net.fortytwo.sesametools.PatternIterator Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of common Show documentation

Common utilities for Sesametools

The newest version!

package net.fortytwo.sesametools;

import org.openrdf.model.IRI;
import org.openrdf.model.Resource;
import org.openrdf.model.Statement;
import org.openrdf.model.Value;
import org.openrdf.util.iterators.FilterIterator;

import java.util.Iterator;

/**
 * A FilterIterator which matches statements against a given
 * subject, predicate, object, and optional context(s).
 */
public class PatternIterator extends FilterIterator {

    private Resource subj;

    private IRI pred;

    private Value obj;

    private Resource[] contexts;

    public PatternIterator(Iterator iter, Resource subj, IRI pred, Value obj,
                           Resource... contexts) {
        super(iter);
        this.subj = subj;
        this.pred = pred;
        this.obj = obj;
        this.contexts = contexts;
    }

    @Override
    protected boolean accept(Statement st) {
        if (subj != null && !subj.equals(st.getSubject())) {
            return false;
        }
        if (pred != null && !pred.equals(st.getPredicate())) {
            return false;
        }
        if (obj != null && !obj.equals(st.getObject())) {
            return false;
        }

        if (contexts.length == 0) {
            // Any context matches
            return true;
        } else {
            // Accept if one of the contexts from the pattern matches
            Resource stContext = st.getContext();

            for (Resource context : contexts) {
                if (context == null && stContext == null) {
                    return true;
                }
                if (context != null && context.equals(stContext)) {
                    return true;
                }
            }

            return false;
        }
    }
}