C# の Markdown ヘッダー

     // Create the MarkdownSyntaxTree
    var markdown = new MarkdownSyntaxTree(new Configuration());

    // Get a SyntaxFactory to create new elements
    var mdf = markdown.SyntaxFactory;

    // Create headings of the required level
    var heading1 = mdf.AtxHeading("Heading 1 level text", 1);
    var heading2 = mdf.AtxHeading("Heading 2 level text", 2);
    var heading3 = mdf.AtxHeading("Heading 3 level text", 3);

    // Create and add newLineTrivia element for an empty line after headings 
    var newLineTrivia = mdf.NewLineTrivia();
    heading1.GetTrailingTrivia().Add(newLineTrivia);
    heading2.GetTrailingTrivia().Add(newLineTrivia);
    heading3.GetTrailingTrivia().Add(newLineTrivia);

    // Add the headers to the Markdown syntax tree
    markdown.AppendChild(heading1);
    markdown.AppendChild(heading2);
    markdown.AppendChild(heading3);

    // Prepare a path for MD file saving 
    string savePath = Path.Combine(OutputDir, "output-headers.md");

    // Save MD file
    markdown.Save(savePath);

    // Specify the path to the source MD file
    var input = "C:/temp/document.md";

    // Create a MarkdownParser object
    var parser = new MarkdownParser();

    // Parse the document and get a Markdown syntax tree
    var syntaxTree = parser.ParseFile(input);

    // The first element of this document is AtxHeading
    var heading = (AtxHeadingSyntaxNode)syntaxTree.FirstChild;

    // Accumulate the text content from its elements
    var sb = new StringBuilder();

    while (heading.FirstChild != null)
    {
        sb.Append(heading.FirstChild);

        //  Remove accumulated first element from the tree
        heading.RemoveChild(heading.FirstChild);
    }

    // Get a SyntaxFactory to create new elements 
    var syntaxFactory = syntaxTree.SyntaxFactory;

    // Сreate a text node consisting of new and old text and add it as a child element of AtxHeading 
    var textSyntaxNode = syntaxFactory.Text("Added some new text! " + sb);
            
    // Add the new element to the document tree
    heading.AppendChild(textSyntaxNode);

    // Prepare a path for MD file saving 
    string savePath = Path.Combine(OutputDir, "edit-header.md");

    // Save MD file
    syntaxTree.Save(savePath);