【C++ Primer 第十三章】4. 拷贝控制示例

拷贝控制示例

 #include<iostream>
 #include<string>
 #include<set>
 #include<vector>
 using namespace std;

 class Folder;

 class Message {
     friend void swap(Message&, Message&);
     friend class Folder;
 public:
     explicit Message(const string &str = "") : contents(str) {}
     Message(const Message&);
     Message& operator=(const Message&);
     ~Message();

     Message(Message&&);
     Message& operator=(Message&&);

     void save(Folder&);
     void remove(Folder&);
     void debug_print();

 private:
     string contents;
     set<Folder*> folders;

     void add_to_Folders(const Message&);
     void remove_from_Folders();
     void addFldr(Folder *f) { folders.insert(f); }
     void remFldr(Folder *f) { folders.erase(f); }
     void move_Folders(Message*);
 };

 /*------------------------------------------------------------------------------------------------------*/

 class Folder {
     friend void swap(Message&, Message&);
     friend class Message;
 public:
     Folder() = default;
     Folder(const Folder&);
     Folder& operator=(const Folder&);

     Folder(Folder&&);
     Folder& operator=(Folder&&);
     ~Folder();

     void save(Message&);
     void remove(Message&);
     void debug_print();

 private:
     set<Message*> msgs;

     void add_to_Messages(const Folder&);
     void remove_from_Msgs();
     void addMsg(Message *m) { msgs.insert(m); }
     void remMsg(Message *m) { msgs.erase(m); }
     void move_Messages(Folder*);

 };

 /*---------------------------------------Folder类成员函数--------------------------------------------------*/

 Folder::Folder(const Folder &f) : msgs(f.msgs)
 {
     add_to_Messages(f);
 }

 void Folder::add_to_Messages(const Folder &f)
 {
     for (auto msg : f.msgs)
         msg->addFldr(this);
 }

 Folder& Folder::operator=(const Folder &f)
 {
     remove_from_Msgs();
     msgs = f.msgs;
     add_to_Messages(f);
     return *this;
 }

 void Folder::remove_from_Msgs()
 {
     while (!msgs.empty())
         (*msgs.begin())->remove(*this); // Message类成员函数
 }

 Folder::~Folder()
 {
     remove_from_Msgs();
 }

 Folder::Folder(Folder &&f)
 {
     move_Messages(&f);
 }

 void Folder::move_Messages(Folder *f)
 {
     msgs = std::move(f->msgs);
     f->msgs.clear();
     for (auto m : msgs)
     {
         m->remFldr(f);
         m->addFldr(this);
     }
 }

 Folder& Folder::operator=(Folder &&f)
 {
     if (this != &f)
     {
         remove_from_Msgs();
         move_Messages(&f);
     }
     return *this;
 }

 void Folder::save(Message &m)
 {
     msgs.insert(&m);
     m.addFldr(this);
 }

 void Folder::remove(Message &m)
 {
     msgs.erase(&m);
     m.remFldr(this);
 }

 void Folder::debug_print()
 {
     cerr << "Folder contains " << msgs.size() << " messages" << endl;
     int ctr = ;
     for (auto m : msgs)
     {
         cerr << "Message " << ctr++ << ":\n\t" << m->contents << endl;
     }
 }

 /*---------------------------------------Message类成员函数------------------------------------------------*/

 Message::Message(const Message &m) : contents(m.contents), folders(m.folders)
 {
     add_to_Folders(m);
 }

 void Message::add_to_Folders(const Message &m)
 {
     for (auto f : m.folders)
         f->addMsg(this); // Folder类成员函数
 }

 Message& Message::operator=(const Message &rhs)
 {
     remove_from_Folders();
     contents = rhs.contents;
     folders = rhs.folders;
     add_to_Folders(rhs);
     return *this;
 }

 void Message::remove_from_Folders()
 {
     for (auto f : folders)
         f->remMsg(this);
     folders.clear();
 }

 Message::Message(Message &&m) : contents(std::move(m.contents))
 {
     move_Folders(&m);
 }

 void Message::move_Folders(Message *m)
 {
     folders = std::move(m->folders);
     for (auto f : folders)
     {
         f->remMsg(m);
         f->addMsg(this);
     }
     m->folders.clear();
 }

