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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
namespace System.Buffers.Text
{
public static partial class Utf8Parser
{
/// <summary>
/// Parses a Decimal 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/g (default)
/// F/f 12.45 Fixed point
/// E/e 1.245000e1 Exponential
/// </remarks>
/// <exceptions>
/// <cref>System.FormatException</cref> if the format is not valid for this data type.
/// </exceptions>
public static unsafe bool TryParse(ReadOnlySpan<byte> source, out decimal value, out int bytesConsumed, char standardFormat = default)
{
ParseNumberOptions options;
switch (standardFormat)
{
case default(char):
case 'G':
case 'g':
case 'E':
case 'e':
options = ParseNumberOptions.AllowExponent;
break;
case 'F':
case 'f':
options = default;
break;
default:
return ParserHelpers.TryParseThrowFormatException(out value, out bytesConsumed);
}
byte* pDigits = stackalloc byte[Number.DecimalNumberBufferLength];
Number.NumberBuffer number = new Number.NumberBuffer(Number.NumberBufferKind.Decimal, pDigits, Number.DecimalNumberBufferLength);
if (!TryParseNumber(source, ref number, out bytesConsumed, options, out bool textUsedExponentNotation))
{
value = default;
return false;
}
if ((!textUsedExponentNotation) && (standardFormat == 'E' || standardFormat == 'e'))
{
value = default;
bytesConsumed = 0;
return false;
}
value = default;
if (!Number.TryNumberToDecimal(ref number, ref value))
{
value = default;
bytesConsumed = 0;
return false;
}
return true;
}
}
}
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