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 * This class is Serializable from Commons Collections 3.1.
033 *
034 * @param <E> the type of elements in this bag
035 * @since 3.0
036 */
037public class TransformedSortedBag<E> extends TransformedBag<E> implements SortedBag<E> {
038
039    /** Serialization version */
040    private static final long serialVersionUID = -251737742649401930L;
041
042    /**
043     * Factory method to create a transforming sorted bag.
044     * <p>
045     * If there are any elements already in the bag being decorated, they
046     * are NOT transformed. Contrast this with {@link #transformedSortedBag(SortedBag, Transformer)}.
047     *
048     * @param <E> the type of the elements in the bag
049     * @param bag  the bag to decorate, must not be null
050     * @param transformer  the transformer to use for conversion, must not be null
051     * @return a new transformed SortedBag
052     * @throws NullPointerException if bag or transformer is null
053     * @since 4.0
054     */
055    public static <E> TransformedSortedBag<E> transformingSortedBag(final SortedBag<E> bag,
056            final Transformer<? super E, ? extends E> transformer) {
057        return new TransformedSortedBag<>(bag, transformer);
058    }
059
060    /**
061     * Factory method to create a transforming sorted bag that will transform
062     * existing contents of the specified sorted bag.
063     * <p>
064     * If there are any elements already in the bag being decorated, they
065     * will be transformed by this method.
066     * Contrast this with {@link #transformingSortedBag(SortedBag, Transformer)}.
067     *
068     * @param <E> the type of the elements in the bag
069     * @param bag  the bag to decorate, must not be null
070     * @param transformer  the transformer to use for conversion, must not be null
071     * @return a new transformed SortedBag
072     * @throws NullPointerException if bag or transformer is null
073     * @since 4.0
074     */
075    public static <E> TransformedSortedBag<E> transformedSortedBag(final SortedBag<E> bag,
076            final Transformer<? super E, ? extends E> transformer) {
077
078        final TransformedSortedBag<E>  decorated = new TransformedSortedBag<>(bag, transformer);
079        if (bag.size() > 0) {
080            @SuppressWarnings("unchecked") // bag is type E
081            final E[] values = (E[]) bag.toArray(); // NOPMD - false positive for generics
082            bag.clear();
083            for (final E value : values) {
084                decorated.decorated().add(transformer.transform(value));
085            }
086        }
087        return decorated;
088    }
089
090    //-----------------------------------------------------------------------
091    /**
092     * Constructor that wraps (not copies).
093     * <p>
094     * If there are any elements already in the bag being decorated, they
095     * are NOT transformed.
096     *
097     * @param bag  the bag to decorate, must not be null
098     * @param transformer  the transformer to use for conversion, must not be null
099     * @throws NullPointerException if bag or transformer is null
100     */
101    protected TransformedSortedBag(final SortedBag<E> bag, final Transformer<? super E, ? extends E> transformer) {
102        super(bag, transformer);
103    }
104
105    /**
106     * Gets the decorated bag.
107     *
108     * @return the decorated bag
109     */
110    protected SortedBag<E> getSortedBag() {
111        return (SortedBag<E>) decorated();
112    }
113
114    //-----------------------------------------------------------------------
115
116    @Override
117    public E first() {
118        return getSortedBag().first();
119    }
120
121    @Override
122    public E last() {
123        return getSortedBag().last();
124    }
125
126    @Override
127    public Comparator<? super E> comparator() {
128        return getSortedBag().comparator();
129    }
130
131}