/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache license, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the license for the specific language governing permissions and
 * limitations under the license.
 */
package org.apache.logging.log4j.core.util.datetime;

import java.text.DateFormat;
import java.text.FieldPosition;
import java.text.ParseException;
import java.text.ParsePosition;
import java.util.Calendar;
import java.util.Date;
import java.util.Locale;
import java.util.TimeZone;

FastDateFormat is a fast and thread-safe version of SimpleDateFormat.
To obtain an instance of FastDateFormat, use one of the static factory methods: getInstance(String, TimeZone, Locale), getDateInstance(int, TimeZone, Locale), getTimeInstance(int, TimeZone, Locale), or getDateTimeInstance(int, int, TimeZone, Locale) 
Since FastDateFormat is thread safe, you can use a static member instance:

  private static final FastDateFormat DATE_FORMATTER = FastDateFormat.getDateTimeInstance(FastDateFormat.LONG, FastDateFormat.SHORT);

This class can be used as a direct replacement to SimpleDateFormat in most formatting and parsing situations. This class is especially useful in multi-threaded server environments. SimpleDateFormat is not thread-safe in any JDK version, nor will it be as Sun have closed the bug/RFE. 
All patterns are compatible with
SimpleDateFormat (except time zones and some year patterns - see below).
Since 3.2, FastDateFormat supports parsing as well as printing.
Java 1.4 introduced a new pattern letter, 'Z', to represent time zones in RFC822 format (eg. +0800 or -1100). This pattern letter can be used here (on all JDK versions).
In addition, the pattern 'ZZ' has been made to represent ISO 8601 extended format time zones (eg. +08:00 or -11:00). This introduces a minor incompatibility with Java 1.4, but at a gain of useful functionality.
Javadoc cites for the year pattern: For formatting, if the number of
pattern letters is 2, the year is truncated to 2 digits; otherwise it is
interpreted as a number. Starting with Java 1.7 a pattern of 'Y' or
'YYY' will be formatted as '2003', while it was '03' in former Java
versions. FastDateFormat implements the behavior of Java 7.

Copied and modified from Apache Commons Lang.

Since:
Apache Commons Lang 2.0/**
 * <p>FastDateFormat is a fast and thread-safe version of
 * {@link java.text.SimpleDateFormat}.</p>
 *
 * <p>To obtain an instance of FastDateFormat, use one of the static factory methods:
 * {@link #getInstance(String, TimeZone, Locale)}, {@link #getDateInstance(int, TimeZone, Locale)},
 * {@link #getTimeInstance(int, TimeZone, Locale)}, or {@link #getDateTimeInstance(int, int, TimeZone, Locale)}
 * </p>
 *
 * <p>Since FastDateFormat is thread safe, you can use a static member instance:</p>
 * <code>
 *   private static final FastDateFormat DATE_FORMATTER = FastDateFormat.getDateTimeInstance(FastDateFormat.LONG, FastDateFormat.SHORT);
 * </code>
 *
 * <p>This class can be used as a direct replacement to
 * {@code SimpleDateFormat} in most formatting and parsing situations.
 * This class is especially useful in multi-threaded server environments.
 * {@code SimpleDateFormat} is not thread-safe in any JDK version,
 * nor will it be as Sun have closed the bug/RFE.
 * </p>
 *
 * <p>All patterns are compatible with
 * SimpleDateFormat (except time zones and some year patterns - see below).</p>
 *
 * <p>Since 3.2, FastDateFormat supports parsing as well as printing.</p>
 *
 * <p>Java 1.4 introduced a new pattern letter, {@code 'Z'}, to represent
 * time zones in RFC822 format (eg. {@code +0800} or {@code -1100}).
 * This pattern letter can be used here (on all JDK versions).</p>
 *
 * <p>In addition, the pattern {@code 'ZZ'} has been made to represent
 * ISO 8601 extended format time zones (eg. {@code +08:00} or {@code -11:00}).
 * This introduces a minor incompatibility with Java 1.4, but at a gain of
 * useful functionality.</p>
 *
 * <p>Javadoc cites for the year pattern: <i>For formatting, if the number of
 * pattern letters is 2, the year is truncated to 2 digits; otherwise it is
 * interpreted as a number.</i> Starting with Java 1.7 a pattern of 'Y' or
 * 'YYY' will be formatted as '2003', while it was '03' in former Java
 * versions. FastDateFormat implements the behavior of Java 7.</p>
 *
 * <p>
 * Copied and modified from <a href="https://commons.apache.org/proper/commons-lang/">Apache Commons Lang</a>.
 * </p>
 *
 * @since Apache Commons Lang 2.0
 */
public class FastDateFormat extends Format implements DateParser, DatePrinter {

