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Lucene example source code file (PositiveIntOutputs.java)

This example Lucene source code file (PositiveIntOutputs.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

dataoutput, io, ioexception, long, long, no_output, no_output, outputs, override, override, positiveintoutputs, positiveintoutputs, string

The Lucene PositiveIntOutputs.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;

/**
 * Output is a long, for each input term.  NOTE: the
 * resulting FST is not guaranteed to be minimal!  See
 * {@link Builder}.  You cannot store 0 output with this
 * (that's reserved to mean "no output")!
 *
 * @lucene.experimental
 */

public final class PositiveIntOutputs extends Outputs<Long> {
  
  private final static Long NO_OUTPUT = new Long(0);

  private final boolean doShare;

  private final static PositiveIntOutputs singletonShare = new PositiveIntOutputs(true);
  private final static PositiveIntOutputs singletonNoShare = new PositiveIntOutputs(false);

  private PositiveIntOutputs(boolean doShare) {
    this.doShare = doShare;
  }

  public static PositiveIntOutputs getSingleton(boolean doShare) {
    return doShare ? singletonShare : singletonNoShare;
  }

  public Long get(long v) {
    if (v == 0) {
      return NO_OUTPUT;
    } else {
      return Long.valueOf(v);
    }
  }

  @Override
  public Long common(Long output1, Long output2) {
    assert valid(output1);
    assert valid(output2);
    if (output1 == NO_OUTPUT || output2 == NO_OUTPUT) {
      return NO_OUTPUT;
    } else if (doShare) {
      assert output1 > 0;
      assert output2 > 0;
      return Math.min(output1, output2);
    } else if (output1.equals(output2)) {
      return output1;
    } else {
      return NO_OUTPUT;
    }
  }

  @Override
  public Long subtract(Long output, Long inc) {
    assert valid(output);
    assert valid(inc);
    assert output >= inc;

    if (inc == NO_OUTPUT) {
      return output;
    } else if (output.equals(inc)) {
      return NO_OUTPUT;
    } else {
      return output - inc;
    }
  }

  @Override
  public Long add(Long prefix, Long output) {
    assert valid(prefix);
    assert valid(output);
    if (prefix == NO_OUTPUT) {
      return output;
    } else if (output == NO_OUTPUT) {
      return prefix;
    } else {
      return prefix + output;
    }
  }

  @Override
  public void write(Long output, DataOutput out) throws IOException {
    assert valid(output);
    out.writeVLong(output);
  }

  @Override
  public Long read(DataInput in) throws IOException {
    long v = in.readVLong();
    if (v == 0) {
      return NO_OUTPUT;
    } else {
      return v;
    }
  }

  private boolean valid(Long o) {
    assert o != null;
    assert o instanceof Long;
    assert o == NO_OUTPUT || o > 0;
    return true;
  }

  @Override
  public Long getNoOutput() {
    return NO_OUTPUT;
  }

  @Override
  public String outputToString(Long output) {
    return output.toString();
  }
}

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