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

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package net.fortytwo.sesametools;

import java.util.Iterator;

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

public class PatternIterator extends FilterIterator {

	private Resource subj;

	private URI pred;

	private Value obj;

	private Resource[] contexts;

	public PatternIterator(Iterator iter, Resource subj, URI 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;
		}
	}
}