1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation. Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25 /*
26 * Copyright (c) 2009-2012, Stephen Colebourne & Michael Nascimento Santos
27 *
28 * All rights reserved.
29 *
30 * Redistribution and use in source and binary forms, with or without
31 * modification, are permitted provided that the following conditions are met:
32 *
33 * * Redistributions of source code must retain the above copyright notice,
34 * this list of conditions and the following disclaimer.
35 *
36 * * Redistributions in binary form must reproduce the above copyright notice,
37 * this list of conditions and the following disclaimer in the documentation
38 * and/or other materials provided with the distribution.
39 *
40 * * Neither the name of JSR-310 nor the names of its contributors
41 * may be used to endorse or promote products derived from this software
42 * without specific prior written permission.
43 *
44 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
45 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
46 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
47 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
48 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
49 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
50 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
51 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
52 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
53 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
54 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
55 */
56 package build.tools.tzdb;
57
58 import java.util.Objects;
59
60 class Utils {
61
62 // Returns the largest (closest to positive infinity)
63 public static long floorDiv(long x, long y) {
64 long r = x / y;
65 // if the signs are different and modulo not zero, round down
66 if ((x ^ y) < 0 && (r * y != x)) {
67 r--;
68 }
69 return r;
70 }
71
72 // Returns the floor modulus of the {@code long} arguments.
73 public static long floorMod(long x, long y) {
74 return x - floorDiv(x, y) * y;
75 }
76
77 // Returns the sum of its arguments,
78 public static long addExact(long x, long y) {
79 long r = x + y;
80 // HD 2-12 Overflow iff both arguments have the opposite sign of the result
81 if (((x ^ r) & (y ^ r)) < 0) {
82 throw new ArithmeticException("long overflow");
83 }
84 return r;
85 }
86
87 // Year
88
89 // Returns true if the specified year is a leap year.
90 public static boolean isLeapYear(int year) {
91 return ((year & 3) == 0) && ((year % 100) != 0 || (year % 400) == 0);
92 }
93
94 // The minimum supported year, '-999,999,999'.
95 public static final int YEAR_MIN_VALUE = -999_999_999;
96
97 // The maximum supported year, '+999,999,999'.
98 public static final int YEAR_MAX_VALUE = 999_999_999;
99
100
101 // Gets the length of the specified month in days.
102 public static int lengthOfMonth(int month, boolean leapYear) {
103 switch (month) {
104 case 2: //FEBRUARY:
105 return (leapYear ? 29 : 28);
106 case 4: //APRIL:
107 case 6: //JUNE:
108 case 9: //SEPTEMBER:
109 case 11: //NOVEMBER:
110 return 30;
111 default:
112 return 31;
113 }
114 }
115
116 // Gets the maximum length of the specified month in days.
117 public static int maxLengthOfMonth(int month) {
118 switch (month) {
119 case 2: //FEBRUARY:
120 return 29;
121 case 4: //APRIL:
122 case 6: //JUNE:
123 case 9: //SEPTEMBER:
124 case 11: //NOVEMBER:
125 return 30;
126 default:
127 return 31;
128 }
129 }
130
131 // DayOfWeek
132
133 // Returns the day-of-week that is the specified number of days after
134 // this one, from 1 to 7 for Monday to Sunday.
135 public static int plusDayOfWeek(int dow, long days) {
136 int amount = (int) (days % 7);
137 return (dow - 1 + (amount + 7)) % 7 + 1;
138 }
139
140 // Returns the day-of-week that is the specified number of days before
141 // this one, from 1 to 7 for Monday to Sunday.
142 public static int minusDayOfWeek(int dow, long days) {
143 return plusDayOfWeek(dow, -(days % 7));
144 }
145
146 // Adjusts the date to the first occurrence of the specified day-of-week
147 // before the date being adjusted unless it is already on that day in
148 // which case the same object is returned.
149 public static LocalDate previousOrSame(LocalDate date, int dayOfWeek) {
150 return adjust(date, dayOfWeek, 1);
151 }
152
153 // Adjusts the date to the first occurrence of the specified day-of-week
154 // after the date being adjusted unless it is already on that day in
155 // which case the same object is returned.
156 public static LocalDate nextOrSame(LocalDate date, int dayOfWeek) {
157 return adjust(date, dayOfWeek, 0);
158 }
159
160 // Implementation of next, previous or current day-of-week.
161 // @param relative whether the current date is a valid answer
162 private static final LocalDate adjust(LocalDate date, int dow, int relative) {
163 int calDow = date.getDayOfWeek();
164 if (relative < 2 && calDow == dow) {
165 return date;
166 }
167 if ((relative & 1) == 0) {
168 int daysDiff = calDow - dow;
169 return date.plusDays(daysDiff >= 0 ? 7 - daysDiff : -daysDiff);
170 } else {
171 int daysDiff = dow - calDow;
172 return date.minusDays(daysDiff >= 0 ? 7 - daysDiff : -daysDiff);
173 }
174 }
175
176 }