DateComponents.java

  1. /* Copyright 2002-2024 CS GROUP
  2.  * Licensed to CS GROUP (CS) under one or more
  3.  * contributor license agreements.  See the NOTICE file distributed with
  4.  * this work for additional information regarding copyright ownership.
  5.  * CS licenses this file to You under the Apache License, Version 2.0
  6.  * (the "License"); you may not use this file except in compliance with
  7.  * the License.  You may obtain a copy of the License at
  8.  *
  9.  *   http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  17. package org.orekit.time;

  19. import java.io.Serializable;
  20. import java.text.DecimalFormatSymbols;
  21. import java.util.Locale;
  22. import java.util.regex.Matcher;
  23. import java.util.regex.Pattern;

  25. import org.orekit.errors.OrekitIllegalArgumentException;
  26. import org.orekit.errors.OrekitMessages;

  28. /** Class representing a date broken up as year, month and day components.
  29.  * <p>This class uses the astronomical convention for calendars,
  30.  * which is also the convention used by <code>java.util.Date</code>:
  31.  * a year zero is present between years -1 and +1, and 10 days are
  32.  * missing in 1582. The calendar used around these special dates are:</p>
  33.  * <ul>
  34.  *   <li>up to 0000-12-31 : proleptic julian calendar</li>
  35.  *   <li>from 0001-01-01 to 1582-10-04: julian calendar</li>
  36.  *   <li>from 1582-10-15: gregorian calendar</li>
  37.  * </ul>
  38.  * <p>Instances of this class are guaranteed to be immutable.</p>
  39.  * @see TimeComponents
  40.  * @see DateTimeComponents
  41.  * @author Luc Maisonobe
  42.  */
  43. public class DateComponents implements Serializable, Comparable<DateComponents> {

  45.     /** Reference epoch for julian dates: -4712-01-01.
  46.      * <p>Both <code>java.util.Date</code> and {@link DateComponents} classes
  47.      * follow the astronomical conventions and consider a year 0 between
  48.      * years -1 and +1, hence this reference date lies in year -4712 and not
  49.      * in year -4713 as can be seen in other documents or programs that obey
  50.      * a different convention (for example the <code>convcal</code> utility).</p>
  51.      */
  52.     public static final DateComponents JULIAN_EPOCH;

  54.     /** Reference epoch for modified julian dates: 1858-11-17. */
  55.     public static final DateComponents MODIFIED_JULIAN_EPOCH;

  57.     /** Reference epoch for 1950 dates: 1950-01-01. */
  58.     public static final DateComponents FIFTIES_EPOCH;

  60.     /** Reference epoch for CCSDS Time Code Format (CCSDS 301.0-B-4): 1958-01-01. */
  61.     public static final DateComponents CCSDS_EPOCH;

  63.     /** Reference epoch for Galileo System Time: 1999-08-22. */
  64.     public static final DateComponents GALILEO_EPOCH;

  66.     /** Reference epoch for GPS weeks: 1980-01-06. */
  67.     public static final DateComponents GPS_EPOCH;

  69.     /** Reference epoch for QZSS weeks: 1980-01-06. */
  70.     public static final DateComponents QZSS_EPOCH;

  72.     /** Reference epoch for IRNSS weeks: 1999-08-22. */
  73.     public static final DateComponents IRNSS_EPOCH;

  75.     /** Reference epoch for BeiDou weeks: 2006-01-01. */
  76.     public static final DateComponents BEIDOU_EPOCH;

  78.     /** Reference epoch for GLONASS four-year interval number: 1996-01-01. */
  79.     public static final DateComponents GLONASS_EPOCH;

  81.     /** J2000.0 Reference epoch: 2000-01-01. */
  82.     public static final DateComponents J2000_EPOCH;

  84.     /** Java Reference epoch: 1970-01-01. */
  85.     public static final DateComponents JAVA_EPOCH;

  87.     /** Maximum supported date.
  88.      * <p>
  89.      * This is date 5881610-07-11 which corresponds to {@code Integer.MAX_VALUE}
  90.      * days after {@link #J2000_EPOCH}.
  91.      * </p>
  92.      * @since 9.0
  93.      */
  94.     public static final DateComponents MAX_EPOCH;

