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.SortedBag;
022import org.apache.commons.collections4.Transformer;
023
024/**
025 * Decorates another {@link SortedBag} to transform objects that are added.
026 * <p>
027 * The add methods are affected by this class.
028 * Thus objects must be removed or searched for using their transformed form.
029 * For example, if the transformation converts Strings to Integers, you must
030 * use the Integer form to remove objects.
031 * </p>
032 * <p>
033 * This class is Serializable from Commons Collections 3.1.
034 * </p>
035 *
036 * @param <E> the type of elements in this bag
037 * @since 3.0
038 */
039public class TransformedSortedBag<E> extends TransformedBag<E> implements SortedBag<E> {
040
041    /** Serialization version */
042    private static final long serialVersionUID = -251737742649401930L;
043
044    /**
045     * Factory method to create a transforming sorted bag that will transform
046     * existing contents of the specified sorted bag.
047     * <p>
048     * If there are any elements already in the bag being decorated, they
049     * will be transformed by this method.
050     * Contrast this with {@link #transformingSortedBag(SortedBag, Transformer)}.
051     *
052     * @param <E> the type of the elements in the bag
053     * @param bag  the bag to decorate, must not be null
054     * @param transformer  the transformer to use for conversion, must not be null
055     * @return a new transformed SortedBag
056     * @throws NullPointerException if bag or transformer is null
057     * @since 4.0
058     */
059    public static <E> TransformedSortedBag<E> transformedSortedBag(final SortedBag<E> bag,
060            final Transformer<? super E, ? extends E> transformer) {
061
062        final TransformedSortedBag<E>  decorated = new TransformedSortedBag<>(bag, transformer);
063        if (!bag.isEmpty()) {
064            @SuppressWarnings("unchecked") // bag is type E
065            final E[] values = (E[]) bag.toArray(); // NOPMD - false positive for generics
066            bag.clear();
067            for (final E value : values) {
068                decorated.decorated().add(transformer.transform(value));
069            }
070        }
071        return decorated;
072    }
073
074    /**
075     * Factory method to create a transforming sorted bag.
076     * <p>
077     * If there are any elements already in the bag being decorated, they
078     * are NOT transformed. Contrast this with {@link #transformedSortedBag(SortedBag, Transformer)}.
079     *
080     * @param <E> the type of the elements in the bag
081     * @param bag  the bag to decorate, must not be null
082     * @param transformer  the transformer to use for conversion, must not be null
083     * @return a new transformed SortedBag
084     * @throws NullPointerException if bag or transformer is null
085     * @since 4.0
086     */
087    public static <E> TransformedSortedBag<E> transformingSortedBag(final SortedBag<E> bag,
088            final Transformer<? super E, ? extends E> transformer) {
089        return new TransformedSortedBag<>(bag, transformer);
090    }
091
092    /**
093     * Constructor that wraps (not copies).
094     * <p>
095     * If there are any elements already in the bag being decorated, they
096     * are NOT transformed.
097     *
098     * @param bag  the bag to decorate, must not be null
099     * @param transformer  the transformer to use for conversion, must not be null
100     * @throws NullPointerException if bag or transformer is null
101     */
102    protected TransformedSortedBag(final SortedBag<E> bag, final Transformer<? super E, ? extends E> transformer) {
103        super(bag, transformer);
104    }
105
106    @Override
107    public Comparator<? super E> comparator() {
108        return getSortedBag().comparator();
109    }
110
111    @Override
112    public E first() {
113        return getSortedBag().first();
114    }
115
116    /**
117     * Gets the decorated bag.
118     *
119     * @return the decorated bag
120     */
121    protected SortedBag<E> getSortedBag() {
122        return (SortedBag<E>) decorated();
123    }
124
125    @Override
126    public E last() {
127        return getSortedBag().last();
128    }
129
130}