content: /*
   * 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.
   */
  
  /*
   * This file is available under and governed by the GNU General Public
   * License version 2 only, as published by the Free Software Foundation.
   * However, the following notice accompanied the original version of this
   * file:
   *
   * Copyright (c) 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.chrono;
  
  import static java.time.temporal.ChronoField.ALIGNED_DAY_OF_WEEK_IN_MONTH;
  import static java.time.temporal.ChronoField.ALIGNED_DAY_OF_WEEK_IN_YEAR;
  import static java.time.temporal.ChronoField.ALIGNED_WEEK_OF_MONTH;
  import static java.time.temporal.ChronoField.ALIGNED_WEEK_OF_YEAR;
  import static java.time.temporal.ChronoField.DAY_OF_MONTH;
  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.ERA;
  import static java.time.temporal.ChronoField.MONTH_OF_YEAR;
  import static java.time.temporal.ChronoField.PROLEPTIC_MONTH;
  import static java.time.temporal.ChronoField.YEAR;
  import static java.time.temporal.ChronoField.YEAR_OF_ERA;
  import static java.time.temporal.ChronoUnit.DAYS;
  import static java.time.temporal.ChronoUnit.MONTHS;
  import static java.time.temporal.ChronoUnit.WEEKS;
  import static java.time.temporal.TemporalAdjusters.nextOrSame;
  
  import java.io.DataInput;
  import java.io.DataOutput;
  import java.io.IOException;
  import java.io.InvalidObjectException;
  import java.io.ObjectInputStream;
  import java.io.ObjectStreamException;
  import java.io.Serializable;
  import java.time.DateTimeException;
  import java.time.DayOfWeek;
  import java.time.format.ResolverStyle;
  import java.time.temporal.ChronoField;
  import java.time.temporal.TemporalAdjusters;
  import java.time.temporal.TemporalField;
  import java.time.temporal.ValueRange;
  import java.util.Comparator;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  import java.util.Objects;
  import java.util.ServiceLoader;
  import java.util.Set;
  import java.util.concurrent.ConcurrentHashMap;
  
  import sun.util.logging.PlatformLogger;
  
  /**
   * An abstract implementation of a calendar system, used to organize and identify dates.
   * <p>
   * The main date and time API is built on the ISO calendar system.
   * The chronology operates behind the scenes to represent the general concept of a calendar system.
   * <p>
   * See {@link Chronology} for more details.
   *
   * @implSpec
   * This class is separated from the {@code Chronology} interface so that the static methods
   * are not inherited. While {@code Chronology} can be implemented directly, it is strongly
   * recommended to extend this abstract class instead.
   * <p>
   * This class must be implemented with care to ensure other classes operate correctly.
   * All implementations that can be instantiated must be final, immutable and thread-safe.
   * Subclasses should be Serializable wherever possible.
   *
   * @since 1.8
   */
  public abstract class AbstractChronology implements Chronology {
  
      /**
       * ChronoLocalDate order constant.
       */
      static final Comparator<ChronoLocalDate> DATE_ORDER =
          (Comparator<ChronoLocalDate> & Serializable) (date1, date2) -> {
              return Long.compare(date1.toEpochDay(), date2.toEpochDay());
          };
      /**
       * ChronoLocalDateTime order constant.
       */
      static final Comparator<ChronoLocalDateTime<? extends ChronoLocalDate>> DATE_TIME_ORDER =
          (Comparator<ChronoLocalDateTime<? extends ChronoLocalDate>> & Serializable) (dateTime1, dateTime2) -> {
              int cmp = Long.compare(dateTime1.toLocalDate().toEpochDay(), dateTime2.toLocalDate().toEpochDay());
              if (cmp == 0) {
                  cmp = Long.compare(dateTime1.toLocalTime().toNanoOfDay(), dateTime2.toLocalTime().toNanoOfDay());
              }
              return cmp;
          };
      /**
       * ChronoZonedDateTime order constant.
       */
      static final Comparator<ChronoZonedDateTime<?>> INSTANT_ORDER =
              (Comparator<ChronoZonedDateTime<?>> & Serializable) (dateTime1, dateTime2) -> {
                  int cmp = Long.compare(dateTime1.toEpochSecond(), dateTime2.toEpochSecond());
                  if (cmp == 0) {
                      cmp = Long.compare(dateTime1.toLocalTime().getNano(), dateTime2.toLocalTime().getNano());
                  }
                  return cmp;
              };
  
