70 lines
2.8 KiB
C#
70 lines
2.8 KiB
C#
// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT license.
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// See the LICENSE file in the project root for more information.
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namespace System
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{
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partial class TimeZoneInfo
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{
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//
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// TransitionTimeToDateTime -
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//
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// Helper function that converts a year and TransitionTime into a DateTime
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//
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static internal DateTime TransitionTimeToDateTime(Int32 year, TransitionTime transitionTime) {
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DateTime value;
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DateTime timeOfDay = transitionTime.TimeOfDay;
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if (transitionTime.IsFixedDateRule) {
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// create a DateTime from the passed in year and the properties on the transitionTime
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// if the day is out of range for the month then use the last day of the month
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Int32 day = DateTime.DaysInMonth(year, transitionTime.Month);
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value = new DateTime(year, transitionTime.Month, (day < transitionTime.Day) ? day : transitionTime.Day,
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timeOfDay.Hour, timeOfDay.Minute, timeOfDay.Second, timeOfDay.Millisecond);
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}
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else {
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if (transitionTime.Week <= 4) {
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//
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// Get the (transitionTime.Week)th Sunday.
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//
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value = new DateTime(year, transitionTime.Month, 1,
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timeOfDay.Hour, timeOfDay.Minute, timeOfDay.Second, timeOfDay.Millisecond);
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int dayOfWeek = (int)value.DayOfWeek;
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int delta = (int)transitionTime.DayOfWeek - dayOfWeek;
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if (delta < 0) {
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delta += 7;
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}
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delta += 7 * (transitionTime.Week - 1);
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if (delta > 0) {
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value = value.AddDays(delta);
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}
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}
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else {
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//
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// If TransitionWeek is greater than 4, we will get the last week.
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//
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Int32 daysInMonth = DateTime.DaysInMonth(year, transitionTime.Month);
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value = new DateTime(year, transitionTime.Month, daysInMonth,
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timeOfDay.Hour, timeOfDay.Minute, timeOfDay.Second, timeOfDay.Millisecond);
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// This is the day of week for the last day of the month.
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int dayOfWeek = (int)value.DayOfWeek;
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int delta = dayOfWeek - (int)transitionTime.DayOfWeek;
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if (delta < 0) {
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delta += 7;
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}
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if (delta > 0) {
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value = value.AddDays(-delta);
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}
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}
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}
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return value;
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}
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} // TimezoneInfo
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} // namespace System
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