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.set;
018    
019    import java.util.Set;
020    
021    import org.apache.commons.collections.Predicate;
022    import org.apache.commons.collections.collection.PredicatedCollection;
023    
024    /**
025     * Decorates another <code>Set</code> to validate that all additions
026     * match a specified predicate.
027     * <p>
028     * This set exists to provide validation for the decorated set.
029     * It is normally created to decorate an empty set.
030     * If an object cannot be added to the set, an IllegalArgumentException is thrown.
031     * <p>
032     * One usage would be to ensure that no null entries are added to the set.
033     * <pre>Set set = PredicatedSet.decorate(new HashSet(), NotNullPredicate.INSTANCE);</pre>
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     * @author Paul Jack
042     */
043    public class PredicatedSet extends PredicatedCollection implements Set {
044    
045        /** Serialization version */
046        private static final long serialVersionUID = -684521469108685117L;
047    
048        /**
049         * Factory method to create a predicated (validating) set.
050         * <p>
051         * If there are any elements already in the set being decorated, they
052         * are validated.
053         * 
054         * @param set  the set to decorate, must not be null
055         * @param predicate  the predicate to use for validation, must not be null
056         * @throws IllegalArgumentException if set or predicate is null
057         * @throws IllegalArgumentException if the set contains invalid elements
058         */
059        public static Set decorate(Set set, Predicate predicate) {
060            return new PredicatedSet(set, predicate);
061        }
062    
063        //-----------------------------------------------------------------------
064        /**
065         * Constructor that wraps (not copies).
066         * <p>
067         * If there are any elements already in the set being decorated, they
068         * are validated.
069         * 
070         * @param set  the set to decorate, must not be null
071         * @param predicate  the predicate to use for validation, must not be null
072         * @throws IllegalArgumentException if set or predicate is null
073         * @throws IllegalArgumentException if the set contains invalid elements
074         */
075        protected PredicatedSet(Set set, Predicate predicate) {
076            super(set, predicate);
077        }
078    
079        /**
080         * Gets the set being decorated.
081         * 
082         * @return the decorated set
083         */
084        protected Set getSet() {
085            return (Set) getCollection();
086        }
087    
088    }