  96.     /** Maximum supported date.
  97.      * <p>
  98.      * This is date -5877490-03-03, which corresponds to {@code Integer.MIN_VALUE}
  99.      * days before {@link #J2000_EPOCH}.
  100.      * </p>
  101.      * @since 9.0
  102.      */
  103.     public static final DateComponents MIN_EPOCH;

  105.     /** Offset between julian day epoch and modified julian day epoch. */
  106.     public static final double JD_TO_MJD = 2400000.5;

  108.     /** Serializable UID. */
  109.     private static final long serialVersionUID = -2462694707837970938L;

  111.     /** Factory for proleptic julian calendar (up to 0000-12-31). */
  112.     private static final YearFactory PROLEPTIC_JULIAN_FACTORY = new ProlepticJulianFactory();

  114.     /** Factory for julian calendar (from 0001-01-01 to 1582-10-04). */
  115.     private static final YearFactory JULIAN_FACTORY           = new JulianFactory();

  117.     /** Factory for gregorian calendar (from 1582-10-15). */
  118.     private static final YearFactory GREGORIAN_FACTORY        = new GregorianFactory();

  120.     /** Factory for leap years. */
  121.     private static final MonthDayFactory LEAP_YEAR_FACTORY    = new LeapYearFactory();

  123.     /** Factory for non-leap years. */
  124.     private static final MonthDayFactory COMMON_YEAR_FACTORY  = new CommonYearFactory();

  126.     /** Formatting symbols used in {@link #toString()}. */
  127.     private static final DecimalFormatSymbols US_SYMBOLS = new DecimalFormatSymbols(Locale.US);

  129.     /** Offset between J2000 epoch and modified julian day epoch. */
  130.     private static final int MJD_TO_J2000 = 51544;


  133.     /** Basic and extended format calendar date. */
  134.     private static final Pattern CALENDAR_FORMAT = Pattern.compile("^(-?\\d\\d\\d\\d)-?(\\d\\d)-?(\\d\\d)$");

  136.     /** Basic and extended format ordinal date. */
  137.     private static final Pattern ORDINAL_FORMAT = Pattern.compile("^(-?\\d\\d\\d\\d)-?(\\d\\d\\d)$");

  139.     /** Basic and extended format week date. */
  140.     private static final Pattern WEEK_FORMAT = Pattern.compile("^(-?\\d\\d\\d\\d)-?W(\\d\\d)-?(\\d)$");

  142.     static {
  143.         // this static statement makes sure the reference epoch are initialized
  144.         // once AFTER the various factories have been set up
  145.         JULIAN_EPOCH          = new DateComponents(-4712,  1,  1);
  146.         MODIFIED_JULIAN_EPOCH = new DateComponents(1858, 11, 17);
  147.         FIFTIES_EPOCH         = new DateComponents(1950, 1, 1);
  148.         CCSDS_EPOCH           = new DateComponents(1958, 1, 1);
  149.         GALILEO_EPOCH         = new DateComponents(1999, 8, 22);
  150.         GPS_EPOCH             = new DateComponents(1980, 1, 6);
  151.         QZSS_EPOCH            = new DateComponents(1980, 1, 6);
  152.         IRNSS_EPOCH           = new DateComponents(1999, 8, 22);
  153.         BEIDOU_EPOCH          = new DateComponents(2006, 1, 1);
  154.         GLONASS_EPOCH         = new DateComponents(1996, 1, 1);
  155.         J2000_EPOCH           = new DateComponents(2000, 1, 1);
  156.         JAVA_EPOCH            = new DateComponents(1970, 1, 1);
  157.         MAX_EPOCH             = new DateComponents(Integer.MAX_VALUE);
  158.         MIN_EPOCH             = new DateComponents(Integer.MIN_VALUE);
  159.     }

  161.     /** Year number. */
  162.     private final int year;

  164.     /** Month number. */
  165.     private final int month;

  167.     /** Day number. */
  168.     private final int day;

