context: /*
   * System.DateTimeOffset.cs
   *
   * Author(s)
   * 	Stephane Delcroix <stephane@delcroix.org>
   *	Marek Safar (marek.safar@gmail.com)
   *
   *  Copyright (C) 2007 Novell, Inc (http://www.novell.com) 
   *  Copyright 2012 Xamarin, Inc (http://www.xamarin.com) 
   *
   * Permission is hereby granted, free of charge, to any person obtaining
   * a copy of this software and associated documentation files (the
   * "Software"), to deal in the Software without restriction, including
   * without limitation the rights to use, copy, modify, merge, publish,
   * distribute, sublicense, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   * 
   * The above copyright notice and this permission notice shall be
   * included in all copies or substantial portions of the Software.
   * 
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
   * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
   * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   */
  
  
  using System.Globalization;
  using System.Runtime.InteropServices;
  using System.Runtime.Serialization;
  using System.Text;
  
  namespace System
  {
  	[Serializable]
  	[StructLayout (LayoutKind.Auto)]
  	public struct DateTimeOffset : IComparable, IFormattable, ISerializable, IDeserializationCallback, IComparable<DateTimeOffset>, IEquatable<DateTimeOffset>
  	{
  #if MONOTOUCH
  		static DateTimeOffset () {
  			if (MonoTouchAOTHelper.FalseFlag) {
  				var comparer = new System.Collections.Generic.GenericComparer <DateTimeOffset> ();
  				var eqcomparer = new System.Collections.Generic.GenericEqualityComparer <DateTimeOffset> ();
  			}
  		}
  #endif
  		public static readonly DateTimeOffset MaxValue = new DateTimeOffset (DateTime.MaxValue, TimeSpan.Zero);
  		public static readonly DateTimeOffset MinValue = new DateTimeOffset (DateTime.MinValue, TimeSpan.Zero);
  		
  		DateTime dt;
  		TimeSpan utc_offset;
  	
  		public DateTimeOffset (DateTime dateTime)
  		{
  			dt = dateTime;
  
  			if (dateTime.Kind == DateTimeKind.Utc)
  				utc_offset = TimeSpan.Zero;
  			else 
  				utc_offset = TimeZone.CurrentTimeZone.GetUtcOffset (dateTime);
  				
  			if (UtcDateTime < DateTime.MinValue || UtcDateTime > DateTime.MaxValue)
  				throw new ArgumentOutOfRangeException ("The UTC date and time that results from applying the offset is earlier than MinValue or later than MaxValue.");
  
  		}
  		
  		public DateTimeOffset (DateTime dateTime, TimeSpan offset)
  		{
  			if (dateTime.Kind == DateTimeKind.Utc && offset != TimeSpan.Zero)
  				throw new ArgumentException ("dateTime.Kind equals Utc and offset does not equal zero.");
  
  			if (dateTime.Kind == DateTimeKind.Local && offset != TimeZone.CurrentTimeZone.GetUtcOffset (dateTime))
  				throw new ArgumentException ("dateTime.Kind equals Local and offset does not equal the offset of the system's local time zone.");
  
  			if (offset.Ticks % TimeSpan.TicksPerMinute != 0)
  				throw new ArgumentException ("offset is not specified in whole minutes.");
  
  			if (offset < new TimeSpan (-14, 0 ,0) || offset > new TimeSpan (14, 0, 0))
  				throw new ArgumentOutOfRangeException ("offset is less than -14 hours or greater than 14 hours.");
  
  			dt = dateTime;
  			utc_offset = offset;
  
  			if (UtcDateTime < DateTime.MinValue || UtcDateTime > DateTime.MaxValue)
  				throw new ArgumentOutOfRangeException ("The UtcDateTime property is earlier than MinValue or later than MaxValue.");
  		}
  
  		public DateTimeOffset (long ticks, TimeSpan offset) : this (new DateTime (ticks), offset)
  		{
  		}
  
  		public DateTimeOffset (int year, int month, int day, int hour, int minute, int second, TimeSpan offset) : 
  			this (new DateTime (year, month, day, hour, minute, second), offset)
  		{
  		}
  
