TripleFilter.java

/*
 * Copyright 2013, 2014 Deutsche Nationalbibliothek
 *
 * Licensed under the Apache License, Version 2.0 the "License";
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.culturegraph.mf.triples;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.culturegraph.mf.framework.FluxCommand;
import org.culturegraph.mf.framework.ObjectReceiver;
import org.culturegraph.mf.framework.annotations.Description;
import org.culturegraph.mf.framework.annotations.In;
import org.culturegraph.mf.framework.annotations.Out;
import org.culturegraph.mf.framework.helpers.DefaultObjectPipe;
import org.culturegraph.mf.framework.objects.Triple;

/**
 * Filters triples. The patterns for subject, predicate and object are disjunctive.
 *
 * @author Christoph Böhme
 *
 */
@Description("Filters triple. The  patterns for subject, predicate and object are disjunctive.")
@In(Triple.class)
@Out(Triple.class)
@FluxCommand("filter-triples")
public final class TripleFilter extends
		DefaultObjectPipe<Triple, ObjectReceiver<Triple>> {

	// A regexp that is guaranteed to never match ( an `a` after the end
	// of the string, see http://stackoverflow.com/a/1723225 for details):
	private static final Matcher MATCH_NOTHING = Pattern.compile("$a").matcher("");

	private Matcher subjectMatcher = MATCH_NOTHING;
	private Matcher predicateMatcher = MATCH_NOTHING;
	private Matcher objectMatcher = MATCH_NOTHING;
	private boolean passMatches = true;

	public String getSubjectPattern() {
		return subjectMatcher.pattern().pattern();
	}

	public void setSubjectPattern(final String pattern) {
		subjectMatcher = Pattern.compile(pattern).matcher("");
	}

	public String getPredicatePattern() {
		return predicateMatcher.pattern().pattern();
	}

	public void setPredicatePattern(final String pattern) {
		predicateMatcher = Pattern.compile(pattern).matcher("");
	}

	public String getObjectPattern() {
		return objectMatcher.pattern().pattern();
	}

	public void setObjectPattern(final String pattern) {
		objectMatcher = Pattern.compile(pattern).matcher("");
	}

	public boolean isPassMatches() {
		return passMatches;
	}

	public void setPassMatches(final boolean passMatches) {
		this.passMatches = passMatches;
	}

	@Override
	public void process(final Triple obj) {
		subjectMatcher.reset(obj.getSubject());
		predicateMatcher.reset(obj.getPredicate());
		objectMatcher.reset(obj.getObject());

		final boolean matches = subjectMatcher.matches() || predicateMatcher.matches() || objectMatcher.matches();

		if ((matches && passMatches) || (!matches && !passMatches)) {
			getReceiver().process(obj);
		}
	}

}