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 *      https://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.multiset;
018
019import java.util.Comparator;
020
021import org.apache.commons.collections4.SortedMultiSet;
022import org.apache.commons.collections4.Transformer;
023
024/**
025 * Decorates another {@link SortedMultiSet} to transform objects that are added.
026 * <p>
027 * The add and setCount 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 *
033 * @param <E> The type held in the multiset.
034 * @since 4.6.0
035 */
036public class TransformedSortedMultiSet<E> extends TransformedMultiSet<E> implements SortedMultiSet<E> {
037
038    /** Serialization version */
039    private static final long serialVersionUID = 20260710L;
040
041    /**
042     * Factory method to create a transforming sorted multiset that will transform
043     * existing contents of the specified sorted multiset.
044     * <p>
045     * If there are any elements already in the multiset being decorated, they
046     * will be transformed by this method.
047     * Contrast this with {@link #transformingSortedMultiSet(SortedMultiSet, Transformer)}.
048     * </p>
049     *
050     * @param <E> The type of the elements in the multiset.
051     * @param multiset  The multiset to decorate, must not be null.
052     * @param transformer  The transformer to use for conversion, must not be null.
053     * @return A new transformed SortedMultiSet.
054     * @throws NullPointerException if multiset or transformer is null.
055     */
056    public static <E> TransformedSortedMultiSet<E> transformedSortedMultiSet(final SortedMultiSet<E> multiset,
057            final Transformer<? super E, ? extends E> transformer) {
058        final TransformedSortedMultiSet<E> decorated = new TransformedSortedMultiSet<>(multiset, transformer);
059        if (!multiset.isEmpty()) {
060            @SuppressWarnings("unchecked") // multiset is of type E
061            final E[] values = (E[]) multiset.toArray(); // NOPMD - false positive for generics
062            multiset.clear();
063            for (final E value : values) {
064                decorated.decorated().add(transformer.apply(value));
065            }
066        }
067        return decorated;
068    }
069
070    /**
071     * Factory method to create a transforming sorted multiset.
072     * <p>
073     * If there are any elements already in the multiset being decorated, they
074     * are NOT transformed. Contrast this with
075     * {@link #transformedSortedMultiSet(SortedMultiSet, Transformer)}.
076     * </p>
077     *
078     * @param <E> The type of the elements in the multiset.
079     * @param multiset  The multiset to decorate, must not be null.
080     * @param transformer  The transformer to use for conversion, must not be null.
081     * @return A new transformed SortedMultiSet.
082     * @throws NullPointerException if multiset or transformer is null.
083     */
084    public static <E> TransformedSortedMultiSet<E> transformingSortedMultiSet(final SortedMultiSet<E> multiset,
085            final Transformer<? super E, ? extends E> transformer) {
086        return new TransformedSortedMultiSet<>(multiset, transformer);
087    }
088
089    /**
090     * Constructor that wraps (not copies).
091     * <p>
092     * If there are any elements already in the multiset being decorated, they
093     * are NOT transformed.
094     * </p>
095     *
096     * @param multiset  The multiset to decorate, must not be null.
097     * @param transformer  The transformer to use for conversion, must not be null.
098     * @throws NullPointerException if multiset or transformer is null.
099     */
100    protected TransformedSortedMultiSet(final SortedMultiSet<E> multiset,
101            final Transformer<? super E, ? extends E> transformer) {
102        super(multiset, transformer);
103    }
104
105    @Override
106    public Comparator<? super E> comparator() {
107        return getSortedMultiSet().comparator();
108    }
109
110    @Override
111    public E first() {
112        return getSortedMultiSet().first();
113    }
114
115    /**
116     * Gets the decorated sorted multiset.
117     *
118     * @return The decorated sorted multiset.
119     */
120    protected SortedMultiSet<E> getSortedMultiSet() {
121        return (SortedMultiSet<E>) decorated();
122    }
123
124    @Override
125    public E last() {
126        return getSortedMultiSet().last();
127    }
128
129}