/// <summary>
/// Selects Statements that match a given Template
/// </summary>
/// <param name="template">Statement Template</param>
/// <param name="sink">Sink</param>
public void Select(Statement template, StatementSink sink)
{
//Implement as a SPARQL SELECT
List <ITriplePattern> patterns = this.TemplateToTriplePatterns(template);
StringBuilder query = new StringBuilder();
query.AppendLine("SELECT * WHERE {");
foreach (ITriplePattern pattern in patterns)
{
query.AppendLine(pattern.ToString() + ".");
}
query.AppendLine("}");
//Get the Results
Object results = this._store.ExecuteQuery(query.ToString());
if (results is SparqlResultSet)
{
SparqlResultSet rset = (SparqlResultSet)results;
foreach (SparqlResult r in rset)
{
Entity s = (template.Subject != null) ? template.Subject : SemWebConverter.ToSemWebEntity(r["s"], this._mapping);
Entity p = (template.Predicate != null) ? template.Predicate : SemWebConverter.ToSemWebEntity(r["p"], this._mapping);
Resource o = (template.Object != null) ? template.Object : SemWebConverter.ToSemWeb(r["o"], this._mapping);
Statement stmt = new Statement(s, p, o);
//Keep returning stuff until the sink tells us to stop
if (!sink.Add(stmt))
{
return;
}
}
}
}
/// <summary>
/// Helper method which converts a SemWeb resource into a PatternItem for use in a SPARQL Triple Pattern
/// </summary>
/// <param name="r">Resource</param>
/// <param name="mapping">Mapping of Variables & Blank Nodes to Pattern Items</param>
/// <returns></returns>
private PatternItem FromSemWeb(Resource r, Dictionary <String, PatternItem> mapping)
{
if (r is Variable)
{
if (mapping.ContainsKey(r.ToString()))
{
return(mapping[r.ToString()]);
}
else
{
PatternItem temp = new VariablePattern(r.ToString());
mapping.Add(r.ToString(), temp);
return(temp);
}
}
else if (r is BNode)
{
if (mapping.ContainsKey(r.ToString()))
{
return(mapping[r.ToString()]);
}
else
{
PatternItem temp = new BlankNodePattern(r.ToString().Substring(2));
mapping.Add(r.ToString(), temp);
return(temp);
}
}
else
{
return(new NodeMatchPattern(SemWebConverter.FromSemWeb(r, this._mapping)));
}
}
/// <summary>
/// Selects all statements from this source and streams them into the given Sink
/// </summary>
/// <param name="sink">Statement Sink</param>
public void Select(StatementSink sink)
{
foreach (IGraph g in this._store.Graphs)
{
//Get the Hash Code of the Graphs URI and create a new empty mapping if necessary
Entity graphUri;
int hash;
if (g.BaseUri == null)
{
graphUri = new Entity(GraphCollection.DefaultGraphUri);
hash = new Uri(GraphCollection.DefaultGraphUri).GetEnhancedHashCode();
}
else
{
graphUri = new Entity(g.BaseUri.ToString());
hash = g.BaseUri.GetEnhancedHashCode();
}
SemWebMapping mapping = this.GetMapping(hash, g);
foreach (Triple t in g.Triples)
{
Statement stmt = SemWebConverter.ToSemWeb(t, mapping);
stmt.Meta = graphUri;
if (!sink.Add(stmt))
{
return;
}
}
}
}
/// <summary>
/// Adds a Statement to the Sink
/// </summary>
/// <param name="statement">Statement</param>
/// <returns></returns>
public bool Add(Statement statement)
{
Triple t = SemWebConverter.FromSemWeb(statement, this._mapping);
this._triples.Add(t);
return(true);
}
/// <summary>
/// Selects all statements from this source and streams them into the given Sink
/// </summary>
/// <param name="sink">Statement Sink</param>
/// <remarks>
/// This is essentially the same code as the <see cref="SemWebConverter.ToSemWeb">ToSemWeb(IGraph g, StatementSink sink)</see> function but we need to maintain a consistent mapping of BNodes for the source
