/// <summary>
/// Generates the Output for a Node in Turtle Syntax
/// </summary>
/// <param name="context">Context for writing the Graph</param>
/// <param name="n">Node to generate Output for</param>
/// <param name="segment">Segment of the Triple being written</param>
/// <returns></returns>
private String GenerateNodeOutput(TurtleWriterContext context, INode n, TripleSegment segment)
{
switch (n.NodeType)
{
case NodeType.Blank:
if (segment == TripleSegment.Predicate) throw new RdfOutputException(WriterErrorMessages.BlankPredicatesUnserializable("Turtle"));
return context.NodeFormatter.Format(n, segment);
case NodeType.GraphLiteral:
throw new RdfOutputException(WriterErrorMessages.GraphLiteralsUnserializable("Turtle"));
case NodeType.Literal:
if (segment == TripleSegment.Subject) throw new RdfOutputException(WriterErrorMessages.LiteralSubjectsUnserializable("Turtle"));
if (segment == TripleSegment.Predicate) throw new RdfOutputException(WriterErrorMessages.LiteralPredicatesUnserializable("Turtle"));
return context.NodeFormatter.Format(n, segment);
case NodeType.Uri:
return context.NodeFormatter.Format(n, segment);
default:
throw new RdfOutputException(WriterErrorMessages.UnknownNodeTypeUnserializable("Turtle"));
}
}
/// <summary>
/// Generates the Output for a Graph
/// </summary>
/// <param name="context">Context for writing the Graph</param>
private void GenerateOutput(TurtleWriterContext context)
{
//Write Base Uri
if (context.Graph.BaseUri != null)
{
context.Output.WriteLine("@base <" + context.UriFormatter.FormatUri(context.Graph.BaseUri) + ">.");
context.Output.WriteLine();
}
//Write Prefixes
foreach (String prefix in context.Graph.NamespaceMap.Prefixes)
{
if (TurtleSpecsHelper.IsValidQName(prefix + ":", this._syntax))
{
context.Output.Write("@prefix " + prefix + ": <");
String nsUri = context.UriFormatter.FormatUri(context.Graph.NamespaceMap.GetNamespaceUri(prefix));
context.Output.WriteLine(nsUri + ">.");
}
}
context.Output.WriteLine();
//Decide which write mode to use
bool hiSpeed = false;
double subjNodes = context.Graph.Triples.SubjectNodes.Count();
double triples = context.Graph.Triples.Count;
if ((subjNodes / triples) > 0.75) hiSpeed = true;
if (hiSpeed && context.HighSpeedModePermitted)
{
//High Speed Writing Mode
//Writes everything as individual Triples
this.RaiseWarning("High Speed Write Mode in use - minimal syntax compressions will be used");
context.NodeFormatter = new UncompressedTurtleFormatter();
foreach (Triple t in context.Graph.Triples)
{
context.Output.Write(this.GenerateNodeOutput(context, t.Subject, TripleSegment.Subject));
context.Output.Write(" ");
context.Output.Write(this.GenerateNodeOutput(context, t.Predicate, TripleSegment.Predicate));
context.Output.Write(" ");
context.Output.Write(this.GenerateNodeOutput(context, t.Object, TripleSegment.Object));
context.Output.WriteLine(".");
}
}
else
{
//Get the Triples as a Sorted List
List<Triple> ts = context.Graph.Triples.ToList();
ts.Sort();
//Variables we need to track our writing
INode lastSubj, lastPred;
lastSubj = lastPred = null;
int subjIndent = 0, predIndent = 0;
String temp;
for (int i = 0; i < ts.Count; i++)
{
Triple t = ts[i];
if (lastSubj == null || !t.Subject.Equals(lastSubj))
{
//Terminate previous Triples
if (lastSubj != null) context.Output.WriteLine(".");
//Start a new set of Triples
temp = this.GenerateNodeOutput(context, t.Subject, TripleSegment.Subject);
