/// <summary>
/// Constructs a Node based on the given Set.
/// </summary>
/// <param name="context">Construct Context.</param>
/// <returns>The Node which is bound to this Variable in this Solution.</returns>
protected internal override INode Construct(ConstructContext context)
{
INode value = context.Set[_varname];
if (value == null)
{
throw new RdfQueryException("Unable to construct a Value for this Variable for this solution as it is bound to a null");
}
switch (value.NodeType)
{
case NodeType.Blank:
if (!context.PreserveBlankNodes && value.GraphUri != null)
{
// Rename Blank Node based on the Graph Uri Hash Code
int hash = value.GraphUri.GetEnhancedHashCode();
if (hash >= 0)
{
return(new BlankNode(context.Graph, ((IBlankNode)value).InternalID + "-" + value.GraphUri.GetEnhancedHashCode()));
}
else
{
return(new BlankNode(context.Graph, ((IBlankNode)value).InternalID + hash));
}
}
else
{
return(new BlankNode(context.Graph, ((IBlankNode)value).InternalID));
}
default:
return(context.GetNode(value));
}
}
/// <summary>
/// Returns a Blank Node with a fixed ID scoped to whichever graph is provided
/// </summary>
/// <param name="context">Construct Context</param>
protected internal override INode Construct(ConstructContext context)
{
if (context.Graph != null)
{
IBlankNode b = context.Graph.GetBlankNode(_id);
if (b != null)
{
return(b);
}
else
{
return(context.Graph.CreateBlankNode(_id));
}
}
else
{
return(new BlankNode(context.Graph, _id));
}
}
/// <summary>
/// Evaluates the Command in the given Context
/// </summary>
/// <param name="context">Evaluation Context</param>
public override void Evaluate(SparqlUpdateEvaluationContext context)
{
//Split the Pattern into the set of Graph Patterns
List <GraphPattern> patterns = new List <GraphPattern>();
if (this._pattern.IsGraph)
{
patterns.Add(this._pattern);
}
else if (this._pattern.TriplePatterns.Count > 0 || this._pattern.HasChildGraphPatterns)
{
if (this._pattern.TriplePatterns.Count > 0)
{
patterns.Add(new GraphPattern());
this._pattern.TriplePatterns.ForEach(tp => patterns[0].AddTriplePattern(tp));
}
this._pattern.ChildGraphPatterns.ForEach(gp => patterns.Add(gp));
}
else
{
//If no Triple Patterns and No Child Graph Patterns nothing to do
return;
}
ConstructContext constructContext = new ConstructContext(null, null, false);
foreach (GraphPattern pattern in patterns)
{
if (!this.IsValidDataPattern(pattern, false))
{
throw new SparqlUpdateException("Cannot evaluate a INSERT DATA command where any of the Triple Patterns are not concrete triples (variables are not permitted) or any of the GRAPH clauses have nested Graph Patterns");
}
//Get the Target Graph
IGraph target;
Uri graphUri;
if (pattern.IsGraph)
{
switch (pattern.GraphSpecifier.TokenType)
{
case Token.QNAME:
throw new NotSupportedException("Graph Specifiers as QNames for INSERT DATA Commands are not supported - please specify an absolute URI instead");
case Token.URI:
graphUri = UriFactory.Create(pattern.GraphSpecifier.Value);
break;
default:
throw new SparqlUpdateException("Cannot evaluate an INSERT DATA Command as the Graph Specifier is not a QName/URI");
}
}
else
{
graphUri = null;
}
if (context.Data.HasGraph(graphUri))
{
target = context.Data.GetModifiableGraph(graphUri);
}
else
{
//If the Graph does not exist then it must be created
target = new Graph();
target.BaseUri = graphUri;
context.Data.AddGraph(target);
}
//Insert the actual Triples
foreach (IConstructTriplePattern p in pattern.TriplePatterns.OfType <IConstructTriplePattern>())
{
INode subj = p.Subject.Construct(constructContext);
INode pred = p.Predicate.Construct(constructContext);
INode obj = p.Object.Construct(constructContext);
target.Assert(new Triple(subj, pred, obj, graphUri));
}
}
}
/// <summary>
/// Evaluates the Command in the given Context
/// </summary>
/// <param name="context">Evaluation Context</param>
public override void Evaluate(SparqlUpdateEvaluationContext context)
{
bool datasetOk = false;
bool defGraphOk = false;
try
{
//First evaluate the WHERE pattern to get the affected bindings
