/*

 * Copyright (c) 1996, 2017, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

/*

 * (C) Copyright Taligent, Inc. 1996 - All Rights Reserved

 * (C) Copyright IBM Corp. 1996-1998 - All Rights Reserved

 *

 *   The original version of this source code and documentation is copyrighted

 * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These

 * materials are provided under terms of a License Agreement between Taligent

 * and Sun. This technology is protected by multiple US and International

 * patents. This notice and attribution to Taligent may not be removed.

 *   Taligent is a registered trademark of Taligent, Inc.

 *

 */

package java.text;

import java.io.IOException;

import java.io.InvalidObjectException;

import java.io.ObjectInputStream;

import static java.text.DateFormatSymbols.*;

import java.util.Calendar;

import java.util.Date;

import java.util.GregorianCalendar;

import java.util.Locale;

import java.util.Map;

import java.util.SimpleTimeZone;

import java.util.SortedMap;

import java.util.TimeZone;

import java.util.concurrent.ConcurrentHashMap;

import java.util.concurrent.ConcurrentMap;

import sun.util.calendar.CalendarUtils;

import sun.util.calendar.ZoneInfoFile;

import sun.util.locale.provider.LocaleProviderAdapter;

/**

 * <code>SimpleDateFormat</code> is a concrete class for formatting and

 * parsing dates in a locale-sensitive manner. It allows for formatting

 * (date → text), parsing (text → date), and normalization.

 *

 * <p>

 * <code>SimpleDateFormat</code> allows you to start by choosing

 * any user-defined patterns for date-time formatting. However, you

 * are encouraged to create a date-time formatter with either

 * <code>getTimeInstance</code>, <code>getDateInstance</code>, or

 * <code>getDateTimeInstance</code> in <code>DateFormat</code>. Each

 * of these class methods can return a date/time formatter initialized

 * with a default format pattern. You may modify the format pattern

 * using the <code>applyPattern</code> methods as desired.

 * For more information on using these methods, see

 * {@link DateFormat}.

 *

 * <h3>Date and Time Patterns</h3>

 * <p>

 * Date and time formats are specified by <em>date and time pattern</em>

 * strings.

 * Within date and time pattern strings, unquoted letters from

 * <code>'A'</code> to <code>'Z'</code> and from <code>'a'</code> to

 * <code>'z'</code> are interpreted as pattern letters representing the

 * components of a date or time string.

 * Text can be quoted using single quotes (<code>'</code>) to avoid

 * interpretation.

 * <code>"''"</code> represents a single quote.

 * All other characters are not interpreted; they're simply copied into the

 * output string during formatting or matched against the input string

 * during parsing.

 * <p>

 * The following pattern letters are defined (all other characters from

 * <code>'A'</code> to <code>'Z'</code> and from <code>'a'</code> to

 * <code>'z'</code> are reserved):

 * <blockquote>

 * <table class="striped">

 * <caption style="display:none">Chart shows pattern letters, date/time component, presentation, and examples.</caption>

 * <thead>

 *     <tr>

 *         <th scope="col" style="text-align:left">Letter

 *         <th scope="col" style="text-align:left">Date or Time Component

 *         <th scope="col" style="text-align:left">Presentation

 *         <th scope="col" style="text-align:left">Examples

 * </thead>

 * <tbody>

 *     <tr>

 *         <th scope="row"><code>G</code>

 *         <td>Era designator

 *         <td><a href="#text">Text</a>

 *         <td><code>AD</code>

 *     <tr>

 *         <th scope="row"><code>y</code>

 *         <td>Year

 *         <td><a href="#year">Year</a>

 *         <td><code>1996</code>; <code>96</code>

 *     <tr>

 *         <th scope="row"><code>Y</code>

 *         <td>Week year

 *         <td><a href="#year">Year</a>

 *         <td><code>2009</code>; <code>09</code>

 *     <tr>

 *         <th scope="row"><code>M</code>

 *         <td>Month in year (context sensitive)

 *         <td><a href="#month">Month</a>

 *         <td><code>July</code>; <code>Jul</code>; <code>07</code>

 *     <tr>

 *         <th scope="row"><code>L</code>

 *         <td>Month in year (standalone form)

