    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      https://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.lang3.time;
    018
    019import java.io.IOException;
    020import java.io.ObjectInputStream;
    021import java.io.Serializable;
    022import java.text.DateFormat;
    023import java.text.DateFormatSymbols;
    024import java.text.FieldPosition;
    025import java.text.SimpleDateFormat;
    026import java.util.ArrayList;
    027import java.util.Calendar;
    028import java.util.Date;
    029import java.util.List;
    030import java.util.Locale;
    031import java.util.TimeZone;
    032import java.util.concurrent.ConcurrentHashMap;
    033import java.util.concurrent.ConcurrentMap;
    034
    035import org.apache.commons.lang3.CharUtils;
    036import org.apache.commons.lang3.ClassUtils;
    037import org.apache.commons.lang3.LocaleUtils;
    038import org.apache.commons.lang3.exception.ExceptionUtils;
    039
    040/**
    041 * FastDatePrinter is a fast and thread-safe version of
    042 * {@link java.text.SimpleDateFormat}.
    043 *
    044 * <p>To obtain a FastDatePrinter, use {@link FastDateFormat#getInstance(String, TimeZone, Locale)}
    045 * or another variation of the factory methods of {@link FastDateFormat}.</p>
    046 *
    047 * <p>Since FastDatePrinter is thread safe, you can use a static member instance:</p>
    048 * {@code
    049 *     private static final DatePrinter DATE_PRINTER = FastDateFormat.getInstance("yyyy-MM-dd");
    050 * }
    051 *
    052 * <p>This class can be used as a direct replacement to
    053 * {@link SimpleDateFormat} in most formatting situations.
    054 * This class is especially useful in multi-threaded server environments.
    055 * {@link SimpleDateFormat} is not thread-safe in any JDK version,
    056 * nor will it be as Sun have closed the bug/RFE.
    057 * </p>
    058 *
    059 * <p>Only formatting is supported by this class, but all patterns are compatible with
    060 * SimpleDateFormat (except time zones and some year patterns - see below).</p>
    061 *
    062 * <p>Java 1.4 introduced a new pattern letter, {@code 'Z'}, to represent
    063 * time zones in RFC822 format (eg. {@code +0800} or {@code -1100}).
    064 * This pattern letter can be used here (on all JDK versions).</p>
    065 *
    066 * <p>In addition, the pattern {@code 'ZZ'} has been made to represent
    067 * ISO 8601 extended format time zones (eg. {@code +08:00} or {@code -11:00}).
    068 * This introduces a minor incompatibility with Java 1.4, but at a gain of
    069 * useful functionality.</p>
    070 *
    071 * <p>Starting with JDK7, ISO 8601 support was added using the pattern {@code 'X'}.
    072 * To maintain compatibility, {@code 'ZZ'} will continue to be supported, but using
    073 * one of the {@code 'X'} formats is recommended.
    074 *
    075 * <p>Javadoc cites for the year pattern: <i>For formatting, if the number of
    076 * pattern letters is 2, the year is truncated to 2 digits; otherwise it is
    077 * interpreted as a number.</i> Starting with Java 1.7 a pattern of 'Y' or
    078 * 'YYY' will be formatted as '2003', while it was '03' in former Java
    079 * versions. FastDatePrinter implements the behavior of Java 7.</p>
    080 *
    081 * @since 3.2
    082 * @see FastDateParser
    083 */
    084public class FastDatePrinter implements DatePrinter, Serializable {
    085    // A lot of the speed in this class comes from caching, but some comes
    086    // from the special int to StringBuffer conversion.
    087    //
    088    // The following produces a padded 2-digit number:
    089    //   buffer.append((char)(value / 10 + '0'));
    090    //   buffer.append((char)(value % 10 + '0'));
    091    //
    092    // Note that the fastest append to StringBuffer is a single char (used here).
    093    // Note that Integer.toString() is not called, the conversion is simply
    094    // taking the value and adding (mathematically) the ASCII value for '0'.
    095    // So, don't change this code! It works and is very fast.
    096
    097    /**
    098     * Inner class to output a constant single character.
    099     */
    100    private static final class CharacterLiteral implements Rule {
    101        private final char value;
    102
    103        /**
    104         * Constructs a new instance of {@link CharacterLiteral}
    105         * to hold the specified value.
    106         *
    107         * @param value the character literal
    108         */
    109        CharacterLiteral(final char value) {
    110            this.value = value;
    111        }
    112
    113        /**
    114         * {@inheritDoc}
    115         */
    116        @Override
    117        public void appendTo(final Appendable buffer, final Calendar calendar) throws IOException {
    118            buffer.append(value);
    119        }
    120
    121        /**
    122         * {@inheritDoc}
    123         */
    124        @Override
    125        public int estimateLength() {
    126            return 1;
    127        }
    128    }
    129
    130    /**
    131     * Inner class to output the numeric day in week.
    132     */
    133    private static final class DayInWeekField implements NumberRule {
    134        private final NumberRule rule;
    135
    136        DayInWeekField(final NumberRule rule) {
    137            this.rule = rule;
    138        }
    139
    140        @Override
    141        public void appendTo(final Appendable buffer, final Calendar calendar) throws IOException {
    142            final int value = calendar.get(Calendar.DAY_OF_WEEK);
    143            rule.appendTo(buffer, value == Calendar.SUNDAY ? 7 : value - 1);
    144        }
    145
    146        @Override
    147        public void appendTo(final Appendable buffer, final int value) throws IOException {
    148            rule.appendTo(buffer, value);
    149        }
    150
    151        @Override
    152        public int estimateLength() {
    153            return rule.estimateLength();
    154        }
    155    }
    156
    157    /**
    158     * Inner class to output a time zone as a number {@code +/-HHMM}
    159     * or {@code +/-HH:MM}.
    160     */
    161    private static final class Iso8601_Rule implements Rule {
    162
    163        // Sign TwoDigitHours or Z
    164        static final Iso8601_Rule ISO8601_HOURS = new Iso8601_Rule(3);
    165        // Sign TwoDigitHours Minutes or Z
    166        static final Iso8601_Rule ISO8601_HOURS_MINUTES = new Iso8601_Rule(5);
    167        // Sign TwoDigitHours : Minutes or Z
    168        static final Iso8601_Rule ISO8601_HOURS_COLON_MINUTES = new Iso8601_Rule(6);
    169
    170        /**
    171         * Factory method for Iso8601_Rules.
    172         *
    173         * @param tokenLen a token indicating the length of the TimeZone String to be formatted.
    174         * @return an Iso8601_Rule that can format TimeZone String of length {@code tokenLen}. If no such
    175         *          rule exists, an IllegalArgumentException will be thrown.