  		public DateTimeOffset (int year, int month, int day, int hour, int minute, int second, int millisecond, TimeSpan offset) :
  			this (new DateTime (year, month, day, hour, minute, second, millisecond), offset)
  		{
  		}
  
  		public DateTimeOffset (int year, int month, int day, int hour, int minute, int second, int millisecond, Calendar calendar, TimeSpan offset) :
  			this (new DateTime (year, month, day, hour, minute, second, millisecond, calendar), offset)
  		{
  		}
  
  		public DateTimeOffset Add (TimeSpan timeSpan)
  		{
  			return new DateTimeOffset (dt.Add (timeSpan).Ticks, utc_offset);
  		}
  	
  		public DateTimeOffset AddDays (double days)
  		{
  			return new DateTimeOffset (dt.AddDays (days).Ticks, utc_offset);	
  		}
  		
  		public DateTimeOffset AddHours (double hours)
  		{
  			return new DateTimeOffset (dt.AddHours (hours).Ticks, utc_offset);
  		}
  
  		public static DateTimeOffset operator + (DateTimeOffset dateTimeOffset, TimeSpan timeSpan)
  		{
  			return dateTimeOffset.Add (timeSpan);
  		}
  
  		public DateTimeOffset AddMilliseconds (double milliseconds)
  		{
  			return new DateTimeOffset (dt.AddMilliseconds (milliseconds).Ticks, utc_offset);
  		}
  
  		public DateTimeOffset AddMinutes (double minutes)
  		{
  			return new DateTimeOffset (dt.AddMinutes (minutes).Ticks, utc_offset);	
  		}
  
  		public DateTimeOffset AddMonths (int months)
  		{
  			return new DateTimeOffset (dt.AddMonths (months).Ticks, utc_offset);
  		}
  
  		public DateTimeOffset AddSeconds (double seconds)
  		{
  			return new DateTimeOffset (dt.AddSeconds (seconds).Ticks, utc_offset);
  		}
  
  		public DateTimeOffset AddTicks (long ticks)
  		{
  			return new DateTimeOffset (dt.AddTicks (ticks).Ticks, utc_offset);	
  		}
  
  		public DateTimeOffset AddYears (int years)
  		{
  			return new DateTimeOffset (dt.AddYears (years).Ticks, utc_offset);
  		}
  
  		public static int Compare (DateTimeOffset first, DateTimeOffset second)
  		{
  			return first.CompareTo (second);	
  		}
  
  		public int CompareTo (DateTimeOffset other)
  		{
  			return UtcDateTime.CompareTo (other.UtcDateTime);
  		}
  
  		int IComparable.CompareTo (object obj)
  		{
  			return CompareTo ((DateTimeOffset) obj);
  		}
  
  		public static bool operator == (DateTimeOffset left, DateTimeOffset right)
  		{
  			return left.Equals (right);	
  		}
  
  		public bool Equals (DateTimeOffset other)
  		{
  			return UtcDateTime == other.UtcDateTime;
  		}
  
  		public override bool Equals (object obj)
  		{
  			if (obj is DateTimeOffset)
  				return UtcDateTime == ((DateTimeOffset) obj).UtcDateTime;
  			return false;
  		}
  
  		public static bool Equals (DateTimeOffset first, DateTimeOffset second)
  		{
  			return first.Equals (second);	
  		}
  
  		public bool EqualsExact (DateTimeOffset other)
  		{
  			return dt == other.dt && utc_offset == other.utc_offset;	
  		}
  
  		public static DateTimeOffset FromFileTime (long fileTime)
  		{
  			if (fileTime < 0 || fileTime > MaxValue.Ticks)
  				throw new ArgumentOutOfRangeException ("fileTime is less than zero or greater than DateTimeOffset.MaxValue.Ticks.");
  			
  			return new DateTimeOffset (DateTime.FromFileTime (fileTime), TimeZone.CurrentTimeZone.GetUtcOffset (DateTime.FromFileTime (fileTime)));
  
