opennlp.tools.util.AbstractEventStream Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 opennlp.tools.util;
import java.io.IOException;
import java.util.Collections;
import java.util.Iterator;
import opennlp.tools.ml.model.Event;
public abstract class AbstractEventStream implements ObjectStream {
private ObjectStream samples;
private Iterator events = Collections.emptyList().iterator();
/**
* Initializes the current instance with a sample {@link Iterator}.
*
* @param samples the sample {@link Iterator}.
*/
public AbstractEventStream(ObjectStream samples) {
this.samples = samples;
}
/**
* Creates events for the provided sample.
*
* @param sample the sample for which training {@link Event}s
* are be created.
*
* @return an {@link Iterator} of training events or
* an empty {@link Iterator}.
*/
protected abstract Iterator createEvents(T sample);
@Override
public final Event read() throws IOException {
if (events.hasNext()) {
return events.next();
}
else {
T sample;
while (!events.hasNext() && (sample = samples.read()) != null) {
events = createEvents(sample);
}
if (events.hasNext()) {
return read();
}
}
return null;
}
@Override
public void reset() throws IOException, UnsupportedOperationException {
events = Collections.emptyIterator();
samples.reset();
}
@Override
public void close() throws IOException {
samples.close();
}
}