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//------------------------------------------------------------
// Copyright (c) Microsoft Corporation. All rights reserved.
//------------------------------------------------------------
using System;
using System.Collections.Generic;
using System.Text;
namespace System.IdentityModel
{
static class DateTimeUtil
{
/// <summary>
/// Add a DateTime and a TimeSpan.
/// The maximum time is DateTime.MaxTime. It is not an error if time + timespan > MaxTime.
/// Just return MaxTime.
/// </summary>
/// <param name="time">Initial <see cref="DateTime"/> value.</param>
/// <param name="timespan"><see cref="TimeSpan"/> to add.</param>
/// <returns></returns>
public static DateTime Add(DateTime time, TimeSpan timespan)
{
if (timespan >= TimeSpan.Zero && DateTime.MaxValue - time <= timespan)
{
return GetMaxValue(time.Kind);
}
if (timespan <= TimeSpan.Zero && DateTime.MinValue - time >= timespan)
{
return GetMinValue(time.Kind);
}
return time + timespan;
}
/// <summary>
/// Add a DateTime and a non-negative TimeSpan.
/// The maximum time is DateTime.MaxTime. It is not an error if time + timespan > MaxTime.
/// Just return MaxTime. If TimeSpan is < TimeSpan.Zero, throw exception.
/// </summary>
/// <param name="time"></param>
/// <param name="timespan"></param>
/// <returns></returns>
public static DateTime AddNonNegative(DateTime time, TimeSpan timespan)
{
if (timespan <= TimeSpan.Zero)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new InvalidOperationException(SR.GetString(SR.ID2082)));
}
return Add(time, timespan);
}
public static DateTime GetMaxValue(DateTimeKind kind)
{
return new DateTime(DateTime.MaxValue.Ticks, kind);
}
public static DateTime GetMinValue(DateTimeKind kind)
{
return new DateTime(DateTime.MinValue.Ticks, kind);
}
public static DateTime? ToUniversalTime(DateTime? value)
{
if (null == value || value.Value.Kind == DateTimeKind.Utc)
{
return value;
}
return ToUniversalTime(value.Value);
}
public static DateTime ToUniversalTime(DateTime value)
{
if (value.Kind == DateTimeKind.Utc)
{
return value;
}
return value.ToUniversalTime();
}
}
}
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