    
Required for serialization support.
See Also:
Serializable/**
     * Required for serialization support.
     *
     * @see java.io.Serializable
     */
    @SuppressWarnings("unused")
    private static final long serialVersionUID = 2L;

    
FULL locale dependent date or time style.
/**
     * FULL locale dependent date or time style.
     */
    public static final int FULL = DateFormat.FULL;
    
    
LONG locale dependent date or time style.
/**
     * LONG locale dependent date or time style.
     */
    public static final int LONG = DateFormat.LONG;
    
    
MEDIUM locale dependent date or time style.
/**
     * MEDIUM locale dependent date or time style.
     */
    public static final int MEDIUM = DateFormat.MEDIUM;
    
    
SHORT locale dependent date or time style.
/**
     * SHORT locale dependent date or time style.
     */
    public static final int SHORT = DateFormat.SHORT;

    private static final FormatCache<FastDateFormat> cache= new FormatCache<FastDateFormat>() {
        @Override
        protected FastDateFormat createInstance(final String pattern, final TimeZone timeZone, final Locale locale) {
            return new FastDateFormat(pattern, timeZone, locale);
        }
    };

    private final FastDatePrinter printer;
    private final FastDateParser parser;

    //-----------------------------------------------------------------------
    
Gets a formatter instance using the default pattern in the
default locale.
Returns:
a date/time formatter/**
     * <p>Gets a formatter instance using the default pattern in the
     * default locale.</p>
     *
     * @return a date/time formatter
     */
    public static FastDateFormat getInstance() {
        return cache.getInstance();
    }

    
Gets a formatter instance using the specified pattern in the
default locale.
Params:
pattern –  SimpleDateFormat compatible pattern
Throws:
IllegalArgumentException – if pattern is invalid
Returns:
a pattern based date/time formatter/**
     * <p>Gets a formatter instance using the specified pattern in the
     * default locale.</p>
     *
     * @param pattern  {@link java.text.SimpleDateFormat} compatible
     *  pattern
     * @return a pattern based date/time formatter
     * @throws IllegalArgumentException if pattern is invalid
     */
    public static FastDateFormat getInstance(final String pattern) {
        return cache.getInstance(pattern, null, null);
    }

    
Gets a formatter instance using the specified pattern and
time zone.
Params:
pattern –  SimpleDateFormat compatible pattern
timeZone –  optional time zone, overrides time zone of
 formatted date
Throws:
IllegalArgumentException – if pattern is invalid
Returns:
a pattern based date/time formatter/**
     * <p>Gets a formatter instance using the specified pattern and
     * time zone.</p>
     *
     * @param pattern  {@link java.text.SimpleDateFormat} compatible
     *  pattern
     * @param timeZone  optional time zone, overrides time zone of
     *  formatted date
     * @return a pattern based date/time formatter
     * @throws IllegalArgumentException if pattern is invalid
     */
    public static FastDateFormat getInstance(final String pattern, final TimeZone timeZone) {
        return cache.getInstance(pattern, timeZone, null);
    }

    
Gets a formatter instance using the specified pattern and
locale.
Params:
pattern –  SimpleDateFormat compatible pattern
locale –  optional locale, overrides system locale
Throws:
IllegalArgumentException – if pattern is invalid
Returns:
a pattern based date/time formatter/**
     * <p>Gets a formatter instance using the specified pattern and
     * locale.</p>
     *
     * @param pattern  {@link java.text.SimpleDateFormat} compatible
     *  pattern
     * @param locale  optional locale, overrides system locale
     * @return a pattern based date/time formatter
     * @throws IllegalArgumentException if pattern is invalid
     */
    public static FastDateFormat getInstance(final String pattern, final Locale locale) {
        return cache.getInstance(pattern, null, locale);
    }

