content: package org.apache.lucene.util.fst;
  
  /**
   * 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.
   */
  
  import java.io.IOException;
  
  import org.apache.lucene.store.DataInput;
  import org.apache.lucene.store.DataOutput;
  
  /**
   * Pairs up two outputs into one.
   *
   * @lucene.experimental
   */
  
  public class PairOutputs<A,B> extends Outputs<PairOutputs.Pair<A,B>> {
  
    private final Pair<A,B> NO_OUTPUT;
    private final Outputs<A> outputs1;
    private final Outputs<B> outputs2;
  
    public static class Pair<A,B> {
      public final A output1;
      public final B output2;
  
      public Pair(A output1, B output2) {
        this.output1 = output1;
        this.output2 = output2;
      }
  
      @Override @SuppressWarnings("rawtypes")
      public boolean equals(Object other) {
        if (other == this) {
          return true;
        } else if (other instanceof Pair) {
          Pair pair = (Pair) other;
          return output1.equals(pair.output1) && output2.equals(pair.output2);
        } else {
          return false;
        }
      }
  
      @Override
      public int hashCode() {
        return output1.hashCode() + output2.hashCode();
      }
    };
  
    public PairOutputs(Outputs<A> outputs1, Outputs<B> outputs2) {
      this.outputs1 = outputs1;
      this.outputs2 = outputs2;
      NO_OUTPUT = new Pair<A,B>(outputs1.getNoOutput(), outputs2.getNoOutput());
    }
    
    public Pair<A,B> get(A output1, B output2) {
      if (output1 == outputs1.getNoOutput() && output2 == outputs2.getNoOutput()) {
        return NO_OUTPUT;
      } else {
        return new Pair<A,B>(output1, output2);
      }
    }
   
    @Override
    public Pair<A,B> common(Pair<A,B> pair1, Pair<A,B> pair2) {
      return get(outputs1.common(pair1.output1, pair2.output1),
                 outputs2.common(pair1.output2, pair2.output2));
    }
  
    @Override
    public Pair<A,B> subtract(Pair<A,B> output, Pair<A,B> inc) {
      return get(outputs1.subtract(output.output1, inc.output1),
                 outputs2.subtract(output.output2, inc.output2));
    }
  
    @Override
    public Pair<A,B> add(Pair<A,B> prefix, Pair<A,B> output) {
      return get(outputs1.add(prefix.output1, output.output1),
                 outputs2.add(prefix.output2, output.output2));
    }
  
    @Override
    public void write(Pair<A,B> output, DataOutput writer) throws IOException {
      outputs1.write(output.output1, writer);
      outputs2.write(output.output2, writer);
    }
  
    @Override
    public Pair<A,B> read(DataInput in) throws IOException {
      A output1 = outputs1.read(in);
      B output2 = outputs2.read(in);
      return get(output1, output2);
    }
  
    @Override
    public Pair<A,B> getNoOutput() {
      return NO_OUTPUT;
    }
  
    @Override
    public String outputToString(Pair<A,B> output) {
      return "<pair:" + outputs1.outputToString(output.output1) + "," + outputs2.outputToString(output.output2) + ">";
    }
  }
  