ISparqlAlgebra where = this._wherePattern.ToAlgebra();
if (context.Commands != null)
{
where = context.Commands.ApplyAlgebraOptimisers(where);
}
//Set Active Graph for the WHERE
//Don't bother if there are USING URIs as these would override any Active Graph we set here
//so we can save ourselves the effort of doing this
if (!this.UsingUris.Any())
{
if (this._graphUri != null)
{
context.Data.SetActiveGraph(this._graphUri);
defGraphOk = true;
}
else
{
context.Data.SetActiveGraph((Uri)null);
defGraphOk = true;
}
}
//We need to make a dummy SparqlQuery object since if the Command has used any
//USING NAMEDs along with GRAPH clauses then the algebra needs to have the
//URIs available to it which it gets from the Query property of the Context
//object
SparqlQuery query = new SparqlQuery();
foreach (Uri u in this.UsingUris)
{
query.AddDefaultGraph(u);
}
foreach (Uri u in this.UsingNamedUris)
{
query.AddNamedGraph(u);
}
SparqlEvaluationContext queryContext = new SparqlEvaluationContext(query, context.Data, context.QueryProcessor);
if (this.UsingUris.Any())
{
//If there are USING URIs set the Active Graph to be formed of the Graphs with those URIs
context.Data.SetActiveGraph(this._usingUris);
datasetOk = true;
}
BaseMultiset results = queryContext.Evaluate(where);
if (results is IdentityMultiset)
{
queryContext.OutputMultiset = new SingletonMultiset(results.Variables);
}
if (this.UsingUris.Any())
{
//If there are USING URIs reset the Active Graph afterwards
//Also flag the dataset as no longer being OK as this flag is used in the finally
//block to determine whether the Active Graph needs resetting which it may do if the
//evaluation of the query fails for any reason
context.Data.ResetActiveGraph();
datasetOk = false;
}
//Reset Active Graph for the WHERE
if (defGraphOk)
{
context.Data.ResetActiveGraph();
defGraphOk = false;
}
//TODO: Need to detect when we create a Graph for Insertion but then fail to insert anything since in this case the Inserted Graph should be removed
//Get the Graph to which we are inserting Triples with no explicit Graph clause
IGraph g = null;
if (this._insertPattern.TriplePatterns.Count > 0)
{
if (context.Data.HasGraph(this._graphUri))
{
g = context.Data.GetModifiableGraph(this._graphUri);
}
else
{
//insertedGraphs.Add(this._graphUri);
g = new Graph();
g.BaseUri = this._graphUri;
context.Data.AddGraph(g);
g = context.Data.GetModifiableGraph(this._graphUri);
}
}
//Keep a record of graphs to which we insert
MultiDictionary <Uri, IGraph> graphs = new MultiDictionary <Uri, IGraph>(u => (u != null ? u.GetEnhancedHashCode() : 0), true, new UriComparer(), MultiDictionaryMode.AVL);
//Insert the Triples for each Solution
foreach (ISet s in queryContext.OutputMultiset.Sets)
{
List <Triple> insertedTriples = new List <Triple>();
try
{
//Create a new Construct Context for each Solution
ConstructContext constructContext = new ConstructContext(null, s, true);
//Triples from raw Triple Patterns
if (this._insertPattern.TriplePatterns.Count > 0)
{
foreach (IConstructTriplePattern p in this._insertPattern.TriplePatterns.OfType <IConstructTriplePattern>())
{
try
{
insertedTriples.Add(p.Construct(constructContext));
}
catch (RdfQueryException)
{
//If we throw an error this means we couldn't construct a specific Triple
//so we continue anyway
}
}
g.Assert(insertedTriples);
}
//Triples from GRAPH clauses
foreach (GraphPattern gp in this._insertPattern.ChildGraphPatterns)
{
insertedTriples.Clear();
try
{
String graphUri;
switch (gp.GraphSpecifier.TokenType)
{
case Token.URI:
graphUri = gp.GraphSpecifier.Value;
break;
case Token.VARIABLE:
String graphVar = gp.GraphSpecifier.Value.Substring(1);
if (s.ContainsVariable(graphVar))
{
INode temp = s[graphVar];
if (temp == null)
{
//If the Variable is not bound then skip
continue;
}
else if (temp.NodeType == NodeType.Uri)
{
graphUri = temp.ToSafeString();
}
else
{
//If the Variable is not bound to a URI then skip
continue;
}
}
else
{
//If the Variable is not bound for this solution then skip
continue;
}
break;
default:
