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.
046     * <p>
047     * If there are any elements already in the bag being decorated, they
048     * are NOT transformed. Contrast this with {@link #transformedSortedBag(SortedBag, Transformer)}.
049     *
050     * @param <E> the type of the elements in the bag
051     * @param bag  the bag to decorate, must not be null
052     * @param transformer  the transformer to use for conversion, must not be null
053     * @return a new transformed SortedBag
054     * @throws NullPointerException if bag or transformer is null
055     * @since 4.0
056     */
057    public static <E> TransformedSortedBag<E> transformingSortedBag(final SortedBag<E> bag,
058            final Transformer<? super E, ? extends E> transformer) {
059        return new TransformedSortedBag<>(bag, transformer);
060    }
061
062    /**
063     * Factory method to create a transforming sorted bag that will transform
064     * existing contents of the specified sorted bag.
065     * <p>
066     * If there are any elements already in the bag being decorated, they
067     * will be transformed by this method.
068     * Contrast this with {@link #transformingSortedBag(SortedBag, Transformer)}.
069     *
070     * @param <E> the type of the elements in the bag
071     * @param bag  the bag to decorate, must not be null
072     * @param transformer  the transformer to use for conversion, must not be null
073     * @return a new transformed SortedBag
074     * @throws NullPointerException if bag or transformer is null
075     * @since 4.0
076     */
077    public static <E> TransformedSortedBag<E> transformedSortedBag(final SortedBag<E> bag,
078            final Transformer<? super E, ? extends E> transformer) {
079
080        final TransformedSortedBag<E>  decorated = new TransformedSortedBag<>(bag, transformer);
081        if (bag.size() > 0) {
082            @SuppressWarnings("unchecked") // bag is type E
083            final E[] values = (E[]) bag.toArray(); // NOPMD - false positive for generics
084            bag.clear();
085            for (final E value : values) {
086                decorated.decorated().add(transformer.transform(value));
087            }
088        }
089        return decorated;
090    }
091
092    //-----------------------------------------------------------------------
093    /**
094     * Constructor that wraps (not copies).
095     * <p>
096     * If there are any elements already in the bag being decorated, they
097     * are NOT transformed.
098     *
099     * @param bag  the bag to decorate, must not be null
100     * @param transformer  the transformer to use for conversion, must not be null
101     * @throws NullPointerException if bag or transformer is null
102     */
103    protected TransformedSortedBag(final SortedBag<E> bag, final Transformer<? super E, ? extends E> transformer) {
104        super(bag, transformer);
105    }
106
107    /**
108     * Gets the decorated bag.
109     *
110     * @return the decorated bag
111     */
112    protected SortedBag<E> getSortedBag() {
113        return (SortedBag<E>) decorated();
114    }
115
116    //-----------------------------------------------------------------------
117
118    @Override
119    public E first() {
120        return getSortedBag().first();
121    }
122
123    @Override
124    public E last() {
125        return getSortedBag().last();
126    }
127
128    @Override
129    public Comparator<? super E> comparator() {
130        return getSortedBag().comparator();
131    }
132
133}