opennlp-tools/src/main/java/opennlp/tools/ml/model/SequenceStreamEventStream.java

/*
 * 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.ml.model;

import java.io.IOException;
import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;

import opennlp.tools.util.ObjectStream;

/**
 * Class which turns a sequence stream into an event stream.
 */
public class SequenceStreamEventStream implements ObjectStream<Event> {

  private final SequenceStream sequenceStream;

  private Iterator<Event> eventIt = Collections.emptyListIterator();

  public SequenceStreamEventStream(SequenceStream sequenceStream) {
    this.sequenceStream = sequenceStream;
  }

  @Override
  public Event read() throws IOException {
    while (!eventIt.hasNext()) {
      Sequence<?> sequence = sequenceStream.read();
      if (sequence == null) {
        return null;
      }
      eventIt = Arrays.asList(sequence.getEvents()).iterator();
    }
    return eventIt.next();
  }

  @Override
  public void reset() throws IOException, UnsupportedOperationException {
    eventIt = Collections.emptyListIterator();
    sequenceStream.reset();
  }

  @Override
  public void close() throws IOException {
    eventIt = Collections.emptyListIterator();
    sequenceStream.close();
  }
}