using System.Collections.Concurrent;

using System.Collections.Generic;

using System.Text.RegularExpressions;

using System.Threading.Tasks;

​

namespace Demo

{

    public class Demo

    {

        private readonly ConcurrentBag<string> _objectifiableMatches = new();

        public async Task<ConcurrentBag<string>> GetKeywordMatchesAsync()

        {

            var keywords = new List<string>()

            {

                "test1",

                "test2",

                "test3",

                "test4",

                "test5",

            };

​

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

            var splittingTasks = new List<Task>();

            foreach (var kw in keywords)

            {

                var keyword = kw.ToUpper();

                splittingTasks.Add(Task.Run(() => SplitMatches(keyword)));

            }

            await Task.WhenAll(splittingTasks);

            watch.Stop();

​

            return _objectifiableMatches;

        }

​

        public void SplitMatches(string keyword)

        {

            var _content = "";

            var patternObject = $@"\/begin {keyword}[\s\S]+?\/end {keyword}";

            var regexObject = new Regex(patternObject);

            var Matches = regexObject.Matches(_content);

            Parallel.ForEach(Matches, m =>

            {

                var replacedQuotes = m.Value.Replace($"\"", "'");

                _objectifiableMatches.Add(replacedQuotes);

            });

        }

    }

    class Program

    {

        static async Task Main()

        {

            var demo = new Demo();

            await demo.GetKeywordMatchesAsync();

        }

    }

}

​