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.calcite.util;
  
  import java.util.AbstractList;
  import java.util.List;
  
  import static org.apache.calcite.linq4j.Nullness.castNonNull;
  
  /**
   * Converts a list whose members are automatically down-cast to a given type.
   *
   * <p>If a member of the backing list is not an instanceof <code>E</code>, the
   * accessing method (such as {@link List#get}) will throw a
   * {@link ClassCastException}.
   *
   * <p>All modifications are automatically written to the backing list. Not
   * synchronized.
   *
   * @param <E> Element type
   */
  public class CastingList<E> extends AbstractList<E> implements List<E> {
    //~ Instance fields --------------------------------------------------------
  
    private final List<? super E> list;
    private final Class<E> clazz;
  
    //~ Constructors -----------------------------------------------------------
  
    protected CastingList(List<? super E> list, Class<E> clazz) {
      super();
      this.list = list;
      this.clazz = clazz;
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override public E get(int index) {
      Object o = list.get(index);
      return clazz.cast(castNonNull(o));
    }
  
    @Override public int size() {
      return list.size();
    }
  
    @Override public E set(int index, E element) {
      final Object o = list.set(index, element);
      return clazz.cast(castNonNull(o));
    }
  
    @Override public E remove(int index) {
      Object o = list.remove(index);
      return clazz.cast(castNonNull(o));
    }
  
    @Override public void add(int pos, E o) {
      list.add(pos, o);
    }
  }
  