  		}
  
  		public override int GetHashCode ()
  		{
  			return dt.GetHashCode () ^ utc_offset.GetHashCode ();
  		}
  
  		[System.Security.Permissions.SecurityPermission (System.Security.Permissions.SecurityAction.LinkDemand, SerializationFormatter = true)]
  		void ISerializable.GetObjectData (SerializationInfo info, StreamingContext context)
  		{
  			if (info == null)
  				throw new ArgumentNullException ("info");
  			// An example SOAP serialization on MSFT is the following, so field 
  			// names "DateTime" and "OffsetMinutes":
  			//    <SOAP-ENV:Envelope ...>
  			//    <SOAP-ENV:Body>
  			//    <a1:DateTimeOffset id="ref-1" xmlns:a1="http://schemas.microsoft.com/clr/ns/System">
  			//    <DateTime xsi:type="xsd:dateTime">2007-01-02T12:30:50.0000000+00:00</DateTime>
  			//    <OffsetMinutes>0</OffsetMinutes>
  			//    </a1:DateTimeOffset>
  			//    </SOAP-ENV:Body>
  			//    </SOAP-ENV:Envelope>
  			DateTime dt0 = new DateTime (dt.Ticks).Subtract (utc_offset);
  			info.AddValue ("DateTime", dt0);
  			// MSFT BinaryFormatter output contains primitive code 6, i.e. Int16.
  			info.AddValue ("OffsetMinutes", (Int16)utc_offset.TotalMinutes);
  		}
  
  		[System.Security.Permissions.SecurityPermission (System.Security.Permissions.SecurityAction.LinkDemand, SerializationFormatter = true)]
  		private DateTimeOffset(SerializationInfo info, StreamingContext context)
  		{
  			DateTime dt0 = (DateTime)info.GetValue ("DateTime", typeof(DateTime));
  			Int16 totalMinutes = info.GetInt16 ("OffsetMinutes");
  			utc_offset = TimeSpan.FromMinutes(totalMinutes);
  			dt = dt0.Add(utc_offset);
  		}
  
  		public static bool operator > (DateTimeOffset left, DateTimeOffset right)
  		{
  			return left.UtcDateTime > right.UtcDateTime;
  		}			
  
  		public static bool operator >= (DateTimeOffset left, DateTimeOffset right)
  		{
  			return left.UtcDateTime >= right.UtcDateTime;
  		}			
  
  		public static implicit operator DateTimeOffset (DateTime dateTime)
  		{
  			return new DateTimeOffset (dateTime);
  		}
  
  		public static bool operator != (DateTimeOffset left, DateTimeOffset right)
  		{
  			return left.UtcDateTime != right.UtcDateTime;
  		}
  
  		public static bool operator < (DateTimeOffset left, DateTimeOffset right)
  		{
  			return left.UtcDateTime < right.UtcDateTime;
  		}
  		
  		public static bool operator <= (DateTimeOffset left, DateTimeOffset right)
  		{
  			return left.UtcDateTime <= right.UtcDateTime;
  		}
  	
  		[MonoTODO]
  		void IDeserializationCallback.OnDeserialization (object sender)
  		{
  		}
  
  		public static DateTimeOffset Parse (string input)
  		{
  			return Parse (input, null);
  		}
  
  		public static DateTimeOffset Parse (string input, IFormatProvider formatProvider)
  		{
  			return Parse (input, formatProvider, DateTimeStyles.AllowWhiteSpaces);
  		}
  
  		public static DateTimeOffset Parse (string input, IFormatProvider formatProvider, DateTimeStyles styles)
  		{
  			if (input == null)
  				throw new ArgumentNullException ("input");
  