    176         */
    177        static Iso8601_Rule getRule(final int tokenLen) {
    178            switch (tokenLen) {
    179            case 1:
    180                return ISO8601_HOURS;
    181            case 2:
    182                return ISO8601_HOURS_MINUTES;
    183            case 3:
    184                return ISO8601_HOURS_COLON_MINUTES;
    185            default:
    186                throw new IllegalArgumentException("invalid number of X");
    187            }
    188        }
    189
    190        private final int length;
    191
    192        /**
    193         * Constructs an instance of {@code Iso8601_Rule} with the specified properties.
    194         *
    195         * @param length The number of characters in output (unless Z is output)
    196         */
    197        Iso8601_Rule(final int length) {
    198            this.length = length;
    199        }
    200
    201        /**
    202         * {@inheritDoc}
    203         */
    204        @Override
    205        public void appendTo(final Appendable buffer, final Calendar calendar) throws IOException {
    206            int offset = calendar.get(Calendar.ZONE_OFFSET) + calendar.get(Calendar.DST_OFFSET);
    207            if (offset == 0) {
    208                buffer.append("Z");
    209                return;
    210            }
    211
    212            if (offset < 0) {
    213                buffer.append('-');
    214                offset = -offset;
    215            } else {
    216                buffer.append('+');
    217            }
    218
    219            final int hours = offset / (60 * 60 * 1000);
    220            appendDigits(buffer, hours);
    221
    222            if (length < 5) {
    223                return;
    224            }
    225
    226            if (length == 6) {
    227                buffer.append(':');
    228            }
    229
    230            final int minutes = offset / (60 * 1000) - 60 * hours;
    231            appendDigits(buffer, minutes);
    232        }
    233
    234        /**
    235         * {@inheritDoc}
    236         */
    237        @Override
    238        public int estimateLength() {
    239            return length;
    240        }
    241    }
    242
    243    /**
    244     * Inner class defining a numeric rule.
    245     */
    246    private interface NumberRule extends Rule {
    247        /**
    248         * Appends the specified value to the output buffer based on the rule implementation.
    249         *
    250         * @param buffer the output buffer
    251         * @param value the value to be appended
    252         * @throws IOException if an I/O error occurs.
    253         */
    254        void appendTo(Appendable buffer, int value) throws IOException;
    255    }
    256
    257    /**
    258     * Inner class to output a padded number.
    259     */
    260    private static final class PaddedNumberField implements NumberRule {
    261        // Note: This is final to avoid Spotbugs CT_CONSTRUCTOR_THROW
    262        private final int field;
    263        private final int size;
    264
    265        /**
    266         * Constructs an instance of {@link PaddedNumberField}.
    267         *
    268         * @param field the field
    269         * @param size size of the output field
    270         */
    271        PaddedNumberField(final int field, final int size) {
    272            if (size < 3) {
    273                // Should use UnpaddedNumberField or TwoDigitNumberField.
    274                throw new IllegalArgumentException();
    275            }
    276            this.field = field;
    277            this.size = size;
    278        }
    279
    280        /**
    281         * {@inheritDoc}
    282         */
    283        @Override
    284        public void appendTo(final Appendable buffer, final Calendar calendar) throws IOException {
    285            appendTo(buffer, calendar.get(field));
    286        }
    287
    288        /**
    289         * {@inheritDoc}
    290         */
    291        @Override
    292        public /* final */ void appendTo(final Appendable buffer, final int value) throws IOException {
    293            // Checkstyle complains about redundant qualifier
    294            appendFullDigits(buffer, value, size);
    295        }
    296
    297        /**
    298         * {@inheritDoc}
    299         */
    300        @Override
    301        public int estimateLength() {
    302            return size;
    303        }
    304    }
    305    // Rules
    306    /**
    307     * Inner class defining a rule.
    308     */
    309    private interface Rule {
    310        /**
    311         * Appends the value of the specified calendar to the output buffer based on the rule implementation.
    312         *
    313         * @param buf the output buffer
    314         * @param calendar calendar to be appended
    315         * @throws IOException if an I/O error occurs.
    316         */
    317        void appendTo(Appendable buf, Calendar calendar) throws IOException;
    318
    319        /**
    320         * Returns the estimated length of the result.
    321         *
    322         * @return the estimated length
    323         */
    324        int estimateLength();
    325    }
    326
    327    /**
    328     * Inner class to output a constant string.
    329     */
    330    private static final class StringLiteral implements Rule {
    331        private final String value;
    332
    333        /**
    334         * Constructs a new instance of {@link StringLiteral}
    335         * to hold the specified value.
    336         *
    337         * @param value the string literal
    338         */
    339        StringLiteral(final String value) {
    340            this.value = value;
    341        }
    342
    343        /**
    344         * {@inheritDoc}
    345         */
    346        @Override
    347        public void appendTo(final Appendable buffer, final Calendar calendar) throws IOException {
    348            buffer.append(value);
    349        }
    350
    351        /**
    352         * {@inheritDoc}
    353         */
    354        @Override
    355        public int estimateLength() {
    356            return value.length();
    357        }
    358    }
    359    /**
    360     * Inner class to output one of a set of values.
    361     */
    362    private static final class TextField implements Rule {
    363        private final int field;
    364        private final String[] values;
    365
    366        /**
    367         * Constructs an instance of {@link TextField}
    368         * with the specified field and values.
    369         *
    370         * @param field the field
    371         * @param values the field values
    372         */
    373        TextField(final int field, final String[] values) {
    374            this.field = field;
    375            this.values = values;
    376        }
    377
    378        /**
    379         * {@inheritDoc}
    380         */
    381        @Override
    382        public void appendTo(final Appendable buffer, final Calendar calendar) throws IOException {
    383            buffer.append(values[calendar.get(field)]);
    384        }
    385
    386        /**
    387         * {@inheritDoc}
    388         */
    389        @Override
    390        public int estimateLength() {
    391            int max = 0;
    392            for (int i = values.length; --i >= 0;) {
    393                final int len = values[i].length();
    394                if (len > max) {
    395                    max = len;
    396                }
    397            }
    398            return max;
    399        }
    400    }
    401    /**
    402     * Inner class that acts as a compound key for time zone names.
    403     */
    404    private static final class TimeZoneDisplayKey {
    405        private final TimeZone timeZone;
    406        private final int style;
    407        private final Locale locale;
    408
    409        /**
    410         * Constructs an instance of {@link TimeZoneDisplayKey} with the specified properties.
