    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.bag;
    018
    019import java.util.Comparator;
    020
    021import org.apache.commons.collections4.Predicate;
    022import org.apache.commons.collections4.SortedBag;
    023
    024/**
    025 * Decorates another {@link SortedBag} to validate that additions
    026 * match a specified predicate.
    027 * <p>
    028 * This bag exists to provide validation for the decorated bag.
    029 * It is normally created to decorate an empty bag.
    030 * If an object cannot be added to the bag, an {@link IllegalArgumentException} is thrown.
    031 * </p>
    032 * <p>
    033 * One usage would be to ensure that no null entries are added to the bag.
    034 * <pre>
    035 * SortedBag bag = PredicatedSortedBag.predicatedSortedBag(new TreeBag(), NotNullPredicate.INSTANCE);
    036 * </pre>
    037 * <p>
    038 * This class is Serializable from Commons Collections 3.1.
    039 * </p>
    040 *
    041 * @param <E> the type of elements in this bag
    042 * @since 3.0
    043 */
    044public class PredicatedSortedBag<E> extends PredicatedBag<E> implements SortedBag<E> {
    045
    046    /** Serialization version */
    047    private static final long serialVersionUID = 3448581314086406616L;
    048
    049    /**
    050     * Factory method to create a predicated (validating) bag.
    051     * <p>
    052     * If there are any elements already in the bag being decorated, they
    053     * are validated.
    054     *
    055     * @param <E> the type of the elements in the bag
    056     * @param bag  the bag to decorate, must not be null
    057     * @param predicate  the predicate to use for validation, must not be null
    058     * @return a new predicated SortedBag
    059     * @throws NullPointerException if bag or predicate is null
    060     * @throws IllegalArgumentException if the bag contains invalid elements
    061     * @since 4.0
    062     */
    063    public static <E> PredicatedSortedBag<E> predicatedSortedBag(final SortedBag<E> bag,
    064                                                                 final Predicate<? super E> predicate) {
    065        return new PredicatedSortedBag<>(bag, predicate);
    066    }
    067
    068    /**
    069     * Constructor that wraps (not copies).
    070     * <p>If there are any elements already in the bag being decorated, they
    071     * are validated.
    072     *
    073     * @param bag  the bag to decorate, must not be null
    074     * @param predicate  the predicate to use for validation, must not be null
    075     * @throws NullPointerException if bag or predicate is null
    076     * @throws IllegalArgumentException if the bag contains invalid elements
    077     */
    078    protected PredicatedSortedBag(final SortedBag<E> bag, final Predicate<? super E> predicate) {
    079        super(bag, predicate);
    080    }
    081
    082    @Override
    083    public Comparator<? super E> comparator() {
    084        return decorated().comparator();
    085    }
    086
    087    /**
    088     * Gets the decorated sorted bag.
    089     *
    090     * @return the decorated bag
    091     */
    092    @Override
    093    protected SortedBag<E> decorated() {
    094        return (SortedBag<E>) super.decorated();
    095    }
    096
    097    @Override
    098    public E first() {
    099        return decorated().first();
    100    }
    101
    102    @Override
    103    public E last() {
    104        return decorated().last();
    105    }
    106
    107}