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.buffer;
018    
019    import org.apache.commons.collections.Buffer;
020    import org.apache.commons.collections.Predicate;
021    import org.apache.commons.collections.collection.PredicatedCollection;
022    
023    /**
024     * Decorates another <code>Buffer</code> to validate that additions
025     * match a specified predicate.
026     * <p>
027     * This buffer exists to provide validation for the decorated buffer.
028     * It is normally created to decorate an empty buffer.
029     * If an object cannot be added to the buffer, an IllegalArgumentException is thrown.
030     * <p>
031     * One usage would be to ensure that no null entries are added to the buffer.
032     * <pre>Buffer buffer = PredicatedBuffer.decorate(new UnboundedFifoBuffer(), NotNullPredicate.INSTANCE);</pre>
033     * <p>
034     * This class is Serializable from Commons Collections 3.1.
035     *
036     * @since Commons Collections 3.0
037     * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
038     * 
039     * @author Stephen Colebourne
040     * @author Paul Jack
041     */
042    public class PredicatedBuffer extends PredicatedCollection implements Buffer {
043    
044        /** Serialization version */
045        private static final long serialVersionUID = 2307609000539943581L;
046    
047        /**
048         * Factory method to create a predicated (validating) buffer.
049         * <p>
050         * If there are any elements already in the buffer being decorated, they
051         * are validated.
052         * 
053         * @param buffer  the buffer to decorate, must not be null
054         * @param predicate  the predicate to use for validation, must not be null
055         * @return a new predicated Buffer
056         * @throws IllegalArgumentException if buffer or predicate is null
057         * @throws IllegalArgumentException if the buffer contains invalid elements
058         */
059        public static Buffer decorate(Buffer buffer, Predicate predicate) {
060            return new PredicatedBuffer(buffer, predicate);
061        }
062        
063        //-----------------------------------------------------------------------
064        /**
065         * Constructor that wraps (not copies).
066         * <p>
067         * If there are any elements already in the collection being decorated, they
068         * are validated.
069         * 
070         * @param buffer  the buffer to decorate, must not be null
071         * @param predicate  the predicate to use for validation, must not be null
072         * @throws IllegalArgumentException if buffer or predicate is null
073         * @throws IllegalArgumentException if the buffer contains invalid elements
074         */
075        protected PredicatedBuffer(Buffer buffer, Predicate predicate) {
076            super(buffer, predicate);
077        }
078    
079        /**
080         * Gets the buffer being decorated.
081         * 
082         * @return the decorated buffer
083         */
084        protected Buffer getBuffer() {
085            return (Buffer) getCollection();
086        }
087    
088        //-----------------------------------------------------------------------
089        public Object get() {
090            return getBuffer().get();
091        }
092    
093        public Object remove() {
094            return getBuffer().remove();
095        }
096    
097    }