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.c;
  
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Set;
  import org.apache.arrow.vector.dictionary.Dictionary;
  import org.apache.arrow.vector.dictionary.DictionaryProvider;
  
  /**
   * A DictionaryProvider that is used in C Data Interface for imports.
   *
   * <p>CDataDictionaryProvider is similar to {@link DictionaryProvider.MapDictionaryProvider} with a
   * key difference that the dictionaries are owned by the provider so it must eventually be closed.
   *
   * <p>The typical usage is to create the CDataDictionaryProvider and pass it to {@link
   * Data#importField} or {@link Data#importSchema} to allocate empty dictionaries based on the
   * information in {@link ArrowSchema}. Then you can re-use the same dictionary provider in any
   * function that imports an {@link ArrowArray} that has the same schema.
   */
  public class CDataDictionaryProvider implements DictionaryProvider, AutoCloseable {
  
    private final Map<Long, Dictionary> map;
  
    public CDataDictionaryProvider() {
      this.map = new HashMap<>();
    }
  
    void put(Dictionary dictionary) {
      Dictionary previous = map.put(dictionary.getEncoding().getId(), dictionary);
      if (previous != null) {
        previous.getVector().close();
      }
    }
  
    @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();
      }
      map.clear();
    }
  }
  