Exer13_53_HasPtr_copy_swap.h

#ifndef HASPTR_H
#define HASPTR_H
#include <iostream>
#include <string>
#include <algorithm>
class HasPtr{
    // swap on page 517
    friend void swap(HasPtr&, HasPtr&);
    // relational operator required by exercise 13.31
    friend bool operator<(const HasPtr&, const HasPtr&);
public:
    HasPtr(const std::string &s = std::string()) : ps(new std::string(s)), i(0) { i = ps->size(); }
    // here, we can use private members directly! Because this is a member
    // function of class HasPtr. They can access any member of the class. Review
    // member functions, access control and class scope for more details.
    HasPtr(const HasPtr &hp) : ps(new std::string(*(hp.ps))), i(hp.i) { }
    // move constructor from page 540
    HasPtr(HasPtr &&p) noexcept : ps(p.ps), i(p.i) { p.ps=0; }
    HasPtr& operator=(HasPtr rhs)
        {swap(*this, rhs); return *this;}
    std::ostream& print(std::ostream&) const;
    // destructor required by exercise 13.11
    ~HasPtr() { delete ps; }
private:
    std::string *ps;
    int i;
};
bool operator<(const HasPtr &lhs, const HasPtr &rhs)
{
    return *lhs.ps < *rhs.ps;
}
std::ostream& HasPtr::print(std::ostream &os) const
{
    if(ps)
        os << *ps;
    return os;
}
inline void swap(HasPtr &lhs, HasPtr &rhs)
{
    using std::swap;
    swap(lhs.ps, rhs.ps);
    swap(lhs.i, rhs.i);
    std::cout << "two HasPtr objects are swapped" << std::endl; // required by exercise 13.30
}
#endif
// value-like copy and assign required by exercise 13.22
// Note: both copy and copy-assign member allocate new memory, so they make the
// class behave like a value.