      /**
       * Map of available calendars by ID.
       */
      private static final ConcurrentHashMap<String, Chronology> CHRONOS_BY_ID = new ConcurrentHashMap<>();
      /**
       * Map of available calendars by calendar type.
       */
      private static final ConcurrentHashMap<String, Chronology> CHRONOS_BY_TYPE = new ConcurrentHashMap<>();
  
      /**
       * Register a Chronology by its ID and type for lookup by {@link #of(String)}.
       * Chronologies must not be registered until they are completely constructed.
       * Specifically, not in the constructor of Chronology.
       *
       * @param chrono the chronology to register; not null
       * @return the already registered Chronology if any, may be null
       */
      static Chronology registerChrono(Chronology chrono) {
          return registerChrono(chrono, chrono.getId());
      }
  
      /**
       * Register a Chronology by ID and type for lookup by {@link #of(String)}.
       * Chronos must not be registered until they are completely constructed.
       * Specifically, not in the constructor of Chronology.
       *
       * @param chrono the chronology to register; not null
       * @param id the ID to register the chronology; not null
       * @return the already registered Chronology if any, may be null
       */
      static Chronology registerChrono(Chronology chrono, String id) {
          Chronology prev = CHRONOS_BY_ID.putIfAbsent(id, chrono);
          if (prev == null) {
              String type = chrono.getCalendarType();
              if (type != null) {
                  CHRONOS_BY_TYPE.putIfAbsent(type, chrono);
              }
          }
          return prev;
      }
  
      /**
       * Initialization of the maps from id and type to Chronology.
       * The ServiceLoader is used to find and register any implementations
       * of {@link AbstractChronology} found in the bootclass loader.
       * The built-in chronologies are registered explicitly.
       * Calendars configured via the Thread's context classloader are local
       * to that thread and are ignored.
       * <p>
       * The initialization is done only once using the registration
       * of the IsoChronology as the test and the final step.
       * Multiple threads may perform the initialization concurrently.
       * Only the first registration of each Chronology is retained by the
       * ConcurrentHashMap.
       * @return true if the cache was initialized
       */
      private static boolean initCache() {
          if (CHRONOS_BY_ID.get("ISO") == null) {
              // Initialization is incomplete
  
              // Register built-in Chronologies
              registerChrono(HijrahChronology.INSTANCE);
              registerChrono(JapaneseChronology.INSTANCE);
              registerChrono(MinguoChronology.INSTANCE);
              registerChrono(ThaiBuddhistChronology.INSTANCE);
  
              // Register Chronologies from the ServiceLoader
              @SuppressWarnings("rawtypes")
              ServiceLoader<AbstractChronology> loader =  ServiceLoader.load(AbstractChronology.class, null);
              for (AbstractChronology chrono : loader) {
                  String id = chrono.getId();
                  if (id.equals("ISO") || registerChrono(chrono) != null) {
                      // Log the attempt to replace an existing Chronology
                      PlatformLogger logger = PlatformLogger.getLogger("java.time.chrono");
                      logger.warning("Ignoring duplicate Chronology, from ServiceLoader configuration "  + id);
                  }
              }
  
              // finally, register IsoChronology to mark initialization is complete
              registerChrono(IsoChronology.INSTANCE);
              return true;
          }
          return false;
      }
  
      //-----------------------------------------------------------------------
      /**
       * Obtains an instance of {@code Chronology} from a locale.
       * <p>
       * See {@link Chronology#ofLocale(Locale)}.
       *
       * @param locale  the locale to use to obtain the calendar system, not null
       * @return the calendar system associated with the locale, not null
       * @throws DateTimeException if the locale-specified calendar cannot be found
       */
      static Chronology ofLocale(Locale locale) {
          Objects.requireNonNull(locale, "locale");
          String type = locale.getUnicodeLocaleType("ca");
          if (type == null || "iso".equals(type) || "iso8601".equals(type)) {
              return IsoChronology.INSTANCE;
          }
          // Not pre-defined; lookup by the type
          do {
              Chronology chrono = CHRONOS_BY_TYPE.get(type);
              if (chrono != null) {
                  return chrono;
              }
              // If not found, do the initialization (once) and repeat the lookup
          } while (initCache());
  
