IGraph CreatePageGraph(INode subject, IGraph graph)
{
Graph pageGraph = new Graph();
Triple idTriple = graph.GetTriplesWithSubjectPredicate(subject, graph.CreateUriNode(Schema.Predicates.Id)).First();
Triple versionTriple = graph.GetTriplesWithSubjectPredicate(subject, graph.CreateUriNode(Schema.Predicates.Version)).First();
pageGraph.Assert(idTriple.CopyTriple(pageGraph));
pageGraph.Assert(versionTriple.CopyTriple(pageGraph));
return(pageGraph);
}
/// <summary>
/// Handles Triples by asserting them into the appropriate Graph creating the Graph if necessary
/// </summary>
/// <param name="t">Triple</param>
/// <returns></returns>
protected override bool HandleTripleInternal(Triple t)
{
if (!_store.HasGraph(t.GraphUri))
{
Graph g = new Graph();
g.BaseUri = t.GraphUri;
_store.Add(g);
}
IGraph target = _store[t.GraphUri];
target.Assert(t.CopyTriple(target));
return(true);
}
/// <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 = _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 (!UsingUris.Any())
{
if (_graphUri != null)
{
context.Data.SetActiveGraph(_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 UsingUris)
{
query.AddDefaultGraph(u);
}
foreach (Uri u in UsingNamedUris)
{
query.AddNamedGraph(u);
}
SparqlEvaluationContext queryContext = new SparqlEvaluationContext(query, context.Data, context.QueryProcessor);
if (UsingUris.Any())
{
// If there are USING URIs set the Active Graph to be formed of the Graphs with those URIs
context.Data.SetActiveGraph(_usingUris);
datasetOk = true;
}
BaseMultiset results = queryContext.Evaluate(where);
if (results is IdentityMultiset)
{
results = new SingletonMultiset(results.Variables);
}
if (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 to which we are deleting and inserting
IGraph g;
bool newGraph = false;
if (context.Data.HasGraph(_graphUri))
{
g = context.Data.GetModifiableGraph(_graphUri);
}
else
{
// Inserting into a new graph. This will raise an exception if the dataset is immutable
context.Data.AddGraph(new Graph {
BaseUri = _graphUri
});
g = context.Data.GetModifiableGraph(_graphUri);
newGraph = true;
}
// Delete the Triples for each Solution
List <Triple> deletedTriples = new List <Triple>();
foreach (ISet s in results.Sets)
{
try
{
// If the Default Graph is non-existent then Deletions have no effect on it
if (g != null)
{
ConstructContext constructContext = new ConstructContext(g, s, true);
foreach (IConstructTriplePattern p in _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 get an error here this means we couldn't construct for this solution so the
// solution is ignored for this graph
}
// Triples from GRAPH clauses
foreach (GraphPattern gp in _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 ignore for this graph
}
}
}
// Insert the Triples for each Solution
foreach (ISet s in results.Sets)
{
List <Triple> insertedTriples = new List <Triple>();
try
{
ConstructContext constructContext = new ConstructContext(g, s, true);
foreach (IConstructTriplePattern p in _insertPattern.TriplePatterns.OfType <IConstructTriplePattern>())
{
try
{
insertedTriples.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.Assert(insertedTriples.Select(t => t.IsGroundTriple ? t : t.CopyTriple(g)));
}
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
}
if (insertedTriples.Count == 0 && newGraph && _graphUri != null)
{
// Remove the named graph we added as we did not insert any triples
context.Data.RemoveGraph(_graphUri);
}
// Triples from GRAPH clauses
foreach (GraphPattern gp in _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 (context.Data.HasGraph(destUri))
{
h = context.Data.GetModifiableGraph(destUri);
}
else
{
h = new Graph();
h.BaseUri = destUri;
context.Data.AddGraph(h);
h = context.Data.GetModifiableGraph(destUri);
}
// Do the actual Insertions
ConstructContext constructContext = new ConstructContext(h, s, true);
foreach (IConstructTriplePattern p in gp.TriplePatterns.OfType <IConstructTriplePattern>())
{
try
{
Triple t = p.Construct(constructContext);
t = new Triple(t.Subject, t.Predicate, t.Object, destUri);
insertedTriples.Add(t);
}
catch (RdfQueryException)
{
// If we get an error here this means we couldn't construct a specific
// triple so we continue anyway
}
}
h.Assert(insertedTriples.Select(t => t.IsGroundTriple ? t : t.CopyTriple(h)));
}
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>
/// Handles Triples by asserting them into the appropriate Graph creating the Graph if necessary
/// </summary>
/// <param name="t">Triple</param>
/// <returns></returns>
protected override bool HandleTripleInternal(Triple t)
{
if (!this._store.HasGraph(t.GraphUri))
{
Graph g = new Graph();
g.BaseUri = t.GraphUri;
this._store.Add(g);
}
IGraph target = this._store.Graph(t.GraphUri);
target.Assert(t.CopyTriple(target));
return true;
}