    
Gets a formatter instance using the specified pattern, time zone
and locale.
Params:
pattern –  SimpleDateFormat compatible pattern
timeZone –  optional time zone, overrides time zone of
 formatted date
locale –  optional locale, overrides system locale
Throws:
IllegalArgumentException – if pattern is invalid or null
Returns:
a pattern based date/time formatter/**
     * <p>Gets a formatter instance using the specified pattern, time zone
     * and locale.</p>
     *
     * @param pattern  {@link java.text.SimpleDateFormat} compatible
     *  pattern
     * @param timeZone  optional time zone, overrides time zone of
     *  formatted date
     * @param locale  optional locale, overrides system locale
     * @return a pattern based date/time formatter
     * @throws IllegalArgumentException if pattern is invalid
     *  or {@code null}
     */
    public static FastDateFormat getInstance(final String pattern, final TimeZone timeZone, final Locale locale) {
        return cache.getInstance(pattern, timeZone, locale);
    }

    //-----------------------------------------------------------------------
    
Gets a date formatter instance using the specified style in the
default time zone and locale.
Params:
style –  date style: FULL, LONG, MEDIUM, or SHORT
Throws:
IllegalArgumentException – if the Locale has no date
 pattern defined
Returns:
a localized standard date formatter
Since:
2.1/**
     * <p>Gets a date formatter instance using the specified style in the
     * default time zone and locale.</p>
     *
     * @param style  date style: FULL, LONG, MEDIUM, or SHORT
     * @return a localized standard date formatter
     * @throws IllegalArgumentException if the Locale has no date
     *  pattern defined
     * @since 2.1
     */
    public static FastDateFormat getDateInstance(final int style) {
        return cache.getDateInstance(style, null, null);
    }

    
Gets a date formatter instance using the specified style and
locale in the default time zone.
Params:
style –  date style: FULL, LONG, MEDIUM, or SHORT
locale –  optional locale, overrides system locale
Throws:
IllegalArgumentException – if the Locale has no date
 pattern defined
Returns:
a localized standard date formatter
Since:
2.1/**
     * <p>Gets a date formatter instance using the specified style and
     * locale in the default time zone.</p>
     *
     * @param style  date style: FULL, LONG, MEDIUM, or SHORT
     * @param locale  optional locale, overrides system locale
     * @return a localized standard date formatter
     * @throws IllegalArgumentException if the Locale has no date
     *  pattern defined
     * @since 2.1
     */
    public static FastDateFormat getDateInstance(final int style, final Locale locale) {
        return cache.getDateInstance(style, null, locale);
    }

    
Gets a date formatter instance using the specified style and
time zone in the default locale.
Params:
style –  date style: FULL, LONG, MEDIUM, or SHORT
timeZone –  optional time zone, overrides time zone of
 formatted date
Throws:
IllegalArgumentException – if the Locale has no date
 pattern defined
Returns:
a localized standard date formatter
Since:
2.1/**
     * <p>Gets a date formatter instance using the specified style and
     * time zone in the default locale.</p>
     *
     * @param style  date style: FULL, LONG, MEDIUM, or SHORT
     * @param timeZone  optional time zone, overrides time zone of
     *  formatted date
     * @return a localized standard date formatter
     * @throws IllegalArgumentException if the Locale has no date
     *  pattern defined
     * @since 2.1
     */
    public static FastDateFormat getDateInstance(final int style, final TimeZone timeZone) {
        return cache.getDateInstance(style, timeZone, null);
    }

    
Gets a date formatter instance using the specified style, time
zone and locale.
Params:
style –  date style: FULL, LONG, MEDIUM, or SHORT
timeZone –  optional time zone, overrides time zone of
 formatted date
locale –  optional locale, overrides system locale
Throws:
IllegalArgumentException – if the Locale has no date
 pattern defined
Returns:
a localized standard date formatter/**
     * <p>Gets a date formatter instance using the specified style, time
     * zone and locale.</p>
     *
     * @param style  date style: FULL, LONG, MEDIUM, or SHORT
     * @param timeZone  optional time zone, overrides time zone of
     *  formatted date
     * @param locale  optional locale, overrides system locale
     * @return a localized standard date formatter
     * @throws IllegalArgumentException if the Locale has no date
     *  pattern defined
     */
    public static FastDateFormat getDateInstance(final int style, final TimeZone timeZone, final Locale locale) {
        return cache.getDateInstance(style, timeZone, locale);
    }

