Microsoft.DocAsCode.Build.TableOfContents.MarkdownTocReader.LoadToc C# (CSharp) Method

        public static TocViewModel LoadToc(string tocContent, string filePath)
        {
            ParseState state = new InitialState(filePath);
            var rules = new ParseRule[]
            {
                new TopicTocParseRule(),
                new ExternalLinkTocParseRule(),
                new TopicXrefAutoLinkTocParseRule(),
                new TopicXrefShortcutTocParseRule(),
                new ContainerParseRule(),
                new CommentParseRule(),
                new WhitespaceParseRule(),
            };
            var content = tocContent.Replace("\r\n", "\n").Replace("\r", "\n");
            int lineNumber = 1;
            while (content.Length > 0)
            {
                state = state.ApplyRules(rules, ref content, ref lineNumber);
            }
            return state.Root;
        }

        // TODO: refactor the return value to TocRootViewModel
        public static TocItemViewModel LoadSingleToc(string file)
        {
            if (string.IsNullOrEmpty(file))
            {
                throw new ArgumentNullException(nameof(file));
            }

            var fileType = Utility.GetTocFileType(file);

            try
            {
                if (fileType == TocFileType.Markdown)
                {
                    return(new TocItemViewModel
                    {
                        Items = MarkdownTocReader.LoadToc(EnvironmentContext.FileAbstractLayer.ReadAllText(file), file)
                    });
                }
                else if (fileType == TocFileType.Yaml)
                {
                    return(LoadYamlToc(file));
                }
            }
            catch (Exception e)
            {
                var message = $"{file} is not a valid TOC File: {e.Message}";
                Logger.LogError(message);
                throw new DocumentException(message, e);
            }

            throw new NotSupportedException($"{file} is not a valid TOC file, supported toc files could be \"{Constants.TableOfContents.MarkdownTocFileName}\" or \"{Constants.TableOfContents.YamlTocFileName}\".");
        }