@Override
protected boolean accepts(Object key, QuadWritable tuple) {
Quad q = tuple.get();
if (!q.isConcrete()) return false;
// Ground if all nodes are URI/Literal
return (q.getGraph().isURI() || q.getGraph().isLiteral())
&& (q.getSubject().isURI() || q.getSubject().isLiteral())
&& (q.getPredicate().isURI() || q.getPredicate().isLiteral())
&& (q.getObject().isURI() || q.getObject().isLiteral());
}
@Override
public QuadBlock rewrite(SDBRequest request, QuadBlock quadBlock) {
// Does not consider if the property slot is a variable.
if (!quadBlock.contains(null, null, rdfType, null)) return quadBlock;
quadBlock = new QuadBlock(quadBlock);
int i = 0;
// Better/clearer : do as copy over from one block to another.
while ((i = quadBlock.findFirst(i, null, null, rdfType, null)) != -1) {
// { :s rdf:type :C } => { :s rdf:type ?V . ?V rdfs:subClassOf :C }
Quad rdfTypeQuad = quadBlock.get(i);
Var var = request.genVar();
Quad q1 = new Quad(rdfTypeQuad.getGraph(), rdfTypeQuad.getSubject(), rdfType, var);
Quad q2 =
new Quad(rdfTypeQuad.getGraph(), var, RDFS.subClassOf.asNode(), rdfTypeQuad.getObject());
quadBlock.set(i, q1); // replace rdf:type statement
quadBlock.add(i + 1, q2); // add subClassOf statement
i = i + 2; // Skip the two statements.
}
return quadBlock;
}