Examples with Statement org.eclipse.rdf4j.model.Statement used on opensource projects

Example 21 with Statement

use of org.eclipse.rdf4j.model.Statement in project rdf4j by eclipse.

the class Models method findMatchingStatements.

private static List<Statement> findMatchingStatements(Statement st, Model model, Map<Resource, Resource> bNodeMapping) {
    Resource s = isBlank(st.getSubject()) ? null : st.getSubject();
    IRI p = st.getPredicate();
    Value o = isBlank(st.getObject()) ? null : st.getObject();
    Resource[] g = isBlank(st.getContext()) ? new Resource[0] : new Resource[] { st.getContext() };
    List<Statement> result = new ArrayList<Statement>();
    for (Statement modelSt : model.filter(s, p, o, g)) {
        if (statementsMatch(st, modelSt, bNodeMapping)) {
            // All components possibly match
            result.add(modelSt);
        }
    }
    return result;
}

Example 22 with Statement

use of org.eclipse.rdf4j.model.Statement in project rdf4j by eclipse.

the class Models method matchModels.

/**
 * A recursive method for finding a complete mapping between blank nodes in model1 and blank nodes in
 * model2. The algorithm does a depth-first search trying to establish a mapping for each blank node
 * occurring in model1.
 *
 * @param model1
 * @param model2
 * @param bNodeMapping
 * @param idx
 * @return true if a complete mapping has been found, false otherwise.
 */
private static boolean matchModels(List<? extends Statement> model1, Model model2, Map<Resource, Resource> bNodeMapping, int idx) {
    boolean result = false;
    if (idx < model1.size()) {
        Statement st1 = model1.get(idx);
        List<Statement> matchingStats = findMatchingStatements(st1, model2, bNodeMapping);
        for (Statement st2 : matchingStats) {
            // Map bNodes in st1 to bNodes in st2
            Map<Resource, Resource> newBNodeMapping = new HashMap<Resource, Resource>(bNodeMapping);
            if (isBlank(st1.getSubject()) && isBlank(st2.getSubject())) {
                newBNodeMapping.put(st1.getSubject(), st2.getSubject());
            }
            if (isBlank(st1.getObject()) && isBlank(st2.getObject())) {
                newBNodeMapping.put((Resource) st1.getObject(), (Resource) st2.getObject());
            }
            if (isBlank(st1.getContext()) && isBlank(st2.getContext())) {
                newBNodeMapping.put(st1.getContext(), st2.getContext());
            }
            // FIXME: this recursive implementation has a high risk of
            // triggering a stack overflow
            // Enter recursion
            result = matchModels(model1, model2, newBNodeMapping, idx + 1);
            if (result == true) {
                // models match, look no further
                break;
            }
        }
    } else {
        // All statements have been mapped successfully
        result = true;
    }
    return result;
}

Example 23 with Statement

use of org.eclipse.rdf4j.model.Statement in project rdf4j by eclipse.

the class RDFCollections method extract.

/**
 * Extracts an RDF Collection starting with the supplied list head from the statement supplier and sends
 * all statements that make up the collection to the supplied {@link Consumer} function. This method
 * expects the RDF Collection to be well-formed. If the collection is not well-formed the method may
 * report only part of the collection, or may throw an exception.
 *
 * @param statementSupplier
 *        the source of the statements from which the RDF collection is to be read, specified as a
 *        functional interface.
 * @param head
 *        the {@link Resource} that represents the list head, that is the start resource of the RDF
 *        Collection to be read. May not be {@code null}.
 * @param collectionConsumer
 *        the Java {@link Consumer} function to which the collection statements are reported.
 * @param exceptionSupplier
 *        a functional interface that produces the exception type this method will throw when an error
 *        occurs.
 * @param contexts
 *        the context(s) from which to read the RDF Collection. This argument is an optional vararg and
 *        can be left out.
 * @throws E
 *         if a problem occurs reading the RDF Collection, for example if it is not well-formed.
 */
public static <E extends RDF4JException> void extract(GetStatementOptional statementSupplier, Resource head, Consumer<Statement> collectionConsumer, Function<String, Supplier<E>> exceptionSupplier, Resource... contexts) throws E {
    OpenRDFUtil.verifyContextNotNull(contexts);
    Objects.requireNonNull(head, "list head may not be null");
    Objects.requireNonNull(collectionConsumer, "collection consumer may not be null");
    Resource current = head;
    final Set<Resource> visited = new HashSet<>();
    while (!RDF.NIL.equals(current)) {
        if (visited.contains(current)) {
            throw exceptionSupplier.apply("list not well-formed: cycle detected").get();
        }
        statementSupplier.get(current, RDF.TYPE, RDF.LIST, contexts).ifPresent(collectionConsumer);
        collectionConsumer.accept(statementSupplier.get(current, RDF.FIRST, null, contexts).orElseThrow(exceptionSupplier.apply("list not wellformed: rdf:first statement missing.")));
        Statement next = statementSupplier.get(current, RDF.REST, null, contexts).orElseThrow(exceptionSupplier.apply("list not well-formed: rdf:rest statement missing."));
        collectionConsumer.accept(next);
        if (!(next.getObject() instanceof Resource)) {
            throw exceptionSupplier.apply("list not well-formed: value of rdf:rest should be one of (IRI, BNode).").get();
        }
        visited.add(current);
        current = (Resource) next.getObject();
    }
}

Example 24 with Statement

use of org.eclipse.rdf4j.model.Statement in project rdf4j by eclipse.

the class RDFXMLHandlingTest method writeRDFXML.

/**
 * Helper method to write the given model to RDFXML and return an InputStream containing the results.
 *
 * @param statements
 * @return An {@link InputStream} containing the results.
 * @throws RDFHandlerException
 */
private InputStream writeRDFXML(Model statements) throws RDFHandlerException {
    StringWriter writer = new StringWriter();
    RDFWriter rdfxmlWriter = new RDFXMLWriter(writer);
    rdfxmlWriter.startRDF();
    for (Statement nextStatement : statements) {
        rdfxmlWriter.handleStatement(nextStatement);
    }
    rdfxmlWriter.endRDF();
    return new ByteArrayInputStream(writer.toString().getBytes(Charset.forName("UTF-8")));
}

Example 25 with Statement

use of org.eclipse.rdf4j.model.Statement in project rdf4j by eclipse.

the class TreeModel method pollFirst.

public Statement pollFirst() {
    try {
        Statement first = trees.get(0).tree.first();
        remove(first);
        return first;
    } catch (NoSuchElementException e) {
        return null;
    }
}