| 1 | /* |
| 2 | * Copyright 2001-2005 Stephen Colebourne |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | package org.joda.time.chrono; |
| 17 | |
| 18 | import java.util.HashMap; |
| 19 | import java.util.Map; |
| 20 | |
| 21 | import org.joda.time.Chronology; |
| 22 | import org.joda.time.DateTime; |
| 23 | import org.joda.time.DateTimeConstants; |
| 24 | import org.joda.time.DateTimeField; |
| 25 | import org.joda.time.DateTimeZone; |
| 26 | import org.joda.time.field.SkipDateTimeField; |
| 27 | |
| 28 | /** |
| 29 | * Implements the Coptic calendar system, which defines every fourth year as |
| 30 | * leap, much like the Julian calendar. The year is broken down into 12 months, |
| 31 | * each 30 days in length. An extra period at the end of the year is either 5 |
| 32 | * or 6 days in length. In this implementation, it is considered a 13th month. |
| 33 | * <p> |
| 34 | * Year 1 in the Coptic calendar began on August 29, 284 CE (Julian), thus |
| 35 | * Coptic years do not begin at the same time as Julian years. This chronology |
| 36 | * is not proleptic, as it does not allow dates before the first Coptic year. |
| 37 | * <p> |
| 38 | * This implementation defines a day as midnight to midnight exactly as per |
| 39 | * the ISO chronology. Some references indicate that a coptic day starts at |
| 40 | * sunset on the previous ISO day, but this has not been confirmed and is not |
| 41 | * implemented. |
| 42 | * <p> |
| 43 | * CopticChronology is thread-safe and immutable. |
| 44 | * |
| 45 | * @see <a href="http://en.wikipedia.org/wiki/Coptic_calendar">Wikipedia</a> |
| 46 | * @see JulianChronology |
| 47 | * |
| 48 | * @author Brian S O'Neill |
| 49 | * @since 1.0 |
| 50 | */ |
| 51 | public final class CopticChronology extends BasicFixedMonthChronology { |
| 52 | |
| 53 | /** Serialization lock */ |
| 54 | private static final long serialVersionUID = -5972804258688333942L; |
| 55 | |
| 56 | /** |
| 57 | * Constant value for 'Anno Martyrum' or 'Era of the Martyrs', equivalent |
| 58 | * to the value returned for AD/CE. |
| 59 | */ |
| 60 | public static final int AM = DateTimeConstants.CE; |
| 61 | |
| 62 | /** A singleton era field. */ |
| 63 | private static final DateTimeField ERA_FIELD = new BasicSingleEraDateTimeField("AM"); |
| 64 | |
| 65 | /** The lowest year that can be fully supported. */ |
| 66 | private static final int MIN_YEAR = -292269337; |
| 67 | |
| 68 | /** The highest year that can be fully supported. */ |
| 69 | private static final int MAX_YEAR = 292272708; |
| 70 | |
| 71 | /** Cache of zone to chronology arrays */ |
| 72 | private static final Map cCache = new HashMap(); |
| 73 | |
| 74 | /** Singleton instance of a UTC CopticChronology */ |
| 75 | private static final CopticChronology INSTANCE_UTC; |
| 76 | static { |
| 77 | // init after static fields |
| 78 | INSTANCE_UTC = getInstance(DateTimeZone.UTC); |
| 79 | } |
| 80 | |
| 81 | //----------------------------------------------------------------------- |
| 82 | /** |
| 83 | * Gets an instance of the CopticChronology. |
| 84 | * The time zone of the returned instance is UTC. |
| 85 | * |
| 86 | * @return a singleton UTC instance of the chronology |
| 87 | */ |
| 88 | public static CopticChronology getInstanceUTC() { |
| 89 | return INSTANCE_UTC; |
| 90 | } |
| 91 | |
| 92 | /** |
| 93 | * Gets an instance of the CopticChronology in the default time zone. |
| 94 | * |
| 95 | * @return a chronology in the default time zone |
| 96 | */ |
| 97 | public static CopticChronology getInstance() { |
| 98 | return getInstance(DateTimeZone.getDefault(), 4); |
| 99 | } |
| 100 | |
| 101 | /** |
| 102 | * Gets an instance of the CopticChronology in the given time zone. |
| 103 | * |
| 104 | * @param zone the time zone to get the chronology in, null is default |
| 105 | * @return a chronology in the specified time zone |
| 106 | */ |
| 107 | public static CopticChronology getInstance(DateTimeZone zone) { |
| 108 | return getInstance(zone, 4); |
| 109 | } |
| 110 | |
| 111 | /** |
| 112 | * Gets an instance of the CopticChronology in the given time zone. |
| 113 | * |
| 114 | * @param zone the time zone to get the chronology in, null is default |
| 115 | * @param minDaysInFirstWeek minimum number of days in first week of the year; default is 4 |
| 116 | * @return a chronology in the specified time zone |
| 117 | */ |
| 118 | public static CopticChronology getInstance(DateTimeZone zone, int minDaysInFirstWeek) { |
| 119 | if (zone == null) { |
| 120 | zone = DateTimeZone.getDefault(); |
| 121 | } |
| 122 | CopticChronology chrono; |
| 123 | synchronized (cCache) { |
| 124 | CopticChronology[] chronos = (CopticChronology[]) cCache.get(zone); |
| 125 | if (chronos == null) { |
| 126 | chronos = new CopticChronology[7]; |
| 127 | cCache.put(zone, chronos); |
| 128 | } |
| 129 | try { |
| 130 | chrono = chronos[minDaysInFirstWeek - 1]; |
| 131 | } catch (ArrayIndexOutOfBoundsException e) { |