  170.     /** Build a date from its components.
  171.      * @param year year number (may be 0 or negative for BC years)
  172.      * @param month month number from 1 to 12
  173.      * @param day day number from 1 to 31
  174.      * @exception IllegalArgumentException if inconsistent arguments
  175.      * are given (parameters out of range, february 29 for non-leap years,
  176.      * dates during the gregorian leap in 1582 ...)
  177.      */
  178.     public DateComponents(final int year, final int month, final int day)
  179.         throws IllegalArgumentException {

  181.         // very rough range check
  182.         // (just to avoid ArrayOutOfboundException in MonthDayFactory later)
  183.         if (month < 1 || month > 12) {
  184.             throw new OrekitIllegalArgumentException(OrekitMessages.NON_EXISTENT_MONTH, month);
  185.         }

  187.         // start by trusting the parameters
  188.         this.year  = year;
  189.         this.month = month;
  190.         this.day   = day;

  192.         // build a check date from the J2000 day
  193.         final DateComponents check = new DateComponents(getJ2000Day());

  195.         // check the parameters for mismatch
  196.         // (i.e. invalid date components, like 29 february on non-leap years)
  197.         if (year != check.year || month != check.month || day != check.day) {
  198.             throw new OrekitIllegalArgumentException(OrekitMessages.NON_EXISTENT_YEAR_MONTH_DAY,
  199.                                                       year, month, day);
  200.         }

  202.     }

  204.     /** Build a date from its components.
  205.      * @param year year number (may be 0 or negative for BC years)
  206.      * @param month month enumerate
  207.      * @param day day number from 1 to 31
  208.      * @exception IllegalArgumentException if inconsistent arguments
  209.      * are given (parameters out of range, february 29 for non-leap years,
  210.      * dates during the gregorian leap in 1582 ...)
  211.      */
  212.     public DateComponents(final int year, final Month month, final int day)
  213.         throws IllegalArgumentException {
  214.         this(year, month.getNumber(), day);
  215.     }

  217.     /** Build a date from a year and day number.
  218.      * @param year year number (may be 0 or negative for BC years)
  219.      * @param dayNumber day number in the year from 1 to 366
  220.      * @exception IllegalArgumentException if dayNumber is out of range
  221.      * with respect to year
  222.      */
  223.     public DateComponents(final int year, final int dayNumber)
  224.         throws IllegalArgumentException {
  225.         this(J2000_EPOCH, new DateComponents(year - 1, 12, 31).getJ2000Day() + dayNumber);
  226.         if (dayNumber != getDayOfYear()) {
  227.             throw new OrekitIllegalArgumentException(OrekitMessages.NON_EXISTENT_DAY_NUMBER_IN_YEAR,
  228.                                                      dayNumber, year);
  229.         }
  230.     }

  232.     /** Build a date from its offset with respect to a {@link #J2000_EPOCH}.
  233.      * @param offset offset with respect to a {@link #J2000_EPOCH}
  234.      * @see #getJ2000Day()
  235.      */
  236.     public DateComponents(final int offset) {

  238.         // we follow the astronomical convention for calendars:
  239.         // we consider a year zero and 10 days are missing in 1582
  240.         // from 1582-10-15: gregorian calendar
  241.         // from 0001-01-01 to 1582-10-04: julian calendar
  242.         // up to 0000-12-31 : proleptic julian calendar
  243.         YearFactory yFactory = GREGORIAN_FACTORY;
  244.         if (offset < -152384) {
  245.             if (offset > -730122) {
  246.                 yFactory = JULIAN_FACTORY;
  247.             } else {
  248.                 yFactory = PROLEPTIC_JULIAN_FACTORY;
  249.             }
  250.         }
  251.         year = yFactory.getYear(offset);
  252.         final int dayInYear = offset - yFactory.getLastJ2000DayOfYear(year - 1);

  254.         // handle month/day according to the year being a common or leap year
  255.         final MonthDayFactory mdFactory =
  256.             yFactory.isLeap(year) ? LEAP_YEAR_FACTORY : COMMON_YEAR_FACTORY;
  257.         month = mdFactory.getMonth(dayInYear);
  258.         day   = mdFactory.getDay(dayInYear, month);