    411         *
    412         * @param timeZone the time zone
    413         * @param daylight adjust the style for daylight saving time if {@code true}
    414         * @param style the time zone style
    415         * @param locale the time zone locale
    416         */
    417        TimeZoneDisplayKey(final TimeZone timeZone,
    418                           final boolean daylight, final int style, final Locale locale) {
    419            this.timeZone = timeZone;
    420            if (daylight) {
    421                this.style = style | 0x80000000;
    422            } else {
    423                this.style = style;
    424            }
    425            this.locale = LocaleUtils.toLocale(locale);
    426        }
    427
    428        /**
    429         * {@inheritDoc}
    430         */
    431        @Override
    432        public boolean equals(final Object obj) {
    433            if (this == obj) {
    434                return true;
    435            }
    436            if (obj instanceof TimeZoneDisplayKey) {
    437                final TimeZoneDisplayKey other = (TimeZoneDisplayKey) obj;
    438                return
    439                    timeZone.equals(other.timeZone) &&
    440                    style == other.style &&
    441                    locale.equals(other.locale);
    442            }
    443            return false;
    444        }
    445
    446        /**
    447         * {@inheritDoc}
    448         */
    449        @Override
    450        public int hashCode() {
    451            return (style * 31 + locale.hashCode()) * 31 + timeZone.hashCode();
    452        }
    453    }
    454    /**
    455     * Inner class to output a time zone name.
    456     */
    457    private static final class TimeZoneNameRule implements Rule {
    458        private final Locale locale;
    459        private final int style;
    460        private final String standard;
    461        private final String daylight;
    462
    463        /**
    464         * Constructs an instance of {@link TimeZoneNameRule} with the specified properties.
    465         *
    466         * @param timeZone the time zone
    467         * @param locale the locale
    468         * @param style the style
    469         */
    470        TimeZoneNameRule(final TimeZone timeZone, final Locale locale, final int style) {
    471            this.locale = LocaleUtils.toLocale(locale);
    472            this.style = style;
    473            this.standard = getTimeZoneDisplay(timeZone, false, style, locale);
    474            this.daylight = getTimeZoneDisplay(timeZone, true, style, locale);
    475        }
    476
    477        /**
    478         * {@inheritDoc}
    479         */
    480        @Override
    481        public void appendTo(final Appendable buffer, final Calendar calendar) throws IOException {
    482            final TimeZone zone = calendar.getTimeZone();
    483            final boolean daylight = calendar.get(Calendar.DST_OFFSET) != 0;
    484            buffer.append(getTimeZoneDisplay(zone, daylight, style, locale));
    485        }
    486
    487        /**
    488         * {@inheritDoc}
    489         */
    490        @Override
    491        public int estimateLength() {
    492            // We have no access to the Calendar object that will be passed to
    493            // appendTo so base estimate on the TimeZone passed to the
    494            // constructor
    495            return Math.max(standard.length(), daylight.length());
    496        }
    497    }
    498    /**
    499     * Inner class to output a time zone as a number {@code +/-HHMM}
    500     * or {@code +/-HH:MM}.
    501     */
    502    private static final class TimeZoneNumberRule implements Rule {
    503        static final TimeZoneNumberRule INSTANCE_COLON = new TimeZoneNumberRule(true);
    504        static final TimeZoneNumberRule INSTANCE_NO_COLON = new TimeZoneNumberRule(false);
    505
    506        private final boolean colon;
    507
    508        /**
    509         * Constructs an instance of {@link TimeZoneNumberRule} with the specified properties.
    510         *
    511         * @param colon add colon between HH and MM in the output if {@code true}
    512         */
    513        TimeZoneNumberRule(final boolean colon) {
    514            this.colon = colon;
    515        }
    516
    517        /**
    518         * {@inheritDoc}
    519         */
    520        @Override
    521        public void appendTo(final Appendable buffer, final Calendar calendar) throws IOException {
    522
    523            int offset = calendar.get(Calendar.ZONE_OFFSET) + calendar.get(Calendar.DST_OFFSET);
    524
    525            if (offset < 0) {
    526                buffer.append('-');
    527                offset = -offset;
    528            } else {
    529                buffer.append('+');
    530            }
    531
    532            final int hours = offset / (60 * 60 * 1000);
    533            appendDigits(buffer, hours);
    534
    535            if (colon) {
    536                buffer.append(':');
    537            }
    538
    539            final int minutes = offset / (60 * 1000) - 60 * hours;
    540            appendDigits(buffer, minutes);
    541        }
    542
    543        /**
    544         * {@inheritDoc}
    545         */
    546        @Override
    547        public int estimateLength() {
    548            return 5;
    549        }
    550    }
    551
    552    /**
    553     * Inner class to output the twelve hour field.
    554     */
    555    private static final class TwelveHourField implements NumberRule {
    556        private final NumberRule rule;
    557
    558        /**
    559         * Constructs an instance of {@link TwelveHourField} with the specified
    560         * {@link NumberRule}.
    561         *
    562         * @param rule the rule
    563         */
    564        TwelveHourField(final NumberRule rule) {
    565            this.rule = rule;
    566        }
    567
    568        /**
    569         * {@inheritDoc}
    570         */
    571        @Override
    572        public void appendTo(final Appendable buffer, final Calendar calendar) throws IOException {
    573            int value = calendar.get(Calendar.HOUR);
    574            if (value == 0) {
    575                value = calendar.getLeastMaximum(Calendar.HOUR) + 1;
    576            }
    577            rule.appendTo(buffer, value);
    578        }
    579
    580        /**
    581         * {@inheritDoc}
    582         */
    583        @Override
    584        public void appendTo(final Appendable buffer, final int value) throws IOException {
    585            rule.appendTo(buffer, value);
    586        }
    587
    588        /**
    589         * {@inheritDoc}
    590         */
    591        @Override
    592        public int estimateLength() {
    593            return rule.estimateLength();
    594        }
    595    }
    596
    597    /**
    598     * Inner class to output the twenty four hour field.
    599     */
    600    private static final class TwentyFourHourField implements NumberRule {
    601        private final NumberRule rule;
    602
    603        /**
    604         * Constructs an instance of {@link TwentyFourHourField} with the specified
    605         * {@link NumberRule}.
