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 */
017package org.apache.commons.collections4.set;
018
019import java.util.Set;
020
021import org.apache.commons.collections4.Predicate;
022import org.apache.commons.collections4.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 * @param <E> the type of the elements in this set
038 * @since 3.0
039 */
040public class PredicatedSet<E> extends PredicatedCollection<E> implements Set<E> {
041
042    /** Serialization version */
043    private static final long serialVersionUID = -684521469108685117L;
044
045    /**
046     * Factory method to create a predicated (validating) set.
047     * <p>
048     * If there are any elements already in the set being decorated, they
049     * are validated.
050     *
051     * @param <E> the element type
052     * @param set  the set to decorate, must not be null
053     * @param predicate  the predicate to use for validation, must not be null
054     * @return a decorated set
055     * @throws NullPointerException if set or predicate is null
056     * @throws IllegalArgumentException if the set contains invalid elements
057     * @since 4.0
058     */
059    public static <E> PredicatedSet<E> predicatedSet(final Set<E> set, final Predicate<? super E> 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 NullPointerException if set or predicate is null
073     * @throws IllegalArgumentException if the set contains invalid elements
074     */
075    protected PredicatedSet(final Set<E> set, final Predicate<? super E> predicate) {
076        super(set, predicate);
077    }
078
079    /**
080     * Gets the set being decorated.
081     *
082     * @return the decorated set
083     */
084    @Override
085    protected Set<E> decorated() {
086        return (Set<E>) super.decorated();
087    }
088
089    @Override
090    public boolean equals(final Object object) {
091        return object == this || decorated().equals(object);
092    }
093
094    @Override
095    public int hashCode() {
096        return decorated().hashCode();
097    }
098
099}