public static bool Try_Parse_Integer(DataConsumer <char> Stream, out long outValue)
{/* Docs: https://html.spec.whatwg.org/multipage/common-microsyntaxes.html#signed-integers */
if (Stream is null)
{
throw new ArgumentNullException(nameof(Stream));
}
Contract.EndContractBlock();
bool sign = true;
/* SKip ASCII whitespace */
Stream.Consume_While(Is_Ascii_Whitespace);
if (Stream.atEnd)
{
outValue = long.MaxValue;
return(false);
}
if (Stream.Next == CHAR_HYPHEN_MINUS)
{
sign = false;
Stream.Consume();
}
else if (Stream.Next == CHAR_PLUS_SIGN)
{
Stream.Consume();
}
if (!Stream.atEnd && !Is_Ascii_Digit(Stream.Next))
{
outValue = long.MaxValue;
return(false);
}
/* Collect sequence of ASCII digit codepoints */
Stream.Consume_While(Is_Ascii_Digit, out ReadOnlySpan <char> outDigits);
var parsed = ParsingCommon.Digits_To_Base10(outDigits);
outValue = sign ? parsed : 0 - parsed;
return(true);
}
public void Digits_To_Base10Test(long expected, string input)
{
Assert.Equal(expected, ParsingCommon.Digits_To_Base10(input));
}
public static bool Try_Parse_FloatingPoint(DataConsumer <char> Stream, out double outValue)
{/* Docs: https://html.spec.whatwg.org/multipage/common-microsyntaxes.html#rules-for-parsing-floating-point-number-values */
if (Stream is null)
{
throw new ArgumentNullException(nameof(Stream));
}
Contract.EndContractBlock();
double value = 1;
double divisor = 1;
double exponent = 1;
/* Skip ASCII whitespace */
Stream.Consume_While(Is_Ascii_Whitespace);
if (Stream.atEnd)
{
outValue = double.NaN;
return(false);
}
switch (Stream.Next)
{
case CHAR_HYPHEN_MINUS:
{
value = divisor = -1;
Stream.Consume();
}
break;
case CHAR_PLUS_SIGN:
{
Stream.Consume();
}
break;
}
if (Stream.atEnd)
{
outValue = double.NaN;
return(false);
}
/* 9) If the character indicated by position is a U+002E FULL STOP (.),
* and that is not the last character in input,
* and the character after the character indicated by position is an ASCII digit,
* then set value to zero and jump to the step labeled fraction. */
if (Stream.Remaining > 1 && Stream.Next == CHAR_FULL_STOP && Is_Ascii_Digit(Stream.NextNext))
{
value = 0;
}
else if (!Is_Ascii_Digit(Stream.Next))
{
outValue = double.NaN;
return(false);
}
else
{
/* 11) Collect a sequence of code points that are ASCII digits from input given position, and interpret the resulting sequence as a base-ten integer. Multiply value by that integer. */
Stream.Consume_While(Is_Ascii_Digit, out ReadOnlySpan <char> outDigits);
value *= ParsingCommon.Digits_To_Base10(outDigits);
}
/* 12) If position is past the end of input, jump to the step labeled conversion. */
if (!Stream.atEnd)
{
/* 13) Fraction: If the character indicated by position is a U+002E FULL STOP (.), run these substeps: */
if (Stream.Next == CHAR_FULL_STOP)
{
Stream.Consume();
/* 2) If position is past the end of input, or if the character indicated by position is not an ASCII digit, U+0065 LATIN SMALL LETTER E (e), or U+0045 LATIN CAPITAL LETTER E (E), then jump to the step labeled conversion. */
if (!Stream.atEnd && (Is_Ascii_Digit(Stream.Next) || Stream.Next == CHAR_E_LOWER || Stream.Next == CHAR_E_UPPER))
{
/* 3) If the character indicated by position is a U+0065 LATIN SMALL LETTER E character (e) or a U+0045 LATIN CAPITAL LETTER E character (E), skip the remainder of these substeps. */
if (Is_Ascii_Digit(Stream.Next))
{
while (Is_Ascii_Digit(Stream.Next))
{
/* 4) Fraction loop: Multiply divisor by ten. */
divisor *= 10;
/* 5) Add the value of the character indicated by position, interpreted as a base-ten digit (0..9) and divided by divisor, to value. */
double n = Ascii_Digit_To_Value(Stream.Next) / divisor;
value += n;
/* 6) Advance position to the next character. */
Stream.Consume();
/* 7) If position is past the end of input, then jump to the step labeled conversion. */
if (Stream.atEnd)
{
break;
}
}
}
}
}
/* 14) If the character indicated by position is U+0065 (e) or a U+0045 (E), then: */
if (Stream.Next == CHAR_E_LOWER || Stream.Next == CHAR_E_UPPER)
{
Stream.Consume();
/* 2) If position is past the end of input, then jump to the step labeled conversion. */
/* 3) If the character indicated by position is a U+002D HYPHEN-MINUS character (-): */
if (Stream.Next == CHAR_HYPHEN_MINUS)
{
exponent = -1;
Stream.Consume();
}
else if (Stream.Next == CHAR_PLUS_SIGN)
{
Stream.Consume();
}
/* 4) If the character indicated by position is not an ASCII digit, then jump to the step labeled conversion. */
if (Is_Ascii_Digit(Stream.Next))
{
/* 5) Collect a sequence of code points that are ASCII digits from input given position, and interpret the resulting sequence as a base-ten integer. Multiply exponent by that integer. */
Stream.Consume_While(Is_Ascii_Digit, out ReadOnlySpan <char> outDigits);
exponent *= ParsingCommon.Digits_To_Base10(outDigits);
/* 6) Multiply value by ten raised to the exponentth power. */
value *= Math.Pow(10, exponent);
}
}
}
/* 15) Conversion: Let S be the set of finite IEEE 754 double-precision floating-point values except −0, but with two special values added: 21024 and −21024. */
/* 16) Let rounded-value be the number in S that is closest to value,
* selecting the number with an even significand if there are two equally close values.
* (The two special values 21024 and −21024 are considered to have even significands for this purpose.) */
var roundedValue = Math.Round(value, MidpointRounding.ToEven);
/* 17) If rounded-value is 21024 or −21024, return an error. */
if ((roundedValue == double.MinValue) || (roundedValue == double.MaxValue))
{
outValue = double.NaN;
return(false);
}
outValue = roundedValue;
return(true);
}
