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;
  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();
    }
  }
  