 Message& Message::operator=(Message &&rhs)
 {
     if (this != &rhs)
     {
         remove_from_Folders();
         contents = std::move(rhs.contents);
         move_Folders(&rhs);
     }
     return *this;
 }

 Message::~Message()
 {
     remove_from_Folders();
 }

 void Message::save(Folder &f)
 {
     folders.insert(&f);
     f.addMsg(this);
 }

 void Message::remove(Folder &f)
 {
     folders.erase(&f);
     f.remMsg(this);
 }

 void Message::debug_print()
 {
     cerr << "Message:\n\t" << contents << endl;
     cerr << "Appears in " << folders.size() << " Folders" << endl;
 }

 void swap(Message &lhs, Message &rhs)
 {
     using std::swap;
     for (auto f : lhs.folders)
         f->remMsg(&lhs);
     for (auto f : rhs.folders)
         f->remMsg(&rhs);
     swap(lhs.folders, rhs.folders);
     swap(lhs.contents, rhs.contents);
     for (auto f : lhs.folders)
         f->addMsg(&lhs);
     for (auto f : rhs.folders)
         f->addMsg(&rhs);
 }

 /*-----------------------------------------------------------------------------------------------------*/

 int main()
 {
     string s1("contents1");
     string s2("contents2");
     string s3("contents3");
     string s4("contents4");
     string s5("contents5");
     string s6("contents6");
     Message m1(s1);
     Message m2(s2);
     Message m3(s3);
     Message m4(s4);
     Message m5(s5);
     Message m6(s6);

     Folder f1;
     Folder f2;

     m1.save(f1); m3.save(f1); m5.save(f1);
     m1.save(f2); m2.save(f2); m4.save(f2);
     m6.save(f2);

     m1.debug_print();
     f2.debug_print();

     Message c1(m1);
     Message c2(m2), c4(m4), c6(m6);

     m1.debug_print();
     f2.debug_print();

     m2 = m3;
     m4 = m5;
     m6 = m3;
     m1 = m5;

     m1.debug_print();
     f2.debug_print();

     m2 = m2;
     m1 = m1;

     m1.debug_print();
     f2.debug_print();

     vector<Message> vm;
     cout << "capacity: " << vm.capacity() << endl;
     vm.push_back(m1);

     cout << "capacity: " << vm.capacity() << endl;
     vm.push_back(m2);

     cout << "capacity: " << vm.capacity() << endl;
     vm.push_back(m3);

     cout << "capacity: " << vm.capacity() << endl;
     vm.push_back(m4);

     cout << "capacity: " << vm.capacity() << endl;
     vm.push_back(m5);

     cout << "capacity: " << vm.capacity() << endl;
     vm.push_back(m6);

     vector<Folder> vf;
     cout << "capacity: " << vf.capacity() << endl;
     vf.push_back(f1);

     cout << "capacity: " << vf.capacity() << endl;
     vf.push_back(f2);

     cout << "capacity: " << vf.capacity() << endl;
     vf.push_back(Folder(f1));

     cout << "capacity: " << vf.capacity() << endl;
     vf.push_back(Folder(f2));

     cout << "capacity: " << vf.capacity() << endl;
     vf.push_back(Folder());

     Folder f3;
     f3.save(m6);
     cout << "capacity: " << vf.capacity() << endl;
     vf.push_back(f3);
     return ;
 }

运行结果：

Message:
        contents1
Appears in  Folders
Folder contains  messages
Message :
        contents6
Message :
        contents4
Message :
        contents2
Message :
        contents1
Message:
        contents1
Appears in  Folders
Folder contains  messages
Message :
        contents6
Message :
        contents4
Message :
        contents2
Message :
        contents1
Message :
        contents6
Message :
        contents4
Message :
        contents2
Message :
        contents1
Message:
        contents5
Appears in  Folders
Folder contains  messages
Message :
        contents6
Message :
        contents4
Message :
        contents2
Message :
        contents1
Message:
        contents5
Appears in  Folders
Folder contains  messages
Message :
        contents6
Message :
        contents4
Message :
        contents2
Message :
        contents1
capacity:
capacity:
capacity:
capacity:
capacity:
capacity:
capacity:
capacity:
capacity:
capacity:
capacity:
capacity:
请按任意键继续. . .