Lexer class 2

    std::stringstream inputStream(input);
    char token;

    Token lastOperator;
    while (!inputStream.eof())
    {
        token = inputStream.get();

        Token inOperator = Token{ TokenTypes{token}, token };

        switch (token)
        {
        case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9':
            if (!outputStack.empty())
            {
                if (lastOperator == TokenTypes::NUMBER)
                {
                    inOperator = Token{ TokenTypes::NUMBER, std::stoi(lastOperator.toString() + inOperator.toString()) };
                    outputStack.pop();
                    outputStack.push(inOperator);
                    break;
                }
            }

            inOperator = Token{ TokenTypes::NUMBER, (int)(token - '0') };
            outputStack.push(inOperator);
            break;

        case '+': case '-': case '*': case '/': case '^':
            while (!operatorStack.empty() && (operatorStack.top() > inOperator || (operatorStack.top() == inOperator && inOperator.isLeftAssociative())) && operatorStack.top() != TokenTypes{ '(' })
            {
                outputStack.push(operatorStack.top());
                operatorStack.pop();
            }

            operatorStack.push(inOperator);
            break;

        case '(':
            operatorStack.push(inOperator);
            break;

        case ')':
            lastOperator = inOperator;

            while (operatorStack.top() != TokenTypes{ '(' })
            {
                inOperator = operatorStack.top();

                if (lastOperator == TokenTypes::NUMBER)
                    inOperator = Token{ TokenTypes::NUMBER, std::stoi(lastOperator.toString() + inOperator.toString()) };

                outputStack.push(inOperator);
                operatorStack.pop();

                lastOperator = inOperator;
            }

            if (operatorStack.top() == TokenTypes{ '(' })
                operatorStack.pop();
            break;
        }

        lastOperator = inOperator;
    }

    while (!operatorStack.empty())
    {
        outputStack.push(operatorStack.top());
        operatorStack.pop();
    }

    size_t size = outputStack.size();
    std::vector<Token> tokens;
    for (size_t i = 0; i < size; i++)
    {
        tokens.push_back(outputStack.top());
        outputStack.pop();
    }

    //std::reverse(tokens.begin(), tokens.end());

    for (size_t i = 0; i < size; i++)
        outputStack.push(tokens[i]);

    /*std::string outputString;

    size_t stackSize = outputStack.size();
    for (size_t i = 0; i < stackSize; i++)
    {
        outputString += outputStack.top().toString() + ' ';
        outputStack.pop();
    }

    std::istringstream iss(outputstring);

    std::vector<std::string> splitstring{ std::istream_iterator<std::string>(iss), {} };

    std::reverse(splitstring.begin(), splitstring.end());

    std::ostringstream oss;
    std::copy(splitstring.begin(), splitstring.end(), std::ostream_iterator<std::string>(oss, " "));

    outputstring = oss.str();*/