/**
* Extended find interface used in situations where the implementator may or may not be able to
* answer the complete query. It will attempt to answer the pattern but if its answers are not
* known to be complete then it will also pass the request on to the nested Finder to append more
* results.
*
* @param pattern a TriplePattern to be matched against the data
* @param continuation either a Finder or a normal Graph which will be asked for additional match
* results if the implementor may not have completely satisfied the query.
*/
@Override
public ExtendedIterator<Triple> findWithContinuation(TriplePattern pattern, Finder continuation) {
if (graph == null) return new NullIterator<Triple>();
if (continuation == null) {
return graph.find(pattern.asTripleMatch());
} else {
return graph.find(pattern.asTripleMatch()).andThen(continuation.find(pattern));
}
}
/** Return true if the given pattern occurs somewhere in the find sequence. */
@Override
public boolean contains(TriplePattern pattern) {
return graph.contains(pattern.getSubject(), pattern.getPredicate(), pattern.getObject());
}
/**
* Basic pattern lookup interface.
*
* @param pattern a TriplePattern to be matched against the data
* @return a ClosableIterator over all Triples in the data set that match the pattern
*/
@Override
public ExtendedIterator<Triple> find(TriplePattern pattern) {
if (graph == null) return new NullIterator<Triple>();
return graph.find(pattern.asTripleMatch());
}