13.49c.cpp

/*
 * Exercise 13.49: Add a move constructor and move-assignment operator to your
 * StrVec, String, and Message classes.
 *
 * By Faisal Saadatmand
 */

#include <iostream>
#include <set>
#include <string>
#include <vector>

class Folder;
class Message {
	friend void swap(Message &, Message &);
	friend std::ostream& print(std::ostream &, const Message &);
	friend std::ostream& print(std::ostream &, const Folder &);
	public:
		explicit Message(const std::string &str = ""): content(str) {}
		Message(const Message &m)
			: content(m.content), folders(m.folders) { add_to_Folders(m); }
		Message(Message &&m) noexcept
			: content(std::move(m.content)) { move_Folders(&m); }
		Message& operator=(const Message &);
		Message& operator=(Message &&);
		~Message() { remove_from_Folders(); }
		void save(Folder &);
		void remove(Folder &);
		void addFolder(Folder *f) { folders.insert(f); }
		void remFolder(Folder *f) { folders.erase(f); }
		void move_Folders(Message *);
	private:
		std::string content;
		std::set<Folder *> folders;
		void add_to_Folders(const Message &);
		void remove_from_Folders();
};

// copy-control functions

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

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

class Folder {
	friend std::ostream& print(std::ostream &, const Message &);
	friend std::ostream& print(std::ostream &, const Folder &);
	public:
		Folder(const std::string &str = ".") : name(str) {}
		Folder(const Folder &f)
			: name(f.name), messages(f.messages) { add_to_Messages(f); }
		Folder(Folder &&f) : name(f.name), messages(f.messages) { }
		Folder& operator=(const Folder &);
		~Folder() { remove_from_Messages(); }
		void addMsg(Message *m) { messages.insert(m); }
		void remMsg(Message *m) { messages.erase(m); }
		void move_Messages(Folder *);
	private:
		std::string name;
		std::set<Message *> messages;
		void add_to_Messages(const Folder &);
		void remove_from_Messages();
};

// copy-control functions

Folder&
Folder::operator=(const Folder &rhs)
{
	remove_from_Messages();
	name = rhs.name;
	messages = rhs.messages;
	add_to_Messages(rhs);
	return *this;
}

// member functions
void
Folder::add_to_Messages(const Folder &f)
{
	for (auto m : f.messages)
		m->addFolder(this);
}

void
Folder::remove_from_Messages()
{
	for (auto m : messages)
		m->remFolder(this);
}

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

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

void
Message::add_to_Folders(const Message &m)
{
	for (auto f : m.folders)
		f->addMsg(this);
}

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

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

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

void
Folder::move_Messages(Folder *f)
{
	messages = std::move(f->messages);
	for (auto m : messages) {
		m->remFolder(f);
		m->addFolder(this);
	}
	f->messages.clear();
}

// non-members functions
std::ostream& print(std::ostream &os, const Message &m)
{
	os << m.content << '\n';
	for (const auto f : m.folders)
		print(std::cout, *f);
	return os;
}

std::ostream& print(std::ostream &os, const Folder &f)
{
	os << f.name << '\n';
	for (const auto m : f.messages)
		std::cout << m->content << '\n';
	return os;
}

int main()
{
	std::vector<Folder>
		dir{{"Inbox"}, {"News"}, {"Important"}, {"Old"}, {"Junk"}, {"Trash"}};
	Message msg1("Meeting at 2:30 PM"), msg2("Let's ski tomorrow!"),
			msg3("Don't forget tonight"), msg4("Buy 2, get the third for free"),
			msg5("overdue balance");

	msg1.save(dir[0]);
	msg2.save(dir[0]);
	msg3.save(dir[0]);
	msg4.save(dir[0]);
	msg5.save(dir[0]);

	msg1.save(dir[2]);
	msg2.save(dir[3]);
	msg3.save(dir[2]);
	msg4.save(dir[4]);
	msg5.save(dir[5]);

	for (const auto &d : dir)
		print(std::cout, d);
	return 0;
}