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.
   */
  
  class ReadOnlySegmentReader extends SegmentReader {
  
    static void noWrite() {
      throw new UnsupportedOperationException("This IndexReader cannot make any changes to the index (it was opened with readOnly = true)");
    }
    
    @Override
    protected void acquireWriteLock() {
      noWrite();
    }
  
    // Not synchronized
    @Override
    public boolean isDeleted(int n) {
      return deletedDocs != null && deletedDocs.get(n);
    }
  }
  