/*vector是可变大小的数组，是顺序存储结构，支持快速的随机访问，在尾部之外的位置插入和删除元素很慢*/
/*类模板*/
#include<cassert>
template<typename T>
class Vector
{
private:
    T *elem;
    int thesize;
    int thecapacity;
public:
    enum{ SPARE_CAPACITY = 16 };
    typedef T* iterator;
    typedef const T* const_iterator;
    /******************************************构造函数******************************************/
    //构造函数,,   问题，它的元素是怎么进行值初始化的？？？
    explicit Vector(int initsize = 0) :thesize(initsize), thecapacity(initsize + SPARE_CAPACITY)
    {
        elem = new T[thecapacity];
        assert(elem != NULL);    //存储分配失败则退出;
    }
    explicit  Vector(int initsize, T value) :thesize(initsize), thecapacity(initsize + SPARE_CAPACITY)
    {
        elem = new T[thecapacity];
        assert(elem != NULL);    //存储分配失败则退出;
        for (int i = 0; i != thesize; ++i)
            elem[i] = value;
    }
    //接受两个迭代器创建拷贝的构造函数 ,这里的迭代器的创建是指针，见上面
    Vector(iterator b, iterator e)
    {
        thesize = e - b;
        thecapacity = thesize + SPARE_CAPACITY;
        elem = new T[thecapacity];
        assert(elem != NULL);
        for (int i = 0; b != e&&i != thesize; ++i)
        {
            elem[i] = *b;
            ++b;
        }
    }

    //拷贝构造函数，接受一个容器为另一个容器的拷贝
    Vector(const Vector &rhs)
    {
        thesize = rhs.thesize;
        thecapacity = rhs.thecapacity;
        elem = new T[thecapacity];
        assert(elem != NULL);
        for (int i = 0; i != thesize; ++i)
            elem[i] = rhs.elem[i];
    }
    /***************************析构函数****************************/
    ~Vector()
    {
        delete[] elem;
    }
    /***************************************************************************/
    //赋值运算符
    Vector &operator=(const Vector & rhs)
    {
        if (this != &rhs) //防止自赋值
        {
            delete[]elem;
            thesize = rhs.thesize;
            thecapacity = rhs.thecapacity;
            elem = new T[thecapacity];
            assert(elem != NULL);
            for (int i = 0; i != thesize; ++i)
                elem[i] = rhs.elem[i];
        }
        return *this;
    }
    //待实现
    //swap函数的实现，通常比从一个向另一个容器拷贝元素快，只是交换了两个容器内部的数据结构，元素本身没有交换。。
    //交换的是相同类型的容器。

    //assign，赋值函数的实现

    /**************************************************************************************/
    bool empty()const    //常量成员函数，不改变类的成员
    {
        return thesize == 0;
    }
    int size() const                                  //要修改,,返回类型为vector<T>::size_type
    {
        return thesize;
    }
    iterator begin()
    {
        return &elem[0];
    }
    iterator end()
    {
        return &elem[thesize];
    }
    const_iterator begin() const
    {
        return &elem[0];
    }

    const_iterator end()  const
    {
        return &elem[thesize];
    }
    /********************************************关系运算符**********************************/
    //关系运算符的实现==，！=，> ,>=, <, <=
    bool operator==(const Vector<T>& rhs)
    {
        if (this->thesize == rhs.thesize)
        {  
            int cnt = 0;
            for (int i = 0; i != thesize; i++)
                if (this->elem[i] == rhs.elem[i])
                    ++cnt;
            if (cnt == thesize)
                return true;              
        }
        return false;
    }                                                                     //是否要友元函数？？？，判断两个vector是否相等
    bool operator!=(const Vector<T>& rhs)
    {
        return !(*this== rhs);
    }
    /*****************************************管理容器大小***********************************************/
    int capacity() const
    {
        return thecapacity;
    }
    void reserve(int newcapacity)  //分配至少容纳newcapacity个的元素空间，，，进行内存分配，释放
    {
        if (newcapacity < thecapacity)
            return;
        T *oldarray = elem;
        elem = new T[newcapacity];
        for (int i = 0; i != thesize; ++i)
            elem[i] = oldarray[i];
        thecapacity = newcapacity;
        delete[] oldarray;
    }
    void shrink_to_fit()  //将capacity（）减少为与size（）相同大小
    {
        reserve(thesize);
    }

