Exer14_48_49_Book.h

#ifndef BOOK_H
#define BOOK_H
#include <iostream>
#include <string>
#include <utility>
using std::ostream;
using std::istream;
using std::string;
class Book {
    // overloaded output operator required by exercise 14.8
    friend ostream &operator<<(ostream&, const Book&);
    // overloaded input operator required by exercise 14.12
    friend istream &operator>>(istream&, Book&);
    // overloaded equality operator required by exercise 14.17
    friend bool operator==(const Book&, const Book&);
    friend bool operator!=(const Book&, const Book&);
public:
    Book() = default;
    Book(string na, string au = "", string no = "") :
        book_name(na), book_author(au), book_no(no) {}
    // copy control constructor
    Book(const Book&) = default; // copy constructor
    Book(Book &&b) noexcept :// move constructor
        book_name(std::move(b.book_name)),
        book_author(std::move(b.book_author)),
        book_no(std::move(book_no)) {}
    Book& operator=(const Book&) = default; // copy-assignment operator
    Book& operator=(Book&&) noexcept; // move assignment operator
    Book& operator=(const string&); // take an ISBN as parameter, required by exercise 14.25
    ~Book() = default;
    // meaningless bool conversion required by exercise 14.49, just for test
    explicit operator bool() const { return book_name.empty() &&
        book_author.empty() && book_no.empty(); }
private:
    string book_name;
    string book_author;
    string book_no;
};
Book& Book::operator=(Book &&rhs) noexcept
{
    if(this != &rhs)
    {
        book_name = std::move(rhs.book_name);
        book_author = std::move(rhs.book_author);
        book_no = std::move(rhs.book_no);
    }
    return *this;
}
Book& Book::operator=(const string &isbn)
{
    book_no = isbn;
    return *this;
}
// friend definition
ostream& operator<<(ostream& os, const Book &b)
{
    os << b.book_name << " " << b.book_author << " " << b.book_no;
    return os;
}
istream& operator>>(istream& is, Book &b)
{
    is >> b.book_name >> b.book_author >> b.book_no;
    if(is)
        b = Book();
    return is;
}bool operator==(const Book &lhs, const Book &rhs)
{
    return lhs.book_name == rhs.book_name &&
           lhs.book_author == rhs.book_name &&
           lhs.book_no == rhs.book_no;
}
bool operator!=(const Book &lhs, const Book &rhs)
{
    return !(lhs == rhs);
}
#endif