 *         <td><a href="#month">Month</a>

 *         <td><code>July</code>; <code>Jul</code>; <code>07</code>

 *     <tr>

 *         <th scope="row"><code>w</code>

 *         <td>Week in year

 *         <td><a href="#number">Number</a>

 *         <td><code>27</code>

 *     <tr>

 *         <th scope="row"><code>W</code>

 *         <td>Week in month

 *         <td><a href="#number">Number</a>

 *         <td><code>2</code>

 *     <tr>

 *         <th scope="row"><code>D</code>

 *         <td>Day in year

 *         <td><a href="#number">Number</a>

 *         <td><code>189</code>

 *     <tr>

 *         <th scope="row"><code>d</code>

 *         <td>Day in month

 *         <td><a href="#number">Number</a>

 *         <td><code>10</code>

 *     <tr>

 *         <th scope="row"><code>F</code>

 *         <td>Day of week in month

 *         <td><a href="#number">Number</a>

 *         <td><code>2</code>

 *     <tr>

 *         <th scope="row"><code>E</code>

 *         <td>Day name in week

 *         <td><a href="#text">Text</a>

 *         <td><code>Tuesday</code>; <code>Tue</code>

 *     <tr>

 *         <th scope="row"><code>u</code>

 *         <td>Day number of week (1 = Monday, ..., 7 = Sunday)

 *         <td><a href="#number">Number</a>

 *         <td><code>1</code>

 *     <tr>

 *         <th scope="row"><code>a</code>

 *         <td>Am/pm marker

 *         <td><a href="#text">Text</a>

 *         <td><code>PM</code>

 *     <tr>

 *         <th scope="row"><code>H</code>

 *         <td>Hour in day (0-23)

 *         <td><a href="#number">Number</a>

 *         <td><code>0</code>

 *     <tr>

 *         <th scope="row"><code>k</code>

 *         <td>Hour in day (1-24)

 *         <td><a href="#number">Number</a>

 *         <td><code>24</code>

 *     <tr>

 *         <th scope="row"><code>K</code>

 *         <td>Hour in am/pm (0-11)

 *         <td><a href="#number">Number</a>

 *         <td><code>0</code>

 *     <tr>

 *         <th scope="row"><code>h</code>

 *         <td>Hour in am/pm (1-12)

 *         <td><a href="#number">Number</a>

 *         <td><code>12</code>

 *     <tr>

 *         <th scope="row"><code>m</code>

 *         <td>Minute in hour

 *         <td><a href="#number">Number</a>

 *         <td><code>30</code>

 *     <tr>

 *         <th scope="row"><code>s</code>

 *         <td>Second in minute

 *         <td><a href="#number">Number</a>

 *         <td><code>55</code>

 *     <tr>

 *         <th scope="row"><code>S</code>

 *         <td>Millisecond

 *         <td><a href="#number">Number</a>

 *         <td><code>978</code>

 *     <tr>

 *         <th scope="row"><code>z</code>

 *         <td>Time zone

 *         <td><a href="#timezone">General time zone</a>

 *         <td><code>Pacific Standard Time</code>; <code>PST</code>; <code>GMT-08:00</code>

 *     <tr>

 *         <th scope="row"><code>Z</code>

 *         <td>Time zone

 *         <td><a href="#rfc822timezone">RFC 822 time zone</a>

 *         <td><code>-0800</code>

 *     <tr>

 *         <th scope="row"><code>X</code>

 *         <td>Time zone

 *         <td><a href="#iso8601timezone">ISO 8601 time zone</a>

 *         <td><code>-08</code>; <code>-0800</code>;  <code>-08:00</code>

 * </tbody>

 * </table>

 * </blockquote>

 * Pattern letters are usually repeated, as their number determines the

 * exact presentation:

 * <ul>

 * <li><strong><a id="text">Text:</a></strong>

 *     For formatting, if the number of pattern letters is 4 or more,

 *     the full form is used; otherwise a short or abbreviated form

 *     is used if available.

 *     For parsing, both forms are accepted, independent of the number

 *     of pattern letters.<br><br></li>

 * <li><strong><a id="number">Number:</a></strong>

 *     For formatting, the number of pattern letters is the minimum

 *     number of digits, and shorter numbers are zero-padded to this amount.