/// </remarks>
public void Select(StatementSink sink)
{
foreach (Triple t in this._g.Triples)
{
Statement stmt = SemWebConverter.ToSemWeb(t, this._mapping);
if (!sink.Add(stmt))
{
return;
}
}
}
/// <summary>
/// Checks whether the Triple exists in the Collection
/// </summary>
/// <param name="t">Triple to check for</param>
/// <returns></returns>
/// <exception cref="RdfStorageException">Thrown if the underlying StatementSource is not a SelectableSource</exception>
public override bool Contains(Triple t)
{
if (this._source is SelectableSource)
{
Statement stmt = SemWebConverter.ToSemWeb(t, this._mapping);
return(((SelectableSource)this._source).Contains(stmt));
}
else
{
throw new RdfStorageException("The underlying StatementSource does not support the Contains() operation");
}
}
/// <summary>
/// Removes a Triple from the underlying SemWeb StatementSource if the Source is modifiable
/// </summary>
/// <param name="t">Triple to remove</param>
/// <exception cref="RdfStorageException">Thrown if the underlying SemWeb data source is not modifiable</exception>
protected override void Delete(Triple t)
{
if (this._source is ModifiableSource)
{
Statement stmt = SemWebConverter.ToSemWeb(t, this._mapping);
((ModifiableSource)this._source).Remove(stmt);
}
else
{
throw new RdfStorageException("The underlying StatementSource does not support the Remove() operation");
}
}
/// <summary>
/// Gets the Enumerator for this Triple Collection
/// </summary>
/// <returns></returns>
public override IEnumerator <Triple> GetEnumerator()
{
if (this._source is IEnumerable <Statement> )
{
IEnumerable <Statement> stmts = (IEnumerable <Statement>) this._source;
return((from stmt in stmts
select SemWebConverter.FromSemWeb(stmt, this._mapping)).GetEnumerator());
}
else
{
throw new RdfStorageException("Underlying StatementSource does not support enumeration");
}
}
/// <summary>
/// Gets all the Triples with a specific Object
/// </summary>
/// <param name="obj">Object</param>
/// <returns></returns>
public override IEnumerable <Triple> WithObject(INode obj)
{
if (this._source is SelectableSource)
{
EnumerationSink sink = new EnumerationSink(this._mapping);
Statement stmt = new Statement(null, null, SemWebConverter.ToSemWeb(obj, this._mapping));
((SelectableSource)this._source).Select(stmt, sink);
return(sink);
}
else
{
return(base.WithObject(obj));
}
}
/// <summary>
/// Gets all the Triples with a specific Subject and Predicate
/// </summary>
/// <param name="subj">Subject</param>
/// <param name="pred">Predicate</param>
/// <returns></returns>
public override IEnumerable <Triple> WithSubjectPredicate(INode subj, INode pred)
{
if (this._source is SelectableSource)
{
EnumerationSink sink = new EnumerationSink(this._mapping);
Statement stmt = new Statement(SemWebConverter.ToSemWebEntity(subj, this._mapping), SemWebConverter.ToSemWebEntity(pred, this._mapping), null);
((SelectableSource)this._source).Select(stmt, sink);
return(sink);
}
else
{
return(base.WithSubjectPredicate(subj, pred));
}
}
/// <summary>
/// Selects Statements from the Source based on a Template
/// </summary>
/// <param name="template">Statement Template</param>
/// <param name="sink">Sink to stream results to</param>
public void Select(Statement template, StatementSink sink)
{
//Convert Template to an Enumerable
IEnumerable <Triple> ts = this.TemplateToEnumerable(template);
foreach (Triple t in ts)
{
//Keep streaming Triples until the sink tells us to stop
