Pair.java revision 2571:10fc81ac75b4 
1/*
2 * Copyright (c) 1999, 2013, 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.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package com.sun.tools.javac.util;
27
28import java.util.Objects;
29
30/** A generic class for pairs.
31 *
32 *  <p><b>This is NOT part of any supported API.
33 *  If you write code that depends on this, you do so at your own risk.
34 *  This code and its internal interfaces are subject to change or
35 *  deletion without notice.</b>
36 */
37public class Pair<A, B> {
38
39    public final A fst;
40    public final B snd;
41
42    public Pair(A fst, B snd) {
43        this.fst = fst;
44        this.snd = snd;
45    }
46
47    public String toString() {
48        return "Pair[" + fst + "," + snd + "]";
49    }
50
51    public boolean equals(Object other) {
52        return
53            other instanceof Pair<?,?> &&
54            Objects.equals(fst, ((Pair<?,?>)other).fst) &&
55            Objects.equals(snd, ((Pair<?,?>)other).snd);
56    }
57
58    public int hashCode() {
59        if (fst == null) return (snd == null) ? 0 : snd.hashCode() + 1;
60        else if (snd == null) return fst.hashCode() + 2;
61        else return fst.hashCode() * 17 + snd.hashCode();
62    }
63
64    public static <A,B> Pair<A,B> of(A a, B b) {
65        return new Pair<>(a,b);
66    }
67}
68