//erase(it);
}
}
~list()
{
clear();
delete _head;
_head = nullptr;
}
//list l2(l1) 拷贝构造
list(list<T>& lt)
{
init();
for (const auto& e : lt)
{
push_back(e);
}
}
//赋值拷贝 传统写法
/*list<T>& operator=(list<T>& lt)
{
if (*this != lt)
{
clear();
for (const auto& e : lt)
{
push_back(e);
}
}
return *this;
}*/
void swap(list<T>& tmp)
{
std::swap(_head, tmp._head);
}
//赋值拷贝 现代写法
list<T>& operator=(list<T> lt)
{
swap(lt);
return *this;
}
private:
Node* _head;//带头节点：哨兵位
};
void test2()
{
lj::list<int> lt;
lt.push_back(1);
lt.push_back(2);
lt.push_back(3);
lt.push_back(4);
lj::list<int>::reverse_iterator rit = lt.rbegin();
while (rit != lt.rend())
{
cout << *rit << " ";
++rit;
}
cout << endl;
}
}
//vector.h
#pragma once
#include <assert.h>
#include"ReverseIterator.h"
namespace lj
{
template<class T>
class vector
{
public:
typedef T* iterator;
typedef const T* const_iterator;
typedef ReverseIterator<iterator, T&, T*> reverse_iterator;
typedef ReverseIterator<const_iterator, const T&, const T*> const_reverse_iterator;
//迭代器构造
template <class Inputiterator>
vector(Inputiterator first, Inputiterator last)
{
while (first != last)
{
push_back(*first);
first++;
}
}
reverse_iterator rbegin()
{
return reverse_iterator(end());//把正向迭代器传输过去
}
reverse_iterator rend()
{
return reverse_iterator(begin());//把正向迭代器传输过去
}
//构造函数
vector()
{
_start = nullptr;
_finish = nullptr;
_endofstorage = nullptr;
}
//拷贝构造 现代写法 v2(v1)
vector(const vector<T>& v)
{
reserve(v.capacity());
for (auto e : v)
{
push_back(e);
}
}
T& operator[](size_t pos)
{
assert(pos < size());
return _start[pos];
}
void swap(vector<T>& v)
{
std::swap(_start,v._start);
std::swap(_finish, v._finish);
std::swap(_endofstorage, v._endofstorage);
}
vector<T>& operator=(vector<T> v)
{
swap(v);
return *this;
}
//析构函数
~vector()
{
if(_start)
delete[] _start;
_start = nullptr;
_finish = nullptr;
_endofstorage = nullptr;
}
size_t capacity()const
{
return _endofstorage - _start;
}
size_t size()const
{
return _finish - _start;
}
iterator begin()
{
return _start;
}
const_iterator begin()const
{
return _start;
}
iterator end()
{
return _finish;
}
const_iterator end()const
{
return _finish;
}
void reserve(size_t n)
{
if (n>capacity())
{
size_t old = size();//记录原空间的大小
T* tmp = new T[n];//开辟新空间——异地扩容
if (_start)
{
for (size_t i = 0; i < old; i++)
{
tmp[i] = _start[i];//赋值拷贝为深拷贝
}
delete[] _start;//释放原空间
}
_start = tmp;//指向新空间
_finish = _start + old;
_endofstorage = _start + n;
}
}
//尾插函数
void push_back(const T& x)
{
//检查扩容
if (_finish == _endofstorage)
{
size_t newcapacity = capacity() == 0 ? 4 : capacity() * 2;
reserve(newcapacity);
}
*_finish = x;
_finish++;
}
//插入函数
iterator insert(iterator pos, const T& x)
{
assert(pos <= _finish && pos >= _start);
//检查扩容
if (_finish == _endofstorage)
{
size_t len = pos - _start;//记录原空间长度
reserve(capacity() == 0 ? 4 : capacity() * 2);
pos = len + _start;//让pos指向新空间并且同步长度
}
//开始利用函数插入,往后挪动数据
//memmove(pos + 1, pos, (_finish - pos) * sizeof(T));
iterator end = _finish - 1;
while (end >= pos)
{
*(end + 1) = *end;
--end;
}
*pos = x;
_finish++;
return pos;
}
//resize 扩容初始化
void resize(size_t n, const T& val = T())
{
if (n > size())
{
reserve(n);//扩容
while (_finish < _start + n)
{
*_finish = val;
_finish++;
}
}
else
{
_finish = _start + n;
}
}
//erase 删除
iterator erase(iterator pos)
{
assert(pos <= _finish && pos >= _start);
iterator it = pos + 1;
while (it<_finish)
{
*(it-1) = *it;
it++;
}
_finish--;
return pos;
}
private:
iterator _start = nullptr;
iterator _finish = nullptr;
iterator _endofstorage = nullptr;
};
void test_vector()
{
vector<int> v;
v.push_back(1);
v.push_back(2);
v.push_back(3);
v.push_back(4);
lj::vector<int>::reverse_iterator rit = v.rbegin();
while (rit != v.rend())
{
cout << *rit << " ";
++rit;
}
cout << endl;
}
}
//test.cpp
#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
#include<list>
#include<vector>
using namespace std;
#include"List.h"
#include"vector.h"
int main()
{
//lj::test2();
lj::test_vector();
return 0;
/*lj::list<int> lt;
lt.push_back(1);
lt.push_back(2);
lt.push_back(3);
lt.push_back(4);
lj::list<int>::reverse_iterator rit = lt.rbegin();
while (rit != lt.rend())
{
cout << *rit << " ";
++rit;
}
cout << endl;
return 0;*/
}