    //-----------------------------------------------------------------------
    
Gets a time formatter instance using the specified style in the
default time zone and locale.
Params:
style –  time style: FULL, LONG, MEDIUM, or SHORT
Throws:
IllegalArgumentException – if the Locale has no time
 pattern defined
Returns:
a localized standard time formatter
Since:
2.1/**
     * <p>Gets a time formatter instance using the specified style in the
     * default time zone and locale.</p>
     *
     * @param style  time style: FULL, LONG, MEDIUM, or SHORT
     * @return a localized standard time formatter
     * @throws IllegalArgumentException if the Locale has no time
     *  pattern defined
     * @since 2.1
     */
    public static FastDateFormat getTimeInstance(final int style) {
        return cache.getTimeInstance(style, null, null);
    }

    
Gets a time formatter instance using the specified style and
locale in the default time zone.
Params:
style –  time style: FULL, LONG, MEDIUM, or SHORT
locale –  optional locale, overrides system locale
Throws:
IllegalArgumentException – if the Locale has no time
 pattern defined
Returns:
a localized standard time formatter
Since:
2.1/**
     * <p>Gets a time formatter instance using the specified style and
     * locale in the default time zone.</p>
     *
     * @param style  time style: FULL, LONG, MEDIUM, or SHORT
     * @param locale  optional locale, overrides system locale
     * @return a localized standard time formatter
     * @throws IllegalArgumentException if the Locale has no time
     *  pattern defined
     * @since 2.1
     */
    public static FastDateFormat getTimeInstance(final int style, final Locale locale) {
        return cache.getTimeInstance(style, null, locale);
    }

    
Gets a time formatter instance using the specified style and
time zone in the default locale.
Params:
style –  time style: FULL, LONG, MEDIUM, or SHORT
timeZone –  optional time zone, overrides time zone of
 formatted time
Throws:
IllegalArgumentException – if the Locale has no time
 pattern defined
Returns:
a localized standard time formatter
Since:
2.1/**
     * <p>Gets a time formatter instance using the specified style and
     * time zone in the default locale.</p>
     *
     * @param style  time style: FULL, LONG, MEDIUM, or SHORT
     * @param timeZone  optional time zone, overrides time zone of
     *  formatted time
     * @return a localized standard time formatter
     * @throws IllegalArgumentException if the Locale has no time
     *  pattern defined
     * @since 2.1
     */
    public static FastDateFormat getTimeInstance(final int style, final TimeZone timeZone) {
        return cache.getTimeInstance(style, timeZone, null);
    }

    
Gets a time formatter instance using the specified style, time
zone and locale.
Params:
style –  time style: FULL, LONG, MEDIUM, or SHORT
timeZone –  optional time zone, overrides time zone of
 formatted time
locale –  optional locale, overrides system locale
Throws:
IllegalArgumentException – if the Locale has no time
 pattern defined
Returns:
a localized standard time formatter/**
     * <p>Gets a time formatter instance using the specified style, time
     * zone and locale.</p>
     *
     * @param style  time style: FULL, LONG, MEDIUM, or SHORT
     * @param timeZone  optional time zone, overrides time zone of
     *  formatted time
     * @param locale  optional locale, overrides system locale
     * @return a localized standard time formatter
     * @throws IllegalArgumentException if the Locale has no time
     *  pattern defined
     */
    public static FastDateFormat getTimeInstance(final int style, final TimeZone timeZone, final Locale locale) {
        return cache.getTimeInstance(style, timeZone, locale);
    }

    //-----------------------------------------------------------------------
    
Gets a date/time formatter instance using the specified style
in the default time zone and locale.
Params:
dateStyle –  date style: FULL, LONG, MEDIUM, or SHORT
timeStyle –  time style: FULL, LONG, MEDIUM, or SHORT
Throws:
IllegalArgumentException – if the Locale has no date/time
 pattern defined
Returns:
a localized standard date/time formatter
Since:
2.1/**
     * <p>Gets a date/time formatter instance using the specified style
     * in the default time zone and locale.</p>
     *
     * @param dateStyle  date style: FULL, LONG, MEDIUM, or SHORT
     * @param timeStyle  time style: FULL, LONG, MEDIUM, or SHORT
     * @return a localized standard date/time formatter
     * @throws IllegalArgumentException if the Locale has no date/time
     *  pattern defined
     * @since 2.1
     */
    public static FastDateFormat getDateTimeInstance(final int dateStyle, final int timeStyle) {
        return cache.getDateTimeInstance(dateStyle, timeStyle, null, null);
    }

