void calculate()
{
const char quit = 'q'; // t.kind==quit means that t is a quit Token
const char print = ';'; // t.kind==print means that t is a print Token
const std::string prompt = "> ";
const std::string equals = "= "; // used to indicate that what follows is an evaluation
TokenStream tokenStream;
std::string enterToClose = "~~";
while (std::cin)
try
{
std::cout << prompt;
Token token = tokenStream.getToken();
if (token.kind == print)
token = tokenStream.getToken(); // eat ';'
if (token.kind == quit)
break;
tokenStream.setToken(token); // reset token into tokenStream
std::cout << equals << expression(tokenStream) << '\n';
}
catch (std::exception& e)
{
std::cerr << e.what() << '\n'; // write error message
tokenStream.ignore(print);
}
}
