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diff --git a/src/mscorlib/src/System/TimeZone.cs b/src/mscorlib/src/System/TimeZone.cs
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-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-/*============================================================
-**
-** Class: TimeZone
-**
-**
-** Purpose:
-** This class is used to represent a TimeZone. It
-** has methods for converting a DateTime to UTC from local time
-** and to local time from UTC and methods for getting the
-** standard name and daylight name of the time zone.
-**
-** The only TimeZone that we support in version 1 is the
-** CurrentTimeZone as determined by the system timezone.
-**
-**
-============================================================*/
-namespace System {
- using System;
- using System.Text;
- using System.Threading;
- using System.Collections;
- using System.Globalization;
-
- [Serializable]
- [Obsolete("System.TimeZone has been deprecated. Please investigate the use of System.TimeZoneInfo instead.")]
- public abstract class TimeZone {
- private static volatile TimeZone currentTimeZone = null;
-
- // Private object for locking instead of locking on a public type for SQL reliability work.
- private static Object s_InternalSyncObject;
- private static Object InternalSyncObject {
- get {
- if (s_InternalSyncObject == null) {
- Object o = new Object();
- Interlocked.CompareExchange<Object>(ref s_InternalSyncObject, o, null);
- }
- return s_InternalSyncObject;
- }
- }
-
-
- protected TimeZone() {
- }
-
- public static TimeZone CurrentTimeZone {
- get {
- //Grabbing the cached value is required at the top of this function so that
- //we don't incur a race condition with the ResetTimeZone method below.
- TimeZone tz = currentTimeZone;
- if (tz == null) {
- lock(InternalSyncObject) {
- if (currentTimeZone == null) {
- currentTimeZone = new CurrentSystemTimeZone();
- }
- tz = currentTimeZone;
- }
- }
- return (tz);
- }
- }
-
- //This method is called by CultureInfo.ClearCachedData in response to control panel
- //change events. It must be synchronized because otherwise there is a race condition
- //with the CurrentTimeZone property above.
- internal static void ResetTimeZone() {
- if (currentTimeZone!=null) {
- lock(InternalSyncObject) {
- currentTimeZone = null;
- }
- }
- }
-
- public abstract String StandardName {
- get;
- }
-
- public abstract String DaylightName {
- get;
- }
-
- public abstract TimeSpan GetUtcOffset(DateTime time);
-
- //
- // Converts the specified datatime to the Universal time base on the current timezone
- //
- public virtual DateTime ToUniversalTime(DateTime time) {
- if (time.Kind == DateTimeKind.Utc) {
- return time;
- }
- long tickCount = time.Ticks - GetUtcOffset(time).Ticks;
- if (tickCount>DateTime.MaxTicks) {
- return new DateTime(DateTime.MaxTicks, DateTimeKind.Utc);
- }
- if (tickCount<DateTime.MinTicks) {
- return new DateTime(DateTime.MinTicks, DateTimeKind.Utc);
- }
- return new DateTime(tickCount, DateTimeKind.Utc);
- }
-
- //
- // Convert the specified datetime value from UTC to the local time based on the time zone.
- //
- public virtual DateTime ToLocalTime(DateTime time) {
- if (time.Kind == DateTimeKind.Local) {
- return time;
- }
- Boolean isAmbiguousLocalDst = false;
- Int64 offset = ((CurrentSystemTimeZone)(TimeZone.CurrentTimeZone)).GetUtcOffsetFromUniversalTime(time, ref isAmbiguousLocalDst);
- return new DateTime(time.Ticks + offset, DateTimeKind.Local, isAmbiguousLocalDst);
- }
-
- // Return an array of DaylightTime which reflects the daylight saving periods in a particular year.
- // We currently only support having one DaylightSavingTime per year.
- // If daylight saving time is not used in this timezone, null will be returned.
- public abstract DaylightTime GetDaylightChanges(int year);
-
- public virtual bool IsDaylightSavingTime(DateTime time) {
- return (IsDaylightSavingTime(time, GetDaylightChanges(time.Year)));
- }
-
- // Check if the specified time is in a daylight saving time. Allows the user to
- // specify the array of Daylight Saving Times.