| 132 | throw new IllegalArgumentException |
| 133 | ("Invalid min days in first week: " + minDaysInFirstWeek); |
| 134 | } |
| 135 | if (chrono == null) { |
| 136 | if (zone == DateTimeZone.UTC) { |
| 137 | // First create without a lower limit. |
| 138 | chrono = new CopticChronology(null, null, minDaysInFirstWeek); |
| 139 | // Impose lower limit and make another CopticChronology. |
| 140 | DateTime lowerLimit = new DateTime(1, 1, 1, 0, 0, 0, 0, chrono); |
| 141 | chrono = new CopticChronology |
| 142 | (LimitChronology.getInstance(chrono, lowerLimit, null), |
| 143 | null, minDaysInFirstWeek); |
| 144 | } else { |
| 145 | chrono = getInstance(DateTimeZone.UTC, minDaysInFirstWeek); |
| 146 | chrono = new CopticChronology |
| 147 | (ZonedChronology.getInstance(chrono, zone), null, minDaysInFirstWeek); |
| 148 | } |
| 149 | chronos[minDaysInFirstWeek - 1] = chrono; |
| 150 | } |
| 151 | } |
| 152 | return chrono; |
| 153 | } |
| 154 | |
| 155 | // Constructors and instance variables |
| 156 | //----------------------------------------------------------------------- |
| 157 | /** |
| 158 | * Restricted constructor. |
| 159 | */ |
| 160 | CopticChronology(Chronology base, Object param, int minDaysInFirstWeek) { |
| 161 | super(base, param, minDaysInFirstWeek); |
| 162 | } |
| 163 | |
| 164 | /** |
| 165 | * Serialization singleton. |
| 166 | */ |
| 167 | private Object readResolve() { |
| 168 | Chronology base = getBase(); |
| 169 | int minDays = getMinimumDaysInFirstWeek(); |
| 170 | minDays = (minDays == 0 ? 4 : minDays); // handle rename of BaseGJChronology |
| 171 | return base == null ? |
| 172 | getInstance(DateTimeZone.UTC, minDays) : |
| 173 | getInstance(base.getZone(), minDays); |
| 174 | } |
| 175 | |
| 176 | // Conversion |
| 177 | //----------------------------------------------------------------------- |
| 178 | /** |
| 179 | * Gets the Chronology in the UTC time zone. |
| 180 | * |
| 181 | * @return the chronology in UTC |
| 182 | */ |
| 183 | public Chronology withUTC() { |
| 184 | return INSTANCE_UTC; |
| 185 | } |
| 186 | |
| 187 | /** |
| 188 | * Gets the Chronology in a specific time zone. |
| 189 | * |
| 190 | * @param zone the zone to get the chronology in, null is default |
| 191 | * @return the chronology |
| 192 | */ |
| 193 | public Chronology withZone(DateTimeZone zone) { |
| 194 | if (zone == null) { |
| 195 | zone = DateTimeZone.getDefault(); |
| 196 | } |
| 197 | if (zone == getZone()) { |
| 198 | return this; |
| 199 | } |
| 200 | return getInstance(zone); |
| 201 | } |
| 202 | |
| 203 | //----------------------------------------------------------------------- |
| 204 | long calculateFirstDayOfYearMillis(int year) { |
| 205 | // Java epoch is 1970-01-01 Gregorian which is 1686-04-23 Coptic. |
| 206 | // Calculate relative to the nearest leap year and account for the |
| 207 | // difference later. |
| 208 | |
| 209 | int relativeYear = year - 1687; |
| 210 | int leapYears; |
| 211 | if (relativeYear <= 0) { |
| 212 | // Add 3 before shifting right since /4 and >>2 behave differently |
| 213 | // on negative numbers. |
| 214 | leapYears = (relativeYear + 3) >> 2; |
| 215 | } else { |
| 216 | leapYears = relativeYear >> 2; |
| 217 | // For post 1687 an adjustment is needed as jan1st is before leap day |
| 218 | if (!isLeapYear(year)) { |
| 219 | leapYears++; |
| 220 | } |
| 221 | } |
| 222 | |
| 223 | long millis = (relativeYear * 365L + leapYears) |
| 224 | * (long)DateTimeConstants.MILLIS_PER_DAY; |
| 225 | |
| 226 | // Adjust to account for difference between 1687-01-01 and 1686-04-23. |
| 227 | |
| 228 | return millis + (365L - 112) * DateTimeConstants.MILLIS_PER_DAY; |
| 229 | } |
| 230 | |
| 231 | //----------------------------------------------------------------------- |
| 232 | int getMinYear() { |
| 233 | return MIN_YEAR; |
| 234 | } |
| 235 | |
| 236 | //----------------------------------------------------------------------- |
| 237 | int getMaxYear() { |
| 238 | return MAX_YEAR; |
| 239 | } |
| 240 | |
| 241 | //----------------------------------------------------------------------- |
| 242 | long getApproxMillisAtEpochDividedByTwo() { |
| 243 | return (1686L * MILLIS_PER_YEAR + 112L * DateTimeConstants.MILLIS_PER_DAY) / 2; |
| 244 | } |
| 245 | |
| 246 | //----------------------------------------------------------------------- |
| 247 | protected void assemble(Fields fields) { |
| 248 | if (getBase() == null) { |
| 249 | super.assemble(fields); |
| 250 | |
| 251 | // Coptic, like Julian, has no year zero. |
| 252 | fields.year = new SkipDateTimeField(this, fields.year); |
| 253 | fields.weekyear = new SkipDateTimeField(this, fields.weekyear); |
| 254 | |
| 255 | fields.era = ERA_FIELD; |
| 256 | fields.monthOfYear = new BasicMonthOfYearDateTimeField(this, 13); |
| 257 | fields.months = fields.monthOfYear.getDurationField(); |
| 258 | } |
| 259 | } |
| 260 | |
| 261 | } |