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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.
#nullable enable
using System.Diagnostics;
namespace System.Buffers.Text
{
public static partial class Utf8Parser
{
/// <summary>
/// Parses a DateTime at the start of a Utf8 string.
/// </summary>
/// <param name="source">The Utf8 string to parse</param>
/// <param name="value">Receives the parsed value</param>
/// <param name="bytesConsumed">On a successful parse, receives the length in bytes of the substring that was parsed </param>
/// <param name="standardFormat">Expected format of the Utf8 string</param>
/// <returns>
/// true for success. "bytesConsumed" contains the length in bytes of the substring that was parsed.
/// false if the string was not syntactically valid or an overflow or underflow occurred. "bytesConsumed" is set to 0.
/// </returns>
/// <remarks>
/// Formats supported:
/// default 05/25/2017 10:30:15 -08:00
/// G 05/25/2017 10:30:15
/// R Tue, 03 Jan 2017 08:08:05 GMT (RFC 1123)
/// l tue, 03 jan 2017 08:08:05 gmt (Lowercase RFC 1123)
/// O 2017-06-12T05:30:45.7680000-07:00 (Round-trippable)
/// </remarks>
/// <exceptions>
/// <cref>System.FormatException</cref> if the format is not valid for this data type.
/// </exceptions>
public static bool TryParse(ReadOnlySpan<byte> source, out DateTime value, out int bytesConsumed, char standardFormat = default)
{
switch (standardFormat)
{
case 'R':
{
if (!TryParseDateTimeOffsetR(source, NoFlipCase, out DateTimeOffset dateTimeOffset, out bytesConsumed))
{
value = default;
return false;
}
value = dateTimeOffset.DateTime; // (returns a DateTimeKind.Unspecified to match DateTime.ParseExact(). Maybe better to return UtcDateTime instead?)
return true;
}
case 'l':
{
if (!TryParseDateTimeOffsetR(source, FlipCase, out DateTimeOffset dateTimeOffset, out bytesConsumed))
{
value = default;
return false;
}
value = dateTimeOffset.DateTime; // (returns a DateTimeKind.Unspecified to match DateTime.ParseExact(). Maybe better to return UtcDateTime instead?)
return true;
}
case 'O':
{
// Emulates DateTime.ParseExact(text, "O", CultureInfo.InvariantCulture, DateTimeStyles.RoundtripKind)
// In particular, the formatted string "encodes" the DateTimeKind according to the following table:
//
// 2017-06-12T05:30:45.7680000 - Unspecified
// 2017-06-12T05:30:45.7680000+00:00 - Local
// 2017-06-12T05:30:45.7680000Z - Utc
if (!TryParseDateTimeOffsetO(source, out DateTimeOffset dateTimeOffset, out bytesConsumed, out DateTimeKind kind))
{
value = default;
bytesConsumed = 0;
return false;
}
switch (kind)
{
case DateTimeKind.Local:
value = dateTimeOffset.LocalDateTime;
break;
case DateTimeKind.Utc:
value = dateTimeOffset.UtcDateTime;
break;
default:
Debug.Assert(kind == DateTimeKind.Unspecified);
value = dateTimeOffset.DateTime;
break;
}
return true;
}
case default(char):
case 'G':
return TryParseDateTimeG(source, out value, out _, out bytesConsumed);
default:
return ParserHelpers.TryParseThrowFormatException(out value, out bytesConsumed);
}
}
/// <summary>
/// Parses a DateTimeOffset at the start of a Utf8 string.
/// </summary>
/// <param name="source">The Utf8 string to parse</param>
/// <param name="value">Receives the parsed value</param>
/// <param name="bytesConsumed">On a successful parse, receives the length in bytes of the substring that was parsed </param>
/// <param name="standardFormat">Expected format of the Utf8 string</param>
/// <returns>
/// true for success. "bytesConsumed" contains the length in bytes of the substring that was parsed.
/// false if the string was not syntactically valid or an overflow or underflow occurred. "bytesConsumed" is set to 0.
/// </returns>
/// <remarks>
/// Formats supported:
/// G (default) 05/25/2017 10:30:15
/// R Tue, 03 Jan 2017 08:08:05 GMT (RFC 1123)
/// l tue, 03 jan 2017 08:08:05 gmt (Lowercase RFC 1123)
/// O 2017-06-12T05:30:45.7680000-07:00 (Round-trippable)
/// </remarks>
/// <exceptions>
/// <cref>System.FormatException</cref> if the format is not valid for this data type.
/// </exceptions>
public static bool TryParse(ReadOnlySpan<byte> source, out DateTimeOffset value, out int bytesConsumed, char standardFormat = default)
{
switch (standardFormat)
{
case 'R':
return TryParseDateTimeOffsetR(source, NoFlipCase, out value, out bytesConsumed);
case 'l':
return TryParseDateTimeOffsetR(source, FlipCase, out value, out bytesConsumed);
case 'O':
return TryParseDateTimeOffsetO(source, out value, out bytesConsumed, out _);
case default(char):
return TryParseDateTimeOffsetDefault(source, out value, out bytesConsumed);
case 'G':
return TryParseDateTimeG(source, out DateTime _, out value, out bytesConsumed);
default:
return ParserHelpers.TryParseThrowFormatException(out value, out bytesConsumed);
}
}
private const uint FlipCase = 0x00000020u; // XOR mask to flip the case of a letter.
private const uint NoFlipCase = 0x00000000u;
}
}
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