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.activemq.artemis.utils.collections;
  
  import java.util.Iterator;
  
  /**
   * Provides an Abstract Iterator that works over multiple underlying iterators.
   *
   * @param <E> type of the class of the iterator.
   * @param <I> type of the iterator
   */
  abstract class MultiIteratorBase<E, I extends Iterator<E>> implements Iterator<E> {
  
     private final I[] iterators;
     private int index = -1;
  
     MultiIteratorBase(I[] iterators) {
        this.iterators = iterators;
     }
  
     @Override
     public boolean hasNext() {
        while (true) {
           if (index != -1) {
              I currentIterator = get(index);
              if (currentIterator.hasNext()) {
                 return true;
              }
           }
           int next = index + 1;
           if (next < iterators.length) {
              moveTo(next);
           } else {
              return false;
           }
        }
     }
  
     @Override
     public E next() {
        while (true) {
           if (index != -1) {
              I currentIterator = get(index);
              if (currentIterator.hasNext()) {
                 return currentIterator.next();
              }
           }
           int next = index + 1;
           if (next < iterators.length) {
              moveTo(next);
           } else {
              return null;
           }
        }
     }
  
     protected void moveTo(int index) {
        this.index = index;
     }
  
     protected I get(int index) {
        return iterators[index];
     }
  }
  