- public static bool IsDaylightSavingTime(DateTime time, DaylightTime daylightTimes) {
- return CalculateUtcOffset(time, daylightTimes)!=TimeSpan.Zero;
- }
-
- //
- // NOTENOTE: Implementation detail
- // In the transition from standard time to daylight saving time,
- // if we convert local time to Universal time, we can have the
- // following (take PST as an example):
- // Local Universal UTC Offset
- // ----- --------- ----------
- // 01:00AM 09:00 -8:00
- // 02:00 (=> 03:00) 10:00 -8:00 [This time doesn't actually exist, but it can be created from DateTime]
- // 03:00 10:00 -7:00
- // 04:00 11:00 -7:00
- // 05:00 12:00 -7:00
- //
- // So from 02:00 - 02:59:59, we should return the standard offset, instead of the daylight saving offset.
- //
- // In the transition from daylight saving time to standard time,
- // if we convert local time to Universal time, we can have the
- // following (take PST as an example):
- // Local Universal UTC Offset
- // ----- --------- ----------
- // 01:00AM 08:00 -7:00
- // 02:00 (=> 01:00) 09:00 -8:00
- // 02:00 10:00 -8:00
- // 03:00 11:00 -8:00
- // 04:00 12:00 -8:00
- //
- // So in this case, the 02:00 does exist after the first 2:00 rolls back to 01:00. We don't need to special case this.
- // But note that there are two 01:00 in the local time.
-
- //
- // And imagine if the daylight saving offset is negative (although this does not exist in real life)
- // In the transition from standard time to daylight saving time,
- // if we convert local time to Universal time, we can have the
- // following (take PST as an example, but the daylight saving offset is -01:00):
- // Local Universal UTC Offset
- // ----- --------- ----------
- // 01:00AM 09:00 -8:00
- // 02:00 (=> 01:00) 10:00 -9:00
- // 02:00 11:00 -9:00
- // 03:00 12:00 -9:00
- // 04:00 13:00 -9:00
- // 05:00 14:00 -9:00
- //
- // So in this case, the 02:00 does exist after the first 2:00 rolls back to 01:00. We don't need to special case this.
- //
- // In the transition from daylight saving time to standard time,
- // if we convert local time to Universal time, we can have the
- // following (take PST as an example, daylight saving offset is -01:00):
- //
- // Local Universal UTC Offset
- // ----- --------- ----------
- // 01:00AM 10:00 -9:00
- // 02:00 (=> 03:00) 11:00 -9:00
- // 03:00 11:00 -8:00
- // 04:00 12:00 -8:00
- // 05:00 13:00 -8:00
- // 06:00 14:00 -8:00
- //
- // So from 02:00 - 02:59:59, we should return the daylight saving offset, instead of the standard offset.
- //
- internal static TimeSpan CalculateUtcOffset(DateTime time, DaylightTime daylightTimes) {
- if (daylightTimes==null) {
- return TimeSpan.Zero;
- }
- DateTimeKind kind = time.Kind;
- if (kind == DateTimeKind.Utc) {
- return TimeSpan.Zero;
- }
-
- DateTime startTime;
- DateTime endTime;
-
- // startTime and endTime represent the period from either the start of DST to the end and includes the
- // potentially overlapped times
- startTime = daylightTimes.Start + daylightTimes.Delta;
- endTime = daylightTimes.End;
-
- // For normal time zones, the ambiguous hour is the last hour of daylight saving when you wind the
- // clock back. It is theoretically possible to have a positive delta, (which would really be daylight
- // reduction time), where you would have to wind the clock back in the begnning.
- DateTime ambiguousStart;
- DateTime ambiguousEnd;
- if (daylightTimes.Delta.Ticks > 0) {
- ambiguousStart = endTime - daylightTimes.Delta;
- ambiguousEnd = endTime;
- } else {
- ambiguousStart = startTime;
- ambiguousEnd = startTime - daylightTimes.Delta;
- }
-
- Boolean isDst = false;
- if (startTime > endTime) {
- // In southern hemisphere, the daylight saving time starts later in the year, and ends in the beginning of next year.
- // Note, the summer in the southern hemisphere begins late in the year.
- if (time >= startTime || time < endTime) {
- isDst = true;
- }
- }
- else if (time>=startTime && time < endTime) {
- // In northern hemisphere, the daylight saving time starts in the middle of the year.
- isDst = true;
- }
-
- // If this date was previously converted from a UTC date and we were able to detect that the local
- // DateTime would be ambiguous, this data is stored in the DateTime to resolve this ambiguity.
- if (isDst && time >= ambiguousStart && time < ambiguousEnd) {
- isDst = time.IsAmbiguousDaylightSavingTime();
- }
-
- if (isDst) {
- return daylightTimes.Delta;
- }
- return TimeSpan.Zero;
- }
- }
-}