          // Look for a Chronology using ServiceLoader of the Thread's ContextClassLoader
          // Application provided Chronologies must not be cached
          @SuppressWarnings("rawtypes")
          ServiceLoader<Chronology> loader = ServiceLoader.load(Chronology.class);
          for (Chronology chrono : loader) {
              if (type.equals(chrono.getCalendarType())) {
                  return chrono;
              }
          }
          throw new DateTimeException("Unknown calendar system: " + type);
      }
  
      //-----------------------------------------------------------------------
      /**
       * Obtains an instance of {@code Chronology} from a chronology ID or
       * calendar system type.
       * <p>
       * See {@link Chronology#of(String)}.
       *
       * @param id  the chronology ID or calendar system type, not null
       * @return the chronology with the identifier requested, not null
       * @throws DateTimeException if the chronology cannot be found
       */
      static Chronology of(String id) {
          Objects.requireNonNull(id, "id");
          do {
              Chronology chrono = of0(id);
              if (chrono != null) {
                  return chrono;
              }
              // If not found, do the initialization (once) and repeat the lookup
          } while (initCache());
  
          // Look for a Chronology using ServiceLoader of the Thread's ContextClassLoader
          // Application provided Chronologies must not be cached
          @SuppressWarnings("rawtypes")
          ServiceLoader<Chronology> loader = ServiceLoader.load(Chronology.class);
          for (Chronology chrono : loader) {
              if (id.equals(chrono.getId()) || id.equals(chrono.getCalendarType())) {
                  return chrono;
              }
          }
          throw new DateTimeException("Unknown chronology: " + id);
      }
  
      /**
       * Obtains an instance of {@code Chronology} from a chronology ID or
       * calendar system type.
       *
       * @param id  the chronology ID or calendar system type, not null
       * @return the chronology with the identifier requested, or {@code null} if not found
       */
      private static Chronology of0(String id) {
          Chronology chrono = CHRONOS_BY_ID.get(id);
          if (chrono == null) {
              chrono = CHRONOS_BY_TYPE.get(id);
          }
          return chrono;
      }
  
      /**
       * Returns the available chronologies.
       * <p>
       * Each returned {@code Chronology} is available for use in the system.
       * The set of chronologies includes the system chronologies and
       * any chronologies provided by the application via ServiceLoader
       * configuration.
       *
       * @return the independent, modifiable set of the available chronology IDs, not null
       */
      static Set<Chronology> getAvailableChronologies() {
          initCache();       // force initialization
          HashSet<Chronology> chronos = new HashSet<>(CHRONOS_BY_ID.values());
  
          /// Add in Chronologies from the ServiceLoader configuration
          @SuppressWarnings("rawtypes")
          ServiceLoader<Chronology> loader = ServiceLoader.load(Chronology.class);
          for (Chronology chrono : loader) {
              chronos.add(chrono);
          }
          return chronos;
      }
  
      //-----------------------------------------------------------------------
      /**
       * Creates an instance.
       */
      protected AbstractChronology() {
      }
  