Statement stmt = SemWebConverter.ToSemWeb(t, this._mapping);
if (!sink.Add(stmt))
{
return;
}
}
}
/// <summary>
/// Returns whether the Source contains any Statement which contains the given Resource
/// </summary>
/// <param name="resource">Resource</param>
/// <returns></returns>
public bool Contains(Resource resource)
{
//First we need to convert the Resource to a Node
INode n = SemWebConverter.FromSemWeb(resource, this._mapping);
if (this._g.Nodes.Contains(n))
{
//If it's in the Node collection check that a Triple with the given Node exists
return(this._g.Triples.Any(t => t.Involves(n)));
}
else
{
//If it's not in the Node collection it can't be in the Graph
return(false);
}
}
/// <summary>
/// Executes a Graph Pattern style query against the Source
/// </summary>
/// <param name="graph">Graph Pattern</param>
/// <param name="options">Query Options</param>
/// <param name="sink">Results Sink</param>
/// <remarks>
/// <para>
/// This is implemented by transforming the Graph Pattern which is a set of SemWeb Statement templates into a SPARQL Algebra BGP. The resulting algebra is then executed using the Leviathan engine and the results converted into VariableBindings for SemWeb
/// </para>
/// <para>
/// The only Query Option that is supported is the Limit option
/// </para>
/// </remarks>
public void Query(Statement[] graph, SW.Query.QueryOptions options, SW.Query.QueryResultSink sink)
{
ISparqlAlgebra algebra = this.ToAlgebra(graph);
if (this._store == null)
{
this._store = new TripleStore();
this._store.Add(this._g);
}
SparqlEvaluationContext context = new SparqlEvaluationContext(null, new InMemoryDataset(this._store));
BaseMultiset results = context.Evaluate(algebra);//algebra.Evaluate(context);
sink.Init(results.Variables.Select(v => new Variable(v)).ToArray());
if (results.Count > 0)
{
int c = 0;
foreach (ISet s in results.Sets)
{
//Apply Limit if applicable
if (options.Limit > 0 && c >= options.Limit)
{
sink.Finished();
return;
}
//Convert the Set to VariableBindings for SemWeb
Variable[] vars = s.Variables.Select(v => new Variable(v)).ToArray();
Resource[] resources = s.Variables.Select(v => SemWebConverter.ToSemWeb(s[v], this._mapping)).ToArray();
SW.Query.VariableBindings bindings = new SW.Query.VariableBindings(vars, resources);
//Keep adding results until the sink tells us to stop
if (!sink.Add(bindings))
{
sink.Finished();
return;
}
c++;
}
sink.Finished();
}
else
{
sink.Finished();
}
}
/// <summary>
/// Adds a statement to this Source
/// </summary>
/// <param name="statement">Statement</param>
/// <returns></returns>
public bool Add(Statement statement)
{
IGraph g;
Uri graphUri;
int hash;
//Set the Graph URI based on the Statement Meta field
if (statement.Meta != Statement.DefaultMeta && statement.Meta.Uri != null)
{
if (statement.Meta.Uri.Equals(GraphCollection.DefaultGraphUri))
{
graphUri = null;
hash = new Uri(GraphCollection.DefaultGraphUri).GetEnhancedHashCode();
}
else
{
graphUri = new Uri(statement.Meta.Uri);
hash = graphUri.GetEnhancedHashCode();
}
}
else
{
graphUri = null;
hash = new Uri(GraphCollection.DefaultGraphUri).GetEnhancedHashCode();
}
if (!this._store.HasGraph(graphUri))
{
g = new Graph();
if (graphUri != null)
{
g.BaseUri = graphUri;
}
this._store.Add(g);
}
else
{
g = this._store.Graph(graphUri);
}
//Assert into the appropriate Graph
g.Assert(SemWebConverter.FromSemWeb(statement, this.GetMapping(hash, g)));
//We never ask the sink to stop streaming statements so we always return true
return(true);
}
/// <summary>