  260.     }

  262.     /** Build a date from its offset with respect to a reference epoch.
  263.      * <p>This constructor is mainly useful to build a date from a modified
  264.      * julian day (using {@link #MODIFIED_JULIAN_EPOCH}) or a GPS week number
  265.      * (using {@link #GPS_EPOCH}).</p>
  266.      * @param epoch reference epoch
  267.      * @param offset offset with respect to a reference epoch
  268.      * @see #DateComponents(int)
  269.      * @see #getMJD()
  270.      */
  271.     public DateComponents(final DateComponents epoch, final int offset) {
  272.         this(epoch.getJ2000Day() + offset);
  273.     }

  275.     /** Build a date from week components.
  276.      * <p>The calendar week number is a number between 1 and 52 or 53 depending
  277.      * on the year. Week 1 is defined by ISO as the one that includes the first
  278.      * Thursday of a year. Week 1 may therefore start the previous year and week
  279.      * 52 or 53 may end in the next year. As an example calendar date 1995-01-01
  280.      * corresponds to week date 1994-W52-7 (i.e. Sunday in the last week of 1994
  281.      * is in fact the first day of year 1995). This date would beAnother example is calendar date
  282.      * 1996-12-31 which corresponds to week date 1997-W01-2 (i.e. Tuesday in the
  283.      * first week of 1997 is in fact the last day of year 1996).</p>
  284.      * @param wYear year associated to week numbering
  285.      * @param week week number in year, from 1 to 52 or 53
  286.      * @param dayOfWeek day of week, from 1 (Monday) to 7 (Sunday)
  287.      * @return a builded date
  288.      * @exception IllegalArgumentException if inconsistent arguments
  289.      * are given (parameters out of range, week 53 on a 52 weeks year ...)
  290.      */
  291.     public static DateComponents createFromWeekComponents(final int wYear, final int week, final int dayOfWeek)
  292.         throws IllegalArgumentException {

  294.         final DateComponents firstWeekMonday = new DateComponents(getFirstWeekMonday(wYear));
  295.         final DateComponents d = new DateComponents(firstWeekMonday, 7 * week + dayOfWeek - 8);

  297.         // check the parameters for invalid date components
  298.         if (week != d.getCalendarWeek() || dayOfWeek != d.getDayOfWeek()) {
  299.             throw new OrekitIllegalArgumentException(OrekitMessages.NON_EXISTENT_WEEK_DATE,
  300.                                                      wYear, week, dayOfWeek);
  301.         }

  303.         return d;

  305.     }

  307.     /** Parse a string in ISO-8601 format to build a date.
  308.      * <p>The supported formats are:
  309.      * <ul>
  310.      *   <li>basic format calendar date: YYYYMMDD</li>
  311.      *   <li>extended format calendar date: YYYY-MM-DD</li>
  312.      *   <li>basic format ordinal date: YYYYDDD</li>
  313.      *   <li>extended format ordinal date: YYYY-DDD</li>
  314.      *   <li>basic format week date: YYYYWwwD</li>
  315.      *   <li>extended format week date: YYYY-Www-D</li>
  316.      * </ul>
  317.      *
  318.      * <p> As shown by the list above, only the complete representations defined in section 4.1
  319.      * of ISO-8601 standard are supported, neither expended representations nor representations
  320.      * with reduced accuracy are supported.
  321.      *
  322.      * <p>
  323.      * Parsing a single integer as a julian day is <em>not</em> supported as it may be ambiguous
  324.      * with either the basic format calendar date or the basic format ordinal date depending
  325.      * on the number of digits.
  326.      * </p>
  327.      * @param string string to parse
  328.      * @return a parsed date
  329.      * @exception IllegalArgumentException if string cannot be parsed
  330.      */
  331.     public static  DateComponents parseDate(final String string) {

  333.         // is the date a calendar date ?
  334.         final Matcher calendarMatcher = CALENDAR_FORMAT.matcher(string);
  335.         if (calendarMatcher.matches()) {
  336.             return new DateComponents(Integer.parseInt(calendarMatcher.group(1)),
  337.                                       Integer.parseInt(calendarMatcher.group(2)),
  338.                                       Integer.parseInt(calendarMatcher.group(3)));
  339.         }

