AbstractStatefulFunction.java

/*
 * Copyright 2016 Christoph Böhme
 *
 * 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.api.helpers;

import org.culturegraph.mf.metamorph.api.NamedValueSource;

/**
 * Base class for functions which maintain a state between invocations.
 *
 * @author Markus Michael Geipel
 */
public abstract class AbstractStatefulFunction extends AbstractFunction {

	private int recordCount;
	private int entityCount;
	private NamedValueSource source;
	private String lastName;

	protected final int getRecordCount() {
		return recordCount;
	}

	protected final int getEntityCount() {
		return entityCount;
	}

	protected final NamedValueSource getNamedValueSource() {
		return source;
	}

	protected final String getLastName() {
		return lastName;
	}

	@Override
	public final void receive(final String name, final String value,
			final NamedValueSource source, final int recordCount,
			final int entityCount) {

		if (!sameRecord(recordCount)) {
			reset();
			this.recordCount = recordCount;
		}
		if (entityClearNeeded(entityCount)) {
			reset();
		}
		this.entityCount = entityCount;
		this.source = source;
		this.lastName = name;

		final String processedValue = process(value);
		if (processedValue == null) {
			return;
		}

		getNamedValueReceiver().receive(name, processedValue, this,
				recordCount, entityCount);
	}

	private boolean entityClearNeeded(final int entityCount) {
		return doResetOnEntityChange() && this.entityCount != entityCount;
	}

	private boolean sameRecord(final int recordCount) {
		return this.recordCount == recordCount;
	}

	protected abstract String process(String value);

	protected abstract void reset();

	protected abstract boolean doResetOnEntityChange();

}