/// Selects all Statements from the underlying Store and adds them to a SemWeb Sink
/// </summary>
/// <param name="sink">Statement Sink</param>
public void Select(StatementSink sink)
{
//Use a CONSTRUCT to get the Statements
String query = "CONSTRUCT {?s ?p ?o} WHERE {?s ?p ?o}";
Object results = this._store.ExecuteQuery(query);
if (results is Graph)
{
Graph g = (Graph)results;
foreach (Triple t in g.Triples)
{
Statement stmt = SemWebConverter.ToSemWeb(t, this._mapping);
//Keep returning stuff until it tells us to stop
if (!sink.Add(stmt))
{
return;
}
}
}
}
/// <summary>
/// Returns whether the Source contains any Statement which contains the given Resource
/// </summary>
/// <param name="resource">Resource</param>
/// <returns></returns>
public bool Contains(Resource resource)
{
//Have to check against each Graph until we find a match
foreach (IGraph g in this._store.Graphs)
{
//First we need to convert the Resource to a Node
INode n = SemWebConverter.FromSemWeb(resource, this.GetMapping(g));
if (g.Nodes.Contains(n))
{
//If it's in the Node collection check that a Triple with the given Node exists
if (g.Triples.Any(t => t.Involves(n)))
{
return(true);
}
}
}
//If none of the Graphs contained it we return false
return(false);
}
private IEnumerable <Triple> FilterToEnumerable(SelectFilter filter, IGraph g)
{
//Want to build an IEnumerable based on the Filter
IEnumerable <Triple> ts = Enumerable.Empty <Triple>();
INode s, p, o;
int hash = (g.BaseUri == null) ? new Uri(GraphCollection.DefaultGraphUri).GetEnhancedHashCode() : g.BaseUri.GetEnhancedHashCode();
if (filter.Subjects != null)
{
if (filter.Predicates != null)
{
//Subject-Predicate filter
foreach (Entity subj in filter.Subjects)
{
s = SemWebConverter.FromSemWeb(subj, this.GetMapping(hash, g));
foreach (Entity pred in filter.Predicates)
{
p = SemWebConverter.FromSemWeb(pred, this.GetMapping(hash, g));
ts = ts.Concat(g.GetTriplesWithSubjectPredicate(s, p));
}
}
}
else if (filter.Objects != null)
{
//Subject-Object filter
foreach (Entity subj in filter.Subjects)
{
s = SemWebConverter.FromSemWeb(subj, this.GetMapping(hash, g));
foreach (Resource obj in filter.Objects)
{
o = SemWebConverter.FromSemWeb(obj, this.GetMapping(hash, g));
ts = ts.Concat(g.GetTriplesWithSubjectObject(s, o));
}
}
}
else
{
//Subjects filter
foreach (Entity subj in filter.Subjects)
{
s = SemWebConverter.FromSemWeb(subj, this.GetMapping(hash, g));
ts = ts.Concat(g.GetTriplesWithSubject(s));
}
}
}
else if (filter.Predicates != null)
{
if (filter.Objects != null)
{
//Predicate-Object Filter
foreach (Entity pred in filter.Predicates)
{
p = SemWebConverter.FromSemWeb(pred, this.GetMapping(hash, g));
foreach (Resource obj in filter.Objects)
{
o = SemWebConverter.FromSemWeb(obj, this.GetMapping(hash, g));
ts = ts.Concat(g.GetTriplesWithPredicateObject(p, o));
}
}
}
else
{
//Predicate Filter
foreach (Entity pred in filter.Predicates)
{
p = SemWebConverter.FromSemWeb(pred, this.GetMapping(hash, g));
ts = ts.Concat(g.GetTriplesWithPredicate(p));
}
}
}
else if (filter.Objects != null)
{
//Object Filter
foreach (Resource obj in filter.Objects)
{
o = SemWebConverter.FromSemWeb(obj, this.GetMapping(hash, g));
ts = ts.Concat(g.GetTriplesWithObject(o));
}
}
else
{
//Everything is null so this is a Select All
ts = g.Triples;
}
return(ts);
}
/// <summary>
/// Adds a Triple to the Triple Collection
/// </summary>
/// <param name="t">Triple to add</param>
protected override void Add(Triple t)
{
Statement stmt = SemWebConverter.ToSemWeb(t, this._mapping);
this._sink.Add(stmt);
