/*
    * 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.commons.lang3.time;
  
  import java.io.IOException;
  import java.io.ObjectInputStream;
  import java.io.Serializable;
  import java.text.DateFormatSymbols;
  import java.text.ParseException;
  import java.text.ParsePosition;
  import java.util.ArrayList;
  import java.util.Calendar;
  import java.util.Date;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  import java.util.SortedMap;
  import java.util.TimeZone;
  import java.util.TreeMap;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  /**
   * <p>FastDateParser is a fast and thread-safe version of
   * {@link java.text.SimpleDateFormat}.</p>
   *
   * <p>To obtain a proxy to a FastDateParser, use {@link FastDateFormat#getInstance(String, TimeZone, Locale)} 
   * or another variation of the factory methods of {@link FastDateFormat}.</p>
   * 
   * <p>Since FastDateParser is thread safe, you can use a static member instance:</p>
   * <code>
   *     private static final DateParser DATE_PARSER = FastDateFormat.getInstance("yyyy-MM-dd");
   * </code>
   * 
   * <p>This class can be used as a direct replacement for
   * <code>SimpleDateFormat</code> in most parsing situations.
   * This class is especially useful in multi-threaded server environments.
   * <code>SimpleDateFormat</code> is not thread-safe in any JDK version,
   * nor will it be as Sun has closed the
   * <a href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4228335">bug</a>/RFE.
   * </p>
   *
   * <p>Only parsing is supported by this class, but all patterns are compatible with
   * SimpleDateFormat.</p>
   *
   * <p>The class operates in lenient mode, so for example a time of 90 minutes is treated as 1 hour 30 minutes.</p>
   *
   * <p>Timing tests indicate this class is as about as fast as SimpleDateFormat
   * in single thread applications and about 25% faster in multi-thread applications.</p>
   *
   * @version $Id$
   * @since 3.2
   * @see FastDatePrinter
   */
  public class FastDateParser implements DateParser, Serializable {
      /**
       * Required for serialization support.
       *
       * @see java.io.Serializable
       */
      private static final long serialVersionUID = 2L;
  
      static final Locale JAPANESE_IMPERIAL = new Locale("ja","JP","JP");
  
      // defining fields
      private final String pattern;
      private final TimeZone timeZone;
      private final Locale locale;
      private final int century;
      private final int startYear;
  
      // derived fields
      private transient Pattern parsePattern;
      private transient Strategy[] strategies;
  
      // dynamic fields to communicate with Strategy
      private transient String currentFormatField;
      private transient Strategy nextStrategy;
  
      /**
       * <p>Constructs a new FastDateParser.</p>
       * 
      * Use {@link FastDateFormat#getInstance(String, TimeZone, Locale)} or another variation of the 
      * factory methods of {@link FastDateFormat} to get a cached FastDateParser instance.
      *
      * @param pattern non-null {@link java.text.SimpleDateFormat} compatible
      *  pattern
      * @param timeZone non-null time zone to use
      * @param locale non-null locale
      */
     protected FastDateParser(final String pattern, final TimeZone timeZone, final Locale locale) {
         this(pattern, timeZone, locale, null);
     }
 
     /**
      * <p>Constructs a new FastDateParser.</p>
      *
      * @param pattern non-null {@link java.text.SimpleDateFormat} compatible
      *  pattern
      * @param timeZone non-null time zone to use
      * @param locale non-null locale
      * @param centuryStart The start of the century for 2 digit year parsing
      *
      * @since 3.3
      */
     protected FastDateParser(final String pattern, final TimeZone timeZone, final Locale locale, final Date centuryStart) {
         this.pattern = pattern;
         this.timeZone = timeZone;
         this.locale = locale;
 
         final Calendar definingCalendar = Calendar.getInstance(timeZone, locale);
         int centuryStartYear;
         if(centuryStart!=null) {
             definingCalendar.setTime(centuryStart);
             centuryStartYear= definingCalendar.get(Calendar.YEAR);
         }
         else if(locale.equals(JAPANESE_IMPERIAL)) {
             centuryStartYear= 0;
         }
         else {
             // from 80 years ago to 20 years from now
             definingCalendar.setTime(new Date());
             centuryStartYear= definingCalendar.get(Calendar.YEAR)-80;
         }
         century= centuryStartYear / 100 * 100;
         startYear= centuryStartYear - century;
 
         init(definingCalendar);
     }
 
     /**
      * Initialize derived fields from defining fields.
      * This is called from constructor and from readObject (de-serialization)
      *
      * @param definingCalendar the {@link java.util.Calendar} instance used to initialize this FastDateParser
      */
     private void init(final Calendar definingCalendar) {
 
         final StringBuilder regex= new StringBuilder();
         final List<Strategy> collector = new ArrayList<Strategy>();
 
         final Matcher patternMatcher= formatPattern.matcher(pattern);
         if(!patternMatcher.lookingAt()) {
             throw new IllegalArgumentException(
                     "Illegal pattern character '" + pattern.charAt(patternMatcher.regionStart()) + "'");
         }
 
         currentFormatField= patternMatcher.group();
         Strategy currentStrategy= getStrategy(currentFormatField, definingCalendar);
         for(;;) {
             patternMatcher.region(patternMatcher.end(), patternMatcher.regionEnd());
             if(!patternMatcher.lookingAt()) {
                 nextStrategy = null;
                 break;
             }
             final String nextFormatField= patternMatcher.group();
             nextStrategy = getStrategy(nextFormatField, definingCalendar);
             if(currentStrategy.addRegex(this, regex)) {
                 collector.add(currentStrategy);
             }
             currentFormatField= nextFormatField;
             currentStrategy= nextStrategy;
         }
         if (patternMatcher.regionStart() != patternMatcher.regionEnd()) {
             throw new IllegalArgumentException("Failed to parse \""+pattern+"\" ; gave up at index "+patternMatcher.regionStart());
         }
         if(currentStrategy.addRegex(this, regex)) {
             collector.add(currentStrategy);
         }
         currentFormatField= null;
         strategies= collector.toArray(new Strategy[collector.size()]);
         parsePattern= Pattern.compile(regex.toString());
     }
 
     // Accessors
     //-----------------------------------------------------------------------
     /* (non-Javadoc)
      * @see org.apache.commons.lang3.time.DateParser#getPattern()
      */
     @Override
     public String getPattern() {
         return pattern;
     }
 
     /* (non-Javadoc)
      * @see org.apache.commons.lang3.time.DateParser#getTimeZone()
      */
     @Override
     public TimeZone getTimeZone() {
         return timeZone;
     }
 
     /* (non-Javadoc)
      * @see org.apache.commons.lang3.time.DateParser#getLocale()
      */
     @Override
     public Locale getLocale() {
         return locale;
     }
 
     /**
      * Returns the generated pattern (for testing purposes).
      *
      * @return the generated pattern
      */
     Pattern getParsePattern() {
         return parsePattern;
     }
 
     // Basics
     //-----------------------------------------------------------------------
     /**
      * <p>Compare another object for equality with this object.</p>
      *
      * @param obj  the object to compare to
      * @return <code>true</code>if equal to this instance
      */
     @Override
     public boolean equals(final Object obj) {
         if (! (obj instanceof FastDateParser) ) {
             return false;
         }
         final FastDateParser other = (FastDateParser) obj;
         return pattern.equals(other.pattern)
             && timeZone.equals(other.timeZone)
             && locale.equals(other.locale);
     }
 
     /**
      * <p>Return a hashcode compatible with equals.</p>
      *
      * @return a hashcode compatible with equals
      */
     @Override
     public int hashCode() {
         return pattern.hashCode() + 13 * (timeZone.hashCode() + 13 * locale.hashCode());
     }
 
     /**
      * <p>Get a string version of this formatter.</p>
      *
      * @return a debugging string
      */
     @Override
     public String toString() {
         return "FastDateParser[" + pattern + "," + locale + "," + timeZone.getID() + "]";
     }
 
     // Serializing
     //-----------------------------------------------------------------------
     /**
      * Create the object after serialization. This implementation reinitializes the
      * transient properties.
      *
      * @param in ObjectInputStream from which the object is being deserialized.
      * @throws IOException if there is an IO issue.
      * @throws ClassNotFoundException if a class cannot be found.
      */
     private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
         in.defaultReadObject();
 
         final Calendar definingCalendar = Calendar.getInstance(timeZone, locale);
         init(definingCalendar);
     }
 
     /* (non-Javadoc)
      * @see org.apache.commons.lang3.time.DateParser#parseObject(java.lang.String)
      */
     @Override
     public Object parseObject(final String source) throws ParseException {
         return parse(source);
     }
 
     /* (non-Javadoc)
      * @see org.apache.commons.lang3.time.DateParser#parse(java.lang.String)
      */
     @Override
     public Date parse(final String source) throws ParseException {
         final Date date= parse(source, new ParsePosition(0));
         if(date==null) {
             // Add a note re supported date range
             if (locale.equals(JAPANESE_IMPERIAL)) {
                 throw new ParseException(
                         "(The " +locale + " locale does not support dates before 1868 AD)\n" +
                                 "Unparseable date: \""+source+"\" does not match "+parsePattern.pattern(), 0);
             }
             throw new ParseException("Unparseable date: \""+source+"\" does not match "+parsePattern.pattern(), 0);
         }
         return date;
     }
 
     /* (non-Javadoc)
      * @see org.apache.commons.lang3.time.DateParser#parseObject(java.lang.String, java.text.ParsePosition)
      */
     @Override
     public Object parseObject(final String source, final ParsePosition pos) {
         return parse(source, pos);
     }
 
     /**
      * This implementation updates the ParsePosition if the parse succeeeds.
      * However, unlike the method {@link java.text.SimpleDateFormat#parse(String, ParsePosition)}
      * it is not able to set the error Index - i.e. {@link ParsePosition#getErrorIndex()} -  if the parse fails.
      * <p>
      * To determine if the parse has succeeded, the caller must check if the current parse position
      * given by {@link ParsePosition#getIndex()} has been updated. If the input buffer has been fully
      * parsed, then the index will point to just after the end of the input buffer.
      *
      * @see org.apache.commons.lang3.time.DateParser#parse(java.lang.String, java.text.ParsePosition)
      * {@inheritDoc}
      */
     @Override
     public Date parse(final String source, final ParsePosition pos) {
         final int offset= pos.getIndex();
         final Matcher matcher= parsePattern.matcher(source.substring(offset));
         if(!matcher.lookingAt()) {
             return null;
         }
         // timing tests indicate getting new instance is 19% faster than cloning
         final Calendar cal= Calendar.getInstance(timeZone, locale);
         cal.clear();
 
         for(int i=0; i<strategies.length;) {
             final Strategy strategy= strategies[i++];
             strategy.setCalendar(this, cal, matcher.group(i));
         }
         pos.setIndex(offset+matcher.end());
         return cal.getTime();
     }
 
     // Support for strategies
     //-----------------------------------------------------------------------
 
     /**
      * Escape constant fields into regular expression
      * @param regex The destination regex
      * @param value The source field
      * @param unquote If true, replace two success quotes ('') with single quote (')
      * @return The <code>StringBuilder</code>
      */
     private static StringBuilder escapeRegex(final StringBuilder regex, final String value, final boolean unquote) {
         regex.append("\\Q");
         for(int i= 0; i<value.length(); ++i) {
             char c= value.charAt(i);
             switch(c) {
             case '\'':
                 if(unquote) {
                     if(++i==value.length()) {
                         return regex;
                     }
                     c= value.charAt(i);
                 }
                 break;
             case '\\':
                 if(++i==value.length()) {
                     break;
                 }
                 /*
                  * If we have found \E, we replace it with \E\\E\Q, i.e. we stop the quoting,
                  * quote the \ in \E, then restart the quoting.
                  *
                  * Otherwise we just output the two characters.
                  * In each case the initial \ needs to be output and the final char is done at the end
                  */
                 regex.append(c); // we always want the original \
                 c = value.charAt(i); // Is it followed by E ?
                 if (c == 'E') { // \E detected
                   regex.append("E\\\\E\\"); // see comment above
                   c = 'Q'; // appended below
                 }
                 break;
             default:
                 break;
             }
             regex.append(c);
         }
         regex.append("\\E");
         return regex;
     }
 
 
     /**
      * Get the short and long values displayed for a field
      * @param field The field of interest
      * @param definingCalendar The calendar to obtain the short and long values
      * @param locale The locale of display names
      * @return A Map of the field key / value pairs
      */
     private static Map<String, Integer> getDisplayNames(final int field, final Calendar definingCalendar, final Locale locale) {
         return definingCalendar.getDisplayNames(field, Calendar.ALL_STYLES, locale);
     }
 
     /**
      * Adjust dates to be within appropriate century
      * @param twoDigitYear The year to adjust
      * @return A value between centuryStart(inclusive) to centuryStart+100(exclusive)
      */
     private int adjustYear(final int twoDigitYear) {
         final int trial= century + twoDigitYear;
         return twoDigitYear>=startYear ?trial :trial+100;
     }
 
     /**
      * Is the next field a number?
      * @return true, if next field will be a number
      */
     boolean isNextNumber() {
         return nextStrategy!=null && nextStrategy.isNumber();
     }
 
     /**
      * What is the width of the current field?
      * @return The number of characters in the current format field
      */
     int getFieldWidth() {
         return currentFormatField.length();
     }
 
     /**
      * A strategy to parse a single field from the parsing pattern
      */
     private static abstract class Strategy {
         
         /**
          * Is this field a number?
          * The default implementation returns false.
          *
          * @return true, if field is a number
          */
         boolean isNumber() {
             return false;
         }
         
         /**
          * Set the Calendar with the parsed field.
          *
          * The default implementation does nothing.
          *
          * @param parser The parser calling this strategy
          * @param cal The <code>Calendar</code> to set
          * @param value The parsed field to translate and set in cal
          */
         void setCalendar(final FastDateParser parser, final Calendar cal, final String value) {
 
         }
         
         /**
          * Generate a <code>Pattern</code> regular expression to the <code>StringBuilder</code>
          * which will accept this field
          * @param parser The parser calling this strategy
          * @param regex The <code>StringBuilder</code> to append to
          * @return true, if this field will set the calendar;
          * false, if this field is a constant value
          */
         abstract boolean addRegex(FastDateParser parser, StringBuilder regex);
 
     }
 
     /**
      * A <code>Pattern</code> to parse the user supplied SimpleDateFormat pattern
      */
     private static final Pattern formatPattern= Pattern.compile(
             "D+|E+|F+|G+|H+|K+|M+|S+|W+|X+|Z+|a+|d+|h+|k+|m+|s+|w+|y+|z+|''|'[^']++(''[^']*+)*+'|[^'A-Za-z]++");
 
     /**
      * Obtain a Strategy given a field from a SimpleDateFormat pattern
      * @param formatField A sub-sequence of the SimpleDateFormat pattern
      * @param definingCalendar The calendar to obtain the short and long values
      * @return The Strategy that will handle parsing for the field
      */
     private Strategy getStrategy(final String formatField, final Calendar definingCalendar) {
         switch(formatField.charAt(0)) {
         case '\'':
             if(formatField.length()>2) {
                 return new CopyQuotedStrategy(formatField.substring(1, formatField.length()-1));
             }
             //$FALL-THROUGH$
         default:
             return new CopyQuotedStrategy(formatField);
         case 'D':
             return DAY_OF_YEAR_STRATEGY;
         case 'E':
             return getLocaleSpecificStrategy(Calendar.DAY_OF_WEEK, definingCalendar);
         case 'F':
             return DAY_OF_WEEK_IN_MONTH_STRATEGY;
         case 'G':
             return getLocaleSpecificStrategy(Calendar.ERA, definingCalendar);
         case 'H':  // Hour in day (0-23)
             return HOUR_OF_DAY_STRATEGY;
         case 'K':  // Hour in am/pm (0-11) 
             return HOUR_STRATEGY;
         case 'M':
             return formatField.length()>=3 ?getLocaleSpecificStrategy(Calendar.MONTH, definingCalendar) :NUMBER_MONTH_STRATEGY;
         case 'S':
             return MILLISECOND_STRATEGY;
         case 'W':
             return WEEK_OF_MONTH_STRATEGY;
         case 'a':
             return getLocaleSpecificStrategy(Calendar.AM_PM, definingCalendar);
         case 'd':
             return DAY_OF_MONTH_STRATEGY;
         case 'h':  // Hour in am/pm (1-12), i.e. midday/midnight is 12, not 0
             return HOUR12_STRATEGY;
         case 'k':  // Hour in day (1-24), i.e. midnight is 24, not 0
             return HOUR24_OF_DAY_STRATEGY;
         case 'm':
             return MINUTE_STRATEGY;
         case 's':
             return SECOND_STRATEGY;
         case 'w':
             return WEEK_OF_YEAR_STRATEGY;
         case 'y':
             return formatField.length()>2 ?LITERAL_YEAR_STRATEGY :ABBREVIATED_YEAR_STRATEGY;
         case 'X':
             return ISO8601TimeZoneStrategy.getStrategy(formatField.length());
         case 'Z':
             if (formatField.equals("ZZ")) {
                 return ISO_8601_STRATEGY;
             }
             //$FALL-THROUGH$
         case 'z':
             return getLocaleSpecificStrategy(Calendar.ZONE_OFFSET, definingCalendar);
         }
     }
 
     @SuppressWarnings("unchecked") // OK because we are creating an array with no entries
     private static final ConcurrentMap<Locale, Strategy>[] caches = new ConcurrentMap[Calendar.FIELD_COUNT];
 
     /**
      * Get a cache of Strategies for a particular field
      * @param field The Calendar field
      * @return a cache of Locale to Strategy
      */
     private static ConcurrentMap<Locale, Strategy> getCache(final int field) {
         synchronized(caches) {
             if(caches[field]==null) {
                 caches[field]= new ConcurrentHashMap<Locale,Strategy>(3);
             }
             return caches[field];
         }
     }
 
     /**
      * Construct a Strategy that parses a Text field
      * @param field The Calendar field
      * @param definingCalendar The calendar to obtain the short and long values
      * @return a TextStrategy for the field and Locale
      */
     private Strategy getLocaleSpecificStrategy(final int field, final Calendar definingCalendar) {
         final ConcurrentMap<Locale,Strategy> cache = getCache(field);
         Strategy strategy= cache.get(locale);
         if(strategy==null) {
             strategy= field==Calendar.ZONE_OFFSET
                     ? new TimeZoneStrategy(locale)
                     : new CaseInsensitiveTextStrategy(field, definingCalendar, locale);
             final Strategy inCache= cache.putIfAbsent(locale, strategy);
             if(inCache!=null) {
                 return inCache;
             }
         }
         return strategy;
     }
 
     /**
      * A strategy that copies the static or quoted field in the parsing pattern
      */
     private static class CopyQuotedStrategy extends Strategy {
         private final String formatField;
 
         /**
          * Construct a Strategy that ensures the formatField has literal text
          * @param formatField The literal text to match
          */
         CopyQuotedStrategy(final String formatField) {
             this.formatField= formatField;
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         boolean isNumber() {
             char c= formatField.charAt(0);
             if(c=='\'') {
                 c= formatField.charAt(1);
             }
             return Character.isDigit(c);
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         boolean addRegex(final FastDateParser parser, final StringBuilder regex) {
             escapeRegex(regex, formatField, true);
             return false;
         }
     }
 
     /**
      * A strategy that handles a text field in the parsing pattern
      */
      private static class CaseInsensitiveTextStrategy extends Strategy {
         private final int field;
         private final Locale locale;
         private final Map<String, Integer> lKeyValues;
 
         /**
          * Construct a Strategy that parses a Text field
          * @param field  The Calendar field
          * @param definingCalendar  The Calendar to use
          * @param locale  The Locale to use
          */
         CaseInsensitiveTextStrategy(final int field, final Calendar definingCalendar, final Locale locale) {
             this.field= field;
             this.locale= locale;
             final Map<String, Integer> keyValues = getDisplayNames(field, definingCalendar, locale);
             this.lKeyValues= new HashMap<String,Integer>();
 
             for(final Map.Entry<String, Integer> entry : keyValues.entrySet()) {
                 lKeyValues.put(entry.getKey().toLowerCase(locale), entry.getValue());
             }
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         boolean addRegex(final FastDateParser parser, final StringBuilder regex) {
             regex.append("((?iu)");
             for(final String textKeyValue : lKeyValues.keySet()) {
                 escapeRegex(regex, textKeyValue, false).append('|');
             }
             regex.setCharAt(regex.length()-1, ')');
             return true;
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         void setCalendar(final FastDateParser parser, final Calendar cal, final String value) {
             final Integer iVal = lKeyValues.get(value.toLowerCase(locale));
             if(iVal == null) {
                 final StringBuilder sb= new StringBuilder(value);
                 sb.append(" not in (");
                 for(final String textKeyValue : lKeyValues.keySet()) {
                     sb.append(textKeyValue).append(' ');
                 }
                 sb.setCharAt(sb.length()-1, ')');
                 throw new IllegalArgumentException(sb.toString());
             }
             cal.set(field, iVal.intValue());
         }
     }
 
 
     /**
      * A strategy that handles a number field in the parsing pattern
      */
     private static class NumberStrategy extends Strategy {
         private final int field;
 
         /**
          * Construct a Strategy that parses a Number field
          * @param field The Calendar field
          */
         NumberStrategy(final int field) {
              this.field= field;
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         boolean isNumber() {
             return true;
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         boolean addRegex(final FastDateParser parser, final StringBuilder regex) {
             // See LANG-954: We use {Nd} rather than {IsNd} because Android does not support the Is prefix
             if(parser.isNextNumber()) {
                 regex.append("(\\p{Nd}{").append(parser.getFieldWidth()).append("}+)");
             }
             else {
                 regex.append("(\\p{Nd}++)");
             }
             return true;
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         void setCalendar(final FastDateParser parser, final Calendar cal, final String value) {
             cal.set(field, modify(Integer.parseInt(value)));
         }
 
         /**
          * Make any modifications to parsed integer
          * @param iValue The parsed integer
          * @return The modified value
          */
         int modify(final int iValue) {
             return iValue;
         }
     }
 
     private static final Strategy ABBREVIATED_YEAR_STRATEGY = new NumberStrategy(Calendar.YEAR) {
         /**
          * {@inheritDoc}
          */
         @Override
         void setCalendar(final FastDateParser parser, final Calendar cal, final String value) {
             int iValue= Integer.parseInt(value);
             if(iValue<100) {
                 iValue= parser.adjustYear(iValue);
             }
             cal.set(Calendar.YEAR, iValue);
         }
     };
 
     /**
      * A strategy that handles a timezone field in the parsing pattern
      */
     private static class TimeZoneStrategy extends Strategy {
 
         private final String validTimeZoneChars;
         private final SortedMap<String, TimeZone> tzNames= new TreeMap<String, TimeZone>(String.CASE_INSENSITIVE_ORDER);
 
         /**
          * Index of zone id
          */
         private static final int ID = 0;
         /**
          * Index of the long name of zone in standard time
          */
         private static final int LONG_STD = 1;
         /**
          * Index of the short name of zone in standard time
          */
         private static final int SHORT_STD = 2;
         /**
          * Index of the long name of zone in daylight saving time
          */
         private static final int LONG_DST = 3;
         /**
          * Index of the short name of zone in daylight saving time
          */
         private static final int SHORT_DST = 4;
 
         /**
          * Construct a Strategy that parses a TimeZone
          * @param locale The Locale
          */
         TimeZoneStrategy(final Locale locale) {
             final String[][] zones = DateFormatSymbols.getInstance(locale).getZoneStrings();
             for (final String[] zone : zones) {
                 if (zone[ID].startsWith("GMT")) {
                     continue;
                 }
                 final TimeZone tz = TimeZone.getTimeZone(zone[ID]);
                 if (!tzNames.containsKey(zone[LONG_STD])){
                     tzNames.put(zone[LONG_STD], tz);
                 }
                 if (!tzNames.containsKey(zone[SHORT_STD])){
                     tzNames.put(zone[SHORT_STD], tz);
                 }
                 if (tz.useDaylightTime()) {
                     if (!tzNames.containsKey(zone[LONG_DST])){
                         tzNames.put(zone[LONG_DST], tz);
                     }
                     if (!tzNames.containsKey(zone[SHORT_DST])){
                         tzNames.put(zone[SHORT_DST], tz);
                     }
                 }
             }
 
             final StringBuilder sb= new StringBuilder();
             sb.append("(GMT[+-]\\d{1,2}:\\d{2}").append('|');
             sb.append("[+-]\\d{4}").append('|');
             for(final String id : tzNames.keySet()) {
                 escapeRegex(sb, id, false).append('|');
             }
             sb.setCharAt(sb.length()-1, ')');
             validTimeZoneChars= sb.toString();
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         boolean addRegex(final FastDateParser parser, final StringBuilder regex) {
             regex.append(validTimeZoneChars);
             return true;
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         void setCalendar(final FastDateParser parser, final Calendar cal, final String value) {
             TimeZone tz;
             if(value.charAt(0)=='+' || value.charAt(0)=='-') {
                 tz= TimeZone.getTimeZone("GMT"+value);
             }
             else if(value.startsWith("GMT")) {
                 tz= TimeZone.getTimeZone(value);
             }
             else {
                 tz= tzNames.get(value);
                 if(tz==null) {
                     throw new IllegalArgumentException(value + " is not a supported timezone name");
                 }
             }
             cal.setTimeZone(tz);
         }
     }
     
     private static class ISO8601TimeZoneStrategy extends Strategy {
         // Z, +hh, -hh, +hhmm, -hhmm, +hh:mm or -hh:mm 
         private final String pattern;
 
         /**
          * Construct a Strategy that parses a TimeZone
          * @param pattern The Pattern
          */
         ISO8601TimeZoneStrategy(String pattern) {
             this.pattern = pattern;
         }
         
         /**
          * {@inheritDoc}
          */
         @Override
         boolean addRegex(FastDateParser parser, StringBuilder regex) {
             regex.append(pattern);
             return true;
         }
         
         /**
          * {@inheritDoc}
          */
         @Override
         void setCalendar(FastDateParser parser, Calendar cal, String value) {
             if (value.equals("Z")) {
                 cal.setTimeZone(TimeZone.getTimeZone("UTC"));
             } else {
                 cal.setTimeZone(TimeZone.getTimeZone("GMT" + value));
             }
         }
         
         private static final Strategy ISO_8601_1_STRATEGY = new ISO8601TimeZoneStrategy("(Z|(?:[+-]\\d{2}))");
         private static final Strategy ISO_8601_2_STRATEGY = new ISO8601TimeZoneStrategy("(Z|(?:[+-]\\d{2}\\d{2}))");
         private static final Strategy ISO_8601_3_STRATEGY = new ISO8601TimeZoneStrategy("(Z|(?:[+-]\\d{2}(?::)\\d{2}))");
 
         /**
          * Factory method for ISO8601TimeZoneStrategies.
          * 
          * @param tokenLen a token indicating the length of the TimeZone String to be formatted.
          * @return a ISO8601TimeZoneStrategy that can format TimeZone String of length {@code tokenLen}. If no such
          *          strategy exists, an IllegalArgumentException will be thrown.
          */
         static Strategy getStrategy(int tokenLen) {
             switch(tokenLen) {
             case 1:
                 return ISO_8601_1_STRATEGY;
             case 2:
                 return ISO_8601_2_STRATEGY;
             case 3:
                 return ISO_8601_3_STRATEGY;
             default:
                 throw new IllegalArgumentException("invalid number of X");
             }
         }
     }
 
     private static final Strategy NUMBER_MONTH_STRATEGY = new NumberStrategy(Calendar.MONTH) {
         @Override
         int modify(final int iValue) {
             return iValue-1;
         }
     };
     private static final Strategy LITERAL_YEAR_STRATEGY = new NumberStrategy(Calendar.YEAR);
     private static final Strategy WEEK_OF_YEAR_STRATEGY = new NumberStrategy(Calendar.WEEK_OF_YEAR);
     private static final Strategy WEEK_OF_MONTH_STRATEGY = new NumberStrategy(Calendar.WEEK_OF_MONTH);
     private static final Strategy DAY_OF_YEAR_STRATEGY = new NumberStrategy(Calendar.DAY_OF_YEAR);
     private static final Strategy DAY_OF_MONTH_STRATEGY = new NumberStrategy(Calendar.DAY_OF_MONTH);
     private static final Strategy DAY_OF_WEEK_IN_MONTH_STRATEGY = new NumberStrategy(Calendar.DAY_OF_WEEK_IN_MONTH);
     private static final Strategy HOUR_OF_DAY_STRATEGY = new NumberStrategy(Calendar.HOUR_OF_DAY);
     private static final Strategy HOUR24_OF_DAY_STRATEGY = new NumberStrategy(Calendar.HOUR_OF_DAY) {
         @Override
         int modify(final int iValue) {
             return iValue == 24 ? 0 : iValue;
         }
     };
     private static final Strategy HOUR12_STRATEGY = new NumberStrategy(Calendar.HOUR) {
         @Override
         int modify(final int iValue) {
             return iValue == 12 ? 0 : iValue;
         }
     };
     private static final Strategy HOUR_STRATEGY = new NumberStrategy(Calendar.HOUR);
     private static final Strategy MINUTE_STRATEGY = new NumberStrategy(Calendar.MINUTE);
     private static final Strategy SECOND_STRATEGY = new NumberStrategy(Calendar.SECOND);
     private static final Strategy MILLISECOND_STRATEGY = new NumberStrategy(Calendar.MILLISECOND);
     private static final Strategy ISO_8601_STRATEGY = new ISO8601TimeZoneStrategy("(Z|(?:[+-]\\d{2}(?::?\\d{2})?))");
 
 
 }