  341.         // is the date an ordinal date ?
  342.         final Matcher ordinalMatcher = ORDINAL_FORMAT.matcher(string);
  343.         if (ordinalMatcher.matches()) {
  344.             return new DateComponents(Integer.parseInt(ordinalMatcher.group(1)),
  345.                                       Integer.parseInt(ordinalMatcher.group(2)));
  346.         }

  348.         // is the date a week date ?
  349.         final Matcher weekMatcher = WEEK_FORMAT.matcher(string);
  350.         if (weekMatcher.matches()) {
  351.             return createFromWeekComponents(Integer.parseInt(weekMatcher.group(1)),
  352.                                             Integer.parseInt(weekMatcher.group(2)),
  353.                                             Integer.parseInt(weekMatcher.group(3)));
  354.         }

  356.         throw new OrekitIllegalArgumentException(OrekitMessages.NON_EXISTENT_DATE, string);

  358.     }

  360.     /** Get the year number.
  361.      * @return year number (may be 0 or negative for BC years)
  362.      */
  363.     public int getYear() {
  364.         return year;
  365.     }

  367.     /** Get the month.
  368.      * @return month number from 1 to 12
  369.      */
  370.     public int getMonth() {
  371.         return month;
  372.     }

  374.     /** Get the month as an enumerate.
  375.      * @return month as an enumerate
  376.      */
  377.     public Month getMonthEnum() {
  378.         return Month.getMonth(month);
  379.     }

  381.     /** Get the day.
  382.      * @return day number from 1 to 31
  383.      */
  384.     public int getDay() {
  385.         return day;
  386.     }

  388.     /** Get the day number with respect to J2000 epoch.
  389.      * @return day number with respect to J2000 epoch
  390.      */
  391.     public int getJ2000Day() {
  392.         YearFactory yFactory = GREGORIAN_FACTORY;
  393.         if (year < 1583) {
  394.             if (year < 1) {
  395.                 yFactory = PROLEPTIC_JULIAN_FACTORY;
  396.             } else if (year < 1582 || month < 10 || month < 11 && day < 5) {
  397.                 yFactory = JULIAN_FACTORY;
  398.             }
  399.         }
  400.         final MonthDayFactory mdFactory =
  401.             yFactory.isLeap(year) ? LEAP_YEAR_FACTORY : COMMON_YEAR_FACTORY;
  402.         return yFactory.getLastJ2000DayOfYear(year - 1) +
  403.                mdFactory.getDayInYear(month, day);
  404.     }

  406.     /** Get the modified julian day.
  407.      * @return modified julian day
  408.      */
  409.     public int getMJD() {
  410.         return MJD_TO_J2000 + getJ2000Day();
  411.     }

  413.     /** Get the calendar week number.
  414.      * <p>The calendar week number is a number between 1 and 52 or 53 depending
  415.      * on the year. Week 1 is defined by ISO as the one that includes the first
  416.      * Thursday of a year. Week 1 may therefore start the previous year and week
  417.      * 52 or 53 may end in the next year. As an example calendar date 1995-01-01
  418.      * corresponds to week date 1994-W52-7 (i.e. Sunday in the last week of 1994
  419.      * is in fact the first day of year 1995). Another example is calendar date
  420.      * 1996-12-31 which corresponds to week date 1997-W01-2 (i.e. Tuesday in the
  421.      * first week of 1997 is in fact the last day of year 1996).</p>
  422.      * @return calendar week number
  423.      */
  424.     public int getCalendarWeek() {
  425.         final int firstWeekMonday = getFirstWeekMonday(year);
  426.         int daysSincefirstMonday = getJ2000Day() - firstWeekMonday;
  427.         if (daysSincefirstMonday < 0) {
  428.             // we are still in a week from previous year
  429.             daysSincefirstMonday += firstWeekMonday - getFirstWeekMonday(year - 1);
  430.         } else if (daysSincefirstMonday > 363) {
  431.             // up to three days at end of year may belong to first week of next year
  432.             // (by chance, there is no need for a specific check in year 1582 ...)
  433.             final int weekYearLength = getFirstWeekMonday(year + 1) - firstWeekMonday;
  434.             if (daysSincefirstMonday >= weekYearLength) {
  435.                 daysSincefirstMonday -= weekYearLength;
  436.             }
  437.         }
  438.         return 1 + daysSincefirstMonday / 7;
  439.     }