}
/// <summary>
/// Queries the Store using the Graph Pattern specified by the set of Statement Patterns
/// </summary>
/// <param name="graph">Graph Pattern</param>
/// <param name="options">Query Options</param>
/// <param name="sink">Results Sink</param>
/// <remarks>
/// <para>
/// Implemented by converting the Statement Patterns into a SPARQL SELECT query and executing that against the underlying Store's SPARQL engine
/// </para>
/// <para>
/// The only Query Option that is supported is the Limit option
/// </para>
/// </remarks>
public void Query(Statement[] graph, SW.Query.QueryOptions options, SW.Query.QueryResultSink sink)
{
//Implement as a SPARQL SELECT
SparqlParameterizedString queryString = new SparqlParameterizedString();
queryString.CommandText = "SELECT * WHERE {";
int p = 0;
foreach (Statement stmt in graph)
{
//Add Subject
queryString.CommandText += "\n";
if (stmt.Subject is Variable)
{
queryString.CommandText += stmt.Subject.ToString();
}
else
{
queryString.CommandText += "@param" + p;
queryString.SetParameter("param" + p, SemWebConverter.FromSemWeb(stmt.Subject, this._mapping));
p++;
}
queryString.CommandText += " ";
//Add Predicate
if (stmt.Predicate is Variable)
{
queryString.CommandText += stmt.Predicate.ToString();
}
else
{
queryString.CommandText += "@param" + p;
queryString.SetParameter("param" + p, SemWebConverter.FromSemWeb(stmt.Predicate, this._mapping));
p++;
}
queryString.CommandText += " ";
//Add Object
if (stmt.Object is Variable)
{
queryString.CommandText += stmt.Object.ToString();
}
else
{
queryString.CommandText += "@param" + p;
queryString.SetParameter("param" + p, SemWebConverter.FromSemWeb(stmt.Object, this._mapping));
p++;
}
queryString.CommandText += " .";
}
queryString.CommandText += "}";
//Execute the Query and convert the Results
Object results = this._store.ExecuteQuery(queryString.ToString());
if (results is SparqlResultSet)
{
SparqlResultSet rset = (SparqlResultSet)results;
sink.Init(rset.Variables.Select(v => new Variable(v)).ToArray());
if (rset.Count > 0)
{
int c = 0;
foreach (SparqlResult r in rset)
{
//Apply Limit if applicable
if (options.Limit > 0 && c >= options.Limit)
{
sink.Finished();
return;
}
//Convert the Set to VariableBindings for SemWeb
Variable[] vars = r.Variables.Select(v => new Variable(v)).ToArray();
Resource[] resources = r.Variables.Select(v => SemWebConverter.ToSemWeb(r[v], this._mapping)).ToArray();
SW.Query.VariableBindings bindings = new SW.Query.VariableBindings(vars, resources);
//Keep adding results until the sink tells us to stop
if (!sink.Add(bindings))
{
sink.Finished();
return;
}
c++;
}
sink.Finished();
}
else
{
sink.Finished();
}
}
else
{
throw new RdfQueryException("Query returned an unexpected result where a SPARQL Result Set was expected");
}
}
/// <summary>
/// Selects Statements from the Source based on a Template
/// </summary>
/// <param name="template">Statement Template</param>
/// <param name="sink">Sink to stream results to</param>
public void Select(Statement template, StatementSink sink)
{
//Convert Template to an Enumerable
IEnumerable <Triple> ts = Enumerable.Empty <Triple>();
int hash;
if (template.Meta != Statement.DefaultMeta && template.Meta != null)
{
//Select from the specific Graph if it exists
Uri graphUri;
if (template.Meta.Uri == null)
{
hash = new Uri(GraphCollection.DefaultGraphUri).GetEnhancedHashCode();
graphUri = null;
}
else
{
graphUri = new Uri(template.Meta.Uri);
hash = graphUri.GetEnhancedHashCode();
}
if (this._store.HasGraph(graphUri))
