Examples with VariableGenerator fr.lirmm.graphik.graal.api.core.VariableGenerator used on opensource projects

Example 1 with VariableGenerator

use of fr.lirmm.graphik.graal.api.core.VariableGenerator in project graal by graphik-team.

the class RdbmsAtomIterator method hasNext.

// /////////////////////////////////////////////////////////////////////////
// METHODS
// /////////////////////////////////////////////////////////////////////////
@Override
public boolean hasNext() throws IteratorException {
    if (!this.hasNextCallDone) {
        this.hasNextCallDone = true;
        while (this.predicateIt.hasNext() && (this.atomIt == null || !this.atomIt.hasNext())) {
            Predicate p = predicateIt.next();
            List<Term> terms = new LinkedList<Term>();
            VariableGenerator gen = new DefaultVariableGenerator("X");
            for (int i = 0; i < p.getArity(); ++i) {
                terms.add(gen.getFreshSymbol());
            }
            InMemoryAtomSet atomSet = new LinkedListAtomSet();
            Atom atom = new DefaultAtom(p, terms);
            atomSet.add(atom);
            ConjunctiveQuery query = DefaultConjunctiveQueryFactory.instance().create(atomSet);
            SqlHomomorphism solver = SqlHomomorphism.instance();
            try {
                this.atomIt = new SubstitutionIterator2AtomIterator(atom, solver.execute(query, this.store));
            } catch (HomomorphismException e) {
                throw new IteratorException(e);
            }
        }
    }
    return this.atomIt != null && this.atomIt.hasNext();
}