  441.     /** Get the monday of a year first week.
  442.      * @param year year to consider
  443.      * @return day of the monday of the first weak of year
  444.      */
  445.     private static int getFirstWeekMonday(final int year) {
  446.         final int yearFirst = new DateComponents(year, 1, 1).getJ2000Day();
  447.         final int offsetToMonday = 4 - (yearFirst + 2) % 7;
  448.         return yearFirst + offsetToMonday + ((offsetToMonday > 3) ? -7 : 0);
  449.     }

  451.     /** Get the day of week.
  452.      * <p>Day of week is a number between 1 (Monday) and 7 (Sunday).</p>
  453.      * @return day of week
  454.      */
  455.     public int getDayOfWeek() {
  456.         final int dow = (getJ2000Day() + 6) % 7; // result is between -6 and +6
  457.         return (dow < 1) ? (dow + 7) : dow;
  458.     }

  460.     /** Get the day number in year.
  461.      * <p>Day number in year is between 1 (January 1st) and either 365 or
  462.      * 366 inclusive depending on year.</p>
  463.      * @return day number in year
  464.      */
  465.     public int getDayOfYear() {
  466.         return getJ2000Day() - new DateComponents(year - 1, 12, 31).getJ2000Day();
  467.     }

  469.     /** Get a string representation (ISO-8601) of the date.
  470.      * @return string representation of the date.
  471.      */
  472.     public String toString() {
  473.         return String.format(Locale.US, "%04d-%02d-%02d", year, month, day);
  474.     }

  476.     /** {@inheritDoc} */
  477.     public int compareTo(final DateComponents other) {
  478.         final int j2000Day = getJ2000Day();
  479.         final int otherJ2000Day = other.getJ2000Day();
  480.         if (j2000Day < otherJ2000Day) {
  481.             return -1;
  482.         } else if (j2000Day > otherJ2000Day) {
  483.             return 1;
  484.         }
  485.         return 0;
  486.     }

  488.     /** {@inheritDoc} */
  489.     public boolean equals(final Object other) {
  490.         try {
  491.             final DateComponents otherDate = (DateComponents) other;
  492.             return otherDate != null && year == otherDate.year &&
  493.                    month == otherDate.month && day == otherDate.day;
  494.         } catch (ClassCastException cce) {
  495.             return false;
  496.         }
  497.     }

  499.     /** {@inheritDoc} */
  500.     public int hashCode() {
  501.         return (year << 16) ^ (month << 8) ^ day;
  502.     }

  504.     /** Interface for dealing with years sequences according to some calendar. */
  505.     private interface YearFactory {

  507.         /** Get the year number for a given day number with respect to J2000 epoch.
  508.          * @param j2000Day day number with respect to J2000 epoch
  509.          * @return year number
  510.          */
  511.         int getYear(int j2000Day);

  513.         /** Get the day number with respect to J2000 epoch for new year's Eve.
  514.          * @param year year number
  515.          * @return day number with respect to J2000 epoch for new year's Eve
  516.          */
  517.         int getLastJ2000DayOfYear(int year);

  519.         /** Check if a year is a leap or common year.
  520.          * @param year year number
  521.          * @return true if year is a leap year
  522.          */
  523.         boolean isLeap(int year);

  525.     }

  527.     /** Class providing a years sequence compliant with the proleptic Julian calendar. */
  528.     private static class ProlepticJulianFactory implements YearFactory {

  530.         /** {@inheritDoc} */
  531.         public int getYear(final int j2000Day) {
  532.             return  (int) -((-4l * j2000Day - 2920488l) / 1461l);
  533.         }

  535.         /** {@inheritDoc} */
  536.         public int getLastJ2000DayOfYear(final int year) {
  537.             return 365 * year + (year + 1) / 4 - 730123;
  538.         }

  540.         /** {@inheritDoc} */
  541.         public boolean isLeap(final int year) {
  542.             return (year % 4) == 0;
  543.         }

  545.     }

  547.     /** Class providing a years sequence compliant with the Julian calendar. */
  548.     private static class JulianFactory implements YearFactory {