{
ts = this.TemplateToEnumerable(template, this._store.Graph(graphUri));
SemWebMapping mapping = this.GetMapping(hash, this._store.Graph(graphUri));
foreach (Triple t in ts)
{
//Keep streaming Triples until the sink tells us to stop
Statement stmt = SemWebConverter.ToSemWeb(t, mapping);
if (!sink.Add(stmt))
{
return;
}
}
}
}
else
{
//Output the results from each Graph in turn
foreach (IGraph g in this._store.Graphs)
{
Entity graphUri;
if (g.BaseUri == null)
{
hash = new Uri(GraphCollection.DefaultGraphUri).GetEnhancedHashCode();
graphUri = new Entity(GraphCollection.DefaultGraphUri);
}
else
{
hash = g.BaseUri.GetEnhancedHashCode();
graphUri = new Entity(g.BaseUri.ToString());
}
SemWebMapping mapping = this.GetMapping(hash, g);
foreach (Triple t in this.TemplateToEnumerable(template, g))
{
Statement stmt = SemWebConverter.ToSemWeb(t, mapping);
stmt.Meta = graphUri;
if (!sink.Add(stmt))
{
return;
}
}
}
}
}
/// <summary>
/// Adds a statement to this Source
/// </summary>
/// <param name="statement">Statement</param>
/// <returns></returns>
public bool Add(Statement statement)
{
this._g.Assert(SemWebConverter.FromSemWeb(statement, this._mapping));
//We never ask the sink to stop streaming statements so we always return true
return(true);
}
/// <summary>
/// Selects Statements from the Source based on a Filter
/// </summary>
/// <param name="filter">Statement Filter</param>
/// <param name="sink">Sink to stream results to</param>
public void Select(SelectFilter filter, StatementSink sink)
{
IEnumerable <Triple> ts = Enumerable.Empty <Triple>();
if (filter.Metas != null)
{
//This applies over some Graphs
foreach (Entity meta in filter.Metas)
{
if (meta.Uri != null)
{
Uri graphUri = new Uri(meta.Uri);
if (this._store.HasGraph(graphUri))
{
ts = ts.Concat(this.FilterToEnumerable(filter, this._store.Graph(graphUri)));
}
}
}
}
else
{
//This applies over all Graphs
foreach (IGraph g in this._store.Graphs)
{
ts = ts.Concat(this.FilterToEnumerable(filter, g));
}
}
int count = 0;
foreach (Triple t in ts)
{
//Apply limit if applicable
if (filter.Limit > 0 && count >= filter.Limit)
{
return;
}
Statement stmt = SemWebConverter.ToSemWeb(t, this.GetMapping(t.Graph));
stmt.Meta = new Entity(t.GraphUri.ToString());
if (filter.LiteralFilters != null)
{
if (LiteralFilter.MatchesFilters(stmt.Object, filter.LiteralFilters, this))
{
//If the Object matched the filters then we return the Triple and stop
//streaming if the sink tells us to
if (!sink.Add(stmt))
{
return;
}
count++;
}
}
else
{
//Just add the statement and stop if the sink tells us to stop streaming
if (!sink.Add(stmt))
{
return;
}
count++;
}
}
}
/// <summary>
/// Converts a SemWeb Statement Template to an IEnumerable of Triples
/// </summary>
/// <param name="template">Statement Template</param>
/// <returns></returns>
private IEnumerable <Triple> TemplateToEnumerable(Statement template)
{
INode s, p, o;
if (template.Subject is Variable)
{
if (template.Predicate is Variable)
{
if (template.Object is Variable)
{
//All three things are variables so this just checks that some Triple(s) are present
return(this._g.Triples);
}
else
{
//Subject & Predicate are Variables
//Convert the Object and do a WithObject().Any() call
o = SemWebConverter.FromSemWeb(template.Object, this._mapping);
return(this._g.GetTriplesWithObject(o));
}
}
else if (template.Object is Variable)
{
//Subject & Object are variables
//Convert the Predicate and do a WithPredicate() call
p = SemWebConverter.FromSemWeb(template.Predicate, this._mapping);
