//
// 3.3.rvalue.cpp
// modern c++ tutorial
//
// created by changkun at changkun.de
// https://github.com/changkun/modern-cpp-tutorial
//


#include <iostream>
#include <string>

void reference(std::string& str) {
 std::cout << "lvalue" << std::endl;
}
void reference(std::string&& str) {
 std::cout << "rvalue" << std::endl;
}

int main()
{
 std::string lv1 = "string,"; // lv1 is a lvalue
 // std::string&& r1 = lv1; // illegal, rvalue can't ref to lvalue
 std::string&& rv1 = std::move(lv1); // legal, std::move can convert lvalue to rvalue
 std::cout << rv1 << std::endl; // string,
 
 const std::string& lv2 = lv1 + lv1; // legal, const lvalue reference can extend temp variable's lifecycle
 // lv2 += "Test"; // illegal, const ref can't be modified
 std::cout << lv2 << std::endl; // string,string
 
 std::string&& rv2 = lv1 + lv2; // legal, rvalue ref extend lifecycle
 rv2 += "string"; // legal, non-const reference can be modified
 std::cout << rv2 << std::endl; // string,string,string,
 
 reference(rv2); // output: lvalue
 
 return 0;
}