Mono.Xml.XmlTextWriter.WriteStartElement C# (CSharp) Method

		public override void WriteStartElement (
			string prefix, string localName, string namespaceUri)
		{
#if NET_2_0
			if (state == WriteState.Error || state == WriteState.Closed)
#else
			if (state == WriteState.Closed)
#endif
				throw StateError ("StartTag");
			node_state = XmlNodeType.Element;

			bool anonPrefix = (prefix == null);
			if (prefix == null)
				prefix = String.Empty;

			// Crazy namespace check goes here.
			//
			// 1. if Namespaces is false, then any significant 
			//    namespace indication is not allowed.
			// 2. if Prefix is non-empty and NamespaceURI is
			//    empty, it is an error in 1.x, or it is reset to
			//    an empty string in 2.0.
			// 3. null NamespaceURI indicates that namespace is
			//    not considered.
			// 4. prefix must not be equivalent to "XML" in
			//    case-insensitive comparison.
			if (!namespaces && namespaceUri != null && namespaceUri.Length > 0)
				throw ArgumentError ("Namespace is disabled in this XmlTextWriter.");
			if (!namespaces && prefix.Length > 0)
				throw ArgumentError ("Namespace prefix is disabled in this XmlTextWriter.");

			// If namespace URI is empty, then either prefix
			// must be empty as well, or there is an
			// existing namespace mapping for the prefix.
			if (prefix.Length > 0 && namespaceUri == null) {
				namespaceUri = nsmanager.LookupNamespace (prefix, false);
				if (namespaceUri == null || namespaceUri.Length == 0)
					throw ArgumentError ("Namespace URI must not be null when prefix is not an empty string.");
			}
			// Considering the fact that WriteStartAttribute()
			// automatically changes argument namespaceURI, this
			// is kind of silly implementation. See bug #77094.
			if (namespaces &&
			    prefix != null && prefix.Length == 3 &&
			    namespaceUri != XmlNamespace &&
			    (prefix [0] == 'x' || prefix [0] == 'X') &&
			    (prefix [1] == 'm' || prefix [1] == 'M') &&
			    (prefix [2] == 'l' || prefix [2] == 'L'))
				throw new ArgumentException ("A prefix cannot be equivalent to \"xml\" in case-insensitive match.");


			if (xmldecl_state == XmlDeclState.Auto)
				OutputAutoStartDocument ();
			if (state == WriteState.Element)
				CloseStartElement ();
			if (open_count > 0)
				elements [open_count - 1].HasElements = true;

			nsmanager.PushScope ();

			if (namespaces && namespaceUri != null) {
				// If namespace URI is empty, then prefix must 
				// be empty as well.
				if (anonPrefix && namespaceUri.Length > 0)
					prefix = LookupPrefix (namespaceUri);
				if (prefix == null || namespaceUri.Length == 0)
					prefix = String.Empty;
			}

			WriteIndent ();

			writer.Write ("<");

			if (prefix.Length > 0) {
				writer.Write (prefix);
				writer.Write (':');
			}
			writer.Write (localName);

			if (elements.Length == open_count) {
				XmlNodeInfo [] tmp = new XmlNodeInfo [open_count << 1];
				Array.Copy (elements, tmp, open_count);
				elements = tmp;
			}
			if (elements [open_count] == null)
				elements [open_count] =
					new XmlNodeInfo ();
			XmlNodeInfo info = elements [open_count];
			info.Prefix = prefix;
			info.LocalName = localName;
			info.NS = namespaceUri;
			info.HasSimple = false;
			info.HasElements = false;
			info.XmlLang = XmlLang;
			info.XmlSpace = XmlSpace;
			open_count++;

			if (namespaces && namespaceUri != null) {
				string oldns = nsmanager.LookupNamespace (prefix, false);
				if (oldns != namespaceUri) {
					nsmanager.AddNamespace (prefix, namespaceUri);
					new_local_namespaces.Push (prefix);
				}
			}

			state = WriteState.Element;
		}