  			DateTime d;
  			DateTimeOffset dto;
  			Exception exception = null;
  			try {
  				if (!DateTime.CoreParse (input, formatProvider, styles, out d, out dto, true, ref exception))
  					throw exception;
  			} catch (ArgumentOutOfRangeException ex) {
  				throw new FormatException ("The UTC representation falls outside the 1-9999 year range", ex);
  			}
  
  			if (d.Ticks != 0 && dto.Ticks == 0)
  				throw new FormatException ("The UTC representation falls outside the 1-9999 year range");
  
  			return dto;
  		}
  
  		public static DateTimeOffset ParseExact (string input, string format, IFormatProvider formatProvider)
  		{
  			return ParseExact (input, format, formatProvider, DateTimeStyles.AssumeLocal);
  		}
  
  		public static DateTimeOffset ParseExact (string input, string format, IFormatProvider formatProvider, DateTimeStyles styles)
  		{
  			if (format == null)
  				throw new ArgumentNullException ("format");
  
  			if (format == String.Empty)
  				throw new FormatException ("format is an empty string");
  
  			return ParseExact (input, new string [] {format}, formatProvider, styles);
  		}
  
  		public static DateTimeOffset ParseExact (string input, string[] formats, IFormatProvider formatProvider, DateTimeStyles styles)
  		{
  			if (input == null)
  				throw new ArgumentNullException ("input");
  
  			if (input == String.Empty)
  				throw new FormatException ("input is an empty string");
  
  			if (formats == null)
  				throw new ArgumentNullException ("formats");
  
  			if (formats.Length == 0)
  				throw new FormatException ("Invalid format specifier");
  
  			if ((styles & DateTimeStyles.AssumeLocal) != 0 && (styles & DateTimeStyles.AssumeUniversal) != 0)
  				throw new ArgumentException ("styles parameter contains incompatible flags");
  
  			DateTimeOffset result;
  			if (!ParseExact (input, formats, DateTimeFormatInfo.GetInstance (formatProvider), styles, out result))
  				throw new FormatException ("Invalid format string");
  
  			return result;
  		}
  
  		private static bool ParseExact (string input, string [] formats,
  				DateTimeFormatInfo dfi, DateTimeStyles styles, out DateTimeOffset ret)
  		{
  			foreach (string format in formats)
  			{
  				if (format == null || format == String.Empty)
  					throw new FormatException ("Invalid format string");
  
  				DateTimeOffset result;
  				if (DoParse (input, format, false, out result, dfi, styles)) {
  					ret = result;
  					return true;
  				}
  			}
  			ret = DateTimeOffset.MinValue;
  			return false;
  		}
  
  		private static bool DoParse (string input, 
  				string format,
  				bool exact,
  				out DateTimeOffset result,
  				DateTimeFormatInfo dfi,
  				DateTimeStyles styles)
  		{
  			if ((styles & DateTimeStyles.AllowLeadingWhite) != 0) {
  				format = format.TrimStart (null);
  				input = input.TrimStart (null);
  			}
  
  			if ((styles & DateTimeStyles.AllowTrailingWhite) != 0) {
  				format = format.TrimEnd (null);
  				input = input.TrimEnd (null);
  			}
  
  			bool allow_white_spaces = false;
  			if ((styles & DateTimeStyles.AllowInnerWhite) != 0)
  				allow_white_spaces = true;
  
  			result = DateTimeOffset.MinValue;
  			
  			bool useutc = false, use_invariants = false;
  			if (format.Length == 1) {
  				format = DateTimeUtils.GetStandardPattern (format[0], dfi, out useutc, out use_invariants, true);
  				if (format == null)
  					return false;
  			}
  
  			int year = -1;
  			int month = -1;
  			int day = -1;
  			int partial_hour = -1; // for 'hh tt' formats
  			int hour = -1;
  			int minute = -1;
  			int second = -1;
  			double fraction = -1;
  			int temp_int = -1;
  			TimeSpan offset = TimeSpan.MinValue;
  
  			int fi = 0; //format iterator
  			int ii = 0; //input iterator
  			while (fi < format.Length) {
  				int tokLen;
  				char ch = format [fi];
  
  				switch (ch) {
  				case 'd':
  					tokLen = DateTimeUtils.CountRepeat (format, fi, ch);
  					if (day != -1 || tokLen > 4)
  						return false;
  
  					if (tokLen <= 2)
  						ii += ParseNumber (input, ii, 2, tokLen == 2, allow_white_spaces, out day);
  					else
  						ii += ParseEnum (input, ii, tokLen == 3 ? dfi.AbbreviatedDayNames : dfi.DayNames, allow_white_spaces, out temp_int); 
  					break;
  				case 'f':
  					tokLen = DateTimeUtils.CountRepeat (format, fi, ch);
  					ii += ParseNumber (input, ii, tokLen, true, allow_white_spaces, out temp_int);
  					if (fraction >= 0 || tokLen > 7 || temp_int == -1)
  						return false;
  					fraction = (double)temp_int / Math.Pow (10, tokLen);
  					break;
  				case 'F':
  					tokLen = DateTimeUtils.CountRepeat (format, fi, ch);
  					int digits;
  					int read = ParseNumber (input, ii, tokLen, true, allow_white_spaces, out temp_int, out digits);
  					if (temp_int == -1)
  						ii += ParseNumber (input, ii, digits, true, allow_white_spaces, out temp_int);
  					else
  						ii += read;
  					if (fraction >= 0 || tokLen > 7 || temp_int == -1)
  						return false;	
  					fraction = (double)temp_int / Math.Pow (10, digits);	
  					break;
  				case 'h':
  					tokLen = DateTimeUtils.CountRepeat (format, fi, ch);
  					if (hour != -1 || tokLen > 2)
  						return false;
  
  					ii += ParseNumber (input, ii, 2, tokLen == 2, allow_white_spaces, out temp_int);
  					if (temp_int == -1)
  						return false;
  
  					if (partial_hour == -1)
  						partial_hour = temp_int;
  					else 
  						hour = partial_hour + temp_int;
  					break;
  				case 'H':
  					tokLen = DateTimeUtils.CountRepeat (format, fi, ch);
  					if (hour != -1 || tokLen > 2)
  						return false;
  
  					ii += ParseNumber (input, ii, 2, tokLen == 2, allow_white_spaces, out hour);
  					break;
  				case 'm':
  					tokLen = DateTimeUtils.CountRepeat (format, fi, ch);
  					if (minute != -1 || tokLen > 2)
  						return false;
  
  					ii += ParseNumber (input, ii, 2, tokLen == 2, allow_white_spaces, out minute);
  					break;
  				case 'M':
  					tokLen = DateTimeUtils.CountRepeat (format, fi, ch);
  					if (month != -1 || tokLen > 4)
  						return false;
  
  					if (tokLen <= 2)
  						ii += ParseNumber (input, ii, 2, tokLen == 2, allow_white_spaces, out month);
  					else {
  						ii += ParseEnum (input, ii, tokLen == 3 ? dfi.AbbreviatedMonthNames : dfi.MonthNames, allow_white_spaces, out month);
  						month += 1;
  					}
  
  					break;
  				case 's':
  					tokLen = DateTimeUtils.CountRepeat (format, fi, ch);
  					if (second != -1 || tokLen > 2)
  						return false;
  					ii += ParseNumber (input, ii, 2, tokLen == 2, allow_white_spaces, out second);
  					break;
  				case 't':
  					tokLen = DateTimeUtils.CountRepeat (format, fi, ch);
  					if (hour != -1 || tokLen > 2)
  						return false;
  
  					ii += ParseEnum (input, ii,
  							 tokLen == 1 ? new string[] {new string (dfi.AMDesignator[0], 1), new string (dfi.PMDesignator[0], 0)} 
  							 	     : new string[] {dfi.AMDesignator, dfi.PMDesignator},
  							 allow_white_spaces, out temp_int);
  					if (temp_int == -1)
  						return false;
  
  					if (partial_hour == -1)
  						partial_hour = temp_int * 12;
  					else
  						hour = partial_hour + temp_int * 12;
  					break;
  				case 'y':
  					if (year != -1)
  						return false;
  
  					tokLen = DateTimeUtils.CountRepeat (format, fi, ch);
  					if (tokLen <= 2) {
  						ii += ParseNumber (input, ii, 2, tokLen == 2, allow_white_spaces, out year);
  						if (year != -1)
  							year = dfi.Calendar.ToFourDigitYear (year);
  					} else if (tokLen <= 4) { // yyy and yyyy accept up to 5 digits with leading 0
  						int digit_parsed;
  						ii += ParseNumber (input, ii, 5, false, allow_white_spaces, out year, out digit_parsed);
  						if (digit_parsed < tokLen || (digit_parsed > tokLen && (year / Math.Pow (10, digit_parsed - 1) < 1)))
  							return false;
  					} else
  						ii += ParseNumber (input, ii, tokLen, true, allow_white_spaces, out year);
  					break;
  
  					// The documentation is incorrect, they claim that K is the same as 'zz', but
  					// it actually allows the format to contain 4 digits for the offset
  				case 'K':
  					tokLen = 1;
  					int off_h, off_m = 0, sign;
  					temp_int = 0;
  					ii += ParseEnum (input, ii, new string [] {"-", "+"}, allow_white_spaces, out sign);
  					ii += ParseNumber (input, ii, 4, false, false, out off_h);
  					if (off_h == -1 || off_m == -1 || sign == -1)
  						return false;
  
  					if (sign == 0)
  						sign = -1;
  					offset = new TimeSpan (sign * off_h, sign * off_m, 0);
  					break;
  					
  				case 'z':
  					tokLen = DateTimeUtils.CountRepeat (format, fi, ch);
  					if (offset != TimeSpan.MinValue || tokLen > 3)
  						return false;
  
  					off_m = 0;
  					temp_int = 0;
  					ii += ParseEnum (input, ii, new string [] {"-", "+"}, allow_white_spaces, out sign);
  					ii += ParseNumber (input, ii, 2, tokLen != 1, false, out off_h);
  					if (tokLen == 3) {
  						ii += ParseEnum (input, ii, new string [] {dfi.TimeSeparator}, false, out temp_int);
  						ii += ParseNumber (input, ii, 2, true, false, out off_m);
  					}
  					if (off_h == -1 || off_m == -1 || sign == -1)
  						return false;
  
  					if (sign == 0)
  						sign = -1;
  					offset = new TimeSpan (sign * off_h, sign * off_m, 0);
  					break;
  				case ':':
  					tokLen = 1;
  					ii += ParseEnum (input, ii, new string [] {dfi.TimeSeparator}, false, out temp_int);
  					if (temp_int == -1)
  						return false;
  					break;
  				case '/':
  					tokLen = 1;
  					ii += ParseEnum (input, ii, new string [] {dfi.DateSeparator}, false, out temp_int);
  					if (temp_int == -1)
  						return false;
  					break;
  				case '%':
  					tokLen = 1;
  					if (fi != 0) 
  						return false;
  					break;
  				case ' ':
  					tokLen = 1;
  					ii += ParseChar (input, ii, ' ', false, out temp_int);
  					if (temp_int == -1)
  						return false;
  					break;
  				case '\\':
  					tokLen = 2;
  					ii += ParseChar (input, ii, format [fi + 1], allow_white_spaces, out temp_int);
  					if (temp_int == -1)
  						return false;
  					break;
  				case '\'':
  				case '"':
  					tokLen = 1;
  					while (ii < input.Length) {
  						var ftoken = format [fi + tokLen];
  						++tokLen;
  						if (ftoken == format [fi]) {
  							if (useutc && tokLen == 5 && input [ii - 3] == 'G' && input [ii - 2] == 'M' && input [ii - 1] == 'T') {
  								offset = TimeSpan.Zero;
  							}
  
  							break;
  						}
  
  						if (ftoken != input [ii++])
  							return false;
  					}
  
  					break;
  				default:
  					//Console.WriteLine ("un-parsed character: {0}", ch);
  					tokLen = 1;
  					ii += ParseChar (input, ii, format [fi], allow_white_spaces, out temp_int);
  					if (temp_int == -1)
  						return false;
  					break;
  				}
  				fi += tokLen;
  			}
  
  			//Console.WriteLine ("{0}-{1}-{2} {3}:{4} {5}", year, month, day, hour, minute, offset);
  			if (offset == TimeSpan.MinValue) {
  				if ((styles & DateTimeStyles.AssumeUniversal) != 0) {
  					offset = TimeSpan.Zero;
  				} else if ((styles & DateTimeStyles.AssumeLocal) != 0) {
  					offset = use_invariants ?
  						TimeSpan.Zero :
  						TimeZone.CurrentTimeZone.GetUtcOffset (DateTime.Now);
  				}
  			}
  
  
  			if (hour < 0)		hour = 0;
  			if (minute < 0)		minute = 0;
  			if (second < 0)		second = 0;
  			if (fraction < 0)	fraction = 0;
  			if (year > 0 && month > 0 && day > 0) {
  				result = new DateTimeOffset (year, month, day, hour, minute, second, 0, offset);
  				result = result.AddSeconds (fraction);
  				if ((styles & DateTimeStyles.AdjustToUniversal) != 0)
  					result = result.ToUniversalTime ();
  				return true;
  			}
  
  			return false;
  		}
  
  		private static int ParseNumber (string input, int pos, int digits, bool leading_zero, bool allow_leading_white, out int result)
  		{
  			int digit_parsed;
  			return ParseNumber (input, pos, digits, leading_zero, allow_leading_white, out result, out digit_parsed);
  		}
  
  		private static int ParseNumber (string input, int pos, int digits, bool leading_zero, bool allow_leading_white, out int result, out int digit_parsed)
  		{
  			int char_parsed = 0;
  			digit_parsed = 0;
  			result = 0;
  			for (; allow_leading_white && pos < input.Length && input[pos] == ' '; pos++)
  				char_parsed++;
  
  			for (; pos < input.Length && Char.IsDigit (input[pos]) && digits > 0; pos ++, char_parsed++, digit_parsed++, digits --)
  				result = 10 * result + (byte) (input[pos] - '0');
  
  			if (leading_zero && digits > 0)
  				result = -1;
  
  			if (digit_parsed == 0)
  				result = -1;
  
  			return char_parsed;
  		}
  
  		private static int ParseEnum (string input, int pos, string [] enums, bool allow_leading_white, out int result)
  		{
  			int char_parsed = 0;
  			result = -1;
  			for (; allow_leading_white && pos < input.Length && input[pos] == ' '; pos++)
  				char_parsed ++;
  			
  			for (int i = 0; i < enums.Length; i++)
  				if (input.Substring(pos).StartsWith (enums [i])) {
  					result = i;
  					break;
  				}
  
  			if (result >= 0)
  				char_parsed += enums[result].Length;
  
  			return char_parsed;	
  		}
  	
  		private static int ParseChar (string input, int pos, char c, bool allow_leading_white, out int result)
  		{
  			int char_parsed = 0;
  			result = -1;
  			for (; allow_leading_white && pos < input.Length && input[pos] == ' '; pos++, char_parsed++)
  				;
  
  			if (pos < input.Length && input[pos] == c){
  				result = (int) c;
  				char_parsed ++;
  			}
  
  			return char_parsed;
  		}
  
  		public TimeSpan Subtract (DateTimeOffset value)
  		{
  			return UtcDateTime - value.UtcDateTime;
  		}
  
  		public DateTimeOffset Subtract (TimeSpan value)
  		{
  			return Add (-value);
  		}
  
  		public static TimeSpan operator - (DateTimeOffset left, DateTimeOffset right)
  		{
  			return left.Subtract (right);
  		}
  
  		public static DateTimeOffset operator - (DateTimeOffset dateTimeOffset, TimeSpan timeSpan)
  		{
  			return dateTimeOffset.Subtract (timeSpan);	
  		}
  
  		public long ToFileTime ()
  		{
  			return UtcDateTime.ToFileTime ();
  		}
  
  		public DateTimeOffset ToLocalTime ()
  		{
  			return new DateTimeOffset (UtcDateTime.ToLocalTime (), TimeZone.CurrentTimeZone.GetUtcOffset (UtcDateTime.ToLocalTime ()));
  		}
  
