mcs/class/corlib/System/TimeZone.cs

   1 //
   2 // System.TimeZone.cs
   3 //
   4 // Authors:
   5 //   Duncan Mak (duncan@ximian.com)
   6 //   Ajay Kumar Dwivedi (adwiv@yahoo.com)
   7 //   Martin Baulig (martin@gnome.org)
   8 //
   9 // (C) Ximian, Inc.
  10 // Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
  11 //
  12 // Permission is hereby granted, free of charge, to any person obtaining
  13 // a copy of this software and associated documentation files (the
  14 // "Software"), to deal in the Software without restriction, including
  15 // without limitation the rights to use, copy, modify, merge, publish,
  16 // distribute, sublicense, and/or sell copies of the Software, and to
  17 // permit persons to whom the Software is furnished to do so, subject to
  18 // the following conditions:
  19 //
  20 // The above copyright notice and this permission notice shall be
  21 // included in all copies or substantial portions of the Software.
  22 //
  23 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  27 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  28 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  29 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  30 //
  31
  32 using System.Collections;
  33 using System.Globalization;
  34 using System.Runtime.CompilerServices;
  35 using System.Runtime.Serialization;
  36
  37 namespace System
  38 {
  39         [Serializable]
  40         public abstract class TimeZone
  41         {
  42                 // Fields
  43                 private static TimeZone currentTimeZone;
  44
  45                 // Constructor
  46                 protected TimeZone ()
  47                 {
  48                 }
  49
  50                 // Properties
  51                 public static TimeZone CurrentTimeZone {
  52                         get {
  53                                 if (currentTimeZone == null) {
  54                                         DateTime now = new DateTime (DateTime.GetNow ());
  55                                         currentTimeZone = new CurrentSystemTimeZone (now);
  56                                 }
  57                                 return currentTimeZone;
  58                         }
  59                 }
  60
  61                 internal static void ClearCurrentTimeZone ()
  62                 {
  63                         currentTimeZone = null;
  64                 }
  65
  66                 public abstract string DaylightName {
  67                         get;
  68                 }
  69
  70                 public abstract string StandardName {
  71                         get;
  72                 }
  73
  74                 // Methods
  75                 public abstract DaylightTime GetDaylightChanges (int year);
  76
  77                 public abstract TimeSpan GetUtcOffset (DateTime time);
  78
  79                 public virtual bool IsDaylightSavingTime (DateTime time)
  80                 {
  81                         return IsDaylightSavingTime (time, GetDaylightChanges (time.Year));
  82                 }
  83
  84                 public static bool IsDaylightSavingTime (DateTime time, DaylightTime daylightTimes)
  85                 {
  86                         if (daylightTimes == null)
  87                                 throw new ArgumentNullException ("daylightTimes");
  88
  89                         // If Start == End, then DST is off
  90                         if (daylightTimes.Start.Ticks == daylightTimes.End.Ticks)
  91                                 return false;
  92
  93                         //We are in the northern hemisphere.
  94                         if (daylightTimes.Start.Ticks < daylightTimes.End.Ticks) {
  95                                 if (daylightTimes.Start.Ticks < time.Ticks && daylightTimes.End.Ticks > time.Ticks)
  96                                         return true; // time lies between Start and End
  97
  98                         }
  99                         else {  // We are in the southern hemisphere.
 100                                 if (time.Year == daylightTimes.Start.Year && time.Year == daylightTimes.End.Year)
 101                                         if (time.Ticks < daylightTimes.End.Ticks || time.Ticks > daylightTimes.Start.Ticks)
 102                                                 return true; // time is less than End OR more than Start
 103                         }
 104
 105                         return false;
 106                 }
 107
 108                 public virtual DateTime ToLocalTime (DateTime time)
 109                 {
 110 #if NET_2_0
 111                         if (time.Kind == DateTimeKind.Local)
 112                                 return time;
 113 #endif
 114
 115                         DaylightTime dlt = GetDaylightChanges (time.Year);
 116                         TimeSpan utcOffset = GetUtcOffset (time);
 117                         if (utcOffset.Ticks > 0) {
 118                                 if (DateTime.MaxValue - utcOffset < time)
 119 #if NET_2_0
 120                                         return DateTime.SpecifyKind (DateTime.MaxValue, DateTimeKind.Local);
 121 #else
 122                                         return DateTime.MaxValue;
 123 #endif
 124                         //} else if (utcOffset.Ticks < 0) {
 125                         //      LAMESPEC: MS.NET fails to check validity here
 126                         //      it may throw ArgumentOutOfRangeException.
