1 /*

     2  * Copyright (c) 2017, 2017, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  */

    23 package org.graalvm.util;

    24 

    25 import java.util.Objects;

    26 

    27 /**

    28  * Utility class representing a pair of values.

    29  */

    30 public final class Pair<L, R> {

    31     private static final Pair<Object, Object> EMPTY = new Pair<>(null, null);

    32 

    33     private final L left;

    34     private final R right;

    35 

    36     @SuppressWarnings("unchecked")

    37     public static <L, R> Pair<L, R> empty() {

    38         return (Pair<L, R>) EMPTY;

    39     }

    40 

    41     public static <L, R> Pair<L, R> createLeft(L left) {

    42         if (left == null) {

    43             return empty();

    44         } else {

    45             return new Pair<>(left, null);

    46         }

    47     }

    48 

    49     public static <L, R> Pair<L, R> createRight(R right) {

    50         if (right == null) {

    51             return empty();

    52         } else {

    53             return new Pair<>(null, right);

    54         }

    55     }

    56 

    57     public static <L, R> Pair<L, R> create(L left, R right) {

    58         if (right == null && left == null) {

    59             return empty();

    60         } else {

    61             return new Pair<>(left, right);

    62         }

    63     }

    64 

    65     private Pair(L left, R right) {

    66         this.left = left;

    67         this.right = right;

    68     }

    69 

    70     public L getLeft() {

    71         return left;

    72     }

    73 

    74     public R getRight() {

    75         return right;

    76     }

    77 

    78     @Override

    79     public int hashCode() {

    80         return Objects.hashCode(left) + 31 * Objects.hashCode(right);

    81     }

    82 

    83     @SuppressWarnings("unchecked")

    84     @Override

    85     public boolean equals(Object obj) {

    86         if (obj == this) {

    87             return true;

    88         }

    89 

    90         if (obj instanceof Pair) {

    91             Pair<L, R> pair = (Pair<L, R>) obj;

    92             return Objects.equals(left, pair.left) && Objects.equals(right, pair.right);

    93         }

    94 

    95         return false;

    96     }

    97 

    98     @Override

    99     public String toString() {

   100         return String.format("(%s, %s)", left, right);

   101     }

   102 }