Examples with ServiceNode com.bigdata.rdf.sparql.ast.service.ServiceNode used on opensource projects

Example 6 with ServiceNode

use of com.bigdata.rdf.sparql.ast.service.ServiceNode in project wikidata-query-rdf by wikimedia.

the class GeoService method getPatternNode.

/**
 * Extract pattern node from parameters.
 *
 * Pattern node looks like:
 *  ?place wdt:P625 ?location .
 * Both variables would be bound by the service.
 */
protected StatementPatternNode getPatternNode(ServiceCallCreateParams params) {
    ServiceNode serviceNode = params.getServiceNode();
    if (serviceNode == null)
        throw new IllegalArgumentException();
    List<StatementPatternNode> patterns = getStatementPatterns(serviceNode);
    if (patterns.isEmpty()) {
        throw new IllegalArgumentException("This service requires arguments");
    }
    StatementPatternNode pattern = patterns.get(0);
    if (pattern == null) {
        throw new IllegalArgumentException();
    }
    if (!pattern.s().isVariable()) {
        throw new IllegalArgumentException("Search pattern subject must be a variable");
    }
    if (!pattern.p().isConstant()) {
        // FIXME: may be not necessary?
        throw new IllegalArgumentException("Search pattern predicate must be a constant");
    }
    if (!pattern.o().isVariable()) {
        throw new IllegalArgumentException("Search pattern object must be a variable");
    }
    return pattern;
}