Atom.NET Enhancement

I was reviewing the caching implementation for this site and I wanted to cache my Atom feed as an XmlDocument that I could write to the response stream. I needed to make a couple of changes to the AtomWriter class so I could create an XmlDocument. I thought about using a memory stream, but my RSS feed already deals with XmlDocuments and I wanted to share the caching logic.

The result of these changes make it possible to pass an XmlNodeWriter to the AtomFeed Save method. So, we get something like this:

...
XmlDocument d = new XmlDocument();
XmlNodeWriter xnw = new XmlNodeWriter(d, false);
feed.Save(xnw);
xnw.Close();
...

The changes are reproduced below (look for Removed in the source code).

internal class AtomWriter
{
    private XmlWriter _writer = null;

    #region Constructors
    internal AtomWriter(TextWriter w)
    {
        this._writer = new XmlTextWriter(w);
        Init();
    }

    internal AtomWriter(Stream w, Encoding encoding)
    {
        this._writer = new XmlTextWriter(w, encoding);
        Init();
    }

    internal AtomWriter(string filename, Encoding encoding)
    {
        this._writer = new XmlTextWriter(filename, encoding);
        Init();
    }

    internal AtomWriter(XmlWriter writer)
    {
        // Removed this._writer = (XmlTextWriter)writer;
        this._writer = writer;
        Init();
    }
    #endregion Constructors

    #region Private methods

    private void WriteHeader()
    {
        this._writer.WriteStartDocument();
        this._writer.WriteComment(DefaultValues.GeneratorMessage);
        // Removed this._writer.WriteRaw(Environment.NewLine);
    }

    /// 

    /// Writes the Atom feed body.
    /// 
    private void WriteFeed(AtomFeed feed)
    {
        if(this._writer == null)
         throw new InvalidOperationException("AtomWriter has been closed, and can not be written to.");


        this.WriteHeader();

        if(feed == null)
            throw new RequiredElementNotFoundException("AtomFeed cannot be null.");

        this._writer.WriteRaw(feed.ToString());

        // finalize the writer
        this._writer.Flush();
        this._writer.Close();
        this._writer = null;
    }

    /// 

    /// Writes the Atom entry body.
    /// 
    private void WriteEntry(AtomEntry entry)
    {
        if(this._writer == null)
            throw new InvalidOperationException("AtomWriter has been closed, and can not be written to.");

        if(entry == null)
            throw new RequiredElementNotFoundException("AtomEntry cannot be null.");

        this._writer.WriteRaw(entry.ToString());

        this._writer.Flush();
        this._writer.Close();
        this._writer = null;
    }

    private void Init()
    {
        // Removed
        //this._writer.Formatting = Formatting.Indented;
        //this._writer.Indentation = 2;
    }

    #endregion Private methods

    #region Internal methods

    internal void Write(AtomFeed feed)
    {
        this.WriteFeed(feed);
    }

    internal void Write(AtomEntry entry)
    {
        this.WriteEntry(entry);
    }

    #endregion Internal methods
}