    606         *
    607         * @param rule the rule
    608         */
    609        TwentyFourHourField(final NumberRule rule) {
    610            this.rule = rule;
    611        }
    612
    613        /**
    614         * {@inheritDoc}
    615         */
    616        @Override
    617        public void appendTo(final Appendable buffer, final Calendar calendar) throws IOException {
    618            int value = calendar.get(Calendar.HOUR_OF_DAY);
    619            if (value == 0) {
    620                value = calendar.getMaximum(Calendar.HOUR_OF_DAY) + 1;
    621            }
    622            rule.appendTo(buffer, value);
    623        }
    624
    625        /**
    626         * {@inheritDoc}
    627         */
    628        @Override
    629        public void appendTo(final Appendable buffer, final int value) throws IOException {
    630            rule.appendTo(buffer, value);
    631        }
    632
    633        /**
    634         * {@inheritDoc}
    635         */
    636        @Override
    637        public int estimateLength() {
    638            return rule.estimateLength();
    639        }
    640    }
    641
    642    /**
    643     * Inner class to output a two digit month.
    644     */
    645    private static final class TwoDigitMonthField implements NumberRule {
    646        static final TwoDigitMonthField INSTANCE = new TwoDigitMonthField();
    647
    648        /**
    649         * Constructs an instance of {@link TwoDigitMonthField}.
    650         */
    651        TwoDigitMonthField() {
    652        }
    653
    654        /**
    655         * {@inheritDoc}
    656         */
    657        @Override
    658        public void appendTo(final Appendable buffer, final Calendar calendar) throws IOException {
    659            appendTo(buffer, calendar.get(Calendar.MONTH) + 1);
    660        }
    661
    662        /**
    663         * {@inheritDoc}
    664         */
    665        @Override
    666        public void appendTo(final Appendable buffer, final int value) throws IOException {
    667            appendDigits(buffer, value);
    668        }
    669
    670        /**
    671         * {@inheritDoc}
    672         */
    673        @Override
    674        public int estimateLength() {
    675            return 2;
    676        }
    677    }
    678
    679    /**
    680     * Inner class to output a two digit number.
    681     */
    682    private static final class TwoDigitNumberField implements NumberRule {
    683        private final int field;
    684
    685        /**
    686         * Constructs an instance of {@link TwoDigitNumberField} with the specified field.
    687         *
    688         * @param field the field
    689         */
    690        TwoDigitNumberField(final int field) {
    691            this.field = field;
    692        }
    693
    694        /**
    695         * {@inheritDoc}
    696         */
    697        @Override
    698        public void appendTo(final Appendable buffer, final Calendar calendar) throws IOException {
    699            appendTo(buffer, calendar.get(field));
    700        }
    701
    702        /**
    703         * {@inheritDoc}
    704         */
    705        @Override
    706        public void appendTo(final Appendable buffer, final int value) throws IOException {
    707            if (value < 100) {
    708                appendDigits(buffer, value);
    709            } else {
    710                appendFullDigits(buffer, value, 2);
    711            }
    712        }
    713
    714        /**
    715         * {@inheritDoc}
    716         */
    717        @Override
    718        public int estimateLength() {
    719            return 2;
    720        }
    721    }
    722
    723    /**
    724     * Inner class to output a two digit year.
    725     */
    726    private static final class TwoDigitYearField implements NumberRule {
    727        static final TwoDigitYearField INSTANCE = new TwoDigitYearField();
    728
    729        /**
    730         * Constructs an instance of {@link TwoDigitYearField}.
    731         */
    732        TwoDigitYearField() {
    733        }
    734
    735        /**
    736         * {@inheritDoc}
    737         */
    738        @Override
    739        public void appendTo(final Appendable buffer, final Calendar calendar) throws IOException {
    740            appendTo(buffer, calendar.get(Calendar.YEAR) % 100);
    741        }
    742
    743        /**
    744         * {@inheritDoc}
    745         */
    746        @Override
    747        public void appendTo(final Appendable buffer, final int value) throws IOException {
    748            appendDigits(buffer, value % 100);
    749        }
    750
    751        /**
    752         * {@inheritDoc}
    753         */
    754        @Override
    755        public int estimateLength() {
    756            return 2;
    757        }
    758    }
    759
    760    /**
    761     * Inner class to output an unpadded month.
    762     */
    763    private static final class UnpaddedMonthField implements NumberRule {
    764        static final UnpaddedMonthField INSTANCE = new UnpaddedMonthField();
    765
    766        /**
    767         * Constructs an instance of {@link UnpaddedMonthField}.
    768         */
    769        UnpaddedMonthField() {
    770        }
    771
    772        /**
    773         * {@inheritDoc}
    774         */
    775        @Override
    776        public void appendTo(final Appendable buffer, final Calendar calendar) throws IOException {
    777            appendTo(buffer, calendar.get(Calendar.MONTH) + 1);
    778        }
    779
    780        /**
    781         * {@inheritDoc}
    782         */
    783        @Override
    784        public void appendTo(final Appendable buffer, final int value) throws IOException {
    785            if (value < 10) {
    786                buffer.append((char) (value + '0'));
    787            } else {
    788                appendDigits(buffer, value);
    789            }
    790        }
    791
    792        /**
    793         * {@inheritDoc}
    794         */
    795        @Override
    796        public int estimateLength() {
    797            return 2;
    798        }
    799    }
    800
    801    /**
    802     * Inner class to output an unpadded number.
    803     */
    804    private static final class UnpaddedNumberField implements NumberRule {
    805        private final int field;
    806
    807        /**
    808         * Constructs an instance of {@link UnpaddedNumberField} with the specified field.
    809         *
    810         * @param field the field
    811         */
    812        UnpaddedNumberField(final int field) {
    813            this.field = field;
    814        }
    815
    816        /**
    817         * {@inheritDoc}
    818         */
    819        @Override
    820        public void appendTo(final Appendable buffer, final Calendar calendar) throws IOException {
    821            appendTo(buffer, calendar.get(field));
    822        }
    823
    824        /**
    825         * {@inheritDoc}
    826         */
    827        @Override
    828        public void appendTo(final Appendable buffer, final int value) throws IOException {
    829            if (value < 10) {
    830                buffer.append((char) (value + '0'));
    831            } else if (value < 100) {
    832                appendDigits(buffer, value);
    833            } else {
    834               appendFullDigits(buffer, value, 1);
    835            }
    836        }
    837
    838        /**
    839         * {@inheritDoc}
    840         */
    841        @Override
    842        public int estimateLength() {
    843            return 4;
    844        }
    845    }
    846
    847    /**
    848     * Inner class to output the numeric day in week.
    849     */
    850    private static final class WeekYear implements NumberRule {
    851        private final NumberRule rule;
    852
    853        WeekYear(final NumberRule rule) {
    854            this.rule = rule;
    855        }
    856
    857        @Override
    858        public void appendTo(final Appendable buffer, final Calendar calendar) throws IOException {
    859            rule.appendTo(buffer, calendar.getWeekYear());
    860        }
    861
    862        @Override
    863        public void appendTo(final Appendable buffer, final int value) throws IOException {
    864            rule.appendTo(buffer, value);
    865        }
    866
    867        @Override
    868        public int estimateLength() {
    869            return rule.estimateLength();
    870        }
    871    }
    872
    873    /** Empty array. */
    874    private static final Rule[] EMPTY_RULE_ARRAY = {};
    875
    876    /**
    877     * Required for serialization support.
