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.beam.runners.dataflow.worker.util.common;
  
  import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkNotNull;
  
  import org.apache.beam.sdk.util.common.Reiterator;
  
  /**
   * A {@link Reiterator} that forwards to another {@code Reiterator}, useful for implementing {@code
   * Reiterator} wrappers.
   *
   * @param <T> the type of elements returned by this iterator
   */
  public abstract class ForwardingReiterator<T> implements Reiterator<T>, Cloneable {
    private Reiterator<T> base;
  
    /**
     * Constructs a {@link ForwardingReiterator}.
     *
     * @param base supplies a base reiterator to forward requests to. This reiterator will be used
     *     directly; it will not be copied by the constructor.
     */
    public ForwardingReiterator(Reiterator<T> base) {
      this.base = checkNotNull(base);
    }
  
    @Override
    protected ForwardingReiterator<T> clone() {
      ForwardingReiterator<T> result;
      try {
        @SuppressWarnings("unchecked")
        ForwardingReiterator<T> declResult = (ForwardingReiterator<T>) super.clone();
        result = declResult;
      } catch (CloneNotSupportedException e) {
        throw new AssertionError(
            "Object.clone() for a ForwardingReiterator<T> threw "
                + "CloneNotSupportedException; this should not happen, "
                + "since ForwardingReiterator<T> implements Cloneable.",
            e);
      }
      result.base = base.copy();
      return result;
    }
  
    @Override
    public boolean hasNext() {
      return base.hasNext();
    }
  
    @Override
    public T next() {
      return base.next();
    }
  
    @Override
    public void remove() {
      base.remove();
    }
  
    /**
     * {@inheritDoc}
     *
     * <p>This implementation uses {@link #clone} to construct a duplicate of the {@link Reiterator}.
     * Derived classes must either implement {@link Cloneable} semantics, or must provide an
     * alternative implementation of this method.
     */
    @Override
    public ForwardingReiterator<T> copy() {
      return clone();
    }
  }
  