jdk/src/share/classes/java/time/temporal/IsoFields.java
changeset 15658 55b829ca2334
child 16852 60207b2b4b42
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/time/temporal/IsoFields.java	Tue Feb 12 09:25:43 2013 -0800
@@ -0,0 +1,587 @@
+/*
+ * Copyright (c) 2012, 2013, 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.
+ */
+
+/*
+ * Copyright (c) 2011-2012, Stephen Colebourne & Michael Nascimento Santos
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ *  * Neither the name of JSR-310 nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package java.time.temporal;
+
+import static java.time.DayOfWeek.THURSDAY;
+import static java.time.DayOfWeek.WEDNESDAY;
+import static java.time.temporal.ChronoField.DAY_OF_WEEK;
+import static java.time.temporal.ChronoField.DAY_OF_YEAR;
+import static java.time.temporal.ChronoField.EPOCH_DAY;
+import static java.time.temporal.ChronoField.MONTH_OF_YEAR;
+import static java.time.temporal.ChronoField.YEAR;
+import static java.time.temporal.ChronoUnit.DAYS;
+import static java.time.temporal.ChronoUnit.FOREVER;
+import static java.time.temporal.ChronoUnit.MONTHS;
+import static java.time.temporal.ChronoUnit.WEEKS;
+import static java.time.temporal.ChronoUnit.YEARS;
+
+import java.time.DateTimeException;
+import java.time.Duration;
+import java.time.LocalDate;
+import java.time.chrono.Chronology;
+import java.time.chrono.IsoChronology;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Fields and units specific to the ISO-8601 calendar system,
+ * including quarter-of-year and week-based-year.
+ * <p>
+ * This class defines fields and units that are specific to the ISO calendar system.
+ *
+ * <h3>Quarter of year</h3>
+ * The ISO-8601 standard is based on the standard civic 12 month year.
+ * This is commonly divided into four quarters, often abbreviated as Q1, Q2, Q3 and Q4.
+ * <p>
+ * January, February and March are in Q1.
+ * April, May and June are in Q2.
+ * July, August and September are in Q3.
+ * October, November and December are in Q4.
+ * <p>
+ * The complete date is expressed using three fields:
+ * <p><ul>
+ * <li>{@link #DAY_OF_QUARTER DAY_OF_QUARTER} - the day within the quarter, from 1 to 90, 91 or 92
+ * <li>{@link #QUARTER_OF_YEAR QUARTER_OF_YEAR} - the week within the week-based-year
+ * <li>{@link ChronoField#YEAR YEAR} - the standard ISO year
+ * </ul><p>
+ *
+ * <h3>Week based years</h3>
+ * The ISO-8601 standard was originally intended as a data interchange format,
+ * defining a string format for dates and times. However, it also defines an
+ * alternate way of expressing the date, based on the concept of week-based-year.
+ * <p>
+ * The date is expressed using three fields:
+ * <p><ul>
+ * <li>{@link ChronoField#DAY_OF_WEEK DAY_OF_WEEK} - the standard field defining the
+ *  day-of-week from Monday (1) to Sunday (7)
+ * <li>{@link #WEEK_OF_WEEK_BASED_YEAR} - the week within the week-based-year
+ * <li>{@link #WEEK_BASED_YEAR WEEK_BASED_YEAR} - the week-based-year
+ * </ul><p>
+ * The week-based-year itself is defined relative to the standard ISO proleptic year.
+ * It differs from the standard year in that it always starts on a Monday.
+ * <p>
+ * The first week of a week-based-year is the first Monday-based week of the standard
+ * ISO year that has at least 4 days in the new year.
+ * <p><ul>
+ * <li>If January 1st is Monday then week 1 starts on January 1st
+ * <li>If January 1st is Tuesday then week 1 starts on December 31st of the previous standard year
+ * <li>If January 1st is Wednesday then week 1 starts on December 30th of the previous standard year
+ * <li>If January 1st is Thursday then week 1 starts on December 29th of the previous standard year
+ * <li>If January 1st is Friday then week 1 starts on January 4th
+ * <li>If January 1st is Saturday then week 1 starts on January 3rd
+ * <li>If January 1st is Sunday then week 1 starts on January 2nd
+ * </ul><p>
+ * There are 52 weeks in most week-based years, however on occasion there are 53 weeks.