    878     *
    879     * @see java.io.Serializable
    880     */
    881    private static final long serialVersionUID = 1L;
    882
    883    /**
    884     * FULL locale dependent date or time style.
    885     */
    886    public static final int FULL = DateFormat.FULL;
    887
    888    /**
    889     * LONG locale dependent date or time style.
    890     */
    891    public static final int LONG = DateFormat.LONG;
    892
    893    /**
    894     * MEDIUM locale dependent date or time style.
    895     */
    896    public static final int MEDIUM = DateFormat.MEDIUM;
    897
    898    /**
    899     * SHORT locale dependent date or time style.
    900     */
    901    public static final int SHORT = DateFormat.SHORT;
    902
    903    private static final int MAX_DIGITS = 10; // log10(Integer.MAX_VALUE) ~= 9.3
    904
    905    private static final ConcurrentMap<TimeZoneDisplayKey, String> timeZoneDisplayCache = new ConcurrentHashMap<>(7);
    906
    907    /**
    908     * Appends two digits to the given buffer.
    909     *
    910     * @param buffer the buffer to append to.
    911     * @param value the value to append digits from.
    912     * @throws IOException If an I/O error occurs
    913     */
    914    private static void appendDigits(final Appendable buffer, final int value) throws IOException {
    915        buffer.append((char) (value / 10 + '0'));
    916        buffer.append((char) (value % 10 + '0'));
    917    }
    918
    919    /**
    920     * Appends all digits to the given buffer.
    921     *
    922     * @param buffer the buffer to append to.
    923     * @param value the value to append digits from.
    924     * @param minFieldWidth Minimum field width.
    925     * @throws IOException If an I/O error occurs
    926     */
    927    private static void appendFullDigits(final Appendable buffer, int value, int minFieldWidth) throws IOException {
    928        // specialized paths for 1 to 4 digits -> avoid the memory allocation from the temporary work array
    929        // see LANG-1248
    930        if (value < 10000) {
    931            // less memory allocation path works for four digits or less
    932
    933            int nDigits = 4;
    934            if (value < 1000) {
    935                --nDigits;
    936                if (value < 100) {
    937                    --nDigits;
    938                    if (value < 10) {
    939                        --nDigits;
    940                    }
    941                }
    942            }
    943            // left zero pad
    944            for (int i = minFieldWidth - nDigits; i > 0; --i) {
    945                buffer.append('0');
    946            }
    947
    948            switch (nDigits) {
    949            case 4:
    950                buffer.append((char) (value / 1000 + '0'));
    951                value %= 1000;
    952                // falls-through
    953            case 3:
    954                if (value >= 100) {
    955                    buffer.append((char) (value / 100 + '0'));
    956                    value %= 100;
    957                } else {
    958                    buffer.append('0');
    959                }
    960                // falls-through
    961            case 2:
    962                if (value >= 10) {
    963                    buffer.append((char) (value / 10 + '0'));
    964                    value %= 10;
    965                } else {
    966                    buffer.append('0');
    967                }
    968                // falls-through
    969            case 1:
    970                buffer.append((char) (value + '0'));
    971            }
    972        } else {
    973            // more memory allocation path works for any digits
    974
    975            // build up decimal representation in reverse
    976            final char[] work = new char[MAX_DIGITS];
    977            int digit = 0;
    978            while (value != 0) {
    979                work[digit++] = (char) (value % 10 + '0');
    980                value /= 10;
    981            }
    982
    983            // pad with zeros
    984            while (digit < minFieldWidth) {
    985                buffer.append('0');
    986                --minFieldWidth;
    987            }
    988
    989            // reverse
    990            while (--digit >= 0) {
    991                buffer.append(work[digit]);
    992            }
    993        }
    994    }
    995
    996    static void clear() {
    997        timeZoneDisplayCache.clear();
    998    }
    999
    1000    /**
    1001     * Gets the time zone display name, using a cache for performance.
    1002     *
    1003     * @param tz  the zone to query
    1004     * @param daylight  true if daylight savings
    1005     * @param style  the style to use {@code TimeZone.LONG} or {@code TimeZone.SHORT}
    1006     * @param locale  the locale to use
    1007     * @return the textual name of the time zone
    1008     */
    1009    static String getTimeZoneDisplay(final TimeZone tz, final boolean daylight, final int style, final Locale locale) {
    1010        final TimeZoneDisplayKey key = new TimeZoneDisplayKey(tz, daylight, style, locale);
    1011        // This is a very slow call, so cache the results.
    1012        return timeZoneDisplayCache.computeIfAbsent(key, k -> tz.getDisplayName(daylight, style, locale));
    1013    }
    1014
    1015    /**
    1016     * The pattern.
    1017     */
    1018    private final String pattern;
    1019
    1020    /**
    1021     * The time zone.
    1022     */
    1023    private final TimeZone timeZone;
    1024
    1025    /**
    1026     * The locale.
    1027     */
    1028    private final Locale locale;
    1029
    1030    /**
    1031     * The parsed rules.
    1032     */
    1033    private transient Rule[] rules;
    1034
    1035    /**
    1036     * The estimated maximum length.
    1037     */
    1038    private transient int maxLengthEstimate;
    1039
    1040    // Constructor
    1041    /**
    1042     * Constructs a new FastDatePrinter.
    1043     * Use {@link FastDateFormat#getInstance(String, TimeZone, Locale)}  or another variation of the
    1044     * factory methods of {@link FastDateFormat} to get a cached FastDatePrinter instance.
    1045     *
    1046     * @param pattern  {@link java.text.SimpleDateFormat} compatible pattern
    1047     * @param timeZone  non-null time zone to use
    1048     * @param locale  non-null locale to use
    1049     * @throws NullPointerException if pattern, timeZone, or locale is null.
    1050     */
    1051    protected FastDatePrinter(final String pattern, final TimeZone timeZone, final Locale locale) {
    1052        this.pattern = pattern;
    1053        this.timeZone = timeZone;
    1054        this.locale = LocaleUtils.toLocale(locale);
    1055        init();
    1056    }
    1057
    1058    /**
    1059     * Performs the formatting by applying the rules to the
    1060     * specified calendar.
    1061     *
    1062     * @param calendar  the calendar to format
    1063     * @param buf  the buffer to format into
    1064     * @param <B> the Appendable class type, usually StringBuilder or StringBuffer.
