Lucene example source code file (PairOutputs.java)

This example Lucene source code file (PairOutputs.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Lucene tags/keywords

a, b, b, dataoutput, io, ioexception, no_output, no_output, outputs, override, override, pair, pair, pairoutputs, string

The Lucene PairOutputs.java source code

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> {

  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 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 pair1, Pair pair2) {
    return get(outputs1.common(pair1.output1, pair2.output1),
               outputs2.common(pair1.output2, pair2.output2));
  }

  @Override
  public Pair<A,B> subtract(Pair output, Pair inc) {
    return get(outputs1.subtract(output.output1, inc.output1),
               outputs2.subtract(output.output2, inc.output2));
  }

  @Override
  public Pair<A,B> add(Pair prefix, Pair 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) + ">";
  }
}