    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 * <p>
    035 * This class is Serializable from Commons Collections 3.1.
    036 * </p>
    037 *
    038 * @param <E> the type of elements in this bag
    039 * @since 3.0
    040 */
    041public class TransformedBag<E> extends TransformedCollection<E> implements Bag<E> {
    042
    043    /** Serialization version */
    044    private static final long serialVersionUID = 5421170911299074185L;
    045
    046    /**
    047     * Factory method to create a transforming bag.
    048     * <p>
    049     * If there are any elements already in the bag being decorated, they
    050     * are NOT transformed. Contrast this with {@link #transformedBag(Bag, Transformer)}.
    051     *
    052     * @param <E> the type of the elements in the bag
    053     * @param bag  the bag to decorate, must not be null
    054     * @param transformer  the transformer to use for conversion, must not be null
    055     * @return a new transformed Bag
    056     * @throws NullPointerException if bag or transformer is null
    057     * @since 4.0
    058     */
    059    public static <E> Bag<E> transformingBag(final Bag<E> bag, final Transformer<? super E, ? extends E> transformer) {
    060        return new TransformedBag<>(bag, transformer);
    061    }
    062
    063    /**
    064     * Factory method to create a transforming bag that will transform
    065     * existing contents of the specified bag.
    066     * <p>
    067     * If there are any elements already in the bag being decorated, they
    068     * will be transformed by this method.
    069     * Contrast this with {@link #transformingBag(Bag, Transformer)}.
    070     *
    071     * @param <E> the type of the elements in the bag
    072     * @param bag  the bag to decorate, must not be null
    073     * @param transformer  the transformer to use for conversion, must not be null
    074     * @return a new transformed Bag
    075     * @throws NullPointerException if bag or transformer is null
    076     * @since 4.0
    077     */
    078    public static <E> Bag<E> transformedBag(final Bag<E> bag, final Transformer<? super E, ? extends E> transformer) {
    079        final TransformedBag<E> decorated = new TransformedBag<>(bag, transformer);
    080        if (bag.size() > 0) {
    081            @SuppressWarnings("unchecked") // Bag is of type E
    082            final E[] values = (E[]) bag.toArray(); // NOPMD - false positive for generics
    083            bag.clear();
    084            for (final E value : values) {
    085                decorated.decorated().add(transformer.transform(value));
    086            }
    087        }
    088        return decorated;
    089    }
    090
    091    //-----------------------------------------------------------------------
    092    /**
    093     * Constructor that wraps (not copies).
    094     * <p>
    095     * If there are any elements already in the bag being decorated, they
    096     * are NOT transformed.
    097     *
    098     * @param bag  the bag to decorate, must not be null
    099     * @param transformer  the transformer to use for conversion, must not be null
    100     * @throws NullPointerException if bag or transformer is null
    101     */
    102    protected TransformedBag(final Bag<E> bag, final Transformer<? super E, ? extends E> transformer) {
    103        super(bag, transformer);
    104    }
    105
    106    /**
    107     * Gets the decorated bag.
    108     *
    109     * @return the decorated bag
    110     */
    111    protected Bag<E> getBag() {
    112        return (Bag<E>) decorated();
    113    }
    114
    115    @Override
    116    public boolean equals(final Object object) {
    117        return object == this || decorated().equals(object);
    118    }
    119
    120    @Override
    121    public int hashCode() {
    122        return decorated().hashCode();
    123    }
    124
    125    //-----------------------------------------------------------------------
    126
    127    @Override
    128    public int getCount(final Object object) {
    129        return getBag().getCount(object);
    130    }
    131
    132    @Override
    133    public boolean remove(final Object object, final int nCopies) {
    134        return getBag().remove(object, nCopies);
    135    }
    136
    137    //-----------------------------------------------------------------------
    138
    139    @Override
    140    public boolean add(final E object, final int nCopies) {
    141        return getBag().add(transform(object), nCopies);
    142    }
    143
    144    @Override
    145    public Set<E> uniqueSet() {
    146        final Set<E> set = getBag().uniqueSet();
    147        return TransformedSet.<E>transformingSet(set, transformer);
    148    }
    149
    150}