    1065     * @return the specified string buffer
    1066     */
    1067    private <B extends Appendable> B applyRules(final Calendar calendar, final B buf) {
    1068        try {
    1069            for (final Rule rule : rules) {
    1070                rule.appendTo(buf, calendar);
    1071            }
    1072        } catch (final IOException ioe) {
    1073            ExceptionUtils.asRuntimeException(ioe);
    1074        }
    1075        return buf;
    1076    }
    1077
    1078    /**
    1079     * Performs the formatting by applying the rules to the
    1080     * specified calendar.
    1081     *
    1082     * @param calendar the calendar to format
    1083     * @param buf the buffer to format into
    1084     * @return the specified string buffer
    1085     * @deprecated use {@link #format(Calendar)} or {@link #format(Calendar, Appendable)}
    1086     */
    1087    @Deprecated
    1088    protected StringBuffer applyRules(final Calendar calendar, final StringBuffer buf) {
    1089        return (StringBuffer) applyRules(calendar, (Appendable) buf);
    1090    }
    1091
    1092    /**
    1093     * Creates a String representation of the given Calendar by applying the rules of this printer to it.
    1094     * @param c the Calendar to apply the rules to.
    1095     * @return a String representation of the given Calendar.
    1096     */
    1097    private String applyRulesToString(final Calendar c) {
    1098        return applyRules(c, new StringBuilder(maxLengthEstimate)).toString();
    1099    }
    1100
    1101    // Basics
    1102    /**
    1103     * Compares two objects for equality.
    1104     *
    1105     * @param obj  the object to compare to
    1106     * @return {@code true} if equal
    1107     */
    1108    @Override
    1109    public boolean equals(final Object obj) {
    1110        if (!(obj instanceof FastDatePrinter)) {
    1111            return false;
    1112        }
    1113        final FastDatePrinter other = (FastDatePrinter) obj;
    1114        return pattern.equals(other.pattern)
    1115            && timeZone.equals(other.timeZone)
    1116            && locale.equals(other.locale);
    1117    }
    1118
    1119    /* (non-Javadoc)
    1120     * @see org.apache.commons.lang3.time.DatePrinter#format(java.util.Calendar)
    1121     */
    1122    @Override
    1123    public String format(final Calendar calendar) {
    1124        return format(calendar, new StringBuilder(maxLengthEstimate)).toString();
    1125    }
    1126
    1127    /* (non-Javadoc)
    1128     * @see org.apache.commons.lang3.time.DatePrinter#format(java.util.Calendar, Appendable)
    1129     */
    1130    @Override
    1131    public <B extends Appendable> B format(Calendar calendar, final B buf) {
    1132        // do not pass in calendar directly, this will cause TimeZone of FastDatePrinter to be ignored
    1133        if (!calendar.getTimeZone().equals(timeZone)) {
    1134            calendar = (Calendar) calendar.clone();
    1135            calendar.setTimeZone(timeZone);
    1136        }
    1137        return applyRules(calendar, buf);
    1138    }
    1139
    1140    /* (non-Javadoc)
    1141     * @see org.apache.commons.lang3.time.DatePrinter#format(java.util.Calendar, StringBuffer)
    1142     */
    1143    @Override
    1144    public StringBuffer format(final Calendar calendar, final StringBuffer buf) {
    1145        // do not pass in calendar directly, this will cause TimeZone of FastDatePrinter to be ignored
    1146        return format(calendar.getTime(), buf);
    1147    }
    1148
    1149    /* (non-Javadoc)
    1150     * @see org.apache.commons.lang3.time.DatePrinter#format(java.util.Date)
    1151     */
    1152    @Override
    1153    public String format(final Date date) {
    1154        final Calendar c = newCalendar();
    1155        c.setTime(date);
    1156        return applyRulesToString(c);
    1157    }
    1158
    1159    /* (non-Javadoc)
    1160     * @see org.apache.commons.lang3.time.DatePrinter#format(java.util.Date, Appendable)
    1161     */
    1162    @Override
    1163    public <B extends Appendable> B format(final Date date, final B buf) {
    1164        final Calendar c = newCalendar();
    1165        c.setTime(date);
    1166        return applyRules(c, buf);
    1167    }
    1168
    1169    /* (non-Javadoc)
    1170     * @see org.apache.commons.lang3.time.DatePrinter#format(java.util.Date, StringBuffer)
    1171     */
    1172    @Override
    1173    public StringBuffer format(final Date date, final StringBuffer buf) {
    1174        final Calendar c = newCalendar();
    1175        c.setTime(date);
    1176        return (StringBuffer) applyRules(c, (Appendable) buf);
    1177    }
    1178
    1179    /* (non-Javadoc)
    1180     * @see org.apache.commons.lang3.time.DatePrinter#format(long)
    1181     */
    1182    @Override
    1183    public String format(final long millis) {
    1184        final Calendar c = newCalendar();
    1185        c.setTimeInMillis(millis);
    1186        return applyRulesToString(c);
    1187    }
    1188
    1189    /* (non-Javadoc)
    1190     * @see org.apache.commons.lang3.time.DatePrinter#format(long, Appendable)
    1191     */
    1192    @Override
    1193    public <B extends Appendable> B format(final long millis, final B buf) {
    1194        final Calendar c = newCalendar();
    1195        c.setTimeInMillis(millis);
    1196        return applyRules(c, buf);
    1197    }
    1198
    1199    /* (non-Javadoc)
    1200     * @see org.apache.commons.lang3.time.DatePrinter#format(long, StringBuffer)
    1201     */
    1202    @Override
    1203    public StringBuffer format(final long millis, final StringBuffer buf) {
    1204        final Calendar c = newCalendar();
    1205        c.setTimeInMillis(millis);
    1206        return (StringBuffer) applyRules(c, (Appendable) buf);
    1207    }
    1208
    1209    /**
    1210     * Formats a {@link Date}, {@link Calendar} or
    1211     * {@link Long} (milliseconds) object.
    1212     * @param obj  the object to format
    1213     * @return The formatted value.
    1214     * @since 3.5
    1215     */
    1216    String format(final Object obj) {
    1217        if (obj instanceof Date) {
    1218            return format((Date) obj);
    1219        }
    1220        if (obj instanceof Calendar) {
    1221            return format((Calendar) obj);
    1222        }
    1223        if (obj instanceof Long) {
    1224            return format(((Long) obj).longValue());
    1225        }
    1226        throw new IllegalArgumentException("Unknown class: " + ClassUtils.getName(obj, "<null>"));
    1227    }
    1228
    1229    // Format methods
    1230    /**
    1231     * Formats a {@link Date}, {@link Calendar} or
    1232     * {@link Long} (milliseconds) object.