      //-----------------------------------------------------------------------
      /**
       * Resolves parsed {@code ChronoField} values into a date during parsing.
       * <p>
       * Most {@code TemporalField} implementations are resolved using the
       * resolve method on the field. By contrast, the {@code ChronoField} class
       * defines fields that only have meaning relative to the chronology.
       * As such, {@code ChronoField} date fields are resolved here in the
       * context of a specific chronology.
       * <p>
       * {@code ChronoField} instances are resolved by this method, which may
       * be overridden in subclasses.
       * <ul>
       * <li>{@code EPOCH_DAY} - If present, this is converted to a date and
       *  all other date fields are then cross-checked against the date.
       * <li>{@code PROLEPTIC_MONTH} - If present, then it is split into the
       *  {@code YEAR} and {@code MONTH_OF_YEAR}. If the mode is strict or smart
       *  then the field is validated.
       * <li>{@code YEAR_OF_ERA} and {@code ERA} - If both are present, then they
       *  are combined to form a {@code YEAR}. In lenient mode, the {@code YEAR_OF_ERA}
       *  range is not validated, in smart and strict mode it is. The {@code ERA} is
       *  validated for range in all three modes. If only the {@code YEAR_OF_ERA} is
       *  present, and the mode is smart or lenient, then the last available era
       *  is assumed. In strict mode, no era is assumed and the {@code YEAR_OF_ERA} is
       *  left untouched. If only the {@code ERA} is present, then it is left untouched.
       * <li>{@code YEAR}, {@code MONTH_OF_YEAR} and {@code DAY_OF_MONTH} -
       *  If all three are present, then they are combined to form a date.
       *  In all three modes, the {@code YEAR} is validated.
       *  If the mode is smart or strict, then the month and day are validated.
       *  If the mode is lenient, then the date is combined in a manner equivalent to
       *  creating a date on the first day of the first month in the requested year,
       *  then adding the difference in months, then the difference in days.
       *  If the mode is smart, and the day-of-month is greater than the maximum for
       *  the year-month, then the day-of-month is adjusted to the last day-of-month.
       *  If the mode is strict, then the three fields must form a valid date.
       * <li>{@code YEAR} and {@code DAY_OF_YEAR} -
       *  If both are present, then they are combined to form a date.
       *  In all three modes, the {@code YEAR} is validated.
       *  If the mode is lenient, then the date is combined in a manner equivalent to
       *  creating a date on the first day of the requested year, then adding
       *  the difference in days.
       *  If the mode is smart or strict, then the two fields must form a valid date.
       * <li>{@code YEAR}, {@code MONTH_OF_YEAR}, {@code ALIGNED_WEEK_OF_MONTH} and
       *  {@code ALIGNED_DAY_OF_WEEK_IN_MONTH} -
       *  If all four are present, then they are combined to form a date.
       *  In all three modes, the {@code YEAR} is validated.
       *  If the mode is lenient, then the date is combined in a manner equivalent to
       *  creating a date on the first day of the first month in the requested year, then adding
       *  the difference in months, then the difference in weeks, then in days.
       *  If the mode is smart or strict, then the all four fields are validated to
       *  their outer ranges. The date is then combined in a manner equivalent to
       *  creating a date on the first day of the requested year and month, then adding
       *  the amount in weeks and days to reach their values. If the mode is strict,
       *  the date is additionally validated to check that the day and week adjustment
       *  did not change the month.
       * <li>{@code YEAR}, {@code MONTH_OF_YEAR}, {@code ALIGNED_WEEK_OF_MONTH} and
       *  {@code DAY_OF_WEEK} - If all four are present, then they are combined to
       *  form a date. The approach is the same as described above for
       *  years, months and weeks in {@code ALIGNED_DAY_OF_WEEK_IN_MONTH}.
       *  The day-of-week is adjusted as the next or same matching day-of-week once
       *  the years, months and weeks have been handled.
       * <li>{@code YEAR}, {@code ALIGNED_WEEK_OF_YEAR} and {@code ALIGNED_DAY_OF_WEEK_IN_YEAR} -
       *  If all three are present, then they are combined to form a date.
       *  In all three modes, the {@code YEAR} is validated.
       *  If the mode is lenient, then the date is combined in a manner equivalent to
       *  creating a date on the first day of the requested year, then adding
       *  the difference in weeks, then in days.
       *  If the mode is smart or strict, then the all three fields are validated to
       *  their outer ranges. The date is then combined in a manner equivalent to
       *  creating a date on the first day of the requested year, then adding
       *  the amount in weeks and days to reach their values. If the mode is strict,
       *  the date is additionally validated to check that the day and week adjustment
       *  did not change the year.
       * <li>{@code YEAR}, {@code ALIGNED_WEEK_OF_YEAR} and {@code DAY_OF_WEEK} -
       *  If all three are present, then they are combined to form a date.
       *  The approach is the same as described above for years and weeks in
       *  {@code ALIGNED_DAY_OF_WEEK_IN_YEAR}. The day-of-week is adjusted as the
       *  next or same matching day-of-week once the years and weeks have been handled.
       * </ul>
       * <p>
       * The default implementation is suitable for most calendar systems.
       * If {@link ChronoField#YEAR_OF_ERA} is found without an {@link ChronoField#ERA}
       * then the last era in {@link #eras()} is used.
       * The implementation assumes a 7 day week, that the first day-of-month
       * has the value 1, that first day-of-year has the value 1, and that the
       * first of the month and year always exists.
       *
       * @param fieldValues  the map of fields to values, which can be updated, not null
       * @param resolverStyle  the requested type of resolve, not null
       * @return the resolved date, null if insufficient information to create a date
       * @throws DateTimeException if the date cannot be resolved, typically
       *  because of a conflict in the input data
       */
      @Override
      public ChronoLocalDate resolveDate(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {
          // check epoch-day before inventing era
          if (fieldValues.containsKey(EPOCH_DAY)) {
              return dateEpochDay(fieldValues.remove(EPOCH_DAY));
          }
  