 *     For parsing, the number of pattern letters is ignored unless

 *     it's needed to separate two adjacent fields.<br><br></li>

 * <li><strong><a id="year">Year:</a></strong>

 *     If the formatter's {@link #getCalendar() Calendar} is the Gregorian

 *     calendar, the following rules are applied.<br>

 *     <ul>

 *     <li>For formatting, if the number of pattern letters is 2, the year

 *         is truncated to 2 digits; otherwise it is interpreted as a

 *         <a href="#number">number</a>.

 *     <li>For parsing, if the number of pattern letters is more than 2,

 *         the year is interpreted literally, regardless of the number of

 *         digits. So using the pattern "MM/dd/yyyy", "01/11/12" parses to

 *         Jan 11, 12 A.D.

 *     <li>For parsing with the abbreviated year pattern ("y" or "yy"),

 *         <code>SimpleDateFormat</code> must interpret the abbreviated year

 *         relative to some century.  It does this by adjusting dates to be

 *         within 80 years before and 20 years after the time the <code>SimpleDateFormat</code>

 *         instance is created. For example, using a pattern of "MM/dd/yy" and a

 *         <code>SimpleDateFormat</code> instance created on Jan 1, 1997,  the string

 *         "01/11/12" would be interpreted as Jan 11, 2012 while the string "05/04/64"

 *         would be interpreted as May 4, 1964.

 *         During parsing, only strings consisting of exactly two digits, as defined by

 *         {@link Character#isDigit(char)}, will be parsed into the default century.

 *         Any other numeric string, such as a one digit string, a three or more digit

 *         string, or a two digit string that isn't all digits (for example, "-1"), is

 *         interpreted literally.  So "01/02/3" or "01/02/003" are parsed, using the

 *         same pattern, as Jan 2, 3 AD.  Likewise, "01/02/-3" is parsed as Jan 2, 4 BC.

 *     </ul>

 *     Otherwise, calendar system specific forms are applied.

 *     For both formatting and parsing, if the number of pattern

 *     letters is 4 or more, a calendar specific {@linkplain

 *     Calendar#LONG long form} is used. Otherwise, a calendar

 *     specific {@linkplain Calendar#SHORT short or abbreviated form}

 *     is used.<br>

 *     <br>

 *     If week year {@code 'Y'} is specified and the {@linkplain

 *     #getCalendar() calendar} doesn't support any <a

 *     href="../util/GregorianCalendar.html#week_year"> week

 *     years</a>, the calendar year ({@code 'y'}) is used instead. The

 *     support of week years can be tested with a call to {@link

 *     DateFormat#getCalendar() getCalendar()}.{@link

 *     java.util.Calendar#isWeekDateSupported()

 *     isWeekDateSupported()}.<br><br></li>

 * <li><strong><a id="month">Month:</a></strong>

 *     If the number of pattern letters is 3 or more, the month is

 *     interpreted as <a href="#text">text</a>; otherwise,

 *     it is interpreted as a <a href="#number">number</a>.<br>

 *     <ul>

 *     <li>Letter <em>M</em> produces context-sensitive month names, such as the

 *         embedded form of names. Letter <em>M</em> is context-sensitive in the

 *         sense that when it is used in the standalone pattern, for example,

 *         "MMMM", it gives the standalone form of a month name and when it is

 *         used in the pattern containing other field(s), for example, "d MMMM",

 *         it gives the format form of a month name. For example, January in the

 *         Catalan language is "de gener" in the format form while it is "gener"

 *         in the standalone form. In this case, "MMMM" will produce "gener" and

 *         the month part of the "d MMMM" will produce "de gener". If a

 *         {@code DateFormatSymbols} has been set explicitly with constructor

 *         {@link #SimpleDateFormat(String,DateFormatSymbols)} or method {@link

 *         #setDateFormatSymbols(DateFormatSymbols)}, the month names given by

 *         the {@code DateFormatSymbols} are used.</li>

 *     <li>Letter <em>L</em> produces the standalone form of month names.</li>

 *     </ul>

 *     <br></li>

 * <li><strong><a id="timezone">General time zone:</a></strong>

 *     Time zones are interpreted as <a href="#text">text</a> if they have

 *     names. For time zones representing a GMT offset value, the

 *     following syntax is used:

 *     <pre>

 *     <a id="GMTOffsetTimeZone"><i>GMTOffsetTimeZone:</i></a>

 *             <code>GMT</code> <i>Sign</i> <i>Hours</i> <code>:</code> <i>Minutes</i>

 *     <i>Sign:</i> one of

 *             <code>+ -</code>

 *     <i>Hours:</i>

 *             <i>Digit</i>

 *             <i>Digit</i> <i>Digit</i>

 *     <i>Minutes:</i>

 *             <i>Digit</i> <i>Digit</i>

 *     <i>Digit:</i> one of

 *             <code>0 1 2 3 4 5 6 7 8 9</code></pre>

 *     <i>Hours</i> must be between 0 and 23, and <i>Minutes</i> must be between

 *     00 and 59. The format is locale independent and digits must be taken

 *     from the Basic Latin block of the Unicode standard.