  		public DateTimeOffset ToOffset (TimeSpan offset)
  		{
  			return new DateTimeOffset (dt - utc_offset + offset, offset);
  		}
  
  		public override string ToString ()
  		{
  			return ToString (null, null);
  		}
  
  		public string ToString (IFormatProvider formatProvider)
  		{
  			return ToString (null, formatProvider);
  		}
  
  		public string ToString (string format)
  		{
  			return ToString (format, null);
  		}
  
  		public string ToString (string format, IFormatProvider formatProvider)
  		{
  			DateTimeFormatInfo dfi = DateTimeFormatInfo.GetInstance(formatProvider);
  
  			if (format == null || format == String.Empty)
  				format = dfi.ShortDatePattern + " " + dfi.LongTimePattern + " zzz";
  
  			bool to_utc = false, use_invariant = false;
  			if (format.Length == 1) {
  				char fchar = format [0];
  				try {
  					format = DateTimeUtils.GetStandardPattern (fchar, dfi, out to_utc, out use_invariant, true);
  				} catch {
  					format = null;
  				}
  		
  				if (format == null)
  					throw new FormatException ("format is not one of the format specifier characters defined for DateTimeFormatInfo");
  			}
  			return to_utc ? DateTimeUtils.ToString (UtcDateTime, TimeSpan.Zero, format, dfi) : DateTimeUtils.ToString (DateTime, Offset, format, dfi);
  		}
  
  		public DateTimeOffset ToUniversalTime ()
  		{
  			return new DateTimeOffset (UtcDateTime, TimeSpan.Zero);	
  		}
  
  		public static bool TryParse (string input, out DateTimeOffset result)
  		{
  			try {
  				result = Parse (input);
  				return true;
  			} catch {
  				result = MinValue;
  				return false;
  			}
  		}
  
  		public static bool TryParse (string input, IFormatProvider formatProvider, DateTimeStyles styles, out DateTimeOffset result)
  		{
  			try {
  				result = Parse (input, formatProvider, styles);
  				return true;
  			} catch {
  				result = MinValue;
  				return false;
  			}	
  		}
  
  		public static bool TryParseExact (string input, string format, IFormatProvider formatProvider, DateTimeStyles styles, out DateTimeOffset result)
  		{
  			try {
  				result = ParseExact (input, format, formatProvider, styles);
  				return true;
  			} catch {
  				result = MinValue;
  				return false;
  			}
  		}
  
  		public static bool TryParseExact (string input, string[] formats, IFormatProvider formatProvider, DateTimeStyles styles, out DateTimeOffset result)
  		{
  			try {
  				result = ParseExact (input, formats, formatProvider, styles);
  				return true;
  			} catch {
  				result = MinValue;
  				return false;
  			}
  		}
  
  		public DateTime Date {
  			get { return DateTime.SpecifyKind (dt.Date, DateTimeKind.Unspecified); }
  		}
  
  		public DateTime DateTime {
  			get { return DateTime.SpecifyKind (dt, DateTimeKind.Unspecified); }
  		}
  
  		public int Day {
  			get { return dt.Day; }
  		}
  
  		public DayOfWeek DayOfWeek {
  			get { return dt.DayOfWeek; }
  		}
  
  		public int DayOfYear {
  			get { return dt.DayOfYear; }
  		}
  
  		public int Hour {
  			get { return dt.Hour; }
  		}
  
  		public DateTime LocalDateTime {
  			get { return UtcDateTime.ToLocalTime (); }
  		}
  
  		public int Millisecond {
  			get { return dt.Millisecond; }
  		}
  
  		public int Minute {
  			get { return dt.Minute; }
  		}
  
  		public int Month {
  			get { return dt.Month; }
  		}
  
  		public static DateTimeOffset Now {
  			get { return new DateTimeOffset (DateTime.Now);}
  		}
  
  		public TimeSpan Offset {
  			get { return utc_offset; }	
  		}
  
  		public int Second {
  			get { return dt.Second; }
  		}
  
  		public long Ticks {
  
gt: 			get { return dt.Ticks; }	