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