Xml.cs

using System;
using System.Security;
using System.Text;
using System.Text.RegularExpressions;
using System.Xml;

namespace S22.Xmpp {
	/// <summary>
	/// Provides a factory method for creating XmlElement instances and adds
	/// a couple of useful shortcut extensions to the XmlElement class.
	/// </summary>
	internal static class Xml {
		/// <summary>
		/// Creates a new XmlElement instance.
		/// </summary>
		/// <param name="name">The name of the element.</param>
		/// <param name="namespace">The namespace of the element.</param>
		/// <returns>An initialized instance of the XmlElement class.</returns>
		/// <exception cref="ArgumentNullException">The name parameter is null.</exception>
		/// <exception cref="ArgumentException">The name parameter is the
		/// empty string.</exception>
		/// <exception cref="XmlException">The name or the namespace parameter
		/// is invalid.</exception>
		public static XmlElement Element(string name, string @namespace = null) {
			name.ThrowIfNullOrEmpty("name");
			return new XmlDocument().CreateElement(name, @namespace);
		}

		/// <summary>
		/// Adds the specified element to the end of the list of child nodes, of
		/// this node.
		/// </summary>
		/// <param name="e">The XmlElement instance the method is invoked for.</param>
		/// <param name="child">The node to add.</param>
		/// <returns>A reference to the XmlElement instance.</returns>
		public static XmlElement Child(this XmlElement e, XmlElement child) {
			XmlNode imported = e.OwnerDocument.ImportNode(child, true);
			e.AppendChild(imported);
			return e;
		}

		/// <summary>
		/// Sets the value of the attribute with the specified name.
		/// </summary>
		/// <param name="e">The XmlElement instance the method is invoked for.</param>
		/// <param name="name">The name of the attribute to create or alter.</param>
		/// <param name="value">The value to set for the attribute.</param>
		/// <returns>A reference to the XmlElement instance.</returns>
		public static XmlElement Attr(this XmlElement e, string name, string value) {
			e.SetAttribute(name, value);
			return e;
		}

		/// <summary>
		/// Adds the specified text to the end of the list of child nodes, of
		/// this node.
		/// </summary>
		/// <param name="e">The XmlElement instance the method is invoked for.</param>
		/// <param name="text">The text to add.</param>
		/// <returns>A reference to the XmlElement instance.</returns>
		public static XmlElement Text(this XmlElement e, string text) {
			e.AppendChild(e.OwnerDocument.CreateTextNode(text));
			return e;
		}

		/// <summary>
		/// Serializes the XmlElement instance into a string.
		/// </summary>
		/// <param name="e">The XmlElement instance the method is invoked for.</param>
		/// <param name="xmlDeclaration">true to include a XML declaration,
		/// otherwise false.</param>
		/// <param name="leaveOpen">true to leave the tag of an empty element
		/// open, otherwise false.</param>
		/// <returns>A textual representation of the XmlElement instance.</returns>
		public static string ToXmlString(this XmlElement e, bool xmlDeclaration = false,
			bool leaveOpen = false) {
			// Can't use e.OuterXml because it "messes up" namespaces for elements with
			// a prefix, i.e. stream:stream (What it does is probably correct, but just
			// not what we need for XMPP).
			StringBuilder b = new StringBuilder("<" + e.Name);
			if (!String.IsNullOrEmpty(e.NamespaceURI))
				b.Append(" xmlns='" + e.NamespaceURI + "'");
			foreach (XmlAttribute a in e.Attributes) {
				if (a.Name == "xmlns")
					continue;
				if (a.Value != null)
					b.Append(" " + a.Name + "='" + SecurityElement.Escape(a.Value.ToString())
						+ "'");
			}
			if (e.IsEmpty)
				b.Append("/>");
			else {
				b.Append(">");
				foreach (var child in e.ChildNodes) {
					if (child is XmlElement)
						b.Append(((XmlElement) child).ToXmlString());
					else if (child is XmlText)
						b.Append(((XmlText) child).InnerText);
				}
				b.Append("</" + e.Name + ">");
			}
			string xml = b.ToString();
			if (xmlDeclaration)
				xml = "<?xml version='1.0' encoding='UTF-8'?>" + xml;
			if (leaveOpen)
				return Regex.Replace(xml, "/>$", ">");
			return xml;
		}
	}
}