    1233     * @deprecated Use {{@link #format(Date)}, {{@link #format(Calendar)}, {{@link #format(long)}.
    1234     * @param obj  the object to format
    1235     * @param toAppendTo  the buffer to append to
    1236     * @param pos  the position - ignored
    1237     * @return the buffer passed in
    1238     */
    1239    @Deprecated
    1240    @Override
    1241    public StringBuffer format(final Object obj, final StringBuffer toAppendTo, final FieldPosition pos) {
    1242        if (obj instanceof Date) {
    1243            return format((Date) obj, toAppendTo);
    1244        }
    1245        if (obj instanceof Calendar) {
    1246            return format((Calendar) obj, toAppendTo);
    1247        }
    1248        if (obj instanceof Long) {
    1249            return format(((Long) obj).longValue(), toAppendTo);
    1250        }
    1251        throw new IllegalArgumentException("Unknown class: " + ClassUtils.getName(obj, "<null>"));
    1252    }
    1253
    1254    /* (non-Javadoc)
    1255     * @see org.apache.commons.lang3.time.DatePrinter#getLocale()
    1256     */
    1257    @Override
    1258    public Locale getLocale() {
    1259        return locale;
    1260    }
    1261
    1262    /**
    1263     * Gets an estimate for the maximum string length that the
    1264     * formatter will produce.
    1265     *
    1266     * <p>The actual formatted length will almost always be less than or
    1267     * equal to this amount.</p>
    1268     *
    1269     * @return the maximum formatted length
    1270     */
    1271    public int getMaxLengthEstimate() {
    1272        return maxLengthEstimate;
    1273    }
    1274
    1275    /* (non-Javadoc)
    1276     * @see org.apache.commons.lang3.time.DatePrinter#getPattern()
    1277     */
    1278    @Override
    1279    public String getPattern() {
    1280        return pattern;
    1281    }
    1282
    1283    /* (non-Javadoc)
    1284     * @see org.apache.commons.lang3.time.DatePrinter#getTimeZone()
    1285     */
    1286    @Override
    1287    public TimeZone getTimeZone() {
    1288        return timeZone;
    1289    }
    1290
    1291    /**
    1292     * Returns a hash code compatible with equals.
    1293     *
    1294     * @return a hash code compatible with equals
    1295     */
    1296    @Override
    1297    public int hashCode() {
    1298        return pattern.hashCode() + 13 * (timeZone.hashCode() + 13 * locale.hashCode());
    1299    }
    1300
    1301    /**
    1302     * Initializes the instance for first use.
    1303     */
    1304    private void init() {
    1305        final List<Rule> rulesList = parsePattern();
    1306        rules = rulesList.toArray(EMPTY_RULE_ARRAY);
    1307
    1308        int len = 0;
    1309        for (int i = rules.length; --i >= 0;) {
    1310            len += rules[i].estimateLength();
    1311        }
    1312
    1313        maxLengthEstimate = len;
    1314    }
    1315
    1316    /**
    1317     * Creates a new Calendar instance.
    1318     * @return a new Calendar instance.
    1319     */
    1320    private Calendar newCalendar() {
    1321        return Calendar.getInstance(timeZone, locale);
    1322    }
    1323
    1324    // Parse the pattern
    1325    /**
    1326     * Returns a list of Rules given a pattern.
    1327     *
    1328     * @return a {@link List} of Rule objects
    1329     * @throws IllegalArgumentException if pattern is invalid
    1330     */
    1331    protected List<Rule> parsePattern() {
    1332        final DateFormatSymbols symbols = new DateFormatSymbols(locale);
    1333        final List<Rule> rules = new ArrayList<>();
    1334
    1335        final String[] ERAs = symbols.getEras();
    1336        final String[] months = symbols.getMonths();
    1337        final String[] shortMonths = symbols.getShortMonths();
    1338        final String[] weekdays = symbols.getWeekdays();
    1339        final String[] shortWeekdays = symbols.getShortWeekdays();
    1340        final String[] AmPmStrings = symbols.getAmPmStrings();
    1341
    1342        final int length = pattern.length();
    1343        final int[] indexRef = new int[1];
    1344
    1345        for (int i = 0; i < length; i++) {
    1346            indexRef[0] = i;
    1347            final String token = parseToken(pattern, indexRef);
    1348            i = indexRef[0];
    1349
    1350            final int tokenLen = token.length();
    1351            if (tokenLen == 0) {
    1352                break;
    1353            }
    1354
    1355            Rule rule;
    1356            final char c = token.charAt(0);
    1357
    1358            switch (c) {
    1359            case 'G': // era designator (text)
    1360                rule = new TextField(Calendar.ERA, ERAs);
    1361                break;
    1362            case 'y': // year (number)
    1363            case 'Y': // week year
    1364                if (tokenLen == 2) {
    1365                    rule = TwoDigitYearField.INSTANCE;
    1366                } else {
    1367                    rule = selectNumberRule(Calendar.YEAR, Math.max(tokenLen, 4));
    1368                }
    1369                if (c == 'Y') {
    1370                    rule = new WeekYear((NumberRule) rule);
    1371                }
    1372                break;
    1373            case 'M': // month in year (text and number)
    1374                if (tokenLen >= 4) {
    1375                    rule = new TextField(Calendar.MONTH, months);
    1376                } else if (tokenLen == 3) {
    1377                    rule = new TextField(Calendar.MONTH, shortMonths);
    1378                } else if (tokenLen == 2) {
    1379                    rule = TwoDigitMonthField.INSTANCE;
    1380                } else {
    1381                    rule = UnpaddedMonthField.INSTANCE;
    1382                }
    1383                break;
    1384            case 'L': // month in year (text and number)
    1385                if (tokenLen >= 4) {
    1386                    rule = new TextField(Calendar.MONTH, CalendarUtils.getInstance(locale).getStandaloneLongMonthNames());
    1387                } else if (tokenLen == 3) {
    1388                    rule = new TextField(Calendar.MONTH, CalendarUtils.getInstance(locale).getStandaloneShortMonthNames());
    1389                } else if (tokenLen == 2) {
    1390                    rule = TwoDigitMonthField.INSTANCE;
    1391                } else {
    1392                    rule = UnpaddedMonthField.INSTANCE;
    1393                }
    1394                break;
    1395            case 'd': // day in month (number)
    1396                rule = selectNumberRule(Calendar.DAY_OF_MONTH, tokenLen);
    1397                break;
    1398            case 'h': // hour in am/pm (number, 1..12)
    1399                rule = new TwelveHourField(selectNumberRule(Calendar.HOUR, tokenLen));
    1400                break;
    1401            case 'H': // hour in day (number, 0..23)
    1402                rule = selectNumberRule(Calendar.HOUR_OF_DAY, tokenLen);
    1403                break;
    1404            case 'm': // minute in hour (number)
