/*
    * 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.chemistry.opencmis.client.runtime.util;
  
  import java.util.Iterator;
  import java.util.NoSuchElementException;
  
  import org.apache.chemistry.opencmis.client.api.ItemIterable;
  
  /**
   * An empty item iterable.
   */
  public class EmptyItemIterable<T> implements ItemIterable<T> {
  
      public static final EmptyItemIterable<?> INSTANCE = new EmptyItemIterable<Object>();
  
      @SuppressWarnings("unchecked")
      public static <U> EmptyItemIterable<U> instance() {
          return (EmptyItemIterable<U>) INSTANCE;
      }
  
      @Override
      public ItemIterable<T> skipTo(long position) {
          if (position != 0) {
              throw new IllegalArgumentException(String.valueOf(position));
          }
          return this;
      }
  
      @Override
      public ItemIterable<T> getPage() {
          return this;
      }
  
      @Override
      public ItemIterable<T> getPage(int maxNumItems) {
          return this;
      }
  
      @Override
      @SuppressWarnings("unchecked")
      public Iterator<T> iterator() {
          return (Iterator<T>) EmptyIterator.INSTANCE;
      }
  
      @Override
      public long getPageNumItems() {
          return 0;
      }
  
      @Override
      public boolean getHasMoreItems() {
          return false;
      }
  
      @Override
      public long getTotalNumItems() {
          return 0;
      }
  
      /**
       * An empty iterator.
       */
      public static class EmptyIterator<V> implements Iterator<V> {
          public static final Iterator<?> INSTANCE = new EmptyIterator<Object>();
  
          @Override
          public boolean hasNext() {
              return false;
          }
  
          @Override
          public V next() {
              throw new NoSuchElementException();
          }
  
          @Override
          public void remove() {
              throw new UnsupportedOperationException();
          }
      }
  
  }