 *     <p>For parsing, <a href="#rfc822timezone">RFC 822 time zones</a> are also

 *     accepted.<br><br></li>

 * <li><strong><a id="rfc822timezone">RFC 822 time zone:</a></strong>

 *     For formatting, the RFC 822 4-digit time zone format is used:

 *

 *     <pre>

 *     <i>RFC822TimeZone:</i>

 *             <i>Sign</i> <i>TwoDigitHours</i> <i>Minutes</i>

 *     <i>TwoDigitHours:</i>

 *             <i>Digit Digit</i></pre>

 *     <i>TwoDigitHours</i> must be between 00 and 23. Other definitions

 *     are as for <a href="#timezone">general time zones</a>.

 *

 *     <p>For parsing, <a href="#timezone">general time zones</a> are also

 *     accepted.

 * <li><strong><a id="iso8601timezone">ISO 8601 Time zone:</a></strong>

 *     The number of pattern letters designates the format for both formatting

 *     and parsing as follows:

 *     <pre>

 *     <i>ISO8601TimeZone:</i>

 *             <i>OneLetterISO8601TimeZone</i>

 *             <i>TwoLetterISO8601TimeZone</i>

 *             <i>ThreeLetterISO8601TimeZone</i>

 *     <i>OneLetterISO8601TimeZone:</i>

 *             <i>Sign</i> <i>TwoDigitHours</i>

 *             {@code Z}

 *     <i>TwoLetterISO8601TimeZone:</i>

 *             <i>Sign</i> <i>TwoDigitHours</i> <i>Minutes</i>

 *             {@code Z}

 *     <i>ThreeLetterISO8601TimeZone:</i>

 *             <i>Sign</i> <i>TwoDigitHours</i> {@code :} <i>Minutes</i>

 *             {@code Z}</pre>

 *     Other definitions are as for <a href="#timezone">general time zones</a> or

 *     <a href="#rfc822timezone">RFC 822 time zones</a>.

 *

 *     <p>For formatting, if the offset value from GMT is 0, {@code "Z"} is

 *     produced. If the number of pattern letters is 1, any fraction of an hour

 *     is ignored. For example, if the pattern is {@code "X"} and the time zone is

 *     {@code "GMT+05:30"}, {@code "+05"} is produced.

 *

 *     <p>For parsing, {@code "Z"} is parsed as the UTC time zone designator.

 *     <a href="#timezone">General time zones</a> are <em>not</em> accepted.

 *

 *     <p>If the number of pattern letters is 4 or more, {@link

 *     IllegalArgumentException} is thrown when constructing a {@code

 *     SimpleDateFormat} or {@linkplain #applyPattern(String) applying a

 *     pattern}.

 * </ul>

 * <code>SimpleDateFormat</code> also supports <em>localized date and time

 * pattern</em> strings. In these strings, the pattern letters described above

 * may be replaced with other, locale dependent, pattern letters.

 * <code>SimpleDateFormat</code> does not deal with the localization of text

 * other than the pattern letters; that's up to the client of the class.

 *

 * <h4>Examples</h4>

 *

 * The following examples show how date and time patterns are interpreted in

 * the U.S. locale. The given date and time are 2001-07-04 12:08:56 local time

 * in the U.S. Pacific Time time zone.