+ * <p>
+ * For example:
+ * <p>
+ * <table cellpadding="0" cellspacing="3" border="0" style="text-align: left; width: 50%;">
+ * <caption>Examples of Week based Years</caption>
+ * <tr><th>Date</th><th>Day-of-week</th><th>Field values</th></tr>
+ * <tr><th>2008-12-28</th><td>Sunday</td><td>Week 52 of week-based-year 2008</td></tr>
+ * <tr><th>2008-12-29</th><td>Monday</td><td>Week 1 of week-based-year 2009</td></tr>
+ * <tr><th>2008-12-31</th><td>Wednesday</td><td>Week 1 of week-based-year 2009</td></tr>
+ * <tr><th>2009-01-01</th><td>Thursday</td><td>Week 1 of week-based-year 2009</td></tr>
+ * <tr><th>2009-01-04</th><td>Sunday</td><td>Week 1 of week-based-year 2009</td></tr>
+ * <tr><th>2009-01-05</th><td>Monday</td><td>Week 2 of week-based-year 2009</td></tr>
+ * </table>
+ *
+ * <h3>Specification for implementors</h3>
+ * <p>
+ * This class is immutable and thread-safe.
+ *
+ * @since 1.8
+ */
+public final class IsoFields {
+
+    /**
+     * The field that represents the day-of-quarter.
+     * <p>
+     * This field allows the day-of-quarter value to be queried and set.
+     * The day-of-quarter has values from 1 to 90 in Q1 of a standard year, from 1 to 91
+     * in Q1 of a leap year, from 1 to 91 in Q2 and from 1 to 92 in Q3 and Q4.
+     * <p>
+     * The day-of-quarter can only be calculated if the day-of-year, month-of-year and year
+     * are available.
+     * <p>
+     * When setting this field, the value is allowed to be partially lenient, taking any
+     * value from 1 to 92. If the quarter has less than 92 days, then day 92, and
+     * potentially day 91, is in the following quarter.
+     * <p>
+     * This unit is an immutable and thread-safe singleton.
+     */
+    public static final TemporalField DAY_OF_QUARTER = Field.DAY_OF_QUARTER;
+    /**
+     * The field that represents the quarter-of-year.
+     * <p>
+     * This field allows the quarter-of-year value to be queried and set.
+     * The quarter-of-year has values from 1 to 4.
+     * <p>
+     * The day-of-quarter can only be calculated if the month-of-year is available.
+     * <p>
+     * This unit is an immutable and thread-safe singleton.
+     */
+    public static final TemporalField QUARTER_OF_YEAR = Field.QUARTER_OF_YEAR;
+    /**
+     * The field that represents the week-of-week-based-year.
+     * <p>
+     * This field allows the week of the week-based-year value to be queried and set.
+     * <p>
+     * This unit is an immutable and thread-safe singleton.
+     */
+    public static final TemporalField WEEK_OF_WEEK_BASED_YEAR = Field.WEEK_OF_WEEK_BASED_YEAR;
+    /**
+     * The field that represents the week-based-year.
+     * <p>
+     * This field allows the week-based-year value to be queried and set.
+     * <p>
+     * This unit is an immutable and thread-safe singleton.
+     */
+    public static final TemporalField WEEK_BASED_YEAR = Field.WEEK_BASED_YEAR;
+    /**
+     * The unit that represents week-based-years for the purpose of addition and subtraction.
+     * <p>
+     * This allows a number of week-based-years to be added to, or subtracted from, a date.
+     * The unit is equal to either 52 or 53 weeks.
+     * The estimated duration of a week-based-year is the same as that of a standard ISO
+     * year at {@code 365.2425 Days}.
+     * <p>
+     * The rules for addition add the number of week-based-years to the existing value
+     * for the week-based-year field. If the resulting week-based-year only has 52 weeks,
+     * then the date will be in week 1 of the following week-based-year.
+     * <p>
+     * This unit is an immutable and thread-safe singleton.
+     */
+    public static final TemporalUnit WEEK_BASED_YEARS = Unit.WEEK_BASED_YEARS;
+    /**
+     * Unit that represents the concept of a quarter-year.
+     * For the ISO calendar system, it is equal to 3 months.
+     * The estimated duration of a quarter-year is one quarter of {@code 365.2425 Days}.
+     * <p>
+     * This unit is an immutable and thread-safe singleton.
+     */
+    public static final TemporalUnit QUARTER_YEARS = Unit.QUARTER_YEARS;
+
+    /**
+     * Restricted constructor.
+     */
+    private IsoFields() {
+        throw new AssertionError("Not instantiable");
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Implementation of the field.
