Examples with RDFHandlerBase org.openrdf.rio.helpers.RDFHandlerBase used on opensource projects

Example 6 with RDFHandlerBase

use of org.openrdf.rio.helpers.RDFHandlerBase in project incubator-rya by apache.

the class InferenceEngine method getList.

/**
 * Queries for all items that are in a list of the form:
 * <pre>
 *     <:A> ?x _:bnode1 .
 *     _:bnode1 rdf:first <:B> .
 *     _:bnode1 rdf:rest _:bnode2 .
 *     _:bnode2 rdf:first <:C> .
 *     _:bnode2 rdf:rest rdf:nil .
 * </pre>
 * Where {@code :_bnode1} represents the first item in the list and
 * {@code ?x} is some restriction on {@code <:A>}. This will return the
 * list of resources, {@code [<:B>, <:C>]}.
 * @param firstItem the first item in the list.
 * @return the {@link List} of {@link Resource}s.
 * @throws QueryEvaluationException
 */
private List<Resource> getList(final URI firstItem) throws QueryEvaluationException {
    URI head = firstItem;
    final List<Resource> list = new ArrayList<>();
    // Go through and find all bnodes that are part of the defined list.
    while (!RDF.NIL.equals(head)) {
        // rdf.first will point to a type item that is in the list.
        ryaDaoQueryWrapper.queryFirst(head, RDF.FIRST, null, new RDFHandlerBase() {

            @Override
            public void handleStatement(final Statement statement) throws RDFHandlerException {
                // The object found in the query represents a type
                // that should be included in the list.
                final URI object = (URI) statement.getObject();
                list.add(object);
            }
        });
        final MutableObject<URI> headHolder = new MutableObject<>();
        // rdf.rest will point to the next bnode that's part of the list.
        ryaDaoQueryWrapper.queryFirst(head, RDF.REST, null, new RDFHandlerBase() {

            @Override
            public void handleStatement(final Statement statement) throws RDFHandlerException {
                // This object is the next bnode head to look for.
                final URI object = (URI) statement.getObject();
                headHolder.setValue(object);
            }
        });
        // of the list. Keep going until we reach rdf.nil.
        if (headHolder.getValue() != null) {
            head = headHolder.getValue();
        } else {
            head = RDF.NIL;
        }
    }
    return list;
}

Example 7 with RDFHandlerBase

use of org.openrdf.rio.helpers.RDFHandlerBase in project incubator-rya by apache.

the class InferenceEngine method refreshOneOf.

private void refreshOneOf() throws QueryEvaluationException {
    final Map<Resource, Set<Resource>> enumTypes = new HashMap<>();
    // First query for all the owl:oneOf's.
    // If we have the following oneOf:
    // :A owl:oneOf (:B, :C)
    // It will be represented by triples following a pattern similar to:
    // <:A> owl:oneOf _:bnode1 .
    // _:bnode1 rdf:first <:B> .
    // _:bnode1 rdf:rest _:bnode2 .
    // _:bnode2 rdf:first <:C> .
    // _:bnode2 rdf:rest rdf:nil .
    ryaDaoQueryWrapper.queryAll(null, OWL.ONEOF, null, new RDFHandlerBase() {

        @Override
        public void handleStatement(final Statement statement) throws RDFHandlerException {
            final Resource enumType = statement.getSubject();
            // listHead will point to a type class of the enumeration.
            final URI listHead = (URI) statement.getObject();
            if (!enumTypes.containsKey(enumType)) {
                enumTypes.put(enumType, new LinkedHashSet<Resource>());
            }
            // enumeration.
            try {
                final Set<Resource> enumeration = new LinkedHashSet<>(getList(listHead));
                if (!enumeration.isEmpty()) {
                    // Add this enumeration for this type.
                    enumTypes.get(enumType).addAll(enumeration);
                }
            } catch (final QueryEvaluationException e) {
                throw new RDFHandlerException("Error getting enumeration list.", e);
            }
        }
    });
    synchronized (enumerations) {
        enumerations.clear();
        enumerations.putAll(enumTypes);
    }
}