    1405                rule = selectNumberRule(Calendar.MINUTE, tokenLen);
    1406                break;
    1407            case 's': // second in minute (number)
    1408                rule = selectNumberRule(Calendar.SECOND, tokenLen);
    1409                break;
    1410            case 'S': // millisecond (number)
    1411                rule = selectNumberRule(Calendar.MILLISECOND, tokenLen);
    1412                break;
    1413            case 'E': // day in week (text)
    1414                rule = new TextField(Calendar.DAY_OF_WEEK, tokenLen < 4 ? shortWeekdays : weekdays);
    1415                break;
    1416            case 'u': // day in week (number)
    1417                rule = new DayInWeekField(selectNumberRule(Calendar.DAY_OF_WEEK, tokenLen));
    1418                break;
    1419            case 'D': // day in year (number)
    1420                rule = selectNumberRule(Calendar.DAY_OF_YEAR, tokenLen);
    1421                break;
    1422            case 'F': // day of week in month (number)
    1423                rule = selectNumberRule(Calendar.DAY_OF_WEEK_IN_MONTH, tokenLen);
    1424                break;
    1425            case 'w': // week in year (number)
    1426                rule = selectNumberRule(Calendar.WEEK_OF_YEAR, tokenLen);
    1427                break;
    1428            case 'W': // week in month (number)
    1429                rule = selectNumberRule(Calendar.WEEK_OF_MONTH, tokenLen);
    1430                break;
    1431            case 'a': // am/pm marker (text)
    1432                rule = new TextField(Calendar.AM_PM, AmPmStrings);
    1433                break;
    1434            case 'k': // hour in day (1..24)
    1435                rule = new TwentyFourHourField(selectNumberRule(Calendar.HOUR_OF_DAY, tokenLen));
    1436                break;
    1437            case 'K': // hour in am/pm (0..11)
    1438                rule = selectNumberRule(Calendar.HOUR, tokenLen);
    1439                break;
    1440            case 'X': // ISO 8601
    1441                rule = Iso8601_Rule.getRule(tokenLen);
    1442                break;
    1443            case 'z': // time zone (text)
    1444                rule = new TimeZoneNameRule(timeZone, locale, tokenLen >= 4 ? TimeZone.LONG : TimeZone.SHORT);
    1445                break;
    1446            case 'Z': // time zone (value)
    1447                if (tokenLen == 1) {
    1448                    rule = TimeZoneNumberRule.INSTANCE_NO_COLON;
    1449                } else if (tokenLen == 2) {
    1450                    rule = Iso8601_Rule.ISO8601_HOURS_COLON_MINUTES;
    1451                } else {
    1452                    rule = TimeZoneNumberRule.INSTANCE_COLON;
    1453                }
    1454                break;
    1455            case '\'': // literal text
    1456                final String sub = token.substring(1);
    1457                if (sub.length() == 1) {
    1458                    rule = new CharacterLiteral(sub.charAt(0));
    1459                } else {
    1460                    rule = new StringLiteral(sub);
    1461                }
    1462                break;
    1463            default:
    1464                throw new IllegalArgumentException("Illegal pattern component: " + token);
    1465            }
    1466
    1467            rules.add(rule);
    1468        }
    1469
    1470        return rules;
    1471    }
    1472
    1473    /**
    1474     * Performs the parsing of tokens.
    1475     *
    1476     * @param pattern  the pattern
    1477     * @param indexRef  index references
    1478     * @return parsed token
    1479     */
    1480    protected String parseToken(final String pattern, final int[] indexRef) {
    1481        final StringBuilder buf = new StringBuilder();
    1482        int i = indexRef[0];
    1483        final int length = pattern.length();
    1484        char c = pattern.charAt(i);
    1485        final char c1 = c;
    1486        if (CharUtils.isAsciiAlpha(c1)) {
    1487            // Scan a run of the same character, which indicates a time
    1488            // pattern.
    1489            buf.append(c);
    1490            while (i + 1 < length) {
    1491                final char peek = pattern.charAt(i + 1);
    1492                if (peek != c) {
    1493                    break;
    1494                }
    1495                buf.append(c);
    1496                i++;
    1497            }
    1498        } else {
    1499            // This will identify token as text.
    1500            buf.append('\'');
    1501            boolean inLiteral = false;
    1502            for (; i < length; i++) {
    1503                c = pattern.charAt(i);
    1504                if (c == '\'') {
    1505                    if (i + 1 < length && pattern.charAt(i + 1) == '\'') {
    1506                        // '' is treated as escaped '
    1507                        i++;
    1508                        buf.append(c);
    1509                    } else {
    1510                        inLiteral = !inLiteral;
    1511                    }
    1512                } else {
    1513                    final char c2 = c;
    1514                    if (!inLiteral && CharUtils.isAsciiAlpha(c2)) {
    1515                        i--;
    1516                        break;
    1517                    }
    1518                    buf.append(c);
    1519                }
    1520            }
    1521        }
    1522        indexRef[0] = i;
    1523        return buf.toString();
    1524    }
    1525
    1526    // Serializing
    1527    /**
    1528     * Create the object after serialization. This implementation reinitializes the
    1529     * transient properties.
    1530     *
    1531     * @param in ObjectInputStream from which the object is being deserialized.
    1532     * @throws IOException if there is an IO issue.
    1533     * @throws ClassNotFoundException if a class cannot be found.
    1534     */
    1535    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
    1536        in.defaultReadObject();
    1537        init();
    1538    }
    1539
    1540    /**
    1541     * Gets an appropriate rule for the padding required.
    1542     *
    1543     * @param field  the field to get a rule for
    1544     * @param padding  the padding required
    1545     * @return a new rule with the correct padding
    1546     */
    1547    protected NumberRule selectNumberRule(final int field, final int padding) {
    1548        switch (padding) {
    1549        case 1:
    1550            return new UnpaddedNumberField(field);
    1551        case 2:
    1552            return new TwoDigitNumberField(field);
    1553        default:
    1554            return new PaddedNumberField(field, padding);
    1555        }
    1556    }
    1557
    1558    /**
    1559     * Gets a debugging string version of this formatter.
    1560     *
    1561     * @return a debugging string
    1562     */
    1563    @Override
    1564    public String toString() {
    1565        return "FastDatePrinter[" + pattern + "," + locale + "," + timeZone.getID() + "]";
    1566    }
    1567}