 127                         }
 128
 129                         DateTime local = time.Add (utcOffset);
 130                         if (dlt.Delta.Ticks == 0)
 131 #if NET_2_0
 132                                 return DateTime.SpecifyKind (local, DateTimeKind.Local);
 133 #else
 134                                 return local;
 135 #endif
 136
 137                         // FIXME: check all of the combination of
 138                         //      - basis: local-based or UTC-based
 139                         //      - hemisphere: Northern or Southern
 140                         //      - offset: positive or negative
 141
 142                         // PST should work fine here.
 143                         if (local < dlt.End && dlt.End.Subtract (dlt.Delta) <= local)
 144 #if NET_2_0
 145                                 return DateTime.SpecifyKind (local, DateTimeKind.Local);
 146 #else
 147                                 return local;
 148 #endif
 149                         if (local >= dlt.Start && dlt.Start.Add (dlt.Delta) > local)
 150 #if NET_2_0
 151                                 return DateTime.SpecifyKind (local.Subtract (dlt.Delta), DateTimeKind.Local);
 152 #else
 153                                 return local.Subtract (dlt.Delta);
 154 #endif
 155
 156                         TimeSpan localOffset = GetUtcOffset (local);
 157 #if NET_2_0
 158                         return DateTime.SpecifyKind (time.Add (localOffset), DateTimeKind.Local);
 159 #else
 160                         return time.Add (localOffset);
 161 #endif
 162                 }
 163
 164                 public virtual DateTime ToUniversalTime (DateTime time)
 165                 {
 166 #if NET_2_0
 167                         if (time.Kind == DateTimeKind.Utc)
 168                                 return time;
 169 #endif
 170
 171                         TimeSpan offset = GetUtcOffset (time);
 172
 173                         if (offset.Ticks < 0) {
 174                                 if (DateTime.MaxValue + offset < time)
 175 #if NET_2_0
 176                                         return DateTime.SpecifyKind (DateTime.MaxValue, DateTimeKind.Utc);
 177 #else
 178                                         return DateTime.MaxValue;
 179 #endif
 180                         } else if (offset.Ticks > 0) {
 181                                 if (DateTime.MinValue + offset > time)
 182 #if NET_2_0
 183                                         return DateTime.SpecifyKind (DateTime.MinValue, DateTimeKind.Utc);
 184 #else
 185                                         return DateTime.MinValue;
 186 #endif
 187                         }
 188
 189 #if NET_2_0
 190                         return DateTime.SpecifyKind (new DateTime (time.Ticks - offset.Ticks), DateTimeKind.Utc);
 191 #else
 192                         return new DateTime (time.Ticks - offset.Ticks);
 193 #endif
 194                 }
 195         }
 196
 197         [Serializable]
 198         internal class CurrentSystemTimeZone : TimeZone, IDeserializationCallback {
 199
 200                 // Fields
 201                 private string m_standardName;
 202                 private string m_daylightName;
 203
 204                 // A yearwise cache of DaylightTime.
 205                 private Hashtable m_CachedDaylightChanges = new Hashtable (1);
 206
 207                 // the offset when daylightsaving is not on (in ticks)
 208                 private long m_ticksOffset;
 209
 210                 // the offset when daylightsaving is not on.
 211                 [NonSerialized]
 212                 private TimeSpan utcOffsetWithOutDLS;
 213
 214                 // the offset when daylightsaving is on.
 215                 [NonSerialized]
 216                 private TimeSpan utcOffsetWithDLS;
 217
 218                 internal enum TimeZoneData
 219                 {
 220                         DaylightSavingStartIdx,
 221                         DaylightSavingEndIdx,
 222                         UtcOffsetIdx,
 223                         AdditionalDaylightOffsetIdx
 224                 };
 225
 226                 internal enum TimeZoneNames
 227                 {
 228                         StandardNameIdx,
 229                         DaylightNameIdx
 230                 };
 231
 232                 // Internal method to get timezone data.
 233                 //    data[0]:  start of daylight saving time (in DateTime ticks).
