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 17 package com.google.common.collect; 18 19 import java.util.Deque; 20 import java.util.Iterator; 21 22 /** 23 * A deque which forwards all its method calls to another deque. Subclasses 24 * should override one or more methods to modify the behavior of the backing 25 * deque as desired per the <a 26 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>. 27 * 28 * <p><b>Warning:</b> The methods of {@code ForwardingDeque} forward 29 * <b>indiscriminately</b> to the methods of the delegate. For example, 30 * overriding {@link #add} alone <b>will not</b> change the behavior of {@link 31 * #offer} which can lead to unexpected behavior. In this case, you should 32 * override {@code offer} as well. 33 * 34 * @author Kurt Alfred Kluever 35 * @since 12.0 36 */ 37 public abstract class ForwardingDeque<E> extends ForwardingQueue<E> 38 implements Deque<E> { 39 40 /** Constructor for use by subclasses. */ 41 protected ForwardingDeque() {} 42 43 @Override protected abstract Deque<E> delegate(); 44 45 @Override 46 public void addFirst(E e) { 47 delegate().addFirst(e); 48 } 49 50 @Override 51 public void addLast(E e) { 52 delegate().addLast(e); 53 } 54 55 @Override 56 public Iterator<E> descendingIterator() { 57 return delegate().descendingIterator(); 58 } 59 60 @Override 61 public E getFirst() { 62 return delegate().getFirst(); 63 } 64 65 @Override 66 public E getLast() { 67 return delegate().getLast(); 68 } 69 70 @Override 71 public boolean offerFirst(E e) { 72 return delegate().offerFirst(e); 73 } 74 75 @Override 76 public boolean offerLast(E e) { 77 return delegate().offerLast(e); 78 } 79 80 @Override 81 public E peekFirst() { 82 return delegate().peekFirst(); 83 } 84 85 @Override 86 public E peekLast() { 87 return delegate().peekLast(); 88 } 89 90 @Override 91 public E pollFirst() { 92 return delegate().pollFirst(); 93 } 94 95 @Override 96 public E pollLast() { 97 return delegate().pollLast(); 98 } 99 100 @Override 101 public E pop() { 102 return delegate().pop(); 103 } 104 105 @Override 106 public void push(E e) { 107 delegate().push(e); 108 } 109 110 @Override 111 public E removeFirst() { 112 return delegate().removeFirst(); 113 } 114 115 @Override 116 public E removeLast() { 117 return delegate().removeLast(); 118 } 119 120 @Override 121 public boolean removeFirstOccurrence(Object o) { 122 return delegate().removeFirstOccurrence(o); 123 } 124 125 @Override 126 public boolean removeLastOccurrence(Object o) { 127 return delegate().removeLastOccurrence(o); 128 } 129 } 130
