Tuples.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.metamorph.collectors;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import org.culturegraph.mf.commons.types.ListMap;
import org.culturegraph.mf.metamorph.api.NamedValueSource;
import org.culturegraph.mf.metamorph.api.helpers.AbstractFlushingCollect;

/**
 * Builds the cross product of the data sources.
 *
 * @author Markus Michael Geipel
 *
 */
public final class Tuples extends AbstractFlushingCollect {

	private final ListMap<String, String> listMap = new ListMap<String, String>();
	private int minN = 1;
	private String separator = "";

	public void setMinN(final int minN) {
		this.minN = minN;
	}

	public void setSeparator(final String separator) {
		this.separator = separator;
	}

	@Override
	protected void receive(final String name, final String value,
			final NamedValueSource source) {
		listMap.add(name, value);
	}

	@Override
	protected boolean isComplete() {
		return false;
	}

	@Override
	protected void clear() {
		listMap.clear();

	}

	@Override
	protected void emit() {

		if (listMap.size() < minN) {
			return;
		}
		final List<String> keys = new ArrayList<String>();
		keys.addAll(listMap.keySet());
		Collections.sort(keys);

		List<String> temp = new ArrayList<String>();
		List<String> nextTemp = new ArrayList<String>();
		temp.add("");

		for (final String key : keys) {
			final List<String> values = listMap.get(key);
			nextTemp = new ArrayList<String>(temp.size() * values.size());
			for (final String value : values) {
				for (final String base : temp) {
					nextTemp.add(base + separator + value);
				}
			}
			temp = nextTemp;
		}

		for (final String string : temp) {
			getNamedValueReceiver().receive(getName(),
					string.substring(separator.length()), this,
					getRecordCount(), getEntityCount());
		}
		clear();
	}

}