    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.Set;
    020
    021import org.apache.commons.collections4.MultiSet;
    022import org.apache.commons.collections4.Transformer;
    023import org.apache.commons.collections4.collection.TransformedCollection;
    024import org.apache.commons.collections4.set.TransformedSet;
    025
    026/**
    027 * Decorates another {@link MultiSet} to transform objects that are added.
    028 * <p>
    029 * The add and setCount methods are affected by this class.
    030 * Thus objects must be removed or searched for using their transformed form.
    031 * For example, if the transformation converts Strings to Integers, you must
    032 * use the Integer form to remove objects.
    033 * </p>
    034 *
    035 * @param <E> The type held in the multiset
    036 * @since 4.6.0
    037 */
    038public class TransformedMultiSet<E> extends TransformedCollection<E> implements MultiSet<E> {
    039
    040    /** Serialization version */
    041    private static final long serialVersionUID = 20260710L;
    042
    043    /**
    044     * Factory method to create a transforming multiset that will transform
    045     * existing contents of the specified multiset.
    046     * <p>
    047     * If there are any elements already in the multiset being decorated, they
    048     * will be transformed by this method.
    049     * Contrast this with {@link #transformingMultiSet(MultiSet, Transformer)}.
    050     * </p>
    051     *
    052     * @param <E> The type of the elements in the multiset.
    053     * @param multiset  The multiset to decorate, must not be null.
    054     * @param transformer  The transformer to use for conversion, must not be null.
    055     * @return A new transformed MultiSet.
    056     * @throws NullPointerException if multiset or transformer is null.
    057     */
    058    public static <E> TransformedMultiSet<E> transformedMultiSet(final MultiSet<E> multiset,
    059            final Transformer<? super E, ? extends E> transformer) {
    060        final TransformedMultiSet<E> decorated = new TransformedMultiSet<>(multiset, transformer);
    061        if (!multiset.isEmpty()) {
    062            @SuppressWarnings("unchecked") // multiset is of type E
    063            final E[] values = (E[]) multiset.toArray(); // NOPMD - false positive for generics
    064            multiset.clear();
    065            for (final E value : values) {
    066                decorated.decorated().add(transformer.apply(value));
    067            }
    068        }
    069        return decorated;
    070    }
    071
    072    /**
    073     * Factory method to create a transforming multiset.
    074     * <p>
    075     * If there are any elements already in the multiset being decorated, they
    076     * are NOT transformed. Contrast this with {@link #transformedMultiSet(MultiSet, Transformer)}.
    077     * </p>
    078     *
    079     *
    080     * @param <E> The type of the elements in the multiset.
    081     * @param multiset  The multiset to decorate, must not be null.
    082     * @param transformer  The transformer to use for conversion, must not be null.
    083     * @return A new transformed MultiSet.
    084     * @throws NullPointerException if multiset or transformer is null.
    085     */
    086    public static <E> TransformedMultiSet<E> transformingMultiSet(final MultiSet<E> multiset,
    087            final Transformer<? super E, ? extends E> transformer) {
    088        return new TransformedMultiSet<>(multiset, transformer);
    089    }
    090
    091    /**
    092     * Constructor that wraps (not copies).
    093     * <p>
    094     * If there are any elements already in the multiset being decorated, they
    095     * are NOT transformed.
    096     * </p>
    097     *
    098     * @param multiset  The multiset to decorate, must not be null.
    099     * @param transformer  The transformer to use for conversion, must not be null.
    100     * @throws NullPointerException if multiset or transformer is null.
    101     */
    102    protected TransformedMultiSet(final MultiSet<E> multiset, final Transformer<? super E, ? extends E> transformer) {
    103        super(multiset, transformer);
    104    }
    105
    106    @Override
    107    public int add(final E object, final int occurrences) {
    108        return getMultiSet().add(transform(object), occurrences);
    109    }
    110
    111    @Override
    112    public Set<MultiSet.Entry<E>> entrySet() {
    113        return getMultiSet().entrySet();
    114    }
    115
    116    @Override
    117    public boolean equals(final Object object) {
    118        return object == this || decorated().equals(object);
    119    }
    120
    121    @Override
    122    public int getCount(final Object object) {
    123        return getMultiSet().getCount(object);
    124    }
    125
    126    /**
    127     * Gets the decorated multiset.
    128     *
    129     * @return The decorated multiset.
    130     */
    131    protected MultiSet<E> getMultiSet() {
    132        return (MultiSet<E>) decorated();
    133    }
    134
    135    @Override
    136    public int hashCode() {
    137        return decorated().hashCode();
    138    }
    139
    140    @Override
    141    public int remove(final Object object, final int occurrences) {
    142        return getMultiSet().remove(object, occurrences);
    143    }
    144
    145    @Override
    146    public int setCount(final E object, final int count) {
    147        return getMultiSet().setCount(transform(object), count);
    148    }
    149
    150    @Override
    151    public Set<E> uniqueSet() {
    152        return TransformedSet.<E>transformingSet(getMultiSet().uniqueSet(), transformer);
    153    }
    154
    155}