如何将表达式从View发送到Model然后解析并计算它？

Question

我在ASP.NET MVC 4中有类似简单的MS Windows计算器。现在我不知道如何将4+5这样的表达式发送到模型，例如public string Expression { get; set }。然后我想解析这个表达式并计算它，但是怎么做呢？

我有控制器：

public class CalculatorController : Controller
{
    //
    // GET: /Calculator/
    public ActionResult Index()
    {
        return View();
    }
    //GET: /Calculator/Calculate
    [HttpGet]
    public ActionResult Calculate(Calculator model)
    {

        return View(model);
    }
    //POST
    [HttpPost]
    public ActionResult Calculate()
    {
        Calculator model = new Calculator();
        return View(model);
    }
}

我有模特：

public class Calculator
{
    public string Expression { get; set; }
    public double Result { get; set; }
}

我使用Razor和JavaScript查看：

@using (Html.BeginForm("Calculate", "Calculator", FormMethod.Post)){    
@Html.LabelFor(model => model.Expression)
@Html.TextBoxFor(model => model.Expression)    
        <table>
            <tr>
                <td><input type="button" name="btnSeven" id="btnSeven" value="7" /></td>
                <td><input type="button" id="btnEight" value="8" /></td>
                <td><input type="button" id="btnNine" value="9" /></td>
                <td><input type="button" id="btnDelete" value="DEL" /></td>
                <td><input type="button" id="btnClear" value="CLR" /></td>
            </tr>
            <tr>
                <td><input type="button" id="btnFour" value="4" /></td>
                <td><input type="button" id="btnFive" value="5" /></td>
                <td><input type="button" id="btnSix" value="6" /></td>
                <td><input type="button" id="btnMultiply" value="*" /></td>
                <td><input type="button" id="btnDivide" value="/" /></td>
            </tr>
            <tr>
                <td><input type="button" id="btnOne" value="1" /></td>
                <td><input type="button" id="btnTwo" value="2" /></td>
                <td><input type="button" id="btnThree" value="3" /></td>
                <td><input type="button" id="btnPlus" value="+" /></td>
                <td><input type="button" id="btnMinus" value="-" /></td>
            </tr>
            <tr>
                <td><input type="button" id="btnZero" value="0" /></td>
                <td><input type="button" id="btnDot" value="." /></td>
                <td><input type="submit" id="btnEqual" value="=" /></td>
                @Html.ValueFor(model => model.Expression)
                <td><input type="button" id="btnLBracket" value="(" /></td>
                <td><input type="button" id="btnRBracket" value=")" /></td>
            </tr>
        </table> 

}

同一视图中的JavaScript：

<script>
            window.onload = function () {
                document.getElementById('btnSeven').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnSeven').value;
                });
                document.getElementById('btnEight').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnEight').value;
                });
                document.getElementById('btnNine').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnNine').value;
                });
                document.getElementById('btnDelete').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnDelete').value;
                });
                document.getElementById('btnClear').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnClear').value;
                });
                document.getElementById('btnFour').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnFour').value;
                });
                document.getElementById('btnFive').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnFive').value;
                });
                document.getElementById('btnSix').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnSix').value;
                });
                document.getElementById('btnMultiply').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnMultiply').value;
                });
                document.getElementById('btnDivide').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnDivide').value;
                });
                document.getElementById('btnOne').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnOne').value;
                });
                document.getElementById('btnTwo').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnTwo').value;
                });
                document.getElementById('btnThree').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnThree').value;
                });
                document.getElementById('btnPlus').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnPlus').value;
                });
                document.getElementById('btnMinus').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnMinus').value;
                });
                document.getElementById('btnZero').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnZero').value;
                });
                document.getElementById('btnDot').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnDot').value;
                });
                @*document.getElementById('btnEqual').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnEqual').value;
                });*@
                document.getElementById('btnLBracket').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnLBracket').value;
                });
                document.getElementById('btnRBracket').addEventListener('click', function () {
                    document.getElementById('Expression').value = document.getElementById('Expression').value + document.getElementById('btnRBracket').value;
                });
            }

如何将表达式发送到Expression，然后解析并计算并发送到Result，然后发送到textBox。单击=按钮后，必须在同一文本框中完成所有操作。