//Any other Graph Specifier we have to ignore this solution
continue;
}
//Ensure the Graph we're inserting to exists in the dataset creating it if necessary
IGraph h;
Uri destUri = UriFactory.Create(graphUri);
if (graphs.ContainsKey(destUri))
{
h = graphs[destUri];
}
else
{
if (context.Data.HasGraph(destUri))
{
h = context.Data.GetModifiableGraph(destUri);
}
else
{
//insertedGraphs.Add(destUri);
h = new Graph();
h.BaseUri = destUri;
context.Data.AddGraph(h);
h = context.Data.GetModifiableGraph(destUri);
}
graphs.Add(destUri, h);
}
//Do the actual Insertions
foreach (IConstructTriplePattern p in gp.TriplePatterns.OfType <IConstructTriplePattern>())
{
try
{
insertedTriples.Add(p.Construct(constructContext));
}
catch (RdfQueryException)
{
//If we throw an error this means we couldn't construct a specific Triple
//so we continue anyway
}
}
h.Assert(insertedTriples);
}
catch (RdfQueryException)
{
//If we throw an error this means we couldn't construct for this solution so the
//solution is ignored for this Graph
}
}
}
catch (RdfQueryException)
{
//If we throw an error this means we couldn't construct for this solution so the
//solution is ignored for this graph
}
}
}
finally
{
//If the Dataset was set and an error occurred in doing the WHERE clause then
//we'll need to Reset the Active Graph
if (datasetOk)
{
context.Data.ResetActiveGraph();
}
if (defGraphOk)
{
context.Data.ResetActiveGraph();
}
}
}
/// <summary>
/// Constructs a Node based on the given Set
/// </summary>
/// <param name="context">Construct Context</param>
protected internal override INode Construct(ConstructContext context)
{
return(context.GetNode(this._node));
}
/// <summary> /// Constructs a Node based on this Pattern for the given Set /// </summary> /// <param name="context">Construct Context</param> /// <returns></returns> protected internal abstract INode Construct(ConstructContext context);
/// <summary>
/// Constructs a Triple from a Set based on this Triple Pattern.
/// </summary>
/// <param name="context">Construct Context.</param>
/// <returns></returns>
public Triple Construct(ConstructContext context)
{
return(new Triple(Tools.CopyNode(_subj.Construct(context), context.Graph), Tools.CopyNode(_pred.Construct(context), context.Graph), Tools.CopyNode(_obj.Construct(context), context.Graph)));
}
/// <summary>
/// Processes a SPARQL Query sending the results to a RDF/SPARQL Results handler as appropriate
/// </summary>
/// <param name="rdfHandler">RDF Handler</param>
/// <param name="resultsHandler">Results Handler</param>
/// <param name="query">SPARQL Query</param>
public void ProcessQuery(IRdfHandler rdfHandler, ISparqlResultsHandler resultsHandler, SparqlQuery query)
{
//Do Handler null checks before evaluating the query
if (query == null)
{
throw new ArgumentNullException("query", "Cannot evaluate a null query");
}
if (rdfHandler == null && (query.QueryType == SparqlQueryType.Construct || query.QueryType == SparqlQueryType.Describe || query.QueryType == SparqlQueryType.DescribeAll))
{
throw new ArgumentNullException("rdfHandler", "Cannot use a null RDF Handler when the Query is a CONSTRUCT/DESCRIBE");
}
if (resultsHandler == null && (query.QueryType == SparqlQueryType.Ask || SparqlSpecsHelper.IsSelectQuery(query.QueryType)))
{
throw new ArgumentNullException("resultsHandler", "Cannot use a null resultsHandler when the Query is an ASK/SELECT");
}
//Handle the Thread Safety of the Query Evaluation
#if !NO_RWLOCK
ReaderWriterLockSlim currLock = (this._dataset is IThreadSafeDataset) ? ((IThreadSafeDataset)this._dataset).Lock : this._lock;
try
{
currLock.EnterReadLock();
#endif
//Reset Query Timers
query.QueryExecutionTime = null;
bool datasetOk = false, defGraphOk = false;
try
{
//Set up the Default and Active Graphs
if (query.DefaultGraphs.Any())
{
//Call HasGraph() on each Default Graph but ignore the results, we just do this
//in case a dataset has any kind of load on demand behaviour
foreach (Uri defGraphUri in query.DefaultGraphs)
{
this._dataset.HasGraph(defGraphUri);
}
this._dataset.SetDefaultGraph(query.DefaultGraphs);