  550.         /** {@inheritDoc} */
  551.         public int getYear(final int j2000Day) {
  552.             return  (int) ((4l * j2000Day + 2921948l) / 1461l);
  553.         }

  555.         /** {@inheritDoc} */
  556.         public int getLastJ2000DayOfYear(final int year) {
  557.             return 365 * year + year / 4 - 730122;
  558.         }

  560.         /** {@inheritDoc} */
  561.         public boolean isLeap(final int year) {
  562.             return (year % 4) == 0;
  563.         }

  565.     }

  567.     /** Class providing a years sequence compliant with the Gregorian calendar. */
  568.     private static class GregorianFactory implements YearFactory {

  570.         /** {@inheritDoc} */
  571.         public int getYear(final int j2000Day) {

  573.             // year estimate
  574.             int year = (int) ((400l * j2000Day + 292194288l) / 146097l);

  576.             // the previous estimate is one unit too high in some rare cases
  577.             // (240 days in the 400 years gregorian cycle, about 0.16%)
  578.             if (j2000Day <= getLastJ2000DayOfYear(year - 1)) {
  579.                 --year;
  580.             }

  582.             // exact year
  583.             return year;

  585.         }

  587.         /** {@inheritDoc} */
  588.         public int getLastJ2000DayOfYear(final int year) {
  589.             return 365 * year + year / 4 - year / 100 + year / 400 - 730120;
  590.         }

  592.         /** {@inheritDoc} */
  593.         public boolean isLeap(final int year) {
  594.             return (year % 4) == 0 && ((year % 400) == 0 || (year % 100) != 0);
  595.         }

  597.     }

  599.     /** Interface for dealing with months sequences according to leap/common years. */
  600.     private interface MonthDayFactory {

  602.         /** Get the month number for a given day number within year.
  603.          * @param dayInYear day number within year
  604.          * @return month number
  605.          */
  606.         int getMonth(int dayInYear);

  608.         /** Get the day number for given month and day number within year.
  609.          * @param dayInYear day number within year
  610.          * @param month month number
  611.          * @return day number
  612.          */
  613.         int getDay(int dayInYear, int month);

  615.         /** Get the day number within year for given month and day numbers.
  616.          * @param month month number
  617.          * @param day day number
  618.          * @return day number within year
  619.          */
  620.         int getDayInYear(int month, int day);

  622.     }

  624.     /** Class providing the months sequence for leap years. */
  625.     private static class LeapYearFactory implements MonthDayFactory {

  627.         /** Months succession definition. */
  628.         private static final int[] PREVIOUS_MONTH_END_DAY = {
  629.             0, 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335
  630.         };

  632.         /** {@inheritDoc} */
  633.         public int getMonth(final int dayInYear) {
  634.             return (dayInYear < 32) ? 1 : (10 * dayInYear + 313) / 306;
  635.         }

  637.         /** {@inheritDoc} */
  638.         public int getDay(final int dayInYear, final int month) {
  639.             return dayInYear - PREVIOUS_MONTH_END_DAY[month];
  640.         }

  642.         /** {@inheritDoc} */
  643.         public int getDayInYear(final int month, final int day) {
  644.             return day + PREVIOUS_MONTH_END_DAY[month];
  645.         }

  647.     }

  649.     /** Class providing the months sequence for common years. */
  650.     private static class CommonYearFactory implements MonthDayFactory {

  652.         /** Months succession definition. */
  653.         private static final int[] PREVIOUS_MONTH_END_DAY = {
  654.             0, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
  655.         };

  657.         /** {@inheritDoc} */
  658.         public int getMonth(final int dayInYear) {
  659.             return (dayInYear < 32) ? 1 : (10 * dayInYear + 323) / 306;
  660.         }

  662.         /** {@inheritDoc} */
  663.         public int getDay(final int dayInYear, final int month) {
  664.             return dayInYear - PREVIOUS_MONTH_END_DAY[month];
  665.         }

  667.         /** {@inheritDoc} */
  668.         public int getDayInYear(final int month, final int day) {
  669.             return day + PREVIOUS_MONTH_END_DAY[month];
  670.         }

  672.     }

  674. }
Created with JaCoCo 0.8.12.202403310830