1/* 2 * Copyright (C) 2012 The Guava Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package com.google.common.collect; 18 19import com.google.common.annotations.GwtCompatible; 20import com.google.common.base.Function; 21 22import java.util.ListIterator; 23 24/** 25 * An iterator that transforms a backing list iterator; for internal use. This 26 * avoids the object overhead of constructing a {@link Function} for internal 27 * methods. 28 * 29 * @author Louis Wasserman 30 */ 31@GwtCompatible 32abstract class TransformedListIterator<F, T> extends TransformedIterator<F, T> 33 implements ListIterator<T> { 34 TransformedListIterator(ListIterator<? extends F> backingIterator) { 35 super(backingIterator); 36 } 37 38 private ListIterator<? extends F> backingIterator() { 39 return Iterators.cast(backingIterator); 40 } 41 42 @Override 43 public final boolean hasPrevious() { 44 return backingIterator().hasPrevious(); 45 } 46 47 @Override 48 public final T previous() { 49 return transform(backingIterator().previous()); 50 } 51 52 @Override 53 public final int nextIndex() { 54 return backingIterator().nextIndex(); 55 } 56 57 @Override 58 public final int previousIndex() { 59 return backingIterator().previousIndex(); 60 } 61 62 @Override 63 public void set(T element) { 64 throw new UnsupportedOperationException(); 65 } 66 67 @Override 68 public void add(T element) { 69 throw new UnsupportedOperationException(); 70 } 71} 72