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Utf8Parser.Integer.Signed.D.cs
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Utf8Parser.Integer.Signed.D.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.
namespace System.Buffers.Text
{
public static partial class Utf8Parser
{
private static bool TryParseSByteD(ReadOnlySpan<byte> source, out sbyte value, out int bytesConsumed)
{
if (source.Length < 1)
goto FalseExit;
int sign = 1;
int index = 0;
int num = source[index];
if (num == '-')
{
sign = -1;
index++;
if ((uint)index >= (uint)source.Length)
goto FalseExit;
num = source[index];
}
else if (num == '+')
{
index++;
if ((uint)index >= (uint)source.Length)
goto FalseExit;
num = source[index];
}
int answer = 0;
if (ParserHelpers.IsDigit(num))
{
if (num == '0')
{
do
{
index++;
if ((uint)index >= (uint)source.Length)
goto Done;
num = source[index];
} while (num == '0');
if (!ParserHelpers.IsDigit(num))
goto Done;
}
answer = num - '0';
index++;
if ((uint)index >= (uint)source.Length)
goto Done;
num = source[index];
if (!ParserHelpers.IsDigit(num))
goto Done;
index++;
answer = 10 * answer + num - '0';
// Potential overflow
if ((uint)index >= (uint)source.Length)
goto Done;
num = source[index];
if (!ParserHelpers.IsDigit(num))
goto Done;
index++;
answer = answer * 10 + num - '0';
// if sign < 0, (-1 * sign + 1) / 2 = 1
// else, (-1 * sign + 1) / 2 = 0
if ((uint)answer > (uint)sbyte.MaxValue + (-1 * sign + 1) / 2)
goto FalseExit; // Overflow
if ((uint)index >= (uint)source.Length)
goto Done;
if (!ParserHelpers.IsDigit(source[index]))
goto Done;
// Guaranteed overflow
goto FalseExit;
}
FalseExit:
bytesConsumed = default;
value = default;
return false;
Done:
bytesConsumed = index;
value = (sbyte)(answer * sign);
return true;
}
private static bool TryParseInt16D(ReadOnlySpan<byte> source, out short value, out int bytesConsumed)
{
if (source.Length < 1)
goto FalseExit;
int sign = 1;
int index = 0;
int num = source[index];
if (num == '-')
{
sign = -1;
index++;
if ((uint)index >= (uint)source.Length)
goto FalseExit;
num = source[index];
}
else if (num == '+')
{
index++;
if ((uint)index >= (uint)source.Length)
goto FalseExit;
num = source[index];
}
int answer = 0;
if (ParserHelpers.IsDigit(num))
{
if (num == '0')
{
do
{
index++;
if ((uint)index >= (uint)source.Length)
goto Done;
num = source[index];
} while (num == '0');
if (!ParserHelpers.IsDigit(num))
goto Done;
}
answer = num - '0';
index++;
if ((uint)index >= (uint)source.Length)
goto Done;
num = source[index];
if (!ParserHelpers.IsDigit(num))
goto Done;
index++;
answer = 10 * answer + num - '0';
if ((uint)index >= (uint)source.Length)
goto Done;
num = source[index];
if (!ParserHelpers.IsDigit(num))
goto Done;
index++;
answer = 10 * answer + num - '0';
if ((uint)index >= (uint)source.Length)
goto Done;
num = source[index];
if (!ParserHelpers.IsDigit(num))
goto Done;
index++;
answer = 10 * answer + num - '0';
// Potential overflow
if ((uint)index >= (uint)source.Length)
goto Done;
num = source[index];
if (!ParserHelpers.IsDigit(num))
goto Done;
index++;
answer = answer * 10 + num - '0';
// if sign < 0, (-1 * sign + 1) / 2 = 1
// else, (-1 * sign + 1) / 2 = 0
if ((uint)answer > (uint)short.MaxValue + (-1 * sign + 1) / 2)
goto FalseExit; // Overflow
if ((uint)index >= (uint)source.Length)
goto Done;
if (!ParserHelpers.IsDigit(source[index]))
goto Done;
// Guaranteed overflow
goto FalseExit;
}
FalseExit:
bytesConsumed = default;
value = default;
return false;
Done:
bytesConsumed = index;
value = (short)(answer * sign);
return true;
}
private static bool TryParseInt32D(ReadOnlySpan<byte> source, out int value, out int bytesConsumed)
{
if (source.Length < 1)
goto FalseExit;
int sign = 1;
int index = 0;
int num = source[index];
if (num == '-')
{
sign = -1;
index++;
if ((uint)index >= (uint)source.Length)
goto FalseExit;
num = source[index];
}
else if (num == '+')
{
index++;
if ((uint)index >= (uint)source.Length)
goto FalseExit;
num = source[index];
}
int answer = 0;
if (ParserHelpers.IsDigit(num))
{
if (num == '0')
{
do
{
index++;
if ((uint)index >= (uint)source.Length)
goto Done;
num = source[index];
} while (num == '0');
if (!ParserHelpers.IsDigit(num))
goto Done;
}
answer = num - '0';
index++;
if ((uint)index >= (uint)source.Length)
goto Done;
num = source[index];
if (!ParserHelpers.IsDigit(num))
goto Done;
index++;
answer = 10 * answer + num - '0';
