lucene/core/src/java/org/apache/lucene/codecs/PointsFormat.java

/*
 * 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.
 */
package org.apache.lucene.codecs;

import java.io.IOException;
import org.apache.lucene.index.PointValues;
import org.apache.lucene.index.SegmentReadState;
import org.apache.lucene.index.SegmentWriteState;

/**
 * Encodes/decodes indexed points.
 *
 * @lucene.experimental
 */
public abstract class PointsFormat {

  /** Creates a new point format. */
  protected PointsFormat() {}

  /** Writes a new segment */
  public abstract PointsWriter fieldsWriter(SegmentWriteState state) throws IOException;

  /**
   * Reads a segment. NOTE: by the time this call returns, it must hold open any files it will need
   * to use; else, those files may be deleted. Additionally, required files may be deleted during
   * the execution of this call before there is a chance to open them. Under these circumstances an
   * IOException should be thrown by the implementation. IOExceptions are expected and will
   * automatically cause a retry of the segment opening logic with the newly revised segments.
   */
  public abstract PointsReader fieldsReader(SegmentReadState state) throws IOException;

  /** A {@code PointsFormat} that has nothing indexed */
  public static final PointsFormat EMPTY =
      new PointsFormat() {
        @Override
        public PointsWriter fieldsWriter(SegmentWriteState state) {
          throw new UnsupportedOperationException();
        }

        @Override
        public PointsReader fieldsReader(SegmentReadState state) {
          return new PointsReader() {
            @Override
            public void close() {}

            @Override
            public long ramBytesUsed() {
              return 0L;
            }

            @Override
            public void checkIntegrity() {}

            @Override
            public PointValues getValues(String field) {
              throw new IllegalArgumentException(
                  "field=\"" + field + "\" was not indexed with points");
            }
          };
        }
      };
}