          // fix proleptic month before inventing era
          resolveProlepticMonth(fieldValues, resolverStyle);
  
          // invent era if necessary to resolve year-of-era
          ChronoLocalDate resolved = resolveYearOfEra(fieldValues, resolverStyle);
          if (resolved != null) {
              return resolved;
          }
  
          // build date
          if (fieldValues.containsKey(YEAR)) {
              if (fieldValues.containsKey(MONTH_OF_YEAR)) {
                  if (fieldValues.containsKey(DAY_OF_MONTH)) {
                      return resolveYMD(fieldValues, resolverStyle);
                  }
                  if (fieldValues.containsKey(ALIGNED_WEEK_OF_MONTH)) {
                      if (fieldValues.containsKey(ALIGNED_DAY_OF_WEEK_IN_MONTH)) {
                          return resolveYMAA(fieldValues, resolverStyle);
                      }
                      if (fieldValues.containsKey(DAY_OF_WEEK)) {
                          return resolveYMAD(fieldValues, resolverStyle);
                      }
                  }
              }
              if (fieldValues.containsKey(DAY_OF_YEAR)) {
                  return resolveYD(fieldValues, resolverStyle);
              }
              if (fieldValues.containsKey(ALIGNED_WEEK_OF_YEAR)) {
                  if (fieldValues.containsKey(ALIGNED_DAY_OF_WEEK_IN_YEAR)) {
                      return resolveYAA(fieldValues, resolverStyle);
                  }
                  if (fieldValues.containsKey(DAY_OF_WEEK)) {
                      return resolveYAD(fieldValues, resolverStyle);
                  }
              }
          }
          return null;
      }
  
      void resolveProlepticMonth(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {
          Long pMonth = fieldValues.remove(PROLEPTIC_MONTH);
          if (pMonth != null) {
              if (resolverStyle != ResolverStyle.LENIENT) {
                  PROLEPTIC_MONTH.checkValidValue(pMonth);
              }
              // first day-of-month is likely to be safest for setting proleptic-month
              // cannot add to year zero, as not all chronologies have a year zero
              ChronoLocalDate chronoDate = dateNow()
                      .with(DAY_OF_MONTH, 1).with(PROLEPTIC_MONTH, pMonth);
              addFieldValue(fieldValues, MONTH_OF_YEAR, chronoDate.get(MONTH_OF_YEAR));
              addFieldValue(fieldValues, YEAR, chronoDate.get(YEAR));
          }
      }
  
      ChronoLocalDate resolveYearOfEra(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {
          Long yoeLong = fieldValues.remove(YEAR_OF_ERA);
          if (yoeLong != null) {
              Long eraLong = fieldValues.remove(ERA);
              int yoe;
              if (resolverStyle != ResolverStyle.LENIENT) {
                  yoe = range(YEAR_OF_ERA).checkValidIntValue(yoeLong, YEAR_OF_ERA);
              } else {
                  yoe = Math.toIntExact(yoeLong);
              }
              if (eraLong != null) {
                  Era eraObj = eraOf(range(ERA).checkValidIntValue(eraLong, ERA));
                  addFieldValue(fieldValues, YEAR, prolepticYear(eraObj, yoe));
              } else {
                  if (fieldValues.containsKey(YEAR)) {
                      int year = range(YEAR).checkValidIntValue(fieldValues.get(YEAR), YEAR);
                      ChronoLocalDate chronoDate = dateYearDay(year, 1);
                      addFieldValue(fieldValues, YEAR, prolepticYear(chronoDate.getEra(), yoe));
                  } else if (resolverStyle == ResolverStyle.STRICT) {
                      // do not invent era if strict
                      // reinstate the field removed earlier, no cross-check issues
                      fieldValues.put(YEAR_OF_ERA, yoeLong);
                  } else {
                      List<Era> eras = eras();
                      if (eras.isEmpty()) {
                          addFieldValue(fieldValues, YEAR, yoe);
                      } else {
                          Era eraObj = eras.get(eras.size() - 1);
                          addFieldValue(fieldValues, YEAR, prolepticYear(eraObj, yoe));
                      }
                  }
              }
          } else if (fieldValues.containsKey(ERA)) {
              range(ERA).checkValidValue(fieldValues.get(ERA), ERA);  // always validated
          }
          return null;
      }
  
