/// <summary>
/// Gets the next event from the XML stream
/// </summary>
/// <returns></returns>
public IRdfXmlEvent GetNextEvent()
{
if (this._stop) return null;
//If the Root Element is filled then return it
if (this._rootEl != null)
{
IRdfXmlEvent temp = this._rootEl;
this._rootEl = null;
return temp;
}
//If Literal Parsing flag is set then we've just read an element which had rdf:parseType="Literal"
if (this._parseLiteral)
{
this._requireEndElement = true;
this._parseLiteral = false;
this._noRead = true;
this._reader.MoveToContent();
String data = this._reader.ReadInnerXml();
return new TypedLiteralEvent(data, RdfSpecsHelper.RdfXmlLiteral, data, this.GetPosition());
}
//If we need to return an end element then do so
if (this._requireEndElement)
{
this._requireEndElement = false;
this._currentBaseUri = this._baseUris.Pop();
return new EndElementEvent(this.GetPosition());
}
//If at EOF throw an error
if (this._reader.EOF) throw new RdfParseException("Unable to read further events as the end of the stream has already been reached");
//Otherwise attempt to read the next node
bool read = true;
if (!this._noRead)
{
read = this._reader.Read();
}
else
{
this._noRead = false;
}
if (read)
{
//Return the appropriate event for the Node Type
switch (this._reader.NodeType)
{
case XmlNodeType.Element:
//Element
if (this._first)
{
this._first = false;
this._rdfRootSeen = this.IsName("RDF", NamespaceMapper.RDF);
this._rootEl = this.GetElement();
RootEvent root = new RootEvent(this.GetBaseUri(), this._reader.Value, this.GetPosition());
root.Children.Add((ElementEvent)this._rootEl);
return root;
}
else
{
if (!this._first && this.IsName("RDF", NamespaceMapper.RDF))
{
if (this._rdfRootSeen) throw new RdfParseException("Unexpected nested rdf:RDF node encountered, this is not valid RDF/XML syntax");
this._noRead = true;
this._first = true;
return new ClearQueueEvent();
}
return this.GetElement();
}
case XmlNodeType.EndElement:
//End of an Element
this._currentBaseUri = this._baseUris.Pop();
if (this.IsName("RDF", NamespaceMapper.RDF))
{
this._stop = true;
}
return new EndElementEvent(this.GetPosition());
case XmlNodeType.Attribute:
//Attribute
throw new RdfParseException("Unexpected Attribute Node encountered");
case XmlNodeType.Text:
return new TextEvent(this._reader.Value, this._reader.Value, this.GetPosition());
case XmlNodeType.CDATA:
return new TextEvent(this._reader.Value, this._reader.Value, this.GetPosition());
case XmlNodeType.Document:
case XmlNodeType.DocumentType:
case XmlNodeType.XmlDeclaration:
case XmlNodeType.Comment:
case XmlNodeType.ProcessingInstruction:
case XmlNodeType.Notation:
case XmlNodeType.Whitespace:
//Node Types that don't generate events and just indicate to continue reading
return this.GetNextEvent();
default:
throw new RdfParseException("Unexpected XML Node Type " + this._reader.NodeType.ToString() + " encountered");
}
}
else
{
return null;
}
}
/// <summary>
/// Given an XML Node that is the Root of the RDF/XML section of the Document Tree creates the RootEvent and generates the rest of the Event Tree by recursive calls to the <see cref="GenerateEvents">GenerateEvents</see> method
/// </summary>
/// <param name="context">Parser Context</param>
/// <param name="docEl">XML Node that is the Root of the RDF/XML section of the Document Tree</param>
/// <returns></returns>
private RootEvent GenerateEventTree(RdfXmlParserContext context, XmlNode docEl)
{
//Get the Document Element
//XmlNode docEl = document.DocumentElement;
//Generate a Root Event and Element Event from it
RootEvent root = new RootEvent(docEl.BaseURI, docEl.OuterXml);
if (docEl.BaseURI.Equals(String.Empty))
{
if (context.BaseUri != null)
{
root.BaseUri = context.BaseUri.ToString();
}
}
ElementEvent element = new ElementEvent(docEl.LocalName, docEl.Prefix, root.BaseUri, docEl.OuterXml);
//Initialise Language Settings
root.Language = String.Empty;
element.Language = root.Language;
//Set as Document Element and add as only Child
root.DocumentElement = element;
root.Children.Add(element);
#region Attribute Processing
//Go through attributes looking for XML Namespace Declarations
foreach (XmlAttribute attr in docEl.Attributes)
{
if (attr.Prefix.Equals("xmlns") || attr.Name == "xmlns")
{
//Define a Namespace
String prefix = attr.LocalName;
if (prefix.Equals("xmlns")) prefix = String.Empty;
String uri;
if (attr.Value.StartsWith("http://"))
{
//Absolute Uri
uri = attr.Value;
}
else if (!root.BaseUri.Equals(String.Empty))
{
//Relative Uri with a Base Uri to resolve against
//uri = root.BaseUri + attr.Value;
uri = Tools.ResolveUri(attr.Value, root.BaseUri);
}
else
{
//Relative Uri with no Base Uri
throw new RdfParseException("Cannot resolve a Relative Namespace URI since there is no in-scope Base URI");
}
context.Namespaces.AddNamespace(prefix, new Uri(uri));
}
else if (attr.Name == "xml:base")
{
//Set the Base Uri
String baseUri = attr.Value;
if (RdfXmlSpecsHelper.IsAbsoluteURI(baseUri))
{
//Absolute Uri
root.BaseUri = baseUri;
}
else if (!element.BaseUri.Equals(String.Empty))
{
//Relative Uri with a Base Uri to resolve against
//root.BaseUri += baseUri;
root.BaseUri = Tools.ResolveUri(baseUri, root.BaseUri);
}
else
{
//Relative Uri with no Base Uri
throw new RdfParseException("Cannot resolve a Relative Base URI since there is no in-scope Base URI");
}
element.BaseUri = root.BaseUri;
}
}
#endregion
//Iterate over Children
foreach (XmlNode child in docEl.ChildNodes)
{
//Ignore Irrelevant Node Types
if (this.IsIgnorableNode(child))
{
continue;
}
//Generate an Event for the Child Node
ElementEvent childEvent = this.GenerateEvents(context, child, element);
element.Children.Add(childEvent);
}
//Return the Root Event
return root;
}
/// <summary>
/// Implementation of the RDF/XML Grammar Production 'doc'
/// </summary>
/// <param name="context">Parser Context</param>
/// <param name="root">Root Event to start applying Productions from</param>
private void GrammarProductionDoc(RdfXmlParserContext context, RootEvent root)
{
//Tracing
if (this._traceparsing)
{
this.ProductionTrace("Doc");
}
//Call the RDF Production on the first child if it's an rdf:RDF element
if (root.Children[0].QName.Equals("rdf:RDF") || root.Children[0].QName.Equals(":RDF"))
{
this.GrammarProductionRDF(context, root.Children[0]);
}
else
{
//No rdf:RDF element
//Drop first element from Queue (which will be a RootEvent)
//Skip straight to NodeElementList production
//context.Events.Dequeue();
this.GrammarProductionNodeElementList(context, context.Events);
}
}