return(this._g.GetTriplesWithPredicate(p));
}
else
{
//Subject is a Variable
//Convert the Predicate and Object and do a WithPredicateObject() call
p = SemWebConverter.FromSemWeb(template.Predicate, this._mapping);
o = SemWebConverter.FromSemWeb(template.Object, this._mapping);
return(this._g.GetTriplesWithPredicateObject(p, o));
}
}
else if (template.Predicate is Variable)
{
if (template.Object is Variable)
{
//Predicate & Object are Variables
//Convert the Subject and do a WithSubject() call
s = SemWebConverter.FromSemWeb(template.Subject, this._mapping);
return(this._g.GetTriplesWithSubject(s));
}
else
{
//Predicate is a Variable
//Convert the Subject and Object and do a WithSubjectObject() call
s = SemWebConverter.FromSemWeb(template.Subject, this._mapping);
o = SemWebConverter.FromSemWeb(template.Object, this._mapping);
return(this._g.GetTriplesWithSubjectObject(s, o));
}
}
else if (template.Object is Variable)
{
//Object is a Variable
//Convert the Subject and Predicate and do a WithSubjectPredicate() call
s = SemWebConverter.FromSemWeb(template.Subject, this._mapping);
p = SemWebConverter.FromSemWeb(template.Predicate, this._mapping);
return(this._g.GetTriplesWithSubjectPredicate(s, p));
}
else
{
//Just convert the Triple and do a Contains() call
Triple t = SemWebConverter.FromSemWeb(template, this._mapping);
if (this._g.ContainsTriple(t))
{
return(t.AsEnumerable());
}
else
{
return(Enumerable.Empty <Triple>());
}
}
}
/// <summary>
/// Converts a SemWeb Statement Template to an IEnumerable of Triples
/// </summary>
/// <param name="template">Statement Template</param>
/// <param name="g">Graph the Template should be created for</param>
/// <returns></returns>
private IEnumerable <Triple> TemplateToEnumerable(Statement template, IGraph g)
{
INode s, p, o;
int hash;
if (g.BaseUri == null)
{
hash = new Uri(GraphCollection.DefaultGraphUri).GetEnhancedHashCode();
}
else
{
hash = g.BaseUri.GetEnhancedHashCode();
}
if (template.Subject is Variable)
{
if (template.Predicate is Variable)
{
if (template.Object is Variable)
{
//All three things are variables so this just checks that some Triple(s) are present
return(g.Triples);
}
else
{
//Subject & Predicate are Variables
//Convert the Object and do a WithObject().Any() call
o = SemWebConverter.FromSemWeb(template.Object, this.GetMapping(hash, g));
return(g.GetTriplesWithObject(o));
}
}
else if (template.Object is Variable)
{
//Subject & Object are variables
//Convert the Predicate and do a WithPredicate() call
p = SemWebConverter.FromSemWeb(template.Predicate, this.GetMapping(hash, g));
return(g.GetTriplesWithPredicate(p));
}
else
{
//Subject is a Variable
//Convert the Predicate and Object and do a WithPredicateObject() call
p = SemWebConverter.FromSemWeb(template.Predicate, this.GetMapping(hash, g));
o = SemWebConverter.FromSemWeb(template.Object, this.GetMapping(hash, g));
return(g.GetTriplesWithPredicateObject(p, o));
}
}
else if (template.Predicate is Variable)
{
if (template.Object is Variable)
{
//Predicate & Object are Variables
//Convert the Subject and do a WithSubject() call
s = SemWebConverter.FromSemWeb(template.Subject, this.GetMapping(hash, g));
return(g.GetTriplesWithSubject(s));
}
else
{
//Predicate is a Variable
//Convert the Subject and Object and do a WithSubjectObject() call
s = SemWebConverter.FromSemWeb(template.Subject, this.GetMapping(hash, g));
o = SemWebConverter.FromSemWeb(template.Object, this.GetMapping(hash, g));
return(g.GetTriplesWithSubjectObject(s, o));
