    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.Set;
    020
    021import org.apache.commons.collections4.Bag;
    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 Bag} to transform objects that are added.
    028 * <p>
    029 * The add 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 * This class is Serializable from Commons Collections 3.1.
    035 *
    036 * @param <E> the type of elements in this bag
    037 * @since 3.0
    038 */
    039public class TransformedBag<E> extends TransformedCollection<E> implements Bag<E> {
    040
    041    /** Serialization version */
    042    private static final long serialVersionUID = 5421170911299074185L;
    043
    044    /**
    045     * Factory method to create a transforming bag.
    046     * <p>
    047     * If there are any elements already in the bag being decorated, they
    048     * are NOT transformed. Contrast this with {@link #transformedBag(Bag, 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 Bag
    054     * @throws NullPointerException if bag or transformer is null
    055     * @since 4.0
    056     */
    057    public static <E> Bag<E> transformingBag(final Bag<E> bag, final Transformer<? super E, ? extends E> transformer) {
    058        return new TransformedBag<>(bag, transformer);
    059    }
    060
    061    /**
    062     * Factory method to create a transforming bag that will transform
    063     * existing contents of the specified bag.
    064     * <p>
    065     * If there are any elements already in the bag being decorated, they
    066     * will be transformed by this method.
    067     * Contrast this with {@link #transformingBag(Bag, Transformer)}.
    068     *
    069     * @param <E> the type of the elements in the bag
    070     * @param bag  the bag to decorate, must not be null
    071     * @param transformer  the transformer to use for conversion, must not be null
    072     * @return a new transformed Bag
    073     * @throws NullPointerException if bag or transformer is null
    074     * @since 4.0
    075     */
    076    public static <E> Bag<E> transformedBag(final Bag<E> bag, final Transformer<? super E, ? extends E> transformer) {
    077        final TransformedBag<E> decorated = new TransformedBag<>(bag, transformer);
    078        if (bag.size() > 0) {
    079            @SuppressWarnings("unchecked") // Bag is of type E
    080            final E[] values = (E[]) bag.toArray(); // NOPMD - false positive for generics
    081            bag.clear();
    082            for (final E value : values) {
    083                decorated.decorated().add(transformer.transform(value));
    084            }
    085        }
    086        return decorated;
    087    }
    088
    089    //-----------------------------------------------------------------------
    090    /**
    091     * Constructor that wraps (not copies).
    092     * <p>
    093     * If there are any elements already in the bag being decorated, they
    094     * are NOT transformed.
    095     *
    096     * @param bag  the bag to decorate, must not be null
    097     * @param transformer  the transformer to use for conversion, must not be null
    098     * @throws NullPointerException if bag or transformer is null
    099     */
    100    protected TransformedBag(final Bag<E> bag, final Transformer<? super E, ? extends E> transformer) {
    101        super(bag, transformer);
    102    }
    103
    104    /**
    105     * Gets the decorated bag.
    106     *
    107     * @return the decorated bag
    108     */
    109    protected Bag<E> getBag() {
    110        return (Bag<E>) decorated();
    111    }
    112
    113    @Override
    114    public boolean equals(final Object object) {
    115        return object == this || decorated().equals(object);
    116    }
    117
    118    @Override
    119    public int hashCode() {
    120        return decorated().hashCode();
    121    }
    122
    123    //-----------------------------------------------------------------------
    124
    125    @Override
    126    public int getCount(final Object object) {
    127        return getBag().getCount(object);
    128    }
    129
    130    @Override
    131    public boolean remove(final Object object, final int nCopies) {
    132        return getBag().remove(object, nCopies);
    133    }
    134
    135    //-----------------------------------------------------------------------
    136
    137    @Override
    138    public boolean add(final E object, final int nCopies) {
    139        return getBag().add(transform(object), nCopies);
    140    }
    141
    142    @Override
    143    public Set<E> uniqueSet() {
    144        final Set<E> set = getBag().uniqueSet();
    145        return TransformedSet.<E>transformingSet(set, transformer);
    146    }
    147
    148}