    /*******************************************改变容器的大小**********************************************/
    void resize(int newsize)    //调整它的大小，若newsize<thesize，多的元素被丢弃，若相反，添加新元素，进行值初始化
    {
        if (newsize>thecapacity)
            reserve(newsize * 2 + 1);
        thesize = newsize;
    }
    void resize(int newsize, T thevalue)  //新添进来的元素初始化为thevalue
    {
        if (newsize > thecapacity)
        {
            reserve(newsize * 2 + 1);
        }
        for (int i = thesize; i < newsize; ++i)
            elem[i] = thevalue;
        thesize = newsize;
    }
    /**************************************访问操作***************************************/
    T &operator[](int index)                                    //要修改，下标index类型是vector<T>::size_type;
    {
        if (index<0 || index >= thesize)
            return;
        return elem[index];
    }
    const T &operator[](int index) const
    {
        if (index<0 || index >= thesize)
            return;
        return elem[index];
    }
    T &front()
    {
        if (!this->empty())
            return elem[0];
    }
    T &back()
    {
        if (!this->empty())
            return elem[thesize - 1];
    }
    /******************************************插入操作*************************************/
    //向容器插入元素，vector不支持push_front,但insert可以实现插入vector的任何位置，但是注意在vector除尾部之外的任何位置很慢，很耗时。。
    void push_back(const T &x)
    {
        if (thesize == thecapacity)
            reserve(2 * thecapacity);
        elem[thesize++] = x;
    }
    //这里的迭代器是指指针,插入了一个元素。
    iterator insert(iterator b, T value)
    {
        if (b < this->begin() || b> this->end()) //b可以为尾后迭代器,这里不知道怎么处理异常就返回尾后迭代器吧
            return this->end();
            if (thesize == thecapacity)
                reserve(thesize * 2);
            for (iterator p = this->end(); p > b; p--)
                *p = *(p - 1);
            *b = value;
            thesize++;
            return b;
    
        
    }
    /********************************************删除操作***************************************/
    void pop_back()
    {
        thesize--;
    }
    //删除了一个元素
    iterator erasea(iterator b)
    {
        if (b < this->begin() || b >= this->end())  //确保迭代器在范围内，，否则未定义，b不能为尾后迭代器
            return this->end();
            iterator q = b + 1;
            iterator p = this->end() - 1;
            for (; b < p; b++)
                *b = *(b + 1);
            thesize--;
            if (thesize <= thecapacity / 4)  //防止删除后空闲空间太大，浪费空间
            {
                reserve(thecapacity / 2);
            }
            return q;
    }
    /*void clear()   //有问题
    {
    delete[] elem;

    }*/

};

#include <string>
#include<iostream>
#include<cassert>
#include"Vector.h"     //注意当这里不是标准库的头文件，是自己写的，要用双引号，整了好久，还以为程序出错了。。
using namespace std;
int main()
{
    // 利用构造函数
    Vector<int> v1; 
    Vector<int> v2(5, 9);
    Vector<int> v3(v2);
    Vector<int> v4(v2.begin(), v2.end());
    if (v1.empty())
    cout <<"v1为空，大小为："<< v1.size() << endl;
    cout << "向v1插入元素：";
    int a;
    while (cin >> a)
        v1.push_back(a);
    if (!v1.empty())
        cout << "v1不为空,大小为:" << v1.size() << "容量为：" << v1.capacity() << endl;
    cout << "元素为：";
    for (Vector<int>::iterator iter = v1.begin(); iter != v1.end(); ++iter)
        cout << *iter << "   ";
    cout << endl;
    cout << "重新插入后：";
    v1.insert(v1.begin() + 1, 4);
    cout << "此时v1大小为:" << v1.size() << "容量为：" << v1.capacity() << endl;
    cout << "元素为：";
    for (Vector<int>::iterator iter = v1.begin(); iter != v1.end(); ++iter)
        cout << *iter << "   ";
    cout << endl;
    cout << "删除元素后为：";
    v1.pop_back();
    for (Vector<int>::iterator iter = v1.begin(); iter != v1.end(); ++iter)
        cout << *iter << "   ";
    cout << endl;
    cout << "再次删除元素后为：";
    v1.erasea(v1.begin() + 2);
    for (Vector<int>::iterator iter = v1.begin(); iter != v1.end(); ++iter)
        cout << *iter << "   ";
    cout << endl;
    cout << "v2元素为：";
    for (Vector<int>::iterator iter = v2.begin(); iter != v2.end(); ++iter)
            cout << *iter << "   ";
        cout << endl;
    cout << "v3元素为：";
    for (Vector<int>::iterator iter = v3.begin(); iter != v3.end(); ++iter)
            cout << *iter << "   ";
        cout << endl;
    cout << "v4元素为：";
    for (Vector<int>::iterator iter = v4.begin(); iter != v4.end(); ++iter)
            cout << *iter << "   ";
        cout << endl;
    if (v1 == v3)
            cout << "v1与v3相等";

    return 0;
}