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#include <iostream>
#include <string>
#include <memory>
#include <sstream>
#include <cstring>
#include <complex>
#include <utility>
#include <algorithm>
using namespace std;
class Complex
{
public:
Complex(double, double)
{
cout << "Complex constructor\n";
}
Complex(Complex const &other)
{
cout << "Complex copy constructor\n";
}
~Complex()
{
cout << "Complex destructor\n";
}
Complex &operator=(Complex const &other)
{
cout << "Complex operator=\n";
}
};
class String
{
friend ostream &operator<<(ostream &out, String const &str);
string d_str;
public:
String(std::string const &txt)
:
d_str(txt)
{
cout << "String constructor\n";
}
String(String const &other)
:
d_str(other.d_str)
{
cout << "String copy constructor\n";
}
~String()
{
cout << "String destructor\n";
}
String &operator=(String const &other)
{
d_str = other.d_str;
cout << "String operator=\n";
}
};
ostream &operator<<(ostream &out, String const &str)
{
return out << str.d_str;
}
union Union
{
#if 0
typedef complex<double> Type1;
typedef string Type2;
#else
typedef Complex Type1;
typedef String Type2;
#endif
pair<int, int> u_int;
pair<int, Type1> u_complex;
pair<int, Type2> u_string;
Union(Union const &other);
Union(int i);
Union(double real, double imaginary);
Union(string const &str);
~Union();
int &asInt();
Type1 &asComplex();
Type2 &asString();
Union &operator=(Union &&tmp);
Union &operator=(Union const &rhs);
void swap(Union &other);
};
int &Union::asInt()
{
return u_int.second;
}
Union::Type1 &Union::asComplex()
{
return u_complex.second;
}
Union::Type2 &Union::asString()
{
return u_string.second;
}
Union::Union(Union const &other)
{
switch (other.u_int.first)
{
case 1:
new (&u_int) pair<int, int>(other.u_int);
break;
case 2:
new (&u_complex) pair<int, Type1>(other.u_complex);
break;
case 3:
new (&u_string) pair<int, Type2>(other.u_string);
break;
}
}
Union::Union(int i)
:
u_int(1, i)
{}
Union::Union(double real, double imaginary)
:
u_complex(2, {real, imaginary})
{}
Union::Union(string const &str)
:
u_string(3, str)
{}
Union::~Union()
{
switch (u_int.first)
{
case 2:
u_complex.second.~Type1();
break;
case 3:
u_string.second.~Type2();
break;
}
}
Union &Union::operator=(Union &&tmp)
{
swap(tmp);
return *this;
}
Union &Union::operator=(Union const &other)
{
Union tmp(other);
return *this = std::move(tmp);
}
void Union::swap(Union &other)
{
char memory[sizeof(Union)];
memcpy(memory, &other, sizeof(Union));
memcpy(&other, this, sizeof(Union));
memcpy(this, memory, sizeof(Union));
}
int main()
{
Union ustr("hello world");
Union ucom(12.4, 12.5);
ustr = ucom;
ustr = Union("hi there, again");
cout << ustr.asString() << '\n';
}
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