/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.jena.sparql.pfunction.library;
import java.util.* ;
import org.apache.jena.graph.Graph ;
import org.apache.jena.graph.Node ;
import org.apache.jena.graph.Triple ;
import org.apache.jena.sparql.core.Var ;
import org.apache.jena.sparql.engine.ExecutionContext ;
import org.apache.jena.sparql.engine.QueryIterator ;
import org.apache.jena.sparql.engine.binding.Binding ;
import org.apache.jena.sparql.engine.binding.BindingFactory ;
import org.apache.jena.sparql.engine.iterator.* ;
import org.apache.jena.sparql.pfunction.PFuncSimple ;
import org.apache.jena.sparql.util.IterLib ;
import org.apache.jena.sparql.util.graph.GraphContainerUtils ;
import org.apache.jena.util.iterator.ExtendedIterator ;
import org.apache.jena.vocabulary.RDF ;
/** container - super class of bag/alt/seq - rdfs:member
* */
public class container extends PFuncSimple
{
Node typeNode = null ; // Null means don't check type.
public container() { this.typeNode = null ; }
protected container(Node typeURI) { this.typeNode = typeURI ; }
@Override
public QueryIterator execEvaluated(Binding binding, Node containerNode, Node predicate, Node member, ExecutionContext execCxt)
{
QueryIterator qIter1 = execEvaluatedConcrete(binding, containerNode, predicate, member, execCxt) ;
QueryIterator qIter2 = execEvaluatedCalc(binding, containerNode, predicate, member, execCxt) ;
QueryIterConcat concat = new QueryIterConcat(execCxt) ;
concat.add(qIter1) ;
concat.add(qIter2) ;
return concat ;
}
// Ask directly.
private QueryIterator execEvaluatedConcrete(Binding binding, Node containerNode, Node predicate, Node member,
ExecutionContext execCxt)
{
QueryIterator input = QueryIterSingleton.create(binding, execCxt) ;
Graph graph = execCxt.getActiveGraph() ;
QueryIterator qIter = new QueryIterTriplePattern(input, new Triple(containerNode, predicate, member), execCxt) ;
return qIter ;
}
// Ask by finding all the rdf:_N + rdf:type
private QueryIterator execEvaluatedCalc(Binding binding, Node containerNode, Node predicate, Node member, ExecutionContext execCxt)
{
Graph graph = execCxt.getActiveGraph() ;
if ( ! containerNode.isVariable() )
{
// Container a ground term.
if ( ! GraphContainerUtils.isContainer(execCxt.getActiveGraph(), containerNode, typeNode) )
return IterLib.noResults(execCxt) ;
return oneContainer(binding, containerNode, member, execCxt) ;
}
// Container a variable.
Collection<Node> c = null ;
if ( member.isVariable() )
c = findContainers(graph, typeNode) ;
else
c = findContainingContainers(graph, typeNode, member) ;
QueryIterConcat cIter = new QueryIterConcat(execCxt) ;
Var cVar = Var.alloc(containerNode) ;
for ( Node cn : c )
{
//Binding the container node.
Binding b = BindingFactory.binding( binding, cVar, cn );
Node m = member;
// Special case of ?x rdfs:member ?x
if ( Var.isVar( member ) && member.equals( cVar ) )
{
m = cn;
}
cIter.add( oneContainer( b, cn, m, execCxt ) );
}
return cIter ;
//throw new QueryFatalException(Utils.className(this)+": Arg 1 is too hard : "+containerNode) ;
}
private QueryIterator oneContainer(Binding binding, Node containerNode, Node member, ExecutionContext execCxt)
{
// containerNode is a fixed term
if ( member.isVariable() )
return members(binding, containerNode, Var.alloc(member), execCxt) ;
else
return verify(binding, containerNode, member, execCxt) ;
}
private QueryIterator members(Binding binding, Node containerNode, Var memberVar, ExecutionContext execCxt)
{
// Not necessarily very efficient
Collection<Node> x = GraphContainerUtils.containerMembers(execCxt.getActiveGraph(), containerNode, typeNode) ;
if ( x == null )
// Wrong type.
return IterLib.noResults(execCxt) ;
List<Binding> bindings = new ArrayList<>() ;
for ( Node n : x )
{
Binding b = BindingFactory.binding( binding, memberVar, n );
bindings.add( b );
}
// Turn into a QueryIterator of extra bindings.
return new QueryIterPlainWrapper(bindings.iterator(), execCxt) ;
}
private QueryIterator verify(Binding binding, Node containerNode, Node member, ExecutionContext execCxt)
{
int count = GraphContainerUtils.countContainerMember(execCxt.getActiveGraph(), containerNode, typeNode, member) ;
return new QueryIterYieldN(count, binding, execCxt) ;
}
static private Collection<Node> findContainers(Graph graph, Node typeNode)
{
Set<Node> acc = new HashSet<>() ;
if ( typeNode != null )
{
findContainers(acc, graph, typeNode) ;
return acc;
}
findContainers(acc, graph, RDF.Bag.asNode()) ;
findContainers(acc, graph, RDF.Seq.asNode()) ;
findContainers(acc, graph, RDF.Alt.asNode()) ;
return acc ;
}
static private void findContainers(Collection<Node> acc, Graph graph, Node typeNode)
{
ExtendedIterator<Triple> iter = graph.find(Node.ANY, RDF.type.asNode(), typeNode) ;
while(iter.hasNext())
{
Triple t = iter.next();
Node containerNode = t.getSubject() ;
acc.add(containerNode) ;
}
}
static private Collection<Node> findContainingContainers(Graph graph, Node typeNode, Node member)
{
Collection<Node> acc = new HashSet<>() ;
// Index off the object
ExtendedIterator<Triple> iter = graph.find(Node.ANY, Node.ANY, member) ;
while(iter.hasNext())
{
Triple t = iter.next();
Node containerNode = t.getSubject() ; // Candidate
if ( GraphContainerUtils.isContainer(graph, containerNode, typeNode) )
acc.add(containerNode) ;
}
return acc ;
}
}