      ChronoLocalDate resolveYMD(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {
          int y = range(YEAR).checkValidIntValue(fieldValues.remove(YEAR), YEAR);
          if (resolverStyle == ResolverStyle.LENIENT) {
              long months = Math.subtractExact(fieldValues.remove(MONTH_OF_YEAR), 1);
              long days = Math.subtractExact(fieldValues.remove(DAY_OF_MONTH), 1);
              return date(y, 1, 1).plus(months, MONTHS).plus(days, DAYS);
          }
          int moy = range(MONTH_OF_YEAR).checkValidIntValue(fieldValues.remove(MONTH_OF_YEAR), MONTH_OF_YEAR);
          ValueRange domRange = range(DAY_OF_MONTH);
          int dom = domRange.checkValidIntValue(fieldValues.remove(DAY_OF_MONTH), DAY_OF_MONTH);
          if (resolverStyle == ResolverStyle.SMART) {  // previous valid
              try {
                  return date(y, moy, dom);
              } catch (DateTimeException ex) {
                  return date(y, moy, 1).with(TemporalAdjusters.lastDayOfMonth());
              }
          }
          return date(y, moy, dom);
      }
  
      ChronoLocalDate resolveYD(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {
          int y = range(YEAR).checkValidIntValue(fieldValues.remove(YEAR), YEAR);
          if (resolverStyle == ResolverStyle.LENIENT) {
              long days = Math.subtractExact(fieldValues.remove(DAY_OF_YEAR), 1);
              return dateYearDay(y, 1).plus(days, DAYS);
          }
          int doy = range(DAY_OF_YEAR).checkValidIntValue(fieldValues.remove(DAY_OF_YEAR), DAY_OF_YEAR);
          return dateYearDay(y, doy);  // smart is same as strict
      }
  
      ChronoLocalDate resolveYMAA(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {
          int y = range(YEAR).checkValidIntValue(fieldValues.remove(YEAR), YEAR);
          if (resolverStyle == ResolverStyle.LENIENT) {
              long months = Math.subtractExact(fieldValues.remove(MONTH_OF_YEAR), 1);
              long weeks = Math.subtractExact(fieldValues.remove(ALIGNED_WEEK_OF_MONTH), 1);
              long days = Math.subtractExact(fieldValues.remove(ALIGNED_DAY_OF_WEEK_IN_MONTH), 1);
              return date(y, 1, 1).plus(months, MONTHS).plus(weeks, WEEKS).plus(days, DAYS);
          }
          int moy = range(MONTH_OF_YEAR).checkValidIntValue(fieldValues.remove(MONTH_OF_YEAR), MONTH_OF_YEAR);
          int aw = range(ALIGNED_WEEK_OF_MONTH).checkValidIntValue(fieldValues.remove(ALIGNED_WEEK_OF_MONTH), ALIGNED_WEEK_OF_MONTH);
          int ad = range(ALIGNED_DAY_OF_WEEK_IN_MONTH).checkValidIntValue(fieldValues.remove(ALIGNED_DAY_OF_WEEK_IN_MONTH), ALIGNED_DAY_OF_WEEK_IN_MONTH);
          ChronoLocalDate date = date(y, moy, 1).plus((aw - 1) * 7 + (ad - 1), DAYS);
          if (resolverStyle == ResolverStyle.STRICT && date.get(MONTH_OF_YEAR) != moy) {
              throw new DateTimeException("Strict mode rejected resolved date as it is in a different month");
          }
          return date;
      }
  
