    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 (for example, {@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 (for example, {@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
    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 of the result.
    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 {@link TimeZone#LONG} or {@link 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    /**
    1041     * Constructs a new FastDatePrinter.
    1042     * Use {@link FastDateFormat#getInstance(String, TimeZone, Locale)}  or another variation of the
    1043     * factory methods of {@link FastDateFormat} to get a cached FastDatePrinter instance.
    1044     *
    1045     * @param pattern  {@link java.text.SimpleDateFormat} compatible pattern.
    1046     * @param timeZone  non-null time zone to use.
    1047     * @param locale  non-null locale to use.
    1048     * @throws NullPointerException if pattern, timeZone, or locale is null.
    1049     */
    1050    protected FastDatePrinter(final String pattern, final TimeZone timeZone, final Locale locale) {
    1051        this.pattern = pattern;
    1052        this.timeZone = timeZone;
    1053        this.locale = LocaleUtils.toLocale(locale);
    1054        init();
    1055    }
    1056
    1057    /**
    1058     * Performs the formatting by applying the rules to the
    1059     * specified calendar.
    1060     *
    1061     * @param calendar  the calendar to format.
    1062     * @param buf  the buffer to format into.
    1063     * @param <B> the Appendable class type, usually StringBuilder or StringBuffer.
    1064     * @return the specified string buffer.
    1065     */
    1066    private <B extends Appendable> B applyRules(final Calendar calendar, final B buf) {
    1067        try {
    1068            for (final Rule rule : rules) {
    1069                rule.appendTo(buf, calendar);
    1070            }
    1071        } catch (final IOException ioe) {
    1072            ExceptionUtils.asRuntimeException(ioe);
    1073        }
    1074        return buf;
    1075    }
    1076
    1077    /**
    1078     * Performs the formatting by applying the rules to the
    1079     * specified calendar.
    1080     *
    1081     * @param calendar the calendar to format.
    1082     * @param buf the buffer to format into.
    1083     * @return the specified string buffer.
    1084     * @deprecated Use {@link #format(Calendar)} or {@link #format(Calendar, Appendable)}
    1085     */
    1086    @Deprecated
    1087    protected StringBuffer applyRules(final Calendar calendar, final StringBuffer buf) {
    1088        return (StringBuffer) applyRules(calendar, (Appendable) buf);
    1089    }
    1090
    1091    /**
    1092     * Creates a String representation of the given Calendar by applying the rules of this printer to it.
    1093     * @param c the Calendar to apply the rules to.
    1094     * @return a String representation of the given Calendar.
    1095     */
    1096    private String applyRulesToString(final Calendar c) {
    1097        return applyRules(c, new StringBuilder(maxLengthEstimate)).toString();
    1098    }
    1099
    1100    // Basics
    1101    /**
    1102     * Compares two objects for equality.
    1103     *
    1104     * @param obj  the object to compare to.
    1105     * @return {@code true} if equal.
    1106     */
    1107    @Override
    1108    public boolean equals(final Object obj) {
    1109        if (!(obj instanceof FastDatePrinter)) {
    1110            return false;
    1111        }
    1112        final FastDatePrinter other = (FastDatePrinter) obj;
    1113        return pattern.equals(other.pattern)
    1114            && timeZone.equals(other.timeZone)
    1115            && locale.equals(other.locale);
    1116    }
    1117
    1118    /* (non-Javadoc)
    1119     * @see org.apache.commons.lang3.time.DatePrinter#format(java.util.Calendar)
    1120     */
    1121    @Override
    1122    public String format(final Calendar calendar) {
    1123        return format(calendar, new StringBuilder(maxLengthEstimate)).toString();
    1124    }
    1125
    1126    /* (non-Javadoc)
    1127     * @see org.apache.commons.lang3.time.DatePrinter#format(java.util.Calendar, Appendable)
    1128     */
    1129    @Override
    1130    public <B extends Appendable> B format(final Calendar calendar, final B buf) {
    1131        // Don't edit the given Calendar, clone it only if needed.
    1132        Calendar actual = calendar;
    1133        if (!calendar.getTimeZone().equals(timeZone)) {
    1134            actual = (Calendar) calendar.clone();
    1135            actual.setTimeZone(timeZone);
    1136        }
    1137        return applyRules(actual, 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    /**
    1230     * Formats a {@link Date}, {@link Calendar} or
    1231     * {@link Long} (milliseconds) object.
    1232     * @deprecated Use {{@link #format(Date)}, {{@link #format(Calendar)}, {{@link #format(long)}.
    1233     * @param obj  the object to format.
    1234     * @param toAppendTo  the buffer to append to.
    1235     * @param pos  the position; ignored.
    1236     * @return the buffer passed in.
    1237     */
    1238    @Deprecated
    1239    @Override
    1240    public StringBuffer format(final Object obj, final StringBuffer toAppendTo, final FieldPosition pos) {
    1241        if (obj instanceof Date) {
    1242            return format((Date) obj, toAppendTo);
    1243        }
    1244        if (obj instanceof Calendar) {
    1245            return format((Calendar) obj, toAppendTo);
    1246        }
    1247        if (obj instanceof Long) {
    1248            return format(((Long) obj).longValue(), toAppendTo);
    1249        }
    1250        throw new IllegalArgumentException("Unknown class: " + ClassUtils.getName(obj, "<null>"));
    1251    }
    1252
    1253    /* (non-Javadoc)
    1254     * @see org.apache.commons.lang3.time.DatePrinter#getLocale()
    1255     */
    1256    @Override
    1257    public Locale getLocale() {
    1258        return locale;
    1259    }
    1260
    1261    /**
    1262     * Gets an estimate for the maximum string length that the
    1263     * formatter will produce.
    1264     *
    1265     * <p>The actual formatted length will almost always be less than or
    1266     * equal to this amount.</p>
    1267     *
    1268     * @return the maximum formatted length.
    1269     */
    1270    public int getMaxLengthEstimate() {
    1271        return maxLengthEstimate;
    1272    }
    1273
    1274    /* (non-Javadoc)
    1275     * @see org.apache.commons.lang3.time.DatePrinter#getPattern()
    1276     */
    1277    @Override
    1278    public String getPattern() {
    1279        return pattern;
    1280    }
    1281
    1282    /* (non-Javadoc)
    1283     * @see org.apache.commons.lang3.time.DatePrinter#getTimeZone()
    1284     */
    1285    @Override
    1286    public TimeZone getTimeZone() {
    1287        return timeZone;
    1288    }
    1289
    1290    /**
    1291     * Returns a hash code compatible with equals.
    1292     *
    1293     * @return a hash code compatible with equals.
    1294     */
    1295    @Override
    1296    public int hashCode() {
    1297        return pattern.hashCode() + 13 * (timeZone.hashCode() + 13 * locale.hashCode());
    1298    }
    1299
    1300    /**
    1301     * Initializes the instance for first use.
    1302     */
    1303    private void init() {
    1304        final List<Rule> rulesList = parsePattern();
    1305        rules = rulesList.toArray(EMPTY_RULE_ARRAY);
    1306
    1307        int len = 0;
    1308        for (int i = rules.length; --i >= 0;) {
    1309            len += rules[i].estimateLength();
    1310        }
    1311
    1312        maxLengthEstimate = len;
    1313    }
    1314
    1315    /**
    1316     * Creates a new Calendar instance.
    1317     * @return a new Calendar instance.
    1318     */
    1319    private Calendar newCalendar() {
    1320        return Calendar.getInstance(timeZone, locale);
    1321    }
    1322
    1323    // Parse the pattern
    1324    /**
    1325     * Returns a list of Rules given a pattern.
    1326     *
    1327     * @return a {@link List} of Rule objects.
    1328     * @throws IllegalArgumentException if pattern is invalid.
    1329     */
    1330    protected List<Rule> parsePattern() {
    1331        final DateFormatSymbols symbols = new DateFormatSymbols(locale);
    1332        final List<Rule> rules = new ArrayList<>();
    1333
    1334        final String[] ERAs = symbols.getEras();
    1335        final String[] months = symbols.getMonths();
    1336        final String[] shortMonths = symbols.getShortMonths();
    1337        final String[] weekdays = symbols.getWeekdays();
    1338        final String[] shortWeekdays = symbols.getShortWeekdays();
    1339        final String[] AmPmStrings = symbols.getAmPmStrings();
    1340
    1341        final int length = pattern.length();
    1342        final int[] indexRef = new int[1];
    1343
    1344        for (int i = 0; i < length; i++) {
    1345            indexRef[0] = i;
    1346            final String token = parseToken(pattern, indexRef);
    1347            i = indexRef[0];
    1348
    1349            final int tokenLen = token.length();
    1350            if (tokenLen == 0) {
    1351                break;
    1352            }
    1353
    1354            Rule rule;
    1355            final char c = token.charAt(0);
    1356
    1357            switch (c) {
    1358            case 'G': // era designator (text)
    1359                rule = new TextField(Calendar.ERA, ERAs);
    1360                break;
    1361            case 'y': // year (number)
    1362            case 'Y': // week year
    1363                if (tokenLen == 2) {
    1364                    rule = TwoDigitYearField.INSTANCE;
    1365                } else {
    1366                    rule = selectNumberRule(Calendar.YEAR, Math.max(tokenLen, 4));
    1367                }
    1368                if (c == 'Y') {
    1369                    rule = new WeekYear((NumberRule) rule);
    1370                }
    1371                break;
    1372            case 'M': // month in year (text and number)
    1373                if (tokenLen >= 4) {
    1374                    rule = new TextField(Calendar.MONTH, months);
    1375                } else if (tokenLen == 3) {
    1376                    rule = new TextField(Calendar.MONTH, shortMonths);
    1377                } else if (tokenLen == 2) {
    1378                    rule = TwoDigitMonthField.INSTANCE;
    1379                } else {
    1380                    rule = UnpaddedMonthField.INSTANCE;
    1381                }
    1382                break;
    1383            case 'L': // month in year (text and number)
    1384                if (tokenLen >= 4) {
    1385                    rule = new TextField(Calendar.MONTH, CalendarUtils.getInstance(locale).getStandaloneLongMonthNames());
    1386                } else if (tokenLen == 3) {
    1387                    rule = new TextField(Calendar.MONTH, CalendarUtils.getInstance(locale).getStandaloneShortMonthNames());
    1388                } else if (tokenLen == 2) {
    1389                    rule = TwoDigitMonthField.INSTANCE;
    1390                } else {
    1391                    rule = UnpaddedMonthField.INSTANCE;
    1392                }
    1393                break;
    1394            case 'd': // day in month (number)
    1395                rule = selectNumberRule(Calendar.DAY_OF_MONTH, tokenLen);
    1396                break;
    1397            case 'h': // hour in am/pm (number, 1..12)
    1398                rule = new TwelveHourField(selectNumberRule(Calendar.HOUR, tokenLen));
    1399                break;
    1400            case 'H': // hour in day (number, 0..23)
    1401                rule = selectNumberRule(Calendar.HOUR_OF_DAY, tokenLen);
    1402                break;
    1403            case 'm': // minute in hour (number)
    1404                rule = selectNumberRule(Calendar.MINUTE, tokenLen);
    1405                break;
    1406            case 's': // second in minute (number)
    1407                rule = selectNumberRule(Calendar.SECOND, tokenLen);
    1408                break;
    1409            case 'S': // millisecond (number)
    1410                rule = selectNumberRule(Calendar.MILLISECOND, tokenLen);
    1411                break;
    1412            case 'E': // day in week (text)
    1413                rule = new TextField(Calendar.DAY_OF_WEEK, tokenLen < 4 ? shortWeekdays : weekdays);
    1414                break;
    1415            case 'u': // day in week (number)
    1416                rule = new DayInWeekField(selectNumberRule(Calendar.DAY_OF_WEEK, tokenLen));
    1417                break;
    1418            case 'D': // day in year (number)
    1419                rule = selectNumberRule(Calendar.DAY_OF_YEAR, tokenLen);
    1420                break;
    1421            case 'F': // day of week in month (number)
    1422                rule = selectNumberRule(Calendar.DAY_OF_WEEK_IN_MONTH, tokenLen);
    1423                break;
    1424            case 'w': // week in year (number)
    1425                rule = selectNumberRule(Calendar.WEEK_OF_YEAR, tokenLen);
    1426                break;
    1427            case 'W': // week in month (number)
    1428                rule = selectNumberRule(Calendar.WEEK_OF_MONTH, tokenLen);
    1429                break;
    1430            case 'a': // am/pm marker (text)
    1431                rule = new TextField(Calendar.AM_PM, AmPmStrings);
    1432                break;
    1433            case 'k': // hour in day (1..24)
    1434                rule = new TwentyFourHourField(selectNumberRule(Calendar.HOUR_OF_DAY, tokenLen));
    1435                break;
    1436            case 'K': // hour in am/pm (0..11)
    1437                rule = selectNumberRule(Calendar.HOUR, tokenLen);
    1438                break;
    1439            case 'X': // ISO 8601
    1440                rule = Iso8601_Rule.getRule(tokenLen);
    1441                break;
    1442            case 'z': // time zone (text)
    1443                rule = new TimeZoneNameRule(timeZone, locale, tokenLen >= 4 ? TimeZone.LONG : TimeZone.SHORT);
    1444                break;
    1445            case 'Z': // time zone (value)
    1446                if (tokenLen == 1) {
    1447                    rule = TimeZoneNumberRule.INSTANCE_NO_COLON;
    1448                } else if (tokenLen == 2) {
    1449                    rule = Iso8601_Rule.ISO8601_HOURS_COLON_MINUTES;
    1450                } else {
    1451                    rule = TimeZoneNumberRule.INSTANCE_COLON;
    1452                }
    1453                break;
    1454            case '\'': // literal text
    1455                final String sub = token.substring(1);
    1456                if (sub.length() == 1) {
    1457                    rule = new CharacterLiteral(sub.charAt(0));
    1458                } else {
    1459                    rule = new StringLiteral(sub);
    1460                }
    1461                break;
    1462            default:
    1463                throw new IllegalArgumentException("Illegal pattern component: " + token);
    1464            }
    1465
    1466            rules.add(rule);
    1467        }
    1468
    1469        return rules;
    1470    }
    1471
    1472    /**
    1473     * Performs the parsing of tokens.
    1474     *
    1475     * @param pattern  the pattern.
    1476     * @param indexRef  index references.
    1477     * @return parsed token.
    1478     */
    1479    protected String parseToken(final String pattern, final int[] indexRef) {
    1480        final StringBuilder buf = new StringBuilder();
    1481        int i = indexRef[0];
    1482        final int length = pattern.length();
    1483        char c = pattern.charAt(i);
    1484        final char c1 = c;
    1485        if (CharUtils.isAsciiAlpha(c1)) {
    1486            // Scan a run of the same character, which indicates a time
    1487            // pattern.
    1488            buf.append(c);
    1489            while (i + 1 < length) {
    1490                final char peek = pattern.charAt(i + 1);
    1491                if (peek != c) {
    1492                    break;
    1493                }
    1494                buf.append(c);
    1495                i++;
    1496            }
    1497        } else {
    1498            // This will identify token as text.
    1499            buf.append('\'');
    1500            boolean inLiteral = false;
    1501            for (; i < length; i++) {
    1502                c = pattern.charAt(i);
    1503                if (c == '\'') {
    1504                    if (i + 1 < length && pattern.charAt(i + 1) == '\'') {
    1505                        // '' is treated as escaped '
    1506                        i++;
    1507                        buf.append(c);
    1508                    } else {
    1509                        inLiteral = !inLiteral;
    1510                    }
    1511                } else {
    1512                    final char c2 = c;
    1513                    if (!inLiteral && CharUtils.isAsciiAlpha(c2)) {
    1514                        i--;
    1515                        break;
    1516                    }
    1517                    buf.append(c);
    1518                }
    1519            }
    1520        }
    1521        indexRef[0] = i;
    1522        return buf.toString();
    1523    }
    1524
    1525    /**
    1526     * Create the object after serialization. This implementation reinitializes the
    1527     * transient properties.
    1528     *
    1529     * @param in ObjectInputStream from which the object is being deserialized.
    1530     * @throws IOException if there is an IO issue.
    1531     * @throws ClassNotFoundException if a class cannot be found.
    1532     */
    1533    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
    1534        in.defaultReadObject();
    1535        init();
    1536    }
    1537
    1538    /**
    1539     * Gets an appropriate rule for the padding required.
    1540     *
    1541     * @param field  the field to get a rule for.
    1542     * @param padding  the padding required.
    1543     * @return a new rule with the correct padding.
    1544     */
    1545    protected NumberRule selectNumberRule(final int field, final int padding) {
    1546        switch (padding) {
    1547        case 1:
    1548            return new UnpaddedNumberField(field);
    1549        case 2:
    1550            return new TwoDigitNumberField(field);
    1551        default:
    1552            return new PaddedNumberField(field, padding);
    1553        }
    1554    }
    1555
    1556    /**
    1557     * Gets a debugging string version of this formatter.
    1558     *
    1559     * @return a debugging string.
    1560     */
    1561    @Override
    1562    public String toString() {
    1563        return "FastDatePrinter[" + pattern + "," + locale + "," + timeZone.getID() + "]";
    1564    }
    1565}