/*
    * Copyright (C) 2012 The Guava Authors
    *
    * Licensed 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 com.google.common.collect;
  
  import com.google.common.annotations.GwtCompatible;
  import com.google.common.base.Function;
  
  import java.util.ListIterator;
  
  /**
   * An iterator that transforms a backing list iterator; for internal use. This
   * avoids the object overhead of constructing a {@link Function} for internal
   * methods.
   *
   * @author Louis Wasserman
   */
  @GwtCompatible
  abstract class TransformedListIterator<F, T> extends TransformedIterator<F, T>
      implements ListIterator<T> {
    TransformedListIterator(ListIterator<? extends F> backingIterator) {
      super(backingIterator);
    }
  
    private ListIterator<? extends F> backingIterator() {
      return Iterators.cast(backingIterator);
    }
  
    @Override
    public final boolean hasPrevious() {
      return backingIterator().hasPrevious();
    }
  
    @Override
    public final T previous() {
      return transform(backingIterator().previous());
    }
  
    @Override
    public final int nextIndex() {
      return backingIterator().nextIndex();
    }
  
    @Override
    public final int previousIndex() {
      return backingIterator().previousIndex();
    }
  
    @Override
    public void set(T element) {
      throw new UnsupportedOperationException();
    }
  
    @Override
    public void add(T element) {
      throw new UnsupportedOperationException();
    }
  }