SOExample, C# - rextester

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            Test().DoIfAny(e => {
                Console.WriteLine("called action");
                foreach (var v in e)
                    Console.WriteLine(v);
            });
        }
        
        private static IEnumerable<string> Test()
        {
            Console.WriteLine("enumerating test");
            yield return "hello";
            yield return "world";
            yield return "moo";
            Console.WriteLine("enumerated test");
        }
    }
    
    public static class LinqExtensions
    {
        public static bool DoIfAny<T>(this IEnumerable<T> collection, Action<IEnumerable<T>> action)
        {
            var enumerator = collection.GetEnumerator();
            if (!enumerator.MoveNext())
            {
                return false;
            }
            
            action(CreateEnumerableFromStartedEnumerable(enumerator));
            return true;
        }
        
        private static IEnumerable<T> CreateEnumerableFromStartedEnumerable<T>(IEnumerator<T> enumerator)
        {
            do
            {
                yield return enumerator.Current;
            }
            while (enumerator.MoveNext());
        }
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,67 sec, absolute running time: 0,09 sec, cpu time: 0,11 sec, average memory usage: 15 Mb, average nr of threads: 3, absolute service time: 0,82 sec