+     */
+    private static enum Field implements TemporalField {
+        DAY_OF_QUARTER {
+            @Override
+            public String getName() {
+                return "DayOfQuarter";
+            }
+            @Override
+            public TemporalUnit getBaseUnit() {
+                return DAYS;
+            }
+            @Override
+            public TemporalUnit getRangeUnit() {
+                return QUARTER_YEARS;
+            }
+            @Override
+            public ValueRange range() {
+                return ValueRange.of(1, 90, 92);
+            }
+            @Override
+            public boolean isSupportedBy(TemporalAccessor temporal) {
+                return temporal.isSupported(DAY_OF_YEAR) && temporal.isSupported(MONTH_OF_YEAR) &&
+                        temporal.isSupported(YEAR) && isIso(temporal);
+            }
+            @Override
+            public ValueRange rangeRefinedBy(TemporalAccessor temporal) {
+                if (isSupportedBy(temporal) == false) {
+                    throw new DateTimeException("Unsupported field: DayOfQuarter");
+                }
+                long qoy = temporal.getLong(QUARTER_OF_YEAR);
+                if (qoy == 1) {
+                    long year = temporal.getLong(YEAR);
+                    return (IsoChronology.INSTANCE.isLeapYear(year) ? ValueRange.of(1, 91) : ValueRange.of(1, 90));
+                } else if (qoy == 2) {
+                    return ValueRange.of(1, 91);
+                } else if (qoy == 3 || qoy == 4) {
+                    return ValueRange.of(1, 92);
+                } // else value not from 1 to 4, so drop through
+                return range();
+            }
+            @Override
+            public long getFrom(TemporalAccessor temporal) {
+                if (isSupportedBy(temporal) == false) {
+                    throw new DateTimeException("Unsupported field: DayOfQuarter");
+                }
+                int doy = temporal.get(DAY_OF_YEAR);
+                int moy = temporal.get(MONTH_OF_YEAR);
+                long year = temporal.getLong(YEAR);
+                return doy - QUARTER_DAYS[((moy - 1) / 3) + (IsoChronology.INSTANCE.isLeapYear(year) ? 4 : 0)];
+            }
+            @SuppressWarnings("unchecked")
+            @Override
+            public <R extends Temporal> R adjustInto(R temporal, long newValue) {
+                // calls getFrom() to check if supported
+                long curValue = getFrom(temporal);
+                range().checkValidValue(newValue, this);  // leniently check from 1 to 92 TODO: check
+                return (R) temporal.with(DAY_OF_YEAR, temporal.getLong(DAY_OF_YEAR) + (newValue - curValue));
+            }
+            @Override
+            public Map<TemporalField, Long> resolve(TemporalAccessor temporal, long value) {
+                if ((temporal.isSupported(YEAR) && temporal.isSupported(DAY_OF_QUARTER)) == false) {
+                    return null;
+                }
+                int y = temporal.get(YEAR);
+                int qoy = temporal.get(QUARTER_OF_YEAR);
+                range().checkValidValue(value, this);  // leniently check from 1 to 92 TODO: check
+                LocalDate date = LocalDate.of(y, ((qoy - 1) * 3) + 1, 1).plusDays(value - 1);
+                Map<TemporalField, Long> result = new HashMap<>(4, 1.0f);
+                result.put(EPOCH_DAY, date.toEpochDay());
+                result.put(YEAR, null);
+                result.put(QUARTER_OF_YEAR, null);
+                return result;
+            }
+        },
+        QUARTER_OF_YEAR {
+            @Override
+            public String getName() {
+                return "QuarterOfYear";
+            }
+            @Override
+            public TemporalUnit getBaseUnit() {
+                return QUARTER_YEARS;
+            }
+            @Override
+            public TemporalUnit getRangeUnit() {
+                return YEARS;
+            }
+            @Override
+            public ValueRange range() {
+                return ValueRange.of(1, 4);
+            }
+            @Override
+            public boolean isSupportedBy(TemporalAccessor temporal) {
+                return temporal.isSupported(MONTH_OF_YEAR) && isIso(temporal);
+            }
+            @Override
+            public long getFrom(TemporalAccessor temporal) {
+                if (isSupportedBy(temporal) == false) {
+                    throw new DateTimeException("Unsupported field: QuarterOfYear");
+                }
+                long moy = temporal.getLong(MONTH_OF_YEAR);
+                return ((moy + 2) / 3);
+            }
+            @SuppressWarnings("unchecked")
+            @Override
+            public <R extends Temporal> R adjustInto(R temporal, long newValue) {
+                // calls getFrom() to check if supported
+                long curValue = getFrom(temporal);
