What asp.net-mvc strongly typed helpers uses underneath?

For example, if i use this in view:

${Html.TextBoxFor(u=>u.UserName)}

How ca开发者_Python百科n i

var name = [xxx].NameFor<User>(u=>u.UserName);

from elsewhere? Is that possible?

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System.Web.Mvc.ExpressionHelper.GetExpressionText(LambdaExpression expression)