context.Output.Write(temp);
context.Output.Write(" ");
subjIndent = temp.Length + 1;
lastSubj = t.Subject;
//Write the first Predicate
temp = this.GenerateNodeOutput(context, t.Predicate, TripleSegment.Predicate);
context.Output.Write(temp);
context.Output.Write(" ");
predIndent = temp.Length + 1;
lastPred = t.Predicate;
}
else if (lastPred == null || !t.Predicate.Equals(lastPred))
{
//Terminate previous Predicate Object list
context.Output.WriteLine(";");
if (context.PrettyPrint) context.Output.Write(new String(' ', subjIndent));
//Write the next Predicate
temp = this.GenerateNodeOutput(context, t.Predicate, TripleSegment.Predicate);
context.Output.Write(temp);
context.Output.Write(" ");
predIndent = temp.Length + 1;
lastPred = t.Predicate;
}
else
{
//Continue Object List
context.Output.WriteLine(",");
if (context.PrettyPrint) context.Output.Write(new String(' ', subjIndent + predIndent));
}
//Write the Object
context.Output.Write(this.GenerateNodeOutput(context, t.Object, TripleSegment.Object));
}
//Terminate Triples
if (ts.Count > 0) context.Output.WriteLine(".");
}
}
/// <summary>
/// Saves a Graph using an arbitrary <see cref="TextWriter">TextWriter</see>
/// </summary>
/// <param name="g">Graph to save</param>
/// <param name="output">Writer to save using</param>
public void Save(IGraph g, TextWriter output)
{
try
{
TurtleWriterContext context = new TurtleWriterContext(g, output, this._prettyprint, this._allowhispeed, this._syntax);
this.GenerateOutput(context);
output.Close();
}
catch
{
try
{
output.Close();
}
catch
{
//No Catch Actions - just trying to clean up
}
throw;
}
}
/// <summary>
/// Thread Worker method which writes Graphs to the output
/// </summary>
/// <param name="globalContext">Context for writing the Store</param>
private void SaveGraphs(TriGWriterContext globalContext)
{
try
{
Uri u = globalContext.GetNextUri();
while (u != null)
{
//Get the Graph from the Store
if (WriterHelper.IsDefaultGraph(u) && !globalContext.Store.HasGraph(u)) u = null;
IGraph g = globalContext.Store.Graphs[u];
//Generate the Graph Output and add to Stream
TurtleWriterContext context = new TurtleWriterContext(g, new System.IO.StringWriter(), globalContext.PrettyPrint, globalContext.HighSpeedModePermitted);
if (globalContext.CompressionLevel > WriterCompressionLevel.None)
{
context.NodeFormatter = new TurtleFormatter(globalContext.QNameMapper);
}
else
{
context.NodeFormatter = new UncompressedTurtleFormatter();
}
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 the Output for a Triple as a String in Turtle syntax
/// </summary>
/// <param name="globalContext">Context for writing the Store</param>
/// <param name="context">Context for writing the Graph</param>
private void GenerateTripleOutput(TriGWriterContext globalContext, TurtleWriterContext context)
{
//Decide which write mode to use
bool hiSpeed = false;
double subjNodes = context.Graph.Triples.SubjectNodes.Count();
double triples = context.Graph.Triples.Count;
if ((subjNodes / triples) > 0.75) hiSpeed = true;
if (globalContext.CompressionLevel == WriterCompressionLevel.None || hiSpeed && context.HighSpeedModePermitted)
{
//Use High Speed Write Mode
String indentation = new String(' ', 4);
context.Output.Write(indentation);
if (globalContext.CompressionLevel > WriterCompressionLevel.None) context.Output.WriteLine("# Written using High Speed Mode");
foreach (Triple t in context.Graph.Triples)
