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Lucene example source code file (IntSequenceOutputs.java)

This example Lucene source code file (IntSequenceOutputs.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, intsequenceoutputs, intsequenceoutputs, intsref, intsref, io, ioexception, no_output, no_output, outputs, override, override, string

The Lucene IntSequenceOutputs.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;
import org.apache.lucene.util.IntsRef;

/**
 * Output is a sequence of ints, for each input term.
 *
 * @lucene.experimental
 */

public final class IntSequenceOutputs extends Outputs<IntsRef> {

  private final static IntsRef NO_OUTPUT = new IntsRef();

  private IntSequenceOutputs() {
  }

  public static IntSequenceOutputs getSingleton() {
    return new IntSequenceOutputs();
  }

  @Override
  public IntsRef common(IntsRef output1, IntsRef output2) {
    assert output1 != null;
    assert output2 != null;

    int pos1 = output1.offset;
    int pos2 = output2.offset;
    int stopAt1 = pos1 + Math.min(output1.length, output2.length);
    while(pos1 < stopAt1) {
      if (output1.ints[pos1] != output2.ints[pos2]) {
        break;
      }
      pos1++;
      pos2++;
    }

    if (pos1 == output1.offset) {
      // no common prefix
      return NO_OUTPUT;
    } else if (pos1 == output1.offset + output1.length) {
      // output1 is a prefix of output2
      return output1;
    } else if (pos2 == output2.offset + output2.length) {
      // output2 is a prefix of output1
      return output2;
    } else {
      return new IntsRef(output1.ints, output1.offset, pos1-output1.offset);
    }
  }

  @Override
  public IntsRef subtract(IntsRef output, IntsRef inc) {
    assert output != null;
    assert inc != null;
    if (inc == NO_OUTPUT) {
      // no prefix removed
      return output;
    } else if (inc.length == output.length) {
      // entire output removed
      return NO_OUTPUT;
    } else {
      assert inc.length < output.length: "inc.length=" + inc.length + " vs output.length=" + output.length;
      assert inc.length > 0;
      return new IntsRef(output.ints, output.offset + inc.length, output.length-inc.length);
    }
  }

  @Override
  public IntsRef add(IntsRef prefix, IntsRef output) {
    assert prefix != null;
    assert output != null;
    if (prefix == NO_OUTPUT) {
      return output;
    } else if (output == NO_OUTPUT) {
      return prefix;
    } else {
      assert prefix.length > 0;
      assert output.length > 0;
      IntsRef result = new IntsRef(prefix.length + output.length);
      System.arraycopy(prefix.ints, prefix.offset, result.ints, 0, prefix.length);
      System.arraycopy(output.ints, output.offset, result.ints, prefix.length, output.length);
      result.length = prefix.length + output.length;
      return result;
    }
  }

  @Override
  public void write(IntsRef prefix, DataOutput out) throws IOException {
    assert prefix != null;
    out.writeVInt(prefix.length);
    for(int idx=0;idx<prefix.length;idx++) {
      out.writeVInt(prefix.ints[prefix.offset+idx]);
    }
  }

  @Override
  public IntsRef read(DataInput in) throws IOException {
    final int len = in.readVInt();
    if (len == 0) {
      return NO_OUTPUT;
    } else {
      final IntsRef output = new IntsRef(len);
      for(int idx=0;idx<len;idx++) {
        output.ints[idx] = in.readVInt();
      }
      output.length = len;
      return output;
    }
  }

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

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

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