}
}
else if (template.Object is Variable)
{
//Object is a Variable
//Convert the Subject and Predicate and do a WithSubjectPredicate() call
s = SemWebConverter.FromSemWeb(template.Subject, this.GetMapping(hash, g));
p = SemWebConverter.FromSemWeb(template.Predicate, this.GetMapping(hash, g));
return(g.GetTriplesWithSubjectPredicate(s, p));
}
else
{
//Just convert the Triple and do a Contains() call
Triple t = SemWebConverter.FromSemWeb(template, this.GetMapping(hash, g));
if (g.ContainsTriple(t))
{
return(t.AsEnumerable());
}
else
{
return(Enumerable.Empty <Triple>());
}
}
}
/// <summary>
/// Selects Statements from the Source based on a Filter
/// </summary>
/// <param name="filter">Statement Filter</param>
/// <param name="sink">Sink to stream results to</param>
public void Select(SelectFilter filter, StatementSink sink)
{
//Don't support filters on Metas for the Graph Source
if (filter.Metas != null)
{
throw new RdfException("The dotNetRDF GraphSource does not support SemWeb filters which use Meta filters");
}
//Want to build an IEnumerable based on the Filter
IEnumerable <Triple> ts = Enumerable.Empty <Triple>();
INode s, p, o;
if (filter.Subjects != null)
{
if (filter.Predicates != null)
{
//Subject-Predicate filter
foreach (Entity subj in filter.Subjects)
{
s = SemWebConverter.FromSemWeb(subj, this._mapping);
foreach (Entity pred in filter.Predicates)
{
p = SemWebConverter.FromSemWeb(pred, this._mapping);
ts = ts.Concat(this._g.GetTriplesWithSubjectPredicate(s, p));
}
}
}
else if (filter.Objects != null)
{
//Subject-Object filter
foreach (Entity subj in filter.Subjects)
{
s = SemWebConverter.FromSemWeb(subj, this._mapping);
foreach (Resource obj in filter.Objects)
{
o = SemWebConverter.FromSemWeb(obj, this._mapping);
ts = ts.Concat(this._g.GetTriplesWithSubjectObject(s, o));
}
}
}
else
{
//Subjects filter
foreach (Entity subj in filter.Subjects)
{
s = SemWebConverter.FromSemWeb(subj, this._mapping);
ts = ts.Concat(this._g.GetTriplesWithSubject(s));
}
}
}
else if (filter.Predicates != null)
{
if (filter.Objects != null)
{
//Predicate-Object Filter
foreach (Entity pred in filter.Predicates)
{
p = SemWebConverter.FromSemWeb(pred, this._mapping);
foreach (Resource obj in filter.Objects)
{
o = SemWebConverter.FromSemWeb(obj, this._mapping);
ts = ts.Concat(this._g.GetTriplesWithPredicateObject(p, o));
}
}
}
else
{
//Predicate Filter
foreach (Entity pred in filter.Predicates)
{
p = SemWebConverter.FromSemWeb(pred, this._mapping);
ts = ts.Concat(this._g.GetTriplesWithPredicate(p));
}
}
}
else if (filter.Objects != null)
{
//Object Filter
foreach (Resource obj in filter.Objects)
{
o = SemWebConverter.FromSemWeb(obj, this._mapping);
ts = ts.Concat(this._g.GetTriplesWithObject(o));
}
}
else
{
//Everything is null so this is a Select All
ts = this._g.Triples;
}
int count = 0;
foreach (Triple t in ts)
{
//Apply limit if applicable
if (filter.Limit > 0 && count >= filter.Limit)
{
return;
}
//Convert to a Statement and apply applicable Literal Filters
Statement stmt = SemWebConverter.ToSemWeb(t, this._mapping);
if (filter.LiteralFilters != null)
{
if (LiteralFilter.MatchesFilters(stmt.Object, filter.LiteralFilters, this))
{
//If the Object matched the filters then we return the Triple and stop
//streaming if the sink tells us to
if (!sink.Add(stmt))
{
return;
}
count++;
}
//If it doesn't match the filter it is ignored
}
else
{
//Just add the statement and stop if the sink tells us to stop streaming
if (!sink.Add(stmt))
{
return;
}
count++;
}
}
}