      ChronoLocalDate resolveYMAD(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {
          int y = range(YEAR).checkValidIntValue(fieldValues.remove(YEAR), YEAR);
          if (resolverStyle == ResolverStyle.LENIENT) {
              long months = Math.subtractExact(fieldValues.remove(MONTH_OF_YEAR), 1);
              long weeks = Math.subtractExact(fieldValues.remove(ALIGNED_WEEK_OF_MONTH), 1);
              long dow = Math.subtractExact(fieldValues.remove(DAY_OF_WEEK), 1);
              return resolveAligned(date(y, 1, 1), months, weeks, dow);
          }
          int moy = range(MONTH_OF_YEAR).checkValidIntValue(fieldValues.remove(MONTH_OF_YEAR), MONTH_OF_YEAR);
          int aw = range(ALIGNED_WEEK_OF_MONTH).checkValidIntValue(fieldValues.remove(ALIGNED_WEEK_OF_MONTH), ALIGNED_WEEK_OF_MONTH);
          int dow = range(DAY_OF_WEEK).checkValidIntValue(fieldValues.remove(DAY_OF_WEEK), DAY_OF_WEEK);
          ChronoLocalDate date = date(y, moy, 1).plus((aw - 1) * 7, DAYS).with(nextOrSame(DayOfWeek.of(dow)));
          if (resolverStyle == ResolverStyle.STRICT && date.get(MONTH_OF_YEAR) != moy) {
              throw new DateTimeException("Strict mode rejected resolved date as it is in a different month");
          }
          return date;
      }
  
      ChronoLocalDate resolveYAA(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {
          int y = range(YEAR).checkValidIntValue(fieldValues.remove(YEAR), YEAR);
          if (resolverStyle == ResolverStyle.LENIENT) {
              long weeks = Math.subtractExact(fieldValues.remove(ALIGNED_WEEK_OF_YEAR), 1);
              long days = Math.subtractExact(fieldValues.remove(ALIGNED_DAY_OF_WEEK_IN_YEAR), 1);
              return dateYearDay(y, 1).plus(weeks, WEEKS).plus(days, DAYS);
          }
          int aw = range(ALIGNED_WEEK_OF_YEAR).checkValidIntValue(fieldValues.remove(ALIGNED_WEEK_OF_YEAR), ALIGNED_WEEK_OF_YEAR);
          int ad = range(ALIGNED_DAY_OF_WEEK_IN_YEAR).checkValidIntValue(fieldValues.remove(ALIGNED_DAY_OF_WEEK_IN_YEAR), ALIGNED_DAY_OF_WEEK_IN_YEAR);
          ChronoLocalDate date = dateYearDay(y, 1).plus((aw - 1) * 7 + (ad - 1), DAYS);
          if (resolverStyle == ResolverStyle.STRICT && date.get(YEAR) != y) {
              throw new DateTimeException("Strict mode rejected resolved date as it is in a different year");
          }
          return date;
      }
  
      ChronoLocalDate resolveYAD(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {
          int y = range(YEAR).checkValidIntValue(fieldValues.remove(YEAR), YEAR);
          if (resolverStyle == ResolverStyle.LENIENT) {
              long weeks = Math.subtractExact(fieldValues.remove(ALIGNED_WEEK_OF_YEAR), 1);
              long dow = Math.subtractExact(fieldValues.remove(DAY_OF_WEEK), 1);
              return resolveAligned(dateYearDay(y, 1), 0, weeks, dow);
          }
          int aw = range(ALIGNED_WEEK_OF_YEAR).checkValidIntValue(fieldValues.remove(ALIGNED_WEEK_OF_YEAR), ALIGNED_WEEK_OF_YEAR);
          int dow = range(DAY_OF_WEEK).checkValidIntValue(fieldValues.remove(DAY_OF_WEEK), DAY_OF_WEEK);
          ChronoLocalDate date = dateYearDay(y, 1).plus((aw - 1) * 7, DAYS).with(nextOrSame(DayOfWeek.of(dow)));
          if (resolverStyle == ResolverStyle.STRICT && date.get(YEAR) != y) {
              throw new DateTimeException("Strict mode rejected resolved date as it is in a different year");
          }
          return date;
      }
  