defGraphOk = true;
}
else if (query.NamedGraphs.Any())
{
//No FROM Clauses but one/more FROM NAMED means the Default Graph is the empty graph
this._dataset.SetDefaultGraph(Enumerable.Empty <Uri>());
}
this._dataset.SetActiveGraph(this._dataset.DefaultGraphUris);
datasetOk = true;
//Convert to Algebra and execute the Query
SparqlEvaluationContext context = this.GetContext(query);
BaseMultiset result;
try
{
context.StartExecution();
ISparqlAlgebra algebra = query.ToAlgebra();
result = context.Evaluate(algebra);
context.EndExecution();
query.QueryExecutionTime = new TimeSpan(context.QueryTimeTicks);
}
catch (RdfQueryException)
{
context.EndExecution();
query.QueryExecutionTime = new TimeSpan(context.QueryTimeTicks);
throw;
}
catch
{
context.EndExecution();
query.QueryExecutionTime = new TimeSpan(context.QueryTimeTicks);
throw;
}
//Return the Results
switch (query.QueryType)
{
case SparqlQueryType.Ask:
case SparqlQueryType.Select:
case SparqlQueryType.SelectAll:
case SparqlQueryType.SelectAllDistinct:
case SparqlQueryType.SelectAllReduced:
case SparqlQueryType.SelectDistinct:
case SparqlQueryType.SelectReduced:
//For SELECT and ASK can populate a Result Set directly from the Evaluation Context
//return new SparqlResultSet(context);
resultsHandler.Apply(context);
break;
case SparqlQueryType.Construct:
//Create a new Empty Graph for the Results
try
{
rdfHandler.StartRdf();
foreach (String prefix in query.NamespaceMap.Prefixes)
{
if (!rdfHandler.HandleNamespace(prefix, query.NamespaceMap.GetNamespaceUri(prefix)))
{
ParserHelper.Stop();
}
}
//Construct the Triples for each Solution
foreach (ISet s in context.OutputMultiset.Sets)
{
//List<Triple> constructedTriples = new List<Triple>();
try
{
ConstructContext constructContext = new ConstructContext(rdfHandler, s, false);
foreach (IConstructTriplePattern p in query.ConstructTemplate.TriplePatterns.OfType <IConstructTriplePattern>())
{
try
{
if (!rdfHandler.HandleTriple(p.Construct(constructContext)))
{
ParserHelper.Stop();
}
//constructedTriples.Add(((IConstructTriplePattern)p).Construct(constructContext));
}
catch (RdfQueryException)
{
//If we get an error here then we could not construct a specific triple
//so we continue anyway
}
}
}
catch (RdfQueryException)
{
//If we get an error here this means we couldn't construct for this solution so the
//entire solution is discarded
continue;
}
//h.Assert(constructedTriples);
}
rdfHandler.EndRdf(true);
}
catch (RdfParsingTerminatedException)
{
rdfHandler.EndRdf(true);
}
catch
{
rdfHandler.EndRdf(false);
throw;
}
break;
case SparqlQueryType.Describe:
case SparqlQueryType.DescribeAll:
//For DESCRIBE we retrieve the Describe algorithm and apply it
ISparqlDescribe describer = query.Describer;
describer.Describe(rdfHandler, context);
break;
default:
throw new RdfQueryException("Unknown query types cannot be processed by Leviathan");
}
}
finally
{
if (defGraphOk)
{
this._dataset.ResetDefaultGraph();
}
if (datasetOk)
{
this._dataset.ResetActiveGraph();
}
}
#if !NO_RWLOCK
}
finally
{
currLock.ExitReadLock();
}
#endif
}
/// <summary>
/// Evaluates the Command in the given Context
/// </summary>
/// <param name="context">Evaluation Context</param>
public override void Evaluate(SparqlUpdateEvaluationContext context)
{
bool defGraphOk = false;
bool datasetOk = false;
try
{
//First evaluate the WHERE pattern to get the affected bindings
ISparqlAlgebra where = this._wherePattern.ToAlgebra();
if (context.Commands != null)
{
where = context.Commands.ApplyAlgebraOptimisers(where);
}
//Set Active Graph for the WHERE based upon the WITH clause
//Don't bother if there are USING URIs as these would override any Active Graph we set here
//so we can save ourselves the effort of doing this
if (!this.UsingUris.Any())
{
if (this._graphUri != null)
{
context.Data.SetActiveGraph(this._graphUri);
defGraphOk = true;
}
else
{
context.Data.SetActiveGraph((Uri)null);
defGraphOk = true;
}
}
//We need to make a dummy SparqlQuery object since if the Command has used any
