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GraalVM is an ecosystem for compiling and running applications written in multiple languages.
GraalVM removes the isolation between programming languages and enables interoperability in a shared runtime.
/*
* 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. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* 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 org.graalvm.collections;
import java.util.Objects;
/**
* Utility class representing a pair of values.
*
* @since 1.0
*/
public final class Pair {
private static final Pair EMPTY = new Pair<>(null, null);
private final L left;
private final R right;
/**
* Returns an empty pair.
*
* @since 1.0
*/
@SuppressWarnings("unchecked")
public static Pair empty() {
return (Pair) 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 Pair 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 Pair 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 Pair 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 pair = (Pair) 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);
}
}