if ((uint)index >= (uint)source.Length)
goto Done;
num = source[index];
if (!ParserHelpers.IsDigit(num))
goto Done;
index++;
answer = 10 * answer + num - '0';
if ((uint)index >= (uint)source.Length)
goto Done;
num = source[index];
if (!ParserHelpers.IsDigit(num))
goto Done;
index++;
answer = 10 * answer + num - '0';
if ((uint)index >= (uint)source.Length)
goto Done;
num = source[index];
if (!ParserHelpers.IsDigit(num))
goto Done;
index++;
answer = 10 * answer + num - '0';
if ((uint)index >= (uint)source.Length)
goto Done;
num = source[index];
if (!ParserHelpers.IsDigit(num))
goto Done;
index++;
answer = 10 * answer + num - '0';
if ((uint)index >= (uint)source.Length)
goto Done;
num = source[index];
if (!ParserHelpers.IsDigit(num))
goto Done;
index++;
answer = 10 * answer + num - '0';
if ((uint)index >= (uint)source.Length)
goto Done;
num = source[index];
if (!ParserHelpers.IsDigit(num))
goto Done;
index++;
answer = 10 * answer + num - '0';
if ((uint)index >= (uint)source.Length)
goto Done;
num = source[index];
if (!ParserHelpers.IsDigit(num))
goto Done;
index++;
answer = 10 * answer + num - '0';
// Potential overflow
if ((uint)index >= (uint)source.Length)
goto Done;
num = source[index];
if (!ParserHelpers.IsDigit(num))
goto Done;
index++;
if (answer > int.MaxValue / 10)
goto FalseExit; // Overflow
answer = answer * 10 + num - '0';
// if sign < 0, (-1 * sign + 1) / 2 = 1
// else, (-1 * sign + 1) / 2 = 0
if ((uint)answer > (uint)int.MaxValue + (-1 * sign + 1) / 2)
goto FalseExit; // Overflow
if ((uint)index >= (uint)source.Length)
goto Done;
if (!ParserHelpers.IsDigit(source[index]))
goto Done;
// Guaranteed overflow
goto FalseExit;
}
FalseExit:
bytesConsumed = default;
value = default;
return false;
Done:
bytesConsumed = index;
value = answer * sign;
return true;
}
private static bool TryParseInt64D(ReadOnlySpan<byte> source, out long value, out int bytesConsumed)
{
if (source.Length < 1)
{
bytesConsumed = 0;
value = default;
return false;
}
int indexOfFirstDigit = 0;
int sign = 1;
if (source[0] == '-')
{
indexOfFirstDigit = 1;
sign = -1;
if (source.Length <= indexOfFirstDigit)
{
bytesConsumed = 0;
value = default;
return false;
}
}
else if (source[0] == '+')
{
indexOfFirstDigit = 1;
if (source.Length <= indexOfFirstDigit)
{
bytesConsumed = 0;
value = default;
return false;
}
}
int overflowLength = ParserHelpers.Int64OverflowLength + indexOfFirstDigit;
// Parse the first digit separately. If invalid here, we need to return false.
long firstDigit = source[indexOfFirstDigit] - 48; // '0'
if (firstDigit < 0 || firstDigit > 9)
{
bytesConsumed = 0;
value = default;
return false;
}
ulong parsedValue = (ulong)firstDigit;
if (source.Length < overflowLength)
{
// Length is less than Parsers.Int64OverflowLength; overflow is not possible
for (int index = indexOfFirstDigit + 1; index < source.Length; index++)
{
long nextDigit = source[index] - 48; // '0'
if (nextDigit < 0 || nextDigit > 9)
{
bytesConsumed = index;
value = ((long)parsedValue) * sign;
return true;
}
parsedValue = parsedValue * 10 + (ulong)nextDigit;
}
}
else
{
// Length is greater than Parsers.Int64OverflowLength; overflow is only possible after Parsers.Int64OverflowLength
// digits. There may be no overflow after Parsers.Int64OverflowLength if there are leading zeroes.
for (int index = indexOfFirstDigit + 1; index < overflowLength - 1; index++)
{
long nextDigit = source[index] - 48; // '0'
if (nextDigit < 0 || nextDigit > 9)
{
bytesConsumed = index;
value = ((long)parsedValue) * sign;
return true;
}
parsedValue = parsedValue * 10 + (ulong)nextDigit;
}
for (int index = overflowLength - 1; index < source.Length; index++)
{
long nextDigit = source[index] - 48; // '0'
if (nextDigit < 0 || nextDigit > 9)
{
bytesConsumed = index;
value = ((long)parsedValue) * sign;
return true;
}
// If parsedValue > (long.MaxValue / 10), any more appended digits will cause overflow.
// if parsedValue == (long.MaxValue / 10), any nextDigit greater than 7 or 8 (depending on sign) implies overflow.
bool positive = sign > 0;
bool nextDigitTooLarge = nextDigit > 8 || (positive && nextDigit > 7);
if (parsedValue > long.MaxValue / 10 || parsedValue == long.MaxValue / 10 && nextDigitTooLarge)
{
bytesConsumed = 0;
value = default;
return false;
}
parsedValue = parsedValue * 10 + (ulong)nextDigit;
}
}
bytesConsumed = source.Length;
value = ((long)parsedValue) * sign;
return true;
}
}
}