Examples with BindingSet org.eclipse.rdf4j.query.BindingSet used on opensource projects

Example 6 with BindingSet

use of org.eclipse.rdf4j.query.BindingSet in project rdf4j by eclipse.

the class MutableTupleQueryResult method previous.

public BindingSet previous() {
    if (hasPrevious()) {
        BindingSet result = bindingSets.get(currentIndex - 1);
        currentIndex--;
        lastReturned = currentIndex;
        return result;
    }
    throw new NoSuchElementException();
}

Example 7 with BindingSet

use of org.eclipse.rdf4j.query.BindingSet in project rdf4j by eclipse.

the class AbstractHTTPUpdate method getBindingsArray.

public Binding[] getBindingsArray() {
    BindingSet bindings = this.getBindings();
    Binding[] bindingsArray = new Binding[bindings.size()];
    Iterator<Binding> iter = bindings.iterator();
    for (int i = 0; i < bindings.size(); i++) {
        bindingsArray[i] = iter.next();
    }
    return bindingsArray;
}

Example 8 with BindingSet

use of org.eclipse.rdf4j.query.BindingSet in project rdf4j by eclipse.

the class RepositoryFederatedService method evaluateInternal.

/**
 * Evaluate the SPARQL query that can be constructed from the SERVICE node at the initialized
 * {@link Repository} of this {@link FederatedService}. Use specified bindings as constraints to the
 * query. Try to evaluate using BINDINGS clause, if this yields an exception fall back to the naive
 * implementation. This method deals with SILENT SERVICEs.
 */
protected CloseableIteration<BindingSet, QueryEvaluationException> evaluateInternal(Service service, CloseableIteration<BindingSet, QueryEvaluationException> bindings, String baseUri) throws QueryEvaluationException {
    // materialize all bindings (to allow for fallback in case of errors)
    // note that this may be blocking depending on the underlying iterator
    List<BindingSet> allBindings = new LinkedList<BindingSet>();
    while (bindings.hasNext()) {
        allBindings.add(bindings.next());
    }
    if (allBindings.size() == 0) {
        return new EmptyIteration<BindingSet, QueryEvaluationException>();
    }
    // projection vars
    Set<String> projectionVars = new HashSet<String>(service.getServiceVars());
    projectionVars.removeAll(allBindings.get(0).getBindingNames());
    // below we need to take care for SILENT services
    CloseableIteration<BindingSet, QueryEvaluationException> result = null;
    try {
        // fallback to simple evaluation (just a single binding)
        if (allBindings.size() == 1) {
            result = select(service, projectionVars, allBindings.get(0), baseUri);
            result = service.isSilent() ? new SilentIteration(result) : result;
            return result;
        }
        // To be able to insert the input bindings again later on, we need some
        // means to identify the row of each binding. hence, we use an
        // additional
        // projection variable, which is also passed in the BINDINGS clause
        // with the value of the actual row. The value corresponds to the index
        // of the binding in the index list
        projectionVars.add("__rowIdx");
        String queryString = service.getSelectQueryString(projectionVars);
        List<String> relevantBindingNames = getRelevantBindingNames(allBindings, service.getServiceVars());
        if (relevantBindingNames.size() != 0) {
            // append the VALUES clause to the query
            queryString += buildVALUESClause(allBindings, relevantBindingNames);
        }
        TupleQuery query = getConnection().prepareTupleQuery(QueryLanguage.SPARQL, queryString, baseUri);
        TupleQueryResult res = null;
        // TODO how to retrieve max query value
        query.setMaxQueryTime(60);
        // from actual setting?
        res = query.evaluate();
        if (relevantBindingNames.size() == 0)
            // cross
            result = new SPARQLCrossProductIteration(res, allBindings);
        else
            // product
            // common
            result = new ServiceJoinConversionIteration(res, allBindings);
        // join
        result = service.isSilent() ? new SilentIteration(result) : result;
        return result;
    } catch (RepositoryException e) {
        Iterations.closeCloseable(result);
        if (service.isSilent())
            return new CollectionIteration<BindingSet, QueryEvaluationException>(allBindings);
        throw new QueryEvaluationException("Repository for endpoint " + rep.toString() + " could not be initialized.", e);
    } catch (MalformedQueryException e) {
        // this exception must not be silenced, bug in our code
        throw new QueryEvaluationException(e);
    } catch (QueryEvaluationException e) {
        Iterations.closeCloseable(result);
        if (service.isSilent())
            return new CollectionIteration<BindingSet, QueryEvaluationException>(allBindings);
        throw e;
    } catch (RuntimeException e) {
        Iterations.closeCloseable(result);
        // QueryEval) if silent
        if (service.isSilent())
            return new CollectionIteration<BindingSet, QueryEvaluationException>(allBindings);
        throw e;
    }
}

Example 9 with BindingSet

use of org.eclipse.rdf4j.query.BindingSet in project rdf4j by eclipse.

the class RepositoryFederatedService method buildVALUESClause.

/**
 * Computes the VALUES clause for the set of relevant input bindings. The VALUES clause is attached to a
 * subquery for block-nested-loop evaluation. Implementation note: we use a special binding to mark the
 * rowIndex of the input binding.
 *
 * @param bindings
 * @param relevantBindingNames
 * @return a string with the VALUES clause for the given set of relevant input bindings
 * @throws QueryEvaluationException
 */
private String buildVALUESClause(List<BindingSet> bindings, List<String> relevantBindingNames) throws QueryEvaluationException {
    StringBuilder sb = new StringBuilder();
    // __rowIdx: see comment in evaluate()
    sb.append(" VALUES (?__rowIdx");
    for (String bName : relevantBindingNames) {
        sb.append(" ?").append(bName);
    }
    sb.append(") { ");
    int rowIdx = 0;
    for (BindingSet b : bindings) {
        sb.append(" (");
        // identification of
        sb.append("\"").append(rowIdx++).append("\" ");
        // processing
        for (String bName : relevantBindingNames) {
            QueryStringUtil.appendValueAsString(sb, b.getValue(bName)).append(" ");
        }
        sb.append(")");
    }
    sb.append(" }");
    return sb.toString();
}

Example 10 with BindingSet

use of org.eclipse.rdf4j.query.BindingSet in project rdf4j by eclipse.

the class HTTPRepository method isWritable.

@Override
public boolean isWritable() throws RepositoryException {
    if (!isInitialized()) {
        throw new IllegalStateException("HTTPRepository not initialized.");
    }
    boolean isWritable = false;
    try (RDF4JProtocolSession client = createHTTPClient()) {
        final String repositoryURL = client.getRepositoryURL();
        final TupleQueryResult repositoryList = client.getRepositoryList();
        try {
            while (repositoryList.hasNext()) {
                final BindingSet bindingSet = repositoryList.next();
                final Value uri = bindingSet.getValue("uri");
                if (uri != null && uri.stringValue().equals(repositoryURL)) {
                    isWritable = Literals.getBooleanValue(bindingSet.getValue("writable"), false);
                    break;
                }
            }
        } finally {
            repositoryList.close();
        }
    } catch (QueryEvaluationException e) {
        throw new RepositoryException(e);
    } catch (IOException e) {
        throw new RepositoryException(e);
    }
    return isWritable;
}