org.aksw.jenax.sparql.fragment.api.Fragment3 Maven / Gradle / Ivy

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package org.aksw.jenax.sparql.fragment.api;

import java.util.List;

import org.aksw.jenax.arq.util.syntax.ElementUtils;
import org.aksw.jenax.sparql.fragment.impl.Fragment3Impl;
import org.apache.jena.graph.Node;
import org.apache.jena.sparql.core.Var;
import org.apache.jena.sparql.expr.E_Equals;
import org.apache.jena.sparql.expr.ExprVar;
import org.apache.jena.sparql.expr.NodeValue;
import org.apache.jena.sparql.syntax.Element;
import org.apache.jena.sparql.syntax.ElementFilter;

public interface Fragment3
    extends Fragment
{
    Var getS();
    Var getP();
    Var getO();

    /**
     * TODO Make the API more generic to filter on arbitrary variables
     * Something like relation.p().filter(...)
     *
     * @param node
     * @return
     */
    default Fragment3 filterP(Node node) {
        Element element = getElement();
        Var s = getS();
        Var p = getP();
        Var o = getO();

        List es = ElementUtils.toElementList(element);
        es.add(new ElementFilter(new E_Equals(new ExprVar(p), NodeValue.makeNode(node))));
        Fragment3 result = new Fragment3Impl(ElementUtils.groupIfNeeded(es), s, p, o);
        return result;
    }
}