content: /*
   * 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.arrow.vector.dictionary;
  
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Set;
  import org.apache.arrow.memory.BufferAllocator;
  import org.apache.arrow.util.VisibleForTesting;
  
  /** A manager for association of dictionary IDs to their corresponding {@link Dictionary}. */
  public interface DictionaryProvider {
  
    /** Return the dictionary for the given ID. */
    Dictionary lookup(long id);
  
    /** Get all dictionary IDs. */
    Set<Long> getDictionaryIds();
  
    /** Implementation of {@link DictionaryProvider} that is backed by a hash-map. */
    class MapDictionaryProvider implements AutoCloseable, DictionaryProvider {
  
      private final Map<Long, Dictionary> map;
  
      /** Constructs a new instance from the given dictionaries. */
      public MapDictionaryProvider(Dictionary... dictionaries) {
        this.map = new HashMap<>();
        for (Dictionary dictionary : dictionaries) {
          put(dictionary);
        }
      }
  
      /**
       * Initialize the map structure from another provider, but with empty vectors.
       *
       * @param other the {@link DictionaryProvider} to copy the ids and fields from
       * @param allocator allocator to create the empty vectors
       */
      // This is currently called using JPype by the integration tests.
      @VisibleForTesting
      public void copyStructureFrom(DictionaryProvider other, BufferAllocator allocator) {
        for (Long id : other.getDictionaryIds()) {
          Dictionary otherDict = other.lookup(id);
          Dictionary newDict =
              new Dictionary(
                  otherDict.getVector().getField().createVector(allocator), otherDict.getEncoding());
          put(newDict);
        }
      }
  
      public void put(Dictionary dictionary) {
        map.put(dictionary.getEncoding().getId(), dictionary);
      }
  
      @Override
      public final Set<Long> getDictionaryIds() {
        return map.keySet();
      }
  
      @Override
      public Dictionary lookup(long id) {
        return map.get(id);
      }
  
      @Override
      public void close() {
        for (Dictionary dictionary : map.values()) {
          dictionary.getVector().close();
        }
      }
    }
  }
  