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//
// System.TimeZone.cs
//
// Author: Duncan Mak (duncan@ximian.com)
// Ajay Kumar Dwivedi (adwiv@yahoo.com)
// Martin Baulig (martin@gnome.org)
//
// (C) Ximian, Inc.
//
using System.Collections;
using System.Globalization;
using System.Runtime.CompilerServices;
namespace System {
[Serializable]
public abstract class TimeZone
{
// Fields
private static TimeZone currentTimeZone;
// Constructor
protected TimeZone ()
{
}
// Properties
public static TimeZone CurrentTimeZone
{
get {
if (currentTimeZone == null)
currentTimeZone = new CurrentTimeZone ();
return currentTimeZone;
}
}
public abstract string DaylightName
{
get;
}
public abstract string StandardName
{
get;
}
// Methods
public abstract DaylightTime GetDaylightChanges (int year);
public abstract TimeSpan GetUtcOffset (DateTime time);
public virtual bool IsDaylightSavingTime (DateTime time)
{
return IsDaylightSavingTime (time, GetDaylightChanges (time.Year));
}
public static bool IsDaylightSavingTime (DateTime time, DaylightTime daylightTimes)
{
if (daylightTimes == null)
throw new ArgumentNullException ("daylightTimes");
// If Start == End, then DST is off
if (daylightTimes.Start.Ticks == daylightTimes.End.Ticks)
return false;
//We are in the northern hemisphere.
if (daylightTimes.Start.Ticks < daylightTimes.End.Ticks) {
if (daylightTimes.Start.Ticks < time.Ticks
&& daylightTimes.End.Ticks > time.Ticks)
return true; // time lies between Start and End
} else { // We are in the southern hemisphere.
if (time.Year == daylightTimes.Start.Year && time.Year == daylightTimes.End.Year)
if (time.Ticks < daylightTimes.End.Ticks
|| time.Ticks > daylightTimes.Start.Ticks)
return true; // time is less than End OR more than Start
}
return false;
}
public virtual DateTime ToLocalTime (DateTime time)
{
return time + GetUtcOffset (time);
}
public virtual DateTime ToUniversalTime (DateTime time)
{
return time - GetUtcOffset (time);
}
}
internal class CurrentTimeZone : TimeZone
{
// Fields
private static string daylightName;
private static string standardName;
// A yearwise cache of DaylightTime.
private static Hashtable daylightCache = new Hashtable (1);
// the offset when daylightsaving is not on.
private static TimeSpan utcOffsetWithOutDLS;
// the offset when daylightsaving is on.
private static TimeSpan utcOffsetWithDLS;
internal enum TimeZoneData {
DaylightSavingStartIdx,
DaylightSavingEndIdx,
UtcOffsetIdx,
AdditionalDaylightOffsetIdx
};
internal enum TimeZoneNames {
StandardNameIdx,
DaylightNameIdx
};
// Internal method to get timezone data.
// data[0]: start of daylight saving time (in DateTime ticks).
// data[1]: end of daylight saving time (in DateTime ticks).
// data[2]: utcoffset (in TimeSpan ticks).
// data[3]: additional offset when daylight saving (in TimeSpan ticks).
// name[0]: name of this timezone when not daylight saving.
// name[1]: name of this timezone when daylight saving.
[MethodImplAttribute(MethodImplOptions.InternalCall)]
private static extern bool GetTimeZoneData (int year,
out Int64[] data,
out string[] names);
// Constructor
internal CurrentTimeZone ()
: base ()
{
Int64[] data;
string[] names;
DateTime now = new DateTime(DateTime.GetNow ());
if (!GetTimeZoneData (now.Year, out data, out names))
throw new NotSupportedException (Locale.GetText ("Can't get timezone name"));
standardName = Locale.GetText (names[(int)TimeZoneNames.StandardNameIdx]);
daylightName = Locale.GetText (names[(int)TimeZoneNames.DaylightNameIdx]);
utcOffsetWithOutDLS = new TimeSpan (data[(int)TimeZoneData.UtcOffsetIdx]);
utcOffsetWithDLS = new TimeSpan (data[(int)TimeZoneData.UtcOffsetIdx] + data[(int)TimeZoneData.AdditionalDaylightOffsetIdx]);
}
// Properties
public override string DaylightName
{
get { return daylightName; }
}
public override string StandardName
{
get { return standardName; }
}
// Methods
[MonoTODO]
public override DaylightTime GetDaylightChanges (int year)
{
if (year < 1 || year > 9999)
throw new ArgumentOutOfRangeException (year + " is not in a range between 1 and 9999.");
if (daylightCache [year] == null) {
Int64[] data;
string[] names;
if (!GetTimeZoneData (year, out data, out names))
throw new ArgumentException (Locale.GetText ("Can't get timezone data for " + year));
DaylightTime dlt = new DaylightTime (new DateTime (data[(int)TimeZoneData.DaylightSavingStartIdx]),
new DateTime (data[(int)TimeZoneData.DaylightSavingEndIdx]),
new TimeSpan (data[(int)TimeZoneData.AdditionalDaylightOffsetIdx]));
daylightCache.Add (year, dlt);
}
return (DaylightTime) daylightCache [year];
}
public override TimeSpan GetUtcOffset (DateTime time)
{
if (IsDaylightSavingTime (time))
return utcOffsetWithDLS;
return utcOffsetWithOutDLS;
}
}
}
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