 * <blockquote>

 * <table class="striped">

 * <caption style="display:none">Examples of date and time patterns interpreted in the U.S. locale</caption>

 * <thead>

 *     <tr>

 *         <th scope="col" style="text-align:left">Date and Time Pattern

 *         <th scope="col" style="text-align:left">Result

 * </thead>

 * <tbody>

 *     <tr>

 *         <th scope="row"><code>"yyyy.MM.dd G 'at' HH:mm:ss z"</code>

 *         <td><code>2001.07.04 AD at 12:08:56 PDT</code>

 *     <tr>

 *         <th scope="row"><code>"EEE, MMM d, ''yy"</code>

 *         <td><code>Wed, Jul 4, '01</code>

 *     <tr>

 *         <th scope="row"><code>"h:mm a"</code>

 *         <td><code>12:08 PM</code>

 *     <tr>

 *         <th scope="row"><code>"hh 'o''clock' a, zzzz"</code>

 *         <td><code>12 o'clock PM, Pacific Daylight Time</code>

 *     <tr>

 *         <th scope="row"><code>"K:mm a, z"</code>

 *         <td><code>0:08 PM, PDT</code>

 *     <tr>

 *         <th scope="row"><code>"yyyyy.MMMMM.dd GGG hh:mm aaa"</code>

 *         <td><code>02001.July.04 AD 12:08 PM</code>

 *     <tr>

 *         <th scope="row"><code>"EEE, d MMM yyyy HH:mm:ss Z"</code>

 *         <td><code>Wed, 4 Jul 2001 12:08:56 -0700</code>

 *     <tr>

 *         <th scope="row"><code>"yyMMddHHmmssZ"</code>

 *         <td><code>010704120856-0700</code>

 *     <tr>

 *         <th scope="row"><code>"yyyy-MM-dd'T'HH:mm:ss.SSSZ"</code>

 *         <td><code>2001-07-04T12:08:56.235-0700</code>

 *     <tr>

 *         <th scope="row"><code>"yyyy-MM-dd'T'HH:mm:ss.SSSXXX"</code>

 *         <td><code>2001-07-04T12:08:56.235-07:00</code>

 *     <tr>

 *         <th scope="row"><code>"YYYY-'W'ww-u"</code>

 *         <td><code>2001-W27-3</code>

 * </tbody>

 * </table>

 * </blockquote>

 *

 * <h4><a id="synchronization">Synchronization</a></h4>

 *

 * <p>

 * Date formats are not synchronized.

 * It is recommended to create separate format instances for each thread.

 * If multiple threads access a format concurrently, it must be synchronized

 * externally.

 *

 * @see          <a href="http://docs.oracle.com/javase/tutorial/i18n/format/simpleDateFormat.html">Java Tutorial</a>

 * @see          java.util.Calendar

 * @see          java.util.TimeZone

 * @see          DateFormat

 * @see          DateFormatSymbols

 * @author       Mark Davis, Chen-Lieh Huang, Alan Liu

 * @since 1.1

 */

public class SimpleDateFormat extends DateFormat {

    // the official serial version ID which says cryptically

    // which version we're compatible with

    static final long serialVersionUID = 4774881970558875024L;

    // the internal serial version which says which version was written

    // - 0 (default) for version up to JDK 1.1.3

    // - 1 for version from JDK 1.1.4, which includes a new field

    static final int currentSerialVersion = 1;

    /**

     * The version of the serialized data on the stream.  Possible values:

     * <ul>

     * <li><b>0</b> or not present on stream: JDK 1.1.3.  This version

     * has no <code>defaultCenturyStart</code> on stream.

     * <li><b>1</b> JDK 1.1.4 or later.  This version adds

     * <code>defaultCenturyStart</code>.

     * </ul>

     * When streaming out this class, the most recent format

     * and the highest allowable <code>serialVersionOnStream</code>

     * is written.

     * @serial

     * @since 1.1.4

     */

    private int serialVersionOnStream = currentSerialVersion;

    /**

     * The pattern string of this formatter.  This is always a non-localized

     * pattern.  May not be null.  See class documentation for details.

     * @serial

     */

    private String pattern;

    /**

     * Saved numberFormat and pattern.

     * @see SimpleDateFormat#checkNegativeNumberExpression

     */

    private transient NumberFormat originalNumberFormat;

    private transient String originalNumberPattern;

    /**

     * The minus sign to be used with format and parse.

     */

    private transient char minusSign = '-';

    /**

     * True when a negative sign follows a number.

     * (True as default in Arabic.)

     */

    private transient boolean hasFollowingMinusSign = false;

    /**

     * True if standalone form needs to be used.

     */

    private transient boolean forceStandaloneForm = false;

    /**

     * The compiled pattern.

     */

    private transient char[] compiledPattern;

    /**

     * Tags for the compiled pattern.

     */