#ifndef STRBLOB_H#define STRBLOB_H#include<iostream>#include<string>#include<vector>#include<memory>using namespace std;class StrBlobPtr;class StrBlob{friend class StrBlobPtr;public:    typedef string::size_type size_type;    //构造函数    StrBlob();    explicit StrBlob(initializer_list<string> il);    size_type size() const { return data->size(); }    bool empty() const { return data->empty();}    void push_back(const string &t) { data->push_back(t);}    void pop_back();    string& front();    string& back();    string& front() const;    string& back() const;    size_type count()    {        return data.use_count();    }    StrBlobPtr begin();    StrBlobPtr end();private:    shared_ptr<vector<string>> data;    void check(size_type i,const string msg) const;};#endif // STRBLOB_H

#include"StrBlob.h"#include"StrBlobPtr.h"StrBlob::StrBlob():data(make_shared<vector<string>>()){}StrBlob::StrBlob(initializer_list<string> il):data(make_shared<vector<string>>(il)){}void StrBlob::pop_back(){    check(0,"pop_back");    data->pop_back();}string& StrBlob::back(){    check(0,"back");    return data->back();}string& StrBlob::front(){    check(0,"front");    return data->front();}string& StrBlob::back() const{    check(0,"back");    return data->back();}string& StrBlob::front() const{    check(0,"front");    return data->front();}void StrBlob::check(size_type i, const string msg) const{    if(i>=data->size())        throw out_of_range(msg);}StrBlobPtr StrBlob::begin(){    return StrBlobPtr(*this);}StrBlobPtr StrBlob::end(){    return StrBlobPtr(*this,data->size());}

#ifndef STRBLOBPTR_H#define STRBLOBPTR_H#include<string>#include<vector>#include<memory>using namespace std;class StrBlobPtr{public:    StrBlobPtr():curr(0) {}    StrBlobPtr(StrBlob &a,size_t sz=0):wptr(a.data),curr(sz) {}    string& deref() const;    StrBlobPtr& incr();private:    shared_ptr<vector<string>> check(size_t,const string &) const;    weak_ptr<vector<string>> wptr;    size_t curr;};#endif

#include"StrBlob.h"#include"StrBlobPtr.h"shared_ptr<vector<string>> StrBlobPtr::check(size_t i, const string& msg) const{    shared_ptr<vector<string>> ret=wptr.lock();    if(!ret)        throw runtime_error("unbound StrBlobPtr");    if(i>=ret->size())        throw out_of_range(msg);    return ret;}string& StrBlobPtr::deref() const{    auto ret=check(curr,"deference");    return (*ret)[curr];}StrBlobPtr& StrBlobPtr::incr(){    check(curr,"increment");    ++curr;    return *this;}

#include"StrBlob.h"#include"StrBlobPtr.h"#include<fstream>int main(){    ifstream in("1.txt");    StrBlob Str;    StrBlobPtr StrP(Str);    string tmp;    while(getline(in,tmp))    {        Str.push_back(tmp);    }    size_t l=Str.size();    while(l)    {        cout<<StrP.deref()<<endl;        StrP.incr();        --l;    }    return 0;}