using System;

using System.Reflection;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        //var test = new List<string>();

        //Console.WriteLine($"Empty List: {IsEmpty(test)}");

        //test.Add("helloWorld");

        //Console.WriteLine($"Value in List: {IsEmpty(test)}");

        //Console.WriteLine($"String: {(IsEmpty("hello world"))}");

        TestListPerformance(ListTest,10000);

        TestListPerformance(YieldTest,10000);

    }

    public static void TestListPerformance(Func<int,IEnumerable<string>> func, int recordsToTest)

    {

        var watch = System.Diagnostics.Stopwatch.StartNew();

        var results = func(recordsToTest);

        foreach(var index in results)

        {

            var temp = index;   

        }

        watch.Stop();

        Console.WriteLine(watch.ElapsedMilliseconds);

        Console.WriteLine(watch.ElapsedTicks);

    }

    public static IEnumerable<string> ListTest(int totalRecords)

    {

        var list = new List<string>();

        for(var i = 0; i < totalRecords; i++)

        {

            list.Add($"Hello World {i}");

        }

        return list;

    }

    public static IEnumerable<string> YieldTest(int totalRecords)

    {

        for(var i = 0; i < totalRecords; i++)

        {

            yield return $"Hello World {i}";

        }

    }

     public static bool IsEmpty(object source)

        {

            if (source == null)

            {

                return true;

            }

            var sourceType = source.GetType();

            if (!sourceType.IsGenericType)

            {

                return true;

            }

            if (!sourceType.GetInterfaces().Any(t => t.GetGenericTypeDefinition() == typeof(IEnumerable<>)))

            {

                return true;

            }

            var childType = sourceType.GetGenericArguments()[0];

            MethodInfo isAny = typeof(System.Linq.Enumerable)

                .GetMethods()

                .First(t => t.Name == nameof(System.Linq.Enumerable.Any) && t.IsGenericMethod)

                .MakeGenericMethod(new Type[]{ childType });

            if (!(bool)isAny.Invoke(null, new object[] { source }))

            {

                return true;

            }

​

            return false;

        }

}