private static bool ParseNumberLiteralDoubleFloat(string text, ref string error, NumberLiteralSuffix type,
out object numberLiteral)
{
numberLiteral = null;
if (text.Contains(".") || text.Contains("e") || type == NumberLiteralSuffix.Float ||
type == NumberLiteralSuffix.Double)
{
const NumberStyles decimalStyle = NumberStyles.AllowLeadingSign | NumberStyles.AllowDecimalPoint;
// real number
switch (type)
{
case NumberLiteralSuffix.None: // double is defualt
case NumberLiteralSuffix.Double:
{
numberLiteral = TryParse <double>(double.TryParse, text, out error, decimalStyle);
return(true);
}
case NumberLiteralSuffix.Float:
{
numberLiteral = TryParse <float>(float.TryParse, text, out error, decimalStyle);
return(true);
}
case NumberLiteralSuffix.Decimal:
{
numberLiteral = TryParse <decimal>(decimal.TryParse, text, out error, decimalStyle);
return(true);
}
default:
error = $"could not parse real number of type {type}";
{
return(true);
}
}
}
return(false);
}
private static bool ParseNumberLiteralSuffix(ref string text, ref string error, char lastDigit, ref NumberLiteralSuffix type)
{
if (char.IsLetter(lastDigit))
{
// number type suffix
if (lastDigit == 'm')
{
type = NumberLiteralSuffix.Decimal;
}
else if (lastDigit == 'f')
{
type = NumberLiteralSuffix.Float;
}
else if (lastDigit == 'd')
{
type = NumberLiteralSuffix.Double;
}
else if (text.EndsWith("ul", StringComparison.Ordinal) || text.EndsWith("lu", StringComparison.Ordinal))
{
type = NumberLiteralSuffix.UnsignedLong;
}
else if (lastDigit == 'u')
{
type = NumberLiteralSuffix.Unsigned;
}
else if (lastDigit == 'l')
{
type = NumberLiteralSuffix.Long;
}
else
{
error = "number literal type suffix not known";
return(true);
}
if (type == NumberLiteralSuffix.UnsignedLong)
{
text = text.Remove(text.Length - 2); // remove 2 last chars
}
else
{
text = text.Remove(text.Length - 1); // remove last char
}
}
return(false);
}
private static object ParseNumberLiteral(string text, out string error)
{
text = text.ToLower();
error = null;
NumberLiteralSuffix type = NumberLiteralSuffix.None;
var lastDigit = text[text.Length - 1];
if (ParseNumberLiteralSuffix(ref text, ref error, lastDigit, ref type))
{
return(null);
}
object numberLiteral;
if (ParseNumberLiteralDoubleFloat(text, ref error, type, out numberLiteral))
{
return(numberLiteral);
}
const NumberStyles integerStyle = NumberStyles.AllowLeadingSign;
// try parse integral constant
object result = null;
if (type == NumberLiteralSuffix.None)
{
result = TryParse <int>(int.TryParse, text, integerStyle) ??
TryParse <uint>(uint.TryParse, text, integerStyle) ??
TryParse <long>(long.TryParse, text, integerStyle) ??
TryParse <ulong>(ulong.TryParse, text, integerStyle);
}
else if (type == NumberLiteralSuffix.Unsigned)
{
result = TryParse <uint>(uint.TryParse, text, integerStyle) ??
TryParse <ulong>(ulong.TryParse, text, integerStyle);
}
else if (type == NumberLiteralSuffix.Long)
{
result = TryParse <long>(long.TryParse, text, integerStyle) ??
TryParse <ulong>(ulong.TryParse, text, integerStyle);
}
else if (type == NumberLiteralSuffix.UnsignedLong)
{
result = TryParse <ulong>(ulong.TryParse, text, integerStyle);
}
if (result != null)
{
return(result);
}
// handle errors
// if all are digits, or '0x' + hