using System;

using System.Collections.Generic;

using System.Text;

using System.Linq;

using System.Xml.Serialization;

using System.Xml;

using System.Xml.Linq;

using System.IO;

using System.Data;

using System.Runtime.Serialization;

using System.Runtime.Serialization.Formatters.Binary;

using System.IO.Compression;

​

using NUnit.Framework; //NUnit.Framework.AssertionException

​

//https://stackoverflow.com/questions/57330246/setting-memorystream-position-based-on-indexof

​

    public static class XmlReaderExtensions

    {

        public static IEnumerable<XmlReader> ReadRoots(this XmlReader reader)

        {

            while (reader.Read())

            {

                if (reader.NodeType == XmlNodeType.Element)

                {

                    using (var subReader = reader.ReadSubtree())

                        yield return subReader;

                }

            }

        }

        public static void SplitDocumentFragments(Stream stream, Func<int, string> makeFileName, Action<string, IXmlLineInfo> onFileWriting, Action<string, IXmlLineInfo> onFileWritten)

        {

            using (var textReader = new StreamReader(stream, Encoding.UTF8, true, 4096, true))

            {

                SplitDocumentFragments(textReader, makeFileName, onFileWriting, onFileWritten);

            }

        }

        public static void SplitDocumentFragments(TextReader textReader, Func<int, string> makeFileName, Action<string, IXmlLineInfo> onFileWriting, Action<string, IXmlLineInfo> onFileWritten)

        {

            if (textReader == null || makeFileName == null)

                throw new ArgumentNullException();

            var settings = new XmlReaderSettings { ConformanceLevel = ConformanceLevel.Fragment, CloseInput = false };

            using (var xmlReader = XmlReader.Create(textReader, settings))

            {

                var lineInfo = xmlReader as IXmlLineInfo;

                var index = 0;

                foreach (var reader in xmlReader.ReadRoots())

                {

                    var outputName = makeFileName(index);

                    reader.MoveToContent();

                    if (onFileWriting != null)

                        onFileWriting(outputName, lineInfo);

                    using(var writer = XmlWriter.Create(outputName))

                    {

                        writer.WriteNode(reader, true);

                    }

                    index++;

                    if (onFileWritten != null)

                        onFileWritten(outputName, lineInfo);

                }

            }

        }

    }

​

    public class TestClass

    {

        public static void Test()

        {

            var fileName = "Question57330246.xml";

            File.WriteAllText(fileName, GetXml());

            var outputPath = ""; // The directory in which to create your XML files.

            using (var stream = File.OpenRead(fileName))

            {

                XmlReaderExtensions.SplitDocumentFragments(stream,

                                                           index => Path.Combine(outputPath, index.ToString() + ".xml"),

                                                           (name, lineInfo) => 

                                                           {

                                                               Console.WriteLine("Writing {0}, starting line info: LineNumber = {1}, LinePosition = {2}...", 

                                                                                 name, lineInfo?.LineNumber, lineInfo?.LinePosition);

                                                           },

                                                           (name, lineInfo) => 

                                                           {

                                                               Console.WriteLine("   Done.  Result: ");

                                                               Console.Write("   ");

                                                               Console.WriteLine(File.ReadAllText(name));

                                                           });

            }

        }

​

        static string GetXml()

        {

            var xml = @"<TestNode active=""1"" lastName=""l""><Foo /> </TestNode>

<TestNode active=""2"" lastName=""l"" />

<TestNode active=""3"" lastName=""l""><Foo />  </TestNode>

<TestNode active=""4"" lastName=""l""><Foo />  </TestNode>

<TestNode active=""5"" lastName=""l""><Foo />  </TestNode>

<TestNode active=""6"" lastName=""l""><Foo />  </TestNode>

<TestNode active=""7"" lastName=""l""><Foo />  </TestNode>

<TestNode active=""8"" lastName=""l""><Foo />  </TestNode>

<TestNode active=""9"" lastName=""l""><Foo />  </TestNode>

<TestNode active=""10"" lastName=""l""><Foo />  </TestNode>

<TestNode active=""11"" lastName=""l"" />

<TestNode active=""12"" lastName=""l""><Foo />  </TestNode>

";

            return xml;

        }

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Roslyn 2.0 Compiler; Environment version: " + Environment.Version);

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

                Console.WriteLine("Uncaught exception: ");

                Console.WriteLine(ex);

                throw;

            }

        }

    }

​