/// <summary>
/// Saves a Graph into GraphViz DOT Format
/// </summary>
/// <param name="g">Graph to save</param>
/// <param name="output">Stream to save to</param>
public void Save(IGraph g, TextWriter output)
{
//Start the Graph
output.WriteLine("digraph G {");
BaseWriterContext context = new BaseWriterContext(g, output);
//Write all the Triples to the Graph
foreach (Triple t in g.Triples)
{
output.WriteLine(this.TripleToDot(t, context));
}
//End the Graph
output.WriteLine("}");
output.Close();
}
/// <summary>
/// Thread Worker method which writes Graphs to the output
/// </summary>
/// <param name="globalContext">Context for writing the Store</param>
private void SaveGraphs(ThreadedStoreWriterContext globalContext)
{
try
{
Uri u = globalContext.GetNextUri();
while (u != null)
{
//Get the Graph from the Store
IGraph g = globalContext.Store.Graphs[u];
//Generate the Graph Output and add to Stream
BaseWriterContext context = new BaseWriterContext(g, new System.IO.StringWriter());
String graphContent = this.GenerateGraphOutput(globalContext, context);
try
{
Monitor.Enter(globalContext.Output);
globalContext.Output.WriteLine(graphContent);
globalContext.Output.Flush();
}
catch
{
throw;
}
finally
{
Monitor.Exit(globalContext.Output);
}
//Get the Next Uri
u = globalContext.GetNextUri();
}
}
catch (ThreadAbortException)
{
//We've been terminated, don't do anything
#if !SILVERLIGHT
Thread.ResetAbort();
#endif
}
catch (Exception ex)
{
throw new RdfStorageException("Error in Threaded Writer in Thread ID " + Thread.CurrentThread.ManagedThreadId, ex);
}
}
/// <summary>
/// Generates Output for the given Node
/// </summary>
/// <param name="context">Writer Context</param>
/// <param name="n">Node</param>
/// <param name="segment">Triple Segment</param>
private void GenerateNodeOutput(BaseWriterContext context, INode n, TripleSegment segment)
{
switch (n.NodeType)
{
case NodeType.Blank:
if (segment == TripleSegment.Predicate) throw new RdfOutputException(WriterErrorMessages.BlankPredicatesUnserializable("CSV"));
context.Output.Write(this._formatter.Format(n));
break;
case NodeType.GraphLiteral:
throw new RdfOutputException(WriterErrorMessages.GraphLiteralsUnserializable("CSV"));
case NodeType.Literal:
if (segment == TripleSegment.Subject) throw new RdfOutputException(WriterErrorMessages.LiteralSubjectsUnserializable("CSV"));
if (segment == TripleSegment.Predicate) throw new RdfOutputException(WriterErrorMessages.LiteralPredicatesUnserializable("CSV"));
context.Output.Write(this._formatter.Format(n));
break;
case NodeType.Uri:
context.Output.Write(this._formatter.Format(n));
break;
default:
throw new RdfOutputException(WriterErrorMessages.UnknownNodeTypeUnserializable("CSV"));
}
}
/// <summary>
/// Generates the Output for a Graph as a String in CSV syntax
/// </summary>
/// <param name="globalContext">Context for writing the Store</param>
/// <param name="context">Context for writing the Graph</param>
/// <returns></returns>
private String GenerateGraphOutput(ThreadedStoreWriterContext globalContext, BaseWriterContext context)
{
if (!WriterHelper.IsDefaultGraph(context.Graph.BaseUri))
{
//Named Graphs have a fourth context field added
foreach (Triple t in context.Graph.Triples)
{
this.GenerateNodeOutput(context, t.Subject, TripleSegment.Subject);
context.Output.Write(',');
this.GenerateNodeOutput(context, t.Predicate, TripleSegment.Predicate);
context.Output.Write(',');
this.GenerateNodeOutput(context, t.Object, TripleSegment.Object);
context.Output.Write(',');
context.Output.Write(this._formatter.FormatUri(context.Graph.BaseUri));
context.Output.Write("\r\n");
}
}
else
{
//Default Graph has an empty field added
foreach (Triple t in context.Graph.Triples)
{
this.GenerateNodeOutput(context, t.Subject, TripleSegment.Subject);
context.Output.Write(',');
this.GenerateNodeOutput(context, t.Predicate, TripleSegment.Predicate);
context.Output.Write(',');
this.GenerateNodeOutput(context, t.Object, TripleSegment.Object);
context.Output.Write(',');
context.Output.Write("\r\n");
}
}
return context.Output.ToString();
}
/// <summary>
/// Internal Helper Method for converting a Triple into DOT notation
/// </summary>
/// <param name="t">Triple to convert</param>
/// <param name="context">Writer Context</param>
/// <returns></returns>
private String TripleToDot(Triple t, BaseWriterContext context)
{
StringBuilder output = new StringBuilder();
//Output Node lines for Literal Node so we show them as Boxes
//This is in keeping with Standard Graph representation of RDF
//Literals are shown in Boxes, Uri Nodes in ellipses (GraphViz's default shape)
if (t.Subject.NodeType == NodeType.Literal)
{
output.Append(this.NodeToDot(t.Subject, context));
output.Append(" [shape=box];\n");
}
if (t.Object.NodeType == NodeType.Literal)
{
output.Append(this.NodeToDot(t.Object, context));
output.Append(" [shape=box];\n");
}
//Output the actual lines that state the relationship between the Nodes
//We use the Predicate as the Label on the relationship
output.Append(this.NodeToDot(t.Subject, context));
output.Append(" -> ");
output.Append(this.NodeToDot(t.Object, context));
output.Append(" [label=");
output.Append(this.NodeToDot(t.Predicate, context));
output.Append("];");
return output.ToString();
}
/// <summary>
/// Internal Helper method for converting Uri Nodes to DOT Notation
/// </summary>
/// <param name="u">Uri Node to convert</param>
/// <param name="context">Writer Context</param>
/// <returns></returns>
private String UriNodeToDot(IUriNode u, BaseWriterContext context)
{
StringBuilder output = new StringBuilder();
output.Append("\"");
//Try QName reduction
String qname;
if (context.QNameMapper.ReduceToQName(u.Uri.ToString(), out qname))
{
//Use the QName
output.Append(qname);
}
else
{
//Use the full Uri
output.Append(u.Uri);
}
output.Append("\"");
return output.ToString();
}
/// <summary>
/// Internal Helper method for converting a Node into DOT notation
/// </summary>
/// <param name="n">Node to Convert</param>
/// <param name="context">Writer Context</param>
/// <returns></returns>
/// <remarks>Currently Graphs containing Graph Literal Nodes cannot be converted</remarks>
private String NodeToDot(INode n, BaseWriterContext context)
{
if (n.NodeType == NodeType.Uri)
{
return this.UriNodeToDot((IUriNode)n, context);
}
else if (n.NodeType == NodeType.Literal)
{
return this.LiteralNodeToDot((ILiteralNode)n);
}
else if (n.NodeType == NodeType.Blank)
{
return this.BlankNodeToDot((IBlankNode)n);
}
else if (n.NodeType == NodeType.GraphLiteral)
{
throw new RdfOutputException("Graphs containing Graph Literal Nodes cannot be converted into GraphViz DOT Format");
}
else
{
throw new RdfOutputException("Unknown Node Type cannot be converted into GraphViz DOT Format");
}
}