//USING/USING NAMEDs along with GRAPH clauses then the algebra needs to have the
//URIs available to it which it gets from the Query property of the Context
//object
SparqlQuery query = new SparqlQuery();
foreach (Uri u in this.UsingUris)
{
query.AddDefaultGraph(u);
}
foreach (Uri u in this.UsingNamedUris)
{
query.AddNamedGraph(u);
}
SparqlEvaluationContext queryContext = new SparqlEvaluationContext(query, context.Data, context.QueryProcessor);
if (this.UsingUris.Any())
{
//If there are USING URIs set the Active Graph to be formed of the Graphs with those URIs
context.Data.SetActiveGraph(this._usingUris);
datasetOk = true;
}
BaseMultiset results = queryContext.Evaluate(where);
if (results is IdentityMultiset)
{
results = new SingletonMultiset(results.Variables);
}
if (this.UsingUris.Any())
{
//If there are USING URIs reset the Active Graph afterwards
//Also flag the dataset as no longer being OK as this flag is used in the finally
//block to determine whether the Active Graph needs resetting which it may do if the
//evaluation of the
context.Data.ResetActiveGraph();
datasetOk = false;
}
//Reset Active Graph for the WHERE
if (defGraphOk)
{
context.Data.ResetActiveGraph();
defGraphOk = false;
}
//Get the Graph from which we are deleting
IGraph g = context.Data.GetModifiableGraph(this._graphUri);
//Delete the Triples for each Solution
foreach (ISet s in results.Sets)
{
List <Triple> deletedTriples = new List <Triple>();
//Triples from raw Triple Patterns
try
{
ConstructContext constructContext = new ConstructContext(g, s, true);
foreach (IConstructTriplePattern p in this._deletePattern.TriplePatterns.OfType <IConstructTriplePattern>())
{
try
{
deletedTriples.Add(p.Construct(constructContext));
}
catch (RdfQueryException)
{
//If we get an error here then we couldn't construct a specific Triple
//so we continue anyway
}
}
g.Retract(deletedTriples);
}
catch (RdfQueryException)
{
//If we throw an error this means we couldn't construct for this solution so the
//solution is ignored this graph
}
//Triples from GRAPH clauses
foreach (GraphPattern gp in this._deletePattern.ChildGraphPatterns)
{
deletedTriples.Clear();
try
{
String graphUri;
switch (gp.GraphSpecifier.TokenType)
{
case Token.URI:
graphUri = gp.GraphSpecifier.Value;
break;
case Token.VARIABLE:
String graphVar = gp.GraphSpecifier.Value.Substring(1);
if (s.ContainsVariable(graphVar))
{
INode temp = s[graphVar];
if (temp == null)
{
//If the Variable is not bound then skip
continue;
}
else if (temp.NodeType == NodeType.Uri)
{
graphUri = temp.ToSafeString();
}
else
{
//If the Variable is not bound to a URI then skip
continue;
}
}
else
{
//If the Variable is not bound for this solution then skip
continue;
}
break;
default:
//Any other Graph Specifier we have to ignore this solution
continue;
}
//If the Dataset doesn't contain the Graph then no need to do the Deletions
if (!context.Data.HasGraph(UriFactory.Create(graphUri)))
{
continue;
}
//Do the actual Deletions
IGraph h = context.Data.GetModifiableGraph(UriFactory.Create(graphUri));
ConstructContext constructContext = new ConstructContext(h, s, true);
foreach (IConstructTriplePattern p in gp.TriplePatterns.OfType <IConstructTriplePattern>())
{
try
{
deletedTriples.Add(p.Construct(constructContext));
}
catch (RdfQueryException)
{
//If we get an error here then we couldn't construct a specific
//triple so we continue anyway
}
}
h.Retract(deletedTriples);
}
catch (RdfQueryException)
{
//If we get an error here this means we couldn't construct for this solution so the
//solution is ignored for this graph
}
}
}
}
finally
{
//If the Dataset was set and an error occurred in doing the WHERE clause then
//we'll need to Reset the Active Graph
if (datasetOk)
{
context.Data.ResetActiveGraph();
}
if (defGraphOk)
{
context.Data.ResetActiveGraph();
}
}
}
/// <summary>
/// Constructs a Node based on the given Set.
/// </summary>
/// <param name="context">Construct Context.</param>
/// <returns></returns>
protected internal override INode Construct(ConstructContext context)
{
return(context.GetBlankNode(_name));
}
