ExprHelper.cs

void Main()
{
	var foo = new C { B = new B { A = new A() }};
	var helper = ExpressionHelper<C>.GetDelegate<A>("B.A");
	helper(foo).Dump();
}

class A {
	public int X => 10;
}


class B {
	public A A { get; set; }
}

class C {
	public B B { get; set; }
}

public static class ExpressionHelper<T>
{
	private class ExpressionHolder<V> {
		public static Dictionary<string, (Expression<Func<T, V>>, Func<T, V>)> CachedExpressions = new Dictionary<string, (System.Linq.Expressions.Expression<System.Func<T, V>>, System.Func<T, V>)>();
	}
	
	public static Expression<Func<T, V>> GetExpression<V>(string path) => GetCachedExpression<V>(path).expression;
	public static Func<T, V> GetDelegate<V>(string path) => GetCachedExpression<V>(path).compiledExpression;
	
	private static (Expression<Func<T, V>> expression, Func<T, V> compiledExpression) GetCachedExpression<V>(string path) 
	{
		if (ExpressionHolder<V>.CachedExpressions.TryGetValue(path, out var result))
		{
			return result;
		}
		var parameter = Expression.Parameter(typeof(T));
		var fieldsAccesses = path.Split('.');
		Debug.Assert(fieldsAccesses.Length > 0);
		var accesses = fieldsAccesses.Aggregate((Expression) parameter, (x, field) => Expression.PropertyOrField(x, field));
		var expression = Expression.Lambda<Func<T, V>>(accesses, parameter);
		var compiledExpression = expression.Compile();
		ExpressionHolder<V>.CachedExpressions[path] = (expression, compiledExpression);
		return (expression, compiledExpression);
	}
}