| /* |
| * Copyright (c) 2017, 2017, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| |
| package jdk.internal.vm.compiler.collections; |
| |
| import java.util.Objects; |
| |
| /** |
| * Utility class representing a pair of values. |
| * |
| * @since 1.0 |
| */ |
| public final class Pair<L, R> { |
| |
| private static final Pair<Object, Object> EMPTY = new Pair<>(null, null); |
| |
| private final L left; |
| private final R right; |
| |
| /** |
| * Returns an empty pair. |
| * |
| * @since 1.0 |
| */ |
| @SuppressWarnings("unchecked") |
| public static <L, R> Pair<L, R> empty() { |
| return (Pair<L, R>) EMPTY; |
| } |
| |
| /** |
| * Constructs a pair with its left value being {@code left}, or returns an empty pair if |
| * {@code left} is null. |
| * |
| * @return the constructed pair or an empty pair if {@code left} is null. |
| * @since 1.0 |
| */ |
| public static <L, R> Pair<L, R> createLeft(L left) { |
| if (left == null) { |
| return empty(); |
| } else { |
| return new Pair<>(left, null); |
| } |
| } |
| |
| /** |
| * Constructs a pair with its right value being {@code right}, or returns an empty pair if |
| * {@code right} is null. |
| * |
| * @return the constructed pair or an empty pair if {@code right} is null. |
| * @since 1.0 |
| */ |
| public static <L, R> Pair<L, R> createRight(R right) { |
| if (right == null) { |
| return empty(); |
| } else { |
| return new Pair<>(null, right); |
| } |
| } |
| |
| /** |
| * Constructs a pair with its left value being {@code left}, and its right value being |
| * {@code right}, or returns an empty pair if both inputs are null. |
| * |
| * @return the constructed pair or an empty pair if both inputs are null. |
| * @since 1.0 |
| */ |
| public static <L, R> Pair<L, R> create(L left, R right) { |
| if (right == null && left == null) { |
| return empty(); |
| } else { |
| return new Pair<>(left, right); |
| } |
| } |
| |
| private Pair(L left, R right) { |
| this.left = left; |
| this.right = right; |
| } |
| |
| /** |
| * Returns the left value of this pair. |
| * |
| * @since 1.0 |
| */ |
| public L getLeft() { |
| return left; |
| } |
| |
| /** |
| * Returns the right value of this pair. |
| * |
| * @since 1.0 |
| */ |
| public R getRight() { |
| return right; |
| } |
| |
| /** |
| * {@inheritDoc} |
| * |
| * @since 1.0 |
| */ |
| @Override |
| public int hashCode() { |
| return Objects.hashCode(left) + 31 * Objects.hashCode(right); |
| } |
| |
| /** |
| * {@inheritDoc} |
| * |
| * @since 1.0 |
| */ |
| @SuppressWarnings("unchecked") |
| @Override |
| public boolean equals(Object obj) { |
| if (obj == this) { |
| return true; |
| } |
| |
| if (obj instanceof Pair) { |
| Pair<L, R> pair = (Pair<L, R>) obj; |
| return Objects.equals(left, pair.left) && Objects.equals(right, pair.right); |
| } |
| |
| return false; |
| } |
| |
| /** |
| * {@inheritDoc} |
| * |
| * @since 1.0 |
| */ |
| @Override |
| public String toString() { |
| return String.format("(%s, %s)", left, right); |
| } |
| } |