001    /*
002     *  Licensed to the Apache Software Foundation (ASF) under one or more
003     *  contributor license agreements.  See the NOTICE file distributed with
004     *  this work for additional information regarding copyright ownership.
005     *  The ASF licenses this file to You under the Apache License, Version 2.0
006     *  (the "License"); you may not use this file except in compliance with
007     *  the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     *  Unless required by applicable law or agreed to in writing, software
012     *  distributed under the License is distributed on an "AS IS" BASIS,
013     *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     *  See the License for the specific language governing permissions and
015     *  limitations under the License.
016     */
017    package org.apache.commons.collections.collection;
018    
019    import java.util.Collection;
020    import java.util.Iterator;
021    
022    import org.apache.commons.collections.BoundedCollection;
023    import org.apache.commons.collections.iterators.UnmodifiableIterator;
024    
025    /**
026     * <code>UnmodifiableBoundedCollection</code> decorates another 
027     * <code>BoundedCollection</code> to ensure it can't be altered.
028     * <p>
029     * If a BoundedCollection is first wrapped in some other collection decorator,
030     * such as synchronized or predicated, the BoundedCollection methods are no 
031     * longer accessible.
032     * The factory on this class will attempt to retrieve the bounded nature by
033     * examining the package scope variables.
034     * <p>
035     * This class is Serializable from Commons Collections 3.1.
036     *
037     * @since Commons Collections 3.0
038     * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
039     * 
040     * @author Stephen Colebourne
041     */
042    public final class UnmodifiableBoundedCollection
043            extends AbstractSerializableCollectionDecorator
044            implements BoundedCollection {
045    
046        /** Serialization version */
047        private static final long serialVersionUID = -7112672385450340330L;
048    
049        /**
050         * Factory method to create an unmodifiable bounded collection.
051         * 
052         * @param coll  the <code>BoundedCollection</code> to decorate, must not be null
053         * @return a new unmodifiable bounded collection
054         * @throws IllegalArgumentException if bag is null
055         */
056        public static BoundedCollection decorate(BoundedCollection coll) {
057            return new UnmodifiableBoundedCollection(coll);
058        }
059        
060        /**
061         * Factory method to create an unmodifiable bounded collection.
062         * <p>
063         * This method is capable of drilling down through up to 1000 other decorators 
064         * to find a suitable BoundedCollection.
065         * 
066         * @param coll  the <code>BoundedCollection</code> to decorate, must not be null
067         * @return a new unmodifiable bounded collection
068         * @throws IllegalArgumentException if bag is null
069         */
070        public static BoundedCollection decorateUsing(Collection coll) {
071            if (coll == null) {
072                throw new IllegalArgumentException("The collection must not be null");
073            }
074            
075            // handle decorators
076            for (int i = 0; i < 1000; i++) {  // counter to prevent infinite looping
077                if (coll instanceof BoundedCollection) {
078                    break;  // normal loop exit
079                } else if (coll instanceof AbstractCollectionDecorator) {
080                    coll = ((AbstractCollectionDecorator) coll).collection;
081                } else if (coll instanceof SynchronizedCollection) {
082                    coll = ((SynchronizedCollection) coll).collection;
083                } else {
084                    break;  // normal loop exit
085                }
086            }
087                
088            if (coll instanceof BoundedCollection == false) {
089                throw new IllegalArgumentException("The collection is not a bounded collection");
090            }
091            return new UnmodifiableBoundedCollection((BoundedCollection) coll);
092        }    
093        
094        /**
095         * Constructor that wraps (not copies).
096         * 
097         * @param coll  the collection to decorate, must not be null
098         * @throws IllegalArgumentException if coll is null
099         */
100        private UnmodifiableBoundedCollection(BoundedCollection coll) {
101            super(coll);
102        }
103    
104        //-----------------------------------------------------------------------
105        public Iterator iterator() {
106            return UnmodifiableIterator.decorate(getCollection().iterator());
107        }
108    
109        public boolean add(Object object) {
110            throw new UnsupportedOperationException();
111        }
112    
113        public boolean addAll(Collection coll) {
114            throw new UnsupportedOperationException();
115        }
116    
117        public void clear() {
118            throw new UnsupportedOperationException();
119        }
120    
121        public boolean remove(Object object) {
122            throw new UnsupportedOperationException();
123        }
124    
125        public boolean removeAll(Collection coll) {
126            throw new UnsupportedOperationException();
127        }
128    
129        public boolean retainAll(Collection coll) {
130            throw new UnsupportedOperationException();
131        }
132    
133        //-----------------------------------------------------------------------    
134        public boolean isFull() {
135            return ((BoundedCollection) collection).isFull();
136        }
137    
138        public int maxSize() {
139            return ((BoundedCollection) collection).maxSize();
140        }
141    
142    }