 234                 //    data[1]:  end of daylight saving time (in DateTime ticks).
 235                 //    data[2]:  utcoffset (in TimeSpan ticks).
 236                 //    data[3]:  additional offset when daylight saving (in TimeSpan ticks).
 237                 //    name[0]:  name of this timezone when not daylight saving.
 238                 //    name[1]:  name of this timezone when daylight saving.
 239                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
 240                 private static extern bool GetTimeZoneData (int year, out Int64[] data, out string[] names);
 241
 242                 // Constructor
 243                 internal CurrentSystemTimeZone ()
 244                 {
 245                 }
 246
 247                 internal CurrentSystemTimeZone (DateTime now)
 248                 {
 249                         Int64[] data;
 250                         string[] names;
 251
 252                         if (!GetTimeZoneData (now.Year, out data, out names))
 253                                 throw new NotSupportedException (Locale.GetText ("Can't get timezone name."));
 254
 255                         m_standardName = Locale.GetText (names[(int)TimeZoneNames.StandardNameIdx]);
 256                         m_daylightName = Locale.GetText (names[(int)TimeZoneNames.DaylightNameIdx]);
 257
 258                         m_ticksOffset = data[(int)TimeZoneData.UtcOffsetIdx];
 259
 260                         DaylightTime dlt = GetDaylightTimeFromData (data);
 261                         m_CachedDaylightChanges.Add (now.Year, dlt);
 262                         OnDeserialization (dlt);
 263                 }
 264
 265                 // Properties
 266                 public override string DaylightName {
 267                         get { return m_daylightName; }
 268                 }
 269
 270                 public override string StandardName {
 271                         get { return m_standardName; }
 272                 }
 273
 274                 // Methods
 275                 [MonoTODO]
 276                 public override DaylightTime GetDaylightChanges (int year)
 277                 {
 278                         if (year < 1 || year > 9999)
 279                                 throw new ArgumentOutOfRangeException ("year", year +
 280                                         Locale.GetText (" is not in a range between 1 and 9999."));
 281
 282                         lock (m_CachedDaylightChanges) {
 283                                 DaylightTime dlt = (DaylightTime) m_CachedDaylightChanges [year];
 284                                 if (dlt == null) {
 285                                         Int64[] data;
 286                                         string[] names;
 287
 288                                         if (!GetTimeZoneData (year, out data, out names))
 289                                                 throw new ArgumentException (Locale.GetText ("Can't get timezone data for " + year));
 290
 291                                         dlt = GetDaylightTimeFromData (data);
 292                                         m_CachedDaylightChanges.Add (year, dlt);
 293                                 }
 294                                 return dlt;
 295                         }
 296                 }
 297
 298                 public override TimeSpan GetUtcOffset (DateTime time)
 299                 {
 300                         if (IsDaylightSavingTime (time))
 301                                 return utcOffsetWithDLS;
 302
 303                         return utcOffsetWithOutDLS;
 304                 }
 305
 306                 void IDeserializationCallback.OnDeserialization (object sender)
 307                 {
 308                         OnDeserialization (null);
 309                 }
 310
 311                 private void OnDeserialization (DaylightTime dlt)
 312                 {
 313                         if (dlt == null) {
 314                                 Int64[] data;
 315                                 string[] names;
 316
 317                                 int year = DateTime.Now.Year;
 318                                 if (!GetTimeZoneData (year, out data, out names))
 319                                         throw new ArgumentException (Locale.GetText ("Can't get timezone data for " + year));
 320                                 dlt = GetDaylightTimeFromData (data);
 321                         }
 322                         utcOffsetWithOutDLS = new TimeSpan (m_ticksOffset);
 323                         utcOffsetWithDLS = new TimeSpan (m_ticksOffset + dlt.Delta.Ticks);
 324                 }
 325
 326                 private DaylightTime GetDaylightTimeFromData (long[] data)
 327                 {
 328                         return new DaylightTime (new DateTime (data[(int)TimeZoneData.DaylightSavingStartIdx]),
 329                                 new DateTime (data[(int)TimeZoneData.DaylightSavingEndIdx]),
 330                                 new TimeSpan (data[(int)TimeZoneData.AdditionalDaylightOffsetIdx]));
 331                 }
 332         }
 333 }