std::wstring _toUtf8(const std::string &str) {
    auto getSymbolLen = [](const char *str, size_t n) {
        if( 0xf0 == (0xf8&str[n]))
            return 4;
        else if( 0xe0 == (0xf0&str[n]))
            return 3;
        else if( 0xc0 == (0xe0&str[n]))
            return 2;
        return 1;
    };

    const char *c_str = str.c_str();
    wchar_t wChar;
    char wcharSymbol[sizeof(wchar_t)] = {0};
    std::vector<wchar_t> characters;

    for (size_t i = 0; i < str.size();) {
        size_t symbLen = getSymbolLen(str.c_str(), i);

        memset(wcharSymbol, 0, sizeof(wchar_t));
        for (size_t j = 0; j < symbLen; ++j)
            wcharSymbol[j] = c_str[i+j];
            for (size_t j = 0; j < sizeof(wchar_t); ++j) {
                *(((unsigned char*)(&wChar))+j)
                    = wcharSymbol[j];
            }

        i += symbLen;
        characters.push_back(wChar);
    }
    return std::wstring(characters.begin(), characters.end());
}