Prepending a comment before serialized RDF

readme.md

CommentHeaderWriter

Simple decorator of IRdfWriter which prepends the output with a comment string.

Note that it is up to the caller to provide a string which will be a valid comment according to the syntax of chose RDF serialization.

CommentHeaderWriter.cs

public class CommentHeaderWriter : BaseRdfWriter
{
	private readonly IRdfWriter inner;
	private readonly string header;

	public CommentHeaderWriter(IRdfWriter writer, string header)
	{
		this.inner = writer;
		this.header = header;
	}

	public override void Save(IGraph g, string filename)
	{
		using (var stream = File.Open(filename, FileMode.Create))
		{
		    this.Save(g, new StreamWriter(stream, new UTF8Encoding(Options.UseBomForUtf8)));
		}
	}

	protected override void SaveInternal(IGraph graph, TextWriter output)
	{
		output.WriteLine(_header);
		output.WriteLine();
		this.inner.Save(graph, output);
	}
  
	public override event RdfWriterWarning Warning
	{
		add
		{
			this.inner.Warning += value;
		}

		remove
		{
			this.inner.Warning -= value;
		}
	}
}

Program.cs

class Program
{
    public static void Main()
    {
        Graph graph = new Graph();
        graph.Assert(
            new VDS.RDF.Triple(
                graph.CreateBlankNode(),
                graph.CreateUriNode(new Uri("http://schema.org/name")),
                graph.CreateLiteralNode("Tomasz")));
        var comment = "# Created with dotNetRDF";

        var output = new System.IO.StringWriter();
        var actualWriter = new CompressingTurtleWriter();
        
        var writer = new CommentHeaderWriter(actualWriter, comment);
        writer.Save(graph, output);
    }
}