001    /*
002     * Copyright (C) 2007 Google Inc.
003     *
004     * Licensed under the Apache License, Version 2.0 (the "License");
005     * you may not use this file except in compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     * http://www.apache.org/licenses/LICENSE-2.0
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS,
012     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     * See the License for the specific language governing permissions and
014     * limitations under the License.
015     */
016    
017    package com.google.common.collect;
018    
019    import com.google.common.annotations.GwtCompatible;
020    
021    import java.util.Queue;
022    
023    /**
024     * A queue which forwards all its method calls to another queue. Subclasses
025     * should override one or more methods to modify the behavior of the backing
026     * queue as desired per the <a
027     * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
028     *
029     * @author Mike Bostock
030     * @since 2 (imported from Google Collections Library)
031     */
032    @GwtCompatible
033    public abstract class ForwardingQueue<E> extends ForwardingCollection<E>
034        implements Queue<E> {
035    
036      /** Constructor for use by subclasses. */
037      protected ForwardingQueue() {}
038    
039      @Override protected abstract Queue<E> delegate();
040    
041      public boolean offer(E o) {
042        return delegate().offer(o);
043      }
044    
045      public E poll() {
046        return delegate().poll();
047      }
048    
049      public E remove() {
050        return delegate().remove();
051      }
052    
053      public E peek() {
054        return delegate().peek();
055      }
056    
057      public E element() {
058        return delegate().element();
059      }
060    }