    
Gets a date/time formatter instance using the specified style and
locale in the default time zone.
Params:
dateStyle –  date style: FULL, LONG, MEDIUM, or SHORT
timeStyle –  time style: FULL, LONG, MEDIUM, or SHORT
locale –  optional locale, overrides system locale
Throws:
IllegalArgumentException – if the Locale has no date/time
 pattern defined
Returns:
a localized standard date/time formatter
Since:
2.1/**
     * <p>Gets a date/time formatter instance using the specified style and
     * locale in the default time zone.</p>
     *
     * @param dateStyle  date style: FULL, LONG, MEDIUM, or SHORT
     * @param timeStyle  time style: FULL, LONG, MEDIUM, or SHORT
     * @param locale  optional locale, overrides system locale
     * @return a localized standard date/time formatter
     * @throws IllegalArgumentException if the Locale has no date/time
     *  pattern defined
     * @since 2.1
     */
    public static FastDateFormat getDateTimeInstance(final int dateStyle, final int timeStyle, final Locale locale) {
        return cache.getDateTimeInstance(dateStyle, timeStyle, null, locale);
    }

    
Gets a date/time formatter instance using the specified style and
time zone in the default locale.
Params:
dateStyle –  date style: FULL, LONG, MEDIUM, or SHORT
timeStyle –  time style: FULL, LONG, MEDIUM, or SHORT
timeZone –  optional time zone, overrides time zone of
 formatted date
Throws:
IllegalArgumentException – if the Locale has no date/time
 pattern defined
Returns:
a localized standard date/time formatter
Since:
2.1/**
     * <p>Gets a date/time formatter instance using the specified style and
     * time zone in the default locale.</p>
     *
     * @param dateStyle  date style: FULL, LONG, MEDIUM, or SHORT
     * @param timeStyle  time style: FULL, LONG, MEDIUM, or SHORT
     * @param timeZone  optional time zone, overrides time zone of
     *  formatted date
     * @return a localized standard date/time formatter
     * @throws IllegalArgumentException if the Locale has no date/time
     *  pattern defined
     * @since 2.1
     */
    public static FastDateFormat getDateTimeInstance(final int dateStyle, final int timeStyle, final TimeZone timeZone) {
        return getDateTimeInstance(dateStyle, timeStyle, timeZone, null);
    }
    
Gets a date/time formatter instance using the specified style,
time zone and locale.
Params:
dateStyle –  date style: FULL, LONG, MEDIUM, or SHORT
timeStyle –  time style: FULL, LONG, MEDIUM, or SHORT
timeZone –  optional time zone, overrides time zone of
 formatted date
locale –  optional locale, overrides system locale
Throws:
IllegalArgumentException – if the Locale has no date/time
 pattern defined
Returns:
a localized standard date/time formatter/**
     * <p>Gets a date/time formatter instance using the specified style,
     * time zone and locale.</p>
     *
     * @param dateStyle  date style: FULL, LONG, MEDIUM, or SHORT
     * @param timeStyle  time style: FULL, LONG, MEDIUM, or SHORT
     * @param timeZone  optional time zone, overrides time zone of
     *  formatted date
     * @param locale  optional locale, overrides system locale
     * @return a localized standard date/time formatter
     * @throws IllegalArgumentException if the Locale has no date/time
     *  pattern defined
     */
    public static FastDateFormat getDateTimeInstance(
            final int dateStyle, final int timeStyle, final TimeZone timeZone, final Locale locale) {
        return cache.getDateTimeInstance(dateStyle, timeStyle, timeZone, locale);
    }

    // Constructor
    //-----------------------------------------------------------------------
    
Constructs a new FastDateFormat.
Params:
pattern –  SimpleDateFormat compatible pattern
timeZone –  non-null time zone to use
locale –  non-null locale to use
Throws:
NullPointerException – if pattern, timeZone, or locale is null./**
     * <p>Constructs a new FastDateFormat.</p>
     *
     * @param pattern  {@link java.text.SimpleDateFormat} compatible pattern
     * @param timeZone  non-null time zone to use
     * @param locale  non-null locale to use
     * @throws NullPointerException if pattern, timeZone, or locale is null.
     */
    protected FastDateFormat(final String pattern, final TimeZone timeZone, final Locale locale) {
        this(pattern, timeZone, locale, null);
    }

