import org.tupeloproject.kernel.Unifier;
import org.tupeloproject.kernel.UnionContext;
import org.tupeloproject.kernel.impl.MemoryContext;
import org.tupeloproject.rdf.Resource;
import org.tupeloproject.rdf.Triple;
import org.tupeloproject.rdf.Vocabulary;
import org.tupeloproject.util.Tuple;

public class UnifierUnion {

    static public void main(String[] args) throws Exception {
        Resource step = Resource.uriRef("tag:cet.ncsa.uiuc.edu,2008:/workflow/step/e3232672-74d0-4f97-8cc7-26d38307ff69");
        Resource tool = Resource.uriRef("tag:cet.ncsa.uiuc.edu,2008:/workflow/tool/065f168b-4604-4c68-8d72-7a71525d6c39");

        MemoryContext mc1 = new MemoryContext();
        MemoryContext mc2 = new MemoryContext();
        UnionContext uc = new UnionContext();
        uc.addChild(mc1);
        uc.addChild(mc2);

        mc1.addTriples(Triple.create(step, Vocabulary.Foaf.KNOWS, tool));
        mc2.addTriples(Triple.create(tool, Vocabulary.Foaf.NAME, "Hello"));

        Unifier uf = new Unifier();
        uf.addPattern(step, Vocabulary.Foaf.KNOWS, "x");
        uf.addPattern("x", Vocabulary.Foaf.NAME, "y");
        uf.addColumnName("x");
        uf.addColumnName("y");

        uc.perform(uf);
        for (Tuple<Resource> row : uf.getResult()) {
            System.out.println(row.toString());
        }
    }
}