    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.lang3.tuple;
    018
    019import java.util.Map;
    020import java.util.Objects;
    021
    022/**
    023 * A mutable pair consisting of two {@link Object} elements.
    024 *
    025 * <p>Not #ThreadSafe#</p>
    026 *
    027 * @param <L> the left element type
    028 * @param <R> the right element type
    029 *
    030 * @since 3.0
    031 */
    032public class MutablePair<L, R> extends Pair<L, R> {
    033
    034    /**
    035     * An empty array.
    036     * <p>
    037     * Consider using {@link #emptyArray()} to avoid generics warnings.
    038     * </p>
    039     *
    040     * @since 3.10.
    041     */
    042    public static final MutablePair<?, ?>[] EMPTY_ARRAY = {};
    043
    044    /** Serialization version */
    045    private static final long serialVersionUID = 4954918890077093841L;
    046
    047    /**
    048     * Returns the empty array singleton that can be assigned without compiler warning.
    049     *
    050     * @param <L> the left element type
    051     * @param <R> the right element type
    052     * @return the empty array singleton that can be assigned without compiler warning.
    053     *
    054     * @since 3.10.
    055     */
    056    @SuppressWarnings("unchecked")
    057    public static <L, R> MutablePair<L, R>[] emptyArray() {
    058        return (MutablePair<L, R>[]) EMPTY_ARRAY;
    059    }
    060
    061    /**
    062     * Creates a mutable pair of two objects inferring the generic types.
    063     *
    064     * <p>This factory allows the pair to be created using inference to
    065     * obtain the generic types.</p>
    066     *
    067     * @param <L> the left element type
    068     * @param <R> the right element type
    069     * @param left  the left element, may be null
    070     * @param right  the right element, may be null
    071     * @return a pair formed from the two parameters, not null
    072     */
    073    public static <L, R> MutablePair<L, R> of(final L left, final R right) {
    074        return new MutablePair<>(left, right);
    075    }
    076
    077    /**
    078     * Creates a mutable pair from a map entry.
    079     *
    080     * <p>This factory allows the pair to be created using inference to
    081     * obtain the generic types.</p>
    082     *
    083     * @param <L> the left element type
    084     * @param <R> the right element type
    085     * @param pair the existing map entry.
    086     * @return a pair formed from the map entry
    087     */
    088    public static <L, R> MutablePair<L, R> of(final Map.Entry<L, R> pair) {
    089        final L left;
    090        final R right;
    091        if (pair != null) {
    092            left = pair.getKey();
    093            right = pair.getValue();
    094        } else {
    095            left = null;
    096            right = null;
    097        }
    098        return new MutablePair<>(left, right);
    099    }
    100
    101    /**
    102     * Creates a mutable pair of two non-null objects inferring the generic types.
    103     *
    104     * <p>This factory allows the pair to be created using inference to
    105     * obtain the generic types.</p>
    106     *
    107     * @param <L> the left element type
    108     * @param <R> the right element type
    109     * @param left  the left element, may not be null
    110     * @param right  the right element, may not be null
    111     * @return a pair formed from the two parameters, not null
    112     * @throws NullPointerException if any input is null
    113     * @since 3.13.0
    114     */
    115    public static <L, R> MutablePair<L, R> ofNonNull(final L left, final R right) {
    116        return of(Objects.requireNonNull(left, "left"), Objects.requireNonNull(right, "right"));
    117    }
    118
    119    /** Left object */
    120    public L left;
    121
    122    /** Right object */
    123    public R right;
    124
    125    /**
    126     * Create a new pair instance of two nulls.
    127     */
    128    public MutablePair() {
    129    }
    130
    131    /**
    132     * Create a new pair instance.
    133     *
    134     * @param left  the left value, may be null
    135     * @param right  the right value, may be null
    136     */
    137    public MutablePair(final L left, final R right) {
    138        this.left = left;
    139        this.right = right;
    140    }
    141
    142    /**
    143     * {@inheritDoc}
    144     */
    145    @Override
    146    public L getLeft() {
    147        return left;
    148    }
    149
    150    /**
    151     * {@inheritDoc}
    152     */
    153    @Override
    154    public R getRight() {
    155        return right;
    156    }
    157
    158    /**
    159     * Sets the left element of the pair.
    160     *
    161     * @param left  the new value of the left element, may be null
    162     */
    163    public void setLeft(final L left) {
    164        this.left = left;
    165    }
    166
    167    /**
    168     * Sets the right element of the pair.
    169     *
    170     * @param right  the new value of the right element, may be null
    171     */
    172    public void setRight(final R right) {
    173        this.right = right;
    174    }
    175
    176    /**
    177     * Sets the {@code Map.Entry} value.
    178     * This sets the right element of the pair.
    179     *
    180     * @param value  the right value to set, not null
    181     * @return the old value for the right element
    182     */
    183    @Override
    184    public R setValue(final R value) {
    185        final R result = getRight();
    186        setRight(value);
    187        return result;
    188    }
    189
    190}