+                range().checkValidValue(newValue, this);  // strictly check from 1 to 4
+                return (R) temporal.with(MONTH_OF_YEAR, temporal.getLong(MONTH_OF_YEAR) + (newValue - curValue) * 3);
+            }
+        },
+        WEEK_OF_WEEK_BASED_YEAR {
+            @Override
+            public String getName() {
+                return "WeekOfWeekBasedYear";
+            }
+            @Override
+            public TemporalUnit getBaseUnit() {
+                return WEEKS;
+            }
+            @Override
+            public TemporalUnit getRangeUnit() {
+                return WEEK_BASED_YEARS;
+            }
+            @Override
+            public ValueRange range() {
+                return ValueRange.of(1, 52, 53);
+            }
+            @Override
+            public boolean isSupportedBy(TemporalAccessor temporal) {
+                return temporal.isSupported(EPOCH_DAY) && isIso(temporal);
+            }
+            @Override
+            public ValueRange rangeRefinedBy(TemporalAccessor temporal) {
+                if (isSupportedBy(temporal) == false) {
+                    throw new DateTimeException("Unsupported field: WeekOfWeekBasedYear");
+                }
+                return getWeekRange(LocalDate.from(temporal));
+            }
+            @Override
+            public long getFrom(TemporalAccessor temporal) {
+                if (isSupportedBy(temporal) == false) {
+                    throw new DateTimeException("Unsupported field: WeekOfWeekBasedYear");
+                }
+                return getWeek(LocalDate.from(temporal));
+            }
+            @SuppressWarnings("unchecked")
+            @Override
+            public <R extends Temporal> R adjustInto(R temporal, long newValue) {
+                // calls getFrom() to check if supported
+                range().checkValidValue(newValue, this);  // lenient range
+                return (R) temporal.plus(Math.subtractExact(newValue, getFrom(temporal)), WEEKS);
+            }
+            @Override
+            public Map<TemporalField, Long> resolve(TemporalAccessor temporal, long value) {
+                if ((temporal.isSupported(WEEK_BASED_YEAR) && temporal.isSupported(DAY_OF_WEEK)) == false) {
+                    return null;
+                }
+                int wby = temporal.get(WEEK_BASED_YEAR);
+                int dow = temporal.get(DAY_OF_WEEK);
+                range().checkValidValue(value, this);  // lenient range
+                LocalDate date = LocalDate.of(wby, 1, 4).plusWeeks(value - 1).with(DAY_OF_WEEK, dow);
+                Map<TemporalField, Long> result = new HashMap<>(2, 1.0f);
+                result.put(EPOCH_DAY, date.toEpochDay());
+                result.put(WEEK_BASED_YEAR, null);
+                result.put(DAY_OF_WEEK, null);
+                return result;
+            }
+        },
+        WEEK_BASED_YEAR {
+            @Override
+            public String getName() {
+                return "WeekBasedYear";
+            }
+            @Override
+            public TemporalUnit getBaseUnit() {
+                return WEEK_BASED_YEARS;
+            }
+            @Override
+            public TemporalUnit getRangeUnit() {
+                return FOREVER;
+            }
+            @Override
+            public ValueRange range() {
+                return YEAR.range();
+            }
+            @Override
+            public boolean isSupportedBy(TemporalAccessor temporal) {
+                return temporal.isSupported(EPOCH_DAY) && isIso(temporal);
+            }
+            @Override
+            public long getFrom(TemporalAccessor temporal) {
+                if (isSupportedBy(temporal) == false) {
+                    throw new DateTimeException("Unsupported field: WeekBasedYear");
+                }
+                return getWeekBasedYear(LocalDate.from(temporal));
+            }
+            @SuppressWarnings("unchecked")
+            @Override
+            public <R extends Temporal> R adjustInto(R temporal, long newValue) {
+                if (isSupportedBy(temporal) == false) {
+                    throw new DateTimeException("Unsupported field: WeekBasedYear");
+                }
+                int newVal = range().checkValidIntValue(newValue, WEEK_BASED_YEAR);  // strict check
+                LocalDate date = LocalDate.from(temporal);
+                int week = getWeek(date);
+                date = date.withDayOfYear(180).withYear(newVal).with(WEEK_OF_WEEK_BASED_YEAR, week);
+                return (R) date.with(date);
+            }
+        };
+
+        @Override
+        public ValueRange rangeRefinedBy(TemporalAccessor temporal) {
+            return range();
+        }
+
+        @Override
+        public String toString() {
+            return getName();
+        }
+
