using System;

using System.Linq;

using System.Linq.Dynamic.Core;

using System.Collections.Generic;

​

public class Program

{

    public static string[] allUsers =

    {

        "user1",

        "user2",

        "admin",

        "test"

    };

    public static void Main()

    {

        UserType currentUser = UserType.Other;

        string condition = "!Contains(\"test\")";

        if (currentUser != UserType.Admin)

        {

            condition += " && !Contains(\"admin\")";

        }

​

        IEnumerable<string> resultUsers = allUsers.AsQueryable().Where(condition);

        foreach (var user in resultUsers)

        {

            Console.WriteLine(user);

        }

    }

}

​

public enum UserType

{

    Admin,

    Manager,

    Other

}