{
context.Output.Write(indentation);
context.Output.Write(this.GenerateNodeOutput(globalContext, context, t.Subject, TripleSegment.Subject));
context.Output.Write(' ');
context.Output.Write(this.GenerateNodeOutput(globalContext, context, t.Predicate, TripleSegment.Predicate));
context.Output.Write(' ');
context.Output.Write(this.GenerateNodeOutput(globalContext, context, t.Object, TripleSegment.Object));
context.Output.WriteLine(".");
}
}
else
{
//Get the Triples as a Sorted List
List<Triple> ts = context.Graph.Triples.ToList();
ts.Sort();
//Variables we need to track our writing
INode lastSubj, lastPred;
lastSubj = lastPred = null;
int subjIndent = 0, predIndent = 0;
int baseIndent = 4;
String temp;
for (int i = 0; i < ts.Count; i++)
{
Triple t = ts[i];
if (lastSubj == null || !t.Subject.Equals(lastSubj))
{
//Terminate previous Triples
if (lastSubj != null) context.Output.WriteLine(".");
if (context.PrettyPrint) context.Output.Write(new String(' ', baseIndent));
//Start a new set of Triples
temp = this.GenerateNodeOutput(globalContext, context, t.Subject, TripleSegment.Subject);
context.Output.Write(temp);
context.Output.Write(" ");
subjIndent = baseIndent + temp.Length + 1;
lastSubj = t.Subject;
//Write the first Predicate
temp = this.GenerateNodeOutput(globalContext, context, t.Predicate, TripleSegment.Predicate);
context.Output.Write(temp);
context.Output.Write(" ");
predIndent = temp.Length + 1;
lastPred = t.Predicate;
}
else if (lastPred == null || !t.Predicate.Equals(lastPred))
{
//Terminate previous Predicate Object list
context.Output.WriteLine(";");
if (context.PrettyPrint) context.Output.Write(new String(' ', subjIndent));
//Write the next Predicate
temp = this.GenerateNodeOutput(globalContext, context, t.Predicate, TripleSegment.Predicate);
context.Output.Write(temp);
context.Output.Write(" ");
predIndent = temp.Length + 1;
lastPred = t.Predicate;
}
else
{
//Continue Object List
context.Output.WriteLine(",");
if (context.PrettyPrint) context.Output.Write(new String(' ', subjIndent + predIndent));
}
//Write the Object
context.Output.Write(this.GenerateNodeOutput(globalContext, context, t.Object, TripleSegment.Object));
}
//Terminate Triples
if (ts.Count > 0) context.Output.WriteLine(".");
}
}
/// <summary>
/// Generates the Output for a Graph as a String in TriG 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(TriGWriterContext globalContext, TurtleWriterContext context)
{
if (!WriterHelper.IsDefaultGraph(context.Graph.BaseUri))
{
//Named Graph
String gname;
String sep = (globalContext.N3CompatabilityMode) ? " = " : " ";
if (globalContext.CompressionLevel > WriterCompressionLevel.None && globalContext.QNameMapper.ReduceToQName(context.Graph.BaseUri.ToString(), out gname))
{
if (TurtleSpecsHelper.IsValidQName(gname))
{
context.Output.WriteLine(gname + sep + "{");
}
else
{
context.Output.WriteLine("<" + context.UriFormatter.FormatUri(context.Graph.BaseUri) + ">" + sep + "{");
}
}
else
{
context.Output.WriteLine("<" + context.UriFormatter.FormatUri(context.Graph.BaseUri) + ">" + sep + "{");
}
}
else
{
context.Output.WriteLine("{");
}
//Generate Triples
this.GenerateTripleOutput(globalContext, context);
//Close the Graph
context.Output.WriteLine("}");
return context.Output.ToString();
}
/// <summary>
/// Saves a Store in TriG (Turtle with Named Graphs) format
/// </summary>
/// <param name="store">Store to save</param>
