RVO/NRVOのテスト

rvotest.cpp

#include <iostream>

// フツーこんなのなしだけどstringを継承したデバッグ用のクラス
class mystring : public std::string {
public:
    // コンストラクタ
    mystring() : std::string()
    {
        std::cout << "mystring constructor"
            << " mystring() called!" << std::endl;
    }
    mystring(const char *str) : std::string(str)
    {
        std::cout << "mystring constructor"
            << " mystring(const char *str) called!" << std::endl;
    }
    mystring(const std::string &s) : std::string(s)
    {
        std::cout << "mystring constructor"
            << " mystring(const std::string &s) called!" << std::endl;
    }

    // コピーコンストラクタ
    mystring(const mystring &rhs) : std::string(rhs.c_str())
    {
        std::cout << "mystring copy constructor"
            << " mystring(const mystring &rhs) called!" << std::endl;
    }

    // 代入演算子
    mystring &operator=(const char *str)
    {
        std::cout << "mystring assignment operator"
            << " mystring &operator=(const char *str) called!" << std::endl;
        std::string::operator=(str);
        return *this;
    }
    mystring &operator=(const std::string& s)
    {
        std::cout << "mystring assignment operator"
            << " mystring &operator=(const std::string& s) called!" << std::endl;
        std::string::operator=(s);
        return *this;
    }
    mystring& operator=(const mystring& rhs)
    {
        std::cout << "mystring assignment operator"
            << " mystring &operator=(const mystring& rhs) called!" << std::endl;
        std::string::operator=(rhs.c_str());
        return *this;
    }
};

mystring test3()
{
    std::cout << "function test3 called!!" << std::endl;
    mystring str = "test";
    return str;    
}

mystring test4()
{
    std::cout << "function test4 called!!" << std::endl;
    return mystring("test");
}


int main()
{
    std::cout << "テスト3_a" << std::endl;
    mystring str3_a = test3();
    std::cout << "[" << str3_a << "]" << std::endl;

    std::cout << "テスト4_a" << std::endl;
    mystring str4_a = test4();
    std::cout << "[" << str4_a << "]" << std::endl;

    return 0;
}