private void DoCompare()

in src/Application/FormMain.cs [2624:2729]
87 lines of code
10 McCabe index (conditional complexity)

        private void DoCompare(string changed)
        {
            CleanupTempFiles();

            // todo: add UI for setting XmlDiffOptions.

            XmlDiffOptions options = XmlDiffOptions.None;

            if ((bool)this._settings["XmlDiffIgnoreChildOrder"])
            {
                options |= XmlDiffOptions.IgnoreChildOrder;
            }
            if ((bool)this._settings["XmlDiffIgnoreComments"])
            {
                options |= XmlDiffOptions.IgnoreComments;
            }
            if ((bool)this._settings["XmlDiffIgnorePI"])
            {
                options |= XmlDiffOptions.IgnorePI;
            }
            if ((bool)this._settings["XmlDiffIgnoreWhitespace"])
            {
                options |= XmlDiffOptions.IgnoreWhitespace;
            }
            if ((bool)this._settings["XmlDiffIgnoreNamespaces"])
            {
                options |= XmlDiffOptions.IgnoreNamespaces;
            }
            if ((bool)this._settings["XmlDiffIgnorePrefixes"])
            {
                options |= XmlDiffOptions.IgnorePrefixes;
            }
            if ((bool)this._settings["XmlDiffIgnoreXmlDecl"])
            {
                options |= XmlDiffOptions.IgnoreXmlDecl;
            }
            if ((bool)this._settings["XmlDiffIgnoreDtd"])
            {
                options |= XmlDiffOptions.IgnoreDtd;
            }

            this.xmlTreeView1.Commit();
            this.SaveIfDirty(false);
            string filename = this._model.FileName;

            // load file from disk, as saved doc can be slightly different
            // (e.g. it might now have an XML declaration).  This ensures we
            // are diffing the exact same doc as we see loaded below on the
            // diffView.Load call.
            XmlDocument original = new XmlDocument();
            XmlReaderSettings settings = _model.GetReaderSettings();
            using (XmlReader reader = XmlReader.Create(filename, settings))
            {
                original.Load(reader);
            }

            XmlDocument doc = new XmlDocument();
            settings = _model.GetReaderSettings();
            using (XmlReader reader = XmlReader.Create(changed, settings))
            {
                doc.Load(reader);
            }

            //output diff file.
            string diffFile = Path.Combine(Path.GetTempPath(),
                Path.GetFileNameWithoutExtension(Path.GetRandomFileName()) + ".xml");
            this._tempFiles.AddFile(diffFile, false);

            bool isEqual = false;
            XmlTextWriter diffWriter = new XmlTextWriter(diffFile, Encoding.UTF8);
            diffWriter.Formatting = Formatting.Indented;
            using (diffWriter)
            {
                XmlDiff diff = new XmlDiff(options);
                isEqual = diff.Compare(original, doc, diffWriter);
            }

            if (isEqual)
            {
                //This means the files were identical for given options.
                MessageBox.Show(this, SR.FilesAreIdenticalPrompt, SR.FilesAreIdenticalCaption,
                    MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                return;
            }

            string tempFile = Path.Combine(Path.GetTempPath(),
                Path.GetFileNameWithoutExtension(Path.GetRandomFileName()) + ".htm");
            _tempFiles.AddFile(tempFile, false);

            using (XmlReader diffGram = XmlReader.Create(diffFile, settings))
            {
                XmlDiffView diffView = new XmlDiffView();
                using (var reader = new XmlTextReader(filename))
                {
                    diffView.Load(reader, diffGram);
                    using (TextWriter htmlWriter = new StreamWriter(tempFile, false, Encoding.UTF8))
                    {
                        SideBySideXmlNotepadHeader(this._model.FileName, changed, htmlWriter);
                        diffView.GetHtml(htmlWriter);
                        htmlWriter.WriteLine("</body></html>");
                    }
                }
            }

            WebBrowser.OpenUrl(this.Handle, tempFile);
        }