+        //-------------------------------------------------------------------------
+        private static final int[] QUARTER_DAYS = {0, 90, 181, 273, 0, 91, 182, 274};
+
+        private static boolean isIso(TemporalAccessor temporal) {
+            return Chronology.from(temporal).equals(IsoChronology.INSTANCE);
+        }
+
+        private static ValueRange getWeekRange(LocalDate date) {
+            int wby = getWeekBasedYear(date);
+            date = date.withDayOfYear(1).withYear(wby);
+            // 53 weeks if standard year starts on Thursday, or Wed in a leap year
+            if (date.getDayOfWeek() == THURSDAY || (date.getDayOfWeek() == WEDNESDAY && date.isLeapYear())) {
+                return ValueRange.of(1, 53);
+            }
+            return ValueRange.of(1, 52);
+        }
+
+        private static int getWeek(LocalDate date) {
+            int dow0 = date.getDayOfWeek().ordinal();
+            int doy0 = date.getDayOfYear() - 1;
+            int doyThu0 = doy0 + (3 - dow0);  // adjust to mid-week Thursday (which is 3 indexed from zero)
+            int alignedWeek = doyThu0 / 7;
+            int firstThuDoy0 = doyThu0 - (alignedWeek * 7);
+            int firstMonDoy0 = firstThuDoy0 - 3;
+            if (firstMonDoy0 < -3) {
+                firstMonDoy0 += 7;
+            }
+            if (doy0 < firstMonDoy0) {
+                return (int) getWeekRange(date.withDayOfYear(180).minusYears(1)).getMaximum();
+            }
+            int week = ((doy0 - firstMonDoy0) / 7) + 1;
+            if (week == 53) {
+                if ((firstMonDoy0 == -3 || (firstMonDoy0 == -2 && date.isLeapYear())) == false) {
+                    week = 1;
+                }
+            }
+            return week;
+        }
+
+        private static int getWeekBasedYear(LocalDate date) {
+            int year = date.getYear();
+            int doy = date.getDayOfYear();
+            if (doy <= 3) {
+                int dow = date.getDayOfWeek().ordinal();
+                if (doy - dow < -2) {
+                    year--;
+                }
+            } else if (doy >= 363) {
+                int dow = date.getDayOfWeek().ordinal();
+                doy = doy - 363 - (date.isLeapYear() ? 1 : 0);
+                if (doy - dow >= 0) {
+                    year++;
+                }
+            }
+            return year;
+        }
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Implementation of the period unit.
+     */
+    private static enum Unit implements TemporalUnit {
+
+        /**
+         * Unit that represents the concept of a week-based-year.
+         */
+        WEEK_BASED_YEARS("WeekBasedYears", Duration.ofSeconds(31556952L)),
+        /**
+         * Unit that represents the concept of a quarter-year.
+         */
+        QUARTER_YEARS("QuarterYears", Duration.ofSeconds(31556952L / 4));
+
+        private final String name;
+        private final Duration duration;
+
+        private Unit(String name, Duration estimatedDuration) {
+            this.name = name;
+            this.duration = estimatedDuration;
+        }
+
+        @Override
+        public String getName() {
+            return name;
+        }
+
+        @Override
+        public Duration getDuration() {
+            return duration;
+        }
+
+        @Override
+        public boolean isDurationEstimated() {
+            return true;
+        }
+
+        @Override
+        public boolean isSupportedBy(Temporal temporal) {
+            return temporal.isSupported(EPOCH_DAY);
+        }
+
+        @SuppressWarnings("unchecked")
+        @Override
+        public <R extends Temporal> R addTo(R temporal, long amount) {
+            switch(this) {
+                case WEEK_BASED_YEARS:
+                    return (R) temporal.with(WEEK_BASED_YEAR,
+                            Math.addExact(temporal.get(WEEK_BASED_YEAR), amount));
+                case QUARTER_YEARS:
+                    // no overflow (256 is multiple of 4)
+                    return (R) temporal.plus(amount / 256, YEARS)
+                            .plus((amount % 256) * 3, MONTHS);
+                default:
+                    throw new IllegalStateException("Unreachable");
+            }
+        }
+
+        @Override
+        public long between(Temporal temporal1, Temporal temporal2) {
+            switch(this) {
+                case WEEK_BASED_YEARS:
+                    return Math.subtractExact(temporal2.getLong(WEEK_BASED_YEAR),
+                            temporal1.getLong(WEEK_BASED_YEAR));
+                case QUARTER_YEARS:
+                    return temporal1.periodUntil(temporal2, MONTHS) / 3;
+                default:
+                    throw new IllegalStateException("Unreachable");
+            }
+        }
+
+        @Override
+        public String toString() {
+            return getName();
+
+        }
+    }
+}