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.complex.impl;
  
  import org.apache.arrow.vector.complex.AbstractContainerVector;
  import org.apache.arrow.vector.complex.reader.FieldReader;
  import org.apache.arrow.vector.complex.writer.BaseWriter.ListWriter;
  import org.apache.arrow.vector.complex.writer.BaseWriter.StructWriter;
  import org.apache.arrow.vector.types.Types.MinorType;
  
  /** An implementation of {@link AbstractFieldReader} for lists vectors. */
  @SuppressWarnings("unused")
  public class SingleListReaderImpl extends AbstractFieldReader {
  
    private final String name;
    private final AbstractContainerVector container;
    private FieldReader reader;
  
    /**
     * Constructs a new instance.
     *
     * @param name The name of field to read in container.
     * @param container The container holding a list.
     */
    public SingleListReaderImpl(String name, AbstractContainerVector container) {
      super();
      this.name = name;
      this.container = container;
    }
  
    @Override
    public void setPosition(int index) {
      super.setPosition(index);
      if (reader != null) {
        reader.setPosition(index);
      }
    }
  
    @Override
    public Object readObject() {
      return reader.readObject();
    }
  
    @Override
    public FieldReader reader() {
      if (reader == null) {
        reader = container.getChild(name).getReader();
        setPosition(idx());
      }
      return reader;
    }
  
    @Override
    public MinorType getMinorType() {
      return MinorType.LIST;
    }
  
    @Override
    public boolean isSet() {
      return false;
    }
  
    @Override
    public void copyAsValue(ListWriter writer) {
      throw new UnsupportedOperationException(
          "Generic list copying not yet supported.  Please resolve to typed list.");
    }
  
    @Override
    public void copyAsField(String name, StructWriter writer) {
      throw new UnsupportedOperationException(
          "Generic list copying not yet supported.  Please resolve to typed list.");
    }
  }
  