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.algorithm.dictionary;
  
  import org.apache.arrow.vector.BaseIntVector;
  import org.apache.arrow.vector.ValueVector;
  
  /**
   * A dictionary encoder translates one vector into another one based on a dictionary vector.
   * According to Arrow specification, the encoded vector must be an integer based vector, which is
   * the index of the original vector element in the dictionary.
   *
   * @param <E> type of the encoded vector.
   * @param <D> type of the vector to encode. It is also the type of the dictionary vector.
   */
  public interface DictionaryEncoder<E extends BaseIntVector, D extends ValueVector> {
  
    /**
     * Translates an input vector into an output vector.
     *
     * @param input the input vector.
     * @param output the output vector. Note that it must be in a fresh state. At least, all its
     *     validity bits should be clear.
     */
    void encode(D input, E output);
  }
  