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} 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 * <p>
033 * One usage would be to ensure that no null entries are added to the set.
034 * </p>
035 * <pre>Set set = PredicatedSet.decorate(new HashSet(), NotNullPredicate.INSTANCE);</pre>
036 * <p>
037 * This class is Serializable from Commons Collections 3.1.
038 * </p>
039 *
040 * @param <E> the type of the elements in this set
041 * @since 3.0
042 */
043public class PredicatedSet<E> extends PredicatedCollection<E> implements Set<E> {
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 <E> the element type
055     * @param set  the set to decorate, must not be null
056     * @param predicate  the predicate to use for validation, must not be null
057     * @return a decorated set
058     * @throws NullPointerException if set or predicate is null
059     * @throws IllegalArgumentException if the set contains invalid elements
060     * @since 4.0
061     */
062    public static <E> PredicatedSet<E> predicatedSet(final Set<E> set, final Predicate<? super E> predicate) {
063        return new PredicatedSet<>(set, predicate);
064    }
065
066    /**
067     * Constructor that wraps (not copies).
068     * <p>
069     * If there are any elements already in the set being decorated, they
070     * are validated.
071     *
072     * @param set  the set to decorate, must not be null
073     * @param predicate  the predicate to use for validation, must not be null
074     * @throws NullPointerException if set or predicate is null
075     * @throws IllegalArgumentException if the set contains invalid elements
076     */
077    protected PredicatedSet(final Set<E> set, final Predicate<? super E> predicate) {
078        super(set, predicate);
079    }
080
081    /**
082     * Gets the set being decorated.
083     *
084     * @return the decorated set
085     */
086    @Override
087    protected Set<E> decorated() {
088        return (Set<E>) super.decorated();
089    }
090
091    @Override
092    public boolean equals(final Object object) {
093        return object == this || decorated().equals(object);
094    }
095
096    @Override
097    public int hashCode() {
098        return decorated().hashCode();
099    }
100
101}