      ChronoLocalDate resolveAligned(ChronoLocalDate base, long months, long weeks, long dow) {
          ChronoLocalDate date = base.plus(months, MONTHS).plus(weeks, WEEKS);
          if (dow > 7) {
              date = date.plus((dow - 1) / 7, WEEKS);
              dow = ((dow - 1) % 7) + 1;
          } else if (dow < 1) {
              date = date.plus(Math.subtractExact(dow,  7) / 7, WEEKS);
              dow = ((dow + 6) % 7) + 1;
          }
          return date.with(nextOrSame(DayOfWeek.of((int) dow)));
      }
  
      /**
       * Adds a field-value pair to the map, checking for conflicts.
       * <p>
       * If the field is not already present, then the field-value pair is added to the map.
       * If the field is already present and it has the same value as that specified, no action occurs.
       * If the field is already present and it has a different value to that specified, then
       * an exception is thrown.
       *
       * @param field  the field to add, not null
       * @param value  the value to add, not null
       * @throws DateTimeException if the field is already present with a different value
       */
      void addFieldValue(Map<TemporalField, Long> fieldValues, ChronoField field, long value) {
          Long old = fieldValues.get(field);  // check first for better error message
          if (old != null && old.longValue() != value) {
              throw new DateTimeException("Conflict found: " + field + " " + old + " differs from " + field + " " + value);
          }
          fieldValues.put(field, value);
      }
  
      //-----------------------------------------------------------------------
      /**
       * Compares this chronology to another chronology.
       * <p>
       * The comparison order first by the chronology ID string, then by any
       * additional information specific to the subclass.
       * It is "consistent with equals", as defined by {@link Comparable}.
       *
       * @implSpec
       * This implementation compares the chronology ID.
       * Subclasses must compare any additional state that they store.
       *
       * @param other  the other chronology to compare to, not null
       * @return the comparator value, negative if less, positive if greater
       */
      @Override
      public int compareTo(Chronology other) {
          return getId().compareTo(other.getId());
      }
  
      /**
       * Checks if this chronology is equal to another chronology.
       * <p>
       * The comparison is based on the entire state of the object.
       *
       * @implSpec
       * This implementation checks the type and calls
       * {@link #compareTo(Chronology)}.
       *
       * @param obj  the object to check, null returns false
       * @return true if this is equal to the other chronology
       */
      @Override
      public boolean equals(Object obj) {
          if (this == obj) {
             return true;
          }
          if (obj instanceof AbstractChronology) {
              return compareTo((AbstractChronology) obj) == 0;
          }
          return false;
      }
  
      /**
       * A hash code for this chronology.
       * <p>
       * The hash code should be based on the entire state of the object.
       *
       * @implSpec
       * This implementation is based on the chronology ID and class.
       * Subclasses should add any additional state that they store.
       *
       * @return a suitable hash code
       */
      @Override
      public int hashCode() {
          return getClass().hashCode() ^ getId().hashCode();
      }
  
      //-----------------------------------------------------------------------
      /**
       * Outputs this chronology as a {@code String}, using the chronology ID.
       *
       * @return a string representation of this chronology, not null
       */
      @Override
      public String toString() {
          return getId();
      }
  
      //-----------------------------------------------------------------------
      /**
       * Writes the Chronology using a
       * <a href="../../../serialized-form.html#java.time.chrono.Ser">dedicated serialized form</a>.
       * <pre>
       *  out.writeByte(1);  // identifies this as a Chronology
       *  out.writeUTF(getId());
       * </pre>
       *
       * @return the instance of {@code Ser}, not null
       */
      Object writeReplace() {
          return new Ser(Ser.CHRONO_TYPE, this);
      }
  
      /**
       * Defend against malicious streams.
       *
       * @param s the stream to read
       * @throws InvalidObjectException always
       */
      private void readObject(ObjectInputStream s) throws ObjectStreamException {
          throw new InvalidObjectException("Deserialization via serialization delegate");
      }
  
      void writeExternal(DataOutput out) throws IOException {
          out.writeUTF(getId());
      }
  
      static Chronology readExternal(DataInput in) throws IOException {
          String id = in.readUTF();
          return Chronology.of(id);
      }
  
  }
  