    // Constructor
    //-----------------------------------------------------------------------
    
Constructs a new FastDateFormat.
Params:
pattern –  SimpleDateFormat compatible pattern
timeZone –  non-null time zone to use
locale –  non-null locale to use
centuryStart – The start of the 100 year period to use as the "default century" for 2 digit year parsing.  If centuryStart is null, defaults to now - 80 years
Throws:
NullPointerException – if pattern, timeZone, or locale is null./**
     * <p>Constructs a new FastDateFormat.</p>
     *
     * @param pattern  {@link java.text.SimpleDateFormat} compatible pattern
     * @param timeZone  non-null time zone to use
     * @param locale  non-null locale to use
     * @param centuryStart The start of the 100 year period to use as the "default century" for 2 digit year parsing.  If centuryStart is null, defaults to now - 80 years
     * @throws NullPointerException if pattern, timeZone, or locale is null.
     */
    protected FastDateFormat(final String pattern, final TimeZone timeZone, final Locale locale, final Date centuryStart) {
        printer= new FastDatePrinter(pattern, timeZone, locale);
        parser= new FastDateParser(pattern, timeZone, locale, centuryStart);
    }

    // Format methods
    //-----------------------------------------------------------------------
    
Formats a Date, Calendar or Long (milliseconds) object.
 This method is an implementation of Format.format(Object, StringBuilder, FieldPosition) 
Params:
obj –  the object to format
toAppendTo –  the buffer to append to
pos –  the position - ignored
Returns:
the buffer passed in/**
     * <p>Formats a {@code Date}, {@code Calendar} or
     * {@code Long} (milliseconds) object.</p>
     * This method is an implementation of {@link Format#format(Object, StringBuilder, FieldPosition)}
     *
     * @param obj  the object to format
     * @param toAppendTo  the buffer to append to
     * @param pos  the position - ignored
     * @return the buffer passed in
     */
    @Override
    public StringBuilder format(final Object obj, final StringBuilder toAppendTo, final FieldPosition pos) {
        return toAppendTo.append(printer.format(obj));
    }

    
Formats a millisecond long value.
Params:
millis –  the millisecond value to format
Returns:
the formatted string
Since:
2.1/**
     * <p>Formats a millisecond {@code long} value.</p>
     *
     * @param millis  the millisecond value to format
     * @return the formatted string
     * @since 2.1
     */
    @Override
    public String format(final long millis) {
        return printer.format(millis);
    }

    
Formats a Date object using a GregorianCalendar.
Params:
date –  the date to format
Returns:
the formatted string/**
     * <p>Formats a {@code Date} object using a {@code GregorianCalendar}.</p>
     *
     * @param date  the date to format
     * @return the formatted string
     */
    @Override
    public String format(final Date date) {
        return printer.format(date);
    }

    
Formats a Calendar object.
Params:
calendar –  the calendar to format
Returns:
the formatted string/**
     * <p>Formats a {@code Calendar} object.</p>
     *
     * @param calendar  the calendar to format
     * @return the formatted string
     */
    @Override
    public String format(final Calendar calendar) {
        return printer.format(calendar);
    }

    
Formats a millisecond long value into the supplied StringBuffer.
Params:
millis –  the millisecond value to format
buf –  the buffer to format into
Returns:
the specified string buffer
Since:
3.5/**
     * <p>Formats a millisecond {@code long} value into the
     * supplied {@code StringBuffer}.</p>
     *
     * @param millis  the millisecond value to format
     * @param buf  the buffer to format into
     * @return the specified string buffer
     * @since 3.5
     */
    @Override
    public <B extends Appendable> B format(final long millis, final B buf) {
        return printer.format(millis, buf);
    }

    
Formats a Date object into the supplied StringBuffer using a GregorianCalendar.
Params:
date –  the date to format
buf –  the buffer to format into
Returns:
the specified string buffer
Since:
3.5/**
     * <p>Formats a {@code Date} object into the
     * supplied {@code StringBuffer} using a {@code GregorianCalendar}.</p>
     *
     * @param date  the date to format
     * @param buf  the buffer to format into
     * @return the specified string buffer
     * @since 3.5
     */
    @Override
    public <B extends Appendable> B format(final Date date, final B buf) {
        return printer.format(date, buf);
    }

