How can I create a method that has a smiliar functionality as the new "?." operator?

Question

With C# 6 we can use the new ? to access properties and methods without heaving to check each one for null. Would it be possible to write a method that has a siliar functionality using expressions?

For example I have to use a weird object structures (that comes from a 3rd party library that we cannot change). Accessing some properties requires often long chains of dots:

rootObject.Services.First().Segments.First().AnotherCollection.First().Weight;

Any of the objects after rootObject can be null. I would rather not put a try/catch around it. Also checking each property separately is a lot of work. So I was wondering if I could pass it to the method taking an expression and traverse each property and check its value there:

var value = PropertyHelper.GetValue(() => rootObject.Services.First().Segments.First().AnotherCollection.First().Weight);

I guess its signature would be something like:

public static T GetValue<T>(Expression<Func<T>> expression)
{
    // analyze the expression and evaluate each property/method
    // stop when null or return the value
}

I'm not realy sure if expressions are capable of what I'm going to do and before I start experimenting I wanted to ask whether it's even possible.

Answer 1

void Main()
{
    var foo = new Foo();

    var qux = NullPropertyExtension.GetValue(() => foo.Bar.Qux);

    Console.WriteLine(qux);


}

public class Foo
{
    public Foo Bar { get; set; }
    public string Qux {get;set;}
}

// Define other methods and classes here
public static class NullPropertyExtension
{
    public static TValue GetValue<TValue>(Expression<Func<TValue>> property)
    {
        var visitor = new Visitor();
        var expression = visitor.Visit(property.Body);
        var lambda = Expression.Lambda<Func<TValue>>(expression);

        var func = lambda.Compile();
        return func();
    }

    private class Visitor : System.Linq.Expressions.ExpressionVisitor
    {
        protected override Expression VisitMember(MemberExpression node)
        {
            var isNotNull = Expression.NotEqual(node.Expression, Expression.Constant(null));
            return Expression.Condition(
                isNotNull,
                node,
                Expression.Constant(null, node.Type));

        }
    }
}