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.RandomAccess;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * A view onto an array that cannot be modified by the client.
   *
   * <p>Since the array is not copied, modifications to the array will be
   * reflected in the list.
   *
   * <p>Null elements are allowed.
   *
   * <p>Quick and low-memory, like {@link java.util.Arrays#asList(Object[])}, but
   * unmodifiable.
   *
   * @param <E> Element type
   */
  public class UnmodifiableArrayList<E>
      extends AbstractList<E>
      implements RandomAccess {
    private final E[] elements;
  
    private UnmodifiableArrayList(E[] elements) {
      this.elements = requireNonNull(elements, "elements");
    }
  
    public static <E> UnmodifiableArrayList<E> of(E... elements) {
      return new UnmodifiableArrayList<>(elements);
    }
  
    @Override public E get(int index) {
      return elements[index];
    }
  
    @Override public int size() {
      return elements.length;
    }
  }
  