content: package org.apache.lucene.index;
  
  /**
   * 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 java.util.Map;
  
  /**
   * A {@link MergePolicy} which never returns merges to execute (hence it's
   * name). It is also a singleton and can be accessed through
   * {@link NoMergePolicy#NO_COMPOUND_FILES} if you want to indicate the index
   * does not use compound files, or through {@link NoMergePolicy#COMPOUND_FILES}
   * otherwise. Use it if you want to prevent an {@link IndexWriter} from ever
   * executing merges, without going through the hassle of tweaking a merge
   * policy's settings to achieve that, such as changing its merge factor.
   */
  public final class NoMergePolicy extends MergePolicy {
  
    /**
     * A singleton {@link NoMergePolicy} which indicates the index does not use
     * compound files.
     */
    public static final MergePolicy NO_COMPOUND_FILES = new NoMergePolicy(false);
  
    /**
     * A singleton {@link NoMergePolicy} which indicates the index uses compound
     * files.
     */
    public static final MergePolicy COMPOUND_FILES = new NoMergePolicy(true);
  
    private final boolean useCompoundFile;
    
    private NoMergePolicy(boolean useCompoundFile) {
      // prevent instantiation
      this.useCompoundFile = useCompoundFile;
    }
  
    @Override
    public void close() {}
  
    @Override
    public MergeSpecification findMerges(SegmentInfos segmentInfos)
        throws CorruptIndexException, IOException { return null; }
  
    @Override
    public MergeSpecification findForcedMerges(SegmentInfos segmentInfos,
               int maxSegmentCount, Map<SegmentInfo,Boolean> segmentsToMerge)
        throws CorruptIndexException, IOException { return null; }
  
    @Override
    public MergeSpecification findForcedDeletesMerges(SegmentInfos segmentInfos)
        throws CorruptIndexException, IOException { return null; }
  
    @Override
    public boolean useCompoundFile(SegmentInfos segments, SegmentInfo newSegment) { return useCompoundFile; }
  
    @Override
    public void setIndexWriter(IndexWriter writer) {}
  
    @Override
    public String toString() {
      return "NoMergePolicy";
    }
  }
  