/// <param name="parameters">Parameters indicating a Stream to write to</param>
public void Save(ITripleStore store, IStoreParams parameters)
{
//Try and determine the TextWriter to output to
TriGWriterContext context = null;
if (parameters is StreamParams)
{
//Create a new Writer Context
((StreamParams)parameters).Encoding = new UTF8Encoding(Options.UseBomForUtf8);
context = new TriGWriterContext(store, ((StreamParams)parameters).StreamWriter, this._prettyprint, this._allowHiSpeed, this._compressionLevel, this._n3compat);
}
else if (parameters is TextWriterParams)
{
context = new TriGWriterContext(store, ((TextWriterParams)parameters).TextWriter, this._prettyprint, this._allowHiSpeed, this._compressionLevel, this._n3compat);
}
if (context != null)
{
//Check there's something to do
if (context.Store.Graphs.Count == 0)
{
context.Output.Close();
return;
}
//Write the Header of the File
foreach (IGraph g in context.Store.Graphs)
{
context.NamespaceMap.Import(g.NamespaceMap);
}
if (context.CompressionLevel > WriterCompressionLevel.None)
{
//Only add @prefix declarations if compression is enabled
context.QNameMapper = new ThreadSafeQNameOutputMapper(context.NamespaceMap);
foreach (String prefix in context.NamespaceMap.Prefixes)
{
if (TurtleSpecsHelper.IsValidQName(prefix + ":"))
{
context.Output.WriteLine("@prefix " + prefix + ": <" + context.FormatUri(context.NamespaceMap.GetNamespaceUri(prefix)) + ">.");
}
}
context.Output.WriteLine();
}
else
{
context.QNameMapper = new ThreadSafeQNameOutputMapper(new NamespaceMapper(true));
}
if (this._useMultiThreading)
{
//Standard Multi-Threaded Writing
//Queue the Graphs to be written
foreach (IGraph g in context.Store.Graphs)
{
if (g.BaseUri == null)
{
context.Add(new Uri(GraphCollection.DefaultGraphUri));
}
else
{
context.Add(g.BaseUri);
}
}
//Start making the async calls
List<IAsyncResult> results = new List<IAsyncResult>();
SaveGraphsDelegate d = new SaveGraphsDelegate(this.SaveGraphs);
for (int i = 0; i < this._threads; i++)
{
results.Add(d.BeginInvoke(context, null, null));
}
//Wait for all the async calls to complete
WaitHandle.WaitAll(results.Select(r => r.AsyncWaitHandle).ToArray());
RdfThreadedOutputException outputEx = new RdfThreadedOutputException(WriterErrorMessages.ThreadedOutputFailure("TriG"));
foreach (IAsyncResult result in results)
{
try
{
d.EndInvoke(result);
}
catch (Exception ex)
{
outputEx.AddException(ex);
}
}
//Make sure to close the output
context.Output.Close();
//If there were any errors we'll throw an RdfThreadedOutputException now
if (outputEx.InnerExceptions.Any()) throw outputEx;
}
else
{
try
{
//Optional Single Threaded Writing
foreach (IGraph g in store.Graphs)
{
TurtleWriterContext graphContext = new TurtleWriterContext(g, new System.IO.StringWriter(), context.PrettyPrint, context.HighSpeedModePermitted);
if (context.CompressionLevel > WriterCompressionLevel.None)
{
graphContext.NodeFormatter = new TurtleFormatter(context.QNameMapper);
}
else
{
graphContext.NodeFormatter = new UncompressedTurtleFormatter();
}
context.Output.WriteLine(this.GenerateGraphOutput(context, graphContext));
}
//Make sure to close the output
context.Output.Close();
}
catch
{
try
{
//Close the output
context.Output.Close();
}
catch
{
//No catch actions, just cleaning up the output stream
}
throw;
}
}
}
else
{
throw new RdfStorageException("Parameters for the TriGWriter must be of the type StreamParams/TextWriterParams");
}
}