    
Formats a Calendar object into the supplied StringBuffer.
Params:
calendar –  the calendar to format
buf –  the buffer to format into
Returns:
the specified string buffer
Since:
3.5/**
     * <p>Formats a {@code Calendar} object into the
     * supplied {@code StringBuffer}.</p>
     *
     * @param calendar  the calendar to format
     * @param buf  the buffer to format into
     * @return the specified string buffer
     * @since 3.5
    */
    @Override
    public <B extends Appendable> B format(final Calendar calendar, final B buf) {
        return printer.format(calendar, buf);
    }

    // Parsing
    //-----------------------------------------------------------------------


    /* (non-Javadoc)
     * @see DateParser#parse(java.lang.String)
     */
    @Override
    public Date parse(final String source) throws ParseException {
        return parser.parse(source);
    }

    /* (non-Javadoc)
     * @see DateParser#parse(java.lang.String, java.text.ParsePosition)
     */
    @Override
    public Date parse(final String source, final ParsePosition pos) {
        return parser.parse(source, pos);
    }

    /*
     * (non-Javadoc)
     * @see org.apache.commons.lang3.time.DateParser#parse(java.lang.String, java.text.ParsePosition, java.util.Calendar)
     */
    @Override
    public boolean parse(final String source, final ParsePosition pos, final Calendar calendar) {
        return parser.parse(source, pos, calendar);
    }

    /* (non-Javadoc)
     * @see java.text.Format#parseObject(java.lang.String, java.text.ParsePosition)
     */
    @Override
    public Object parseObject(final String source, final ParsePosition pos) {
        return parser.parseObject(source, pos);
    }

    // Accessors
    //-----------------------------------------------------------------------
    
Gets the pattern used by this formatter.
Returns:
the pattern, SimpleDateFormat compatible/**
     * <p>Gets the pattern used by this formatter.</p>
     *
     * @return the pattern, {@link java.text.SimpleDateFormat} compatible
     */
    @Override
    public String getPattern() {
        return printer.getPattern();
    }

    
Gets the time zone used by this formatter.
This zone is always used for Date formatting. 
Returns:
the time zone/**
     * <p>Gets the time zone used by this formatter.</p>
     *
     * <p>This zone is always used for {@code Date} formatting. </p>
     *
     * @return the time zone
     */
    @Override
    public TimeZone getTimeZone() {
        return printer.getTimeZone();
    }

    
Gets the locale used by this formatter.
Returns:
the locale/**
     * <p>Gets the locale used by this formatter.</p>
     *
     * @return the locale
     */
    @Override
    public Locale getLocale() {
        return printer.getLocale();
    }

    
Gets an estimate for the maximum string length that the
formatter will produce.
The actual formatted length will almost always be less than or
equal to this amount.
Returns:
the maximum formatted length/**
     * <p>Gets an estimate for the maximum string length that the
     * formatter will produce.</p>
     *
     * <p>The actual formatted length will almost always be less than or
     * equal to this amount.</p>
     *
     * @return the maximum formatted length
     */
    public int getMaxLengthEstimate() {
        return printer.getMaxLengthEstimate();
    }

    // Basics
    //-----------------------------------------------------------------------
    
Compares two objects for equality.
Params:
obj –  the object to compare to
Returns:
true if equal/**
     * <p>Compares two objects for equality.</p>
     *
     * @param obj  the object to compare to
     * @return {@code true} if equal
     */
    @Override
    public boolean equals(final Object obj) {
        if (obj instanceof FastDateFormat == false) {
            return false;
        }
        final FastDateFormat other = (FastDateFormat) obj;
        // no need to check parser, as it has same invariants as printer
        return printer.equals(other.printer);
    }

    
Returns a hash code compatible with equals.
Returns:
a hash code compatible with equals/**
     * <p>Returns a hash code compatible with equals.</p>
     *
     * @return a hash code compatible with equals
     */
    @Override
    public int hashCode() {
        return printer.hashCode();
    }

    
Gets a debugging string version of this formatter.
Returns:
a debugging string/**
     * <p>Gets a debugging string version of this formatter.</p>
     *
     * @return a debugging string
     */
    @Override
    public String toString() {
        return "FastDateFormat[" + printer.getPattern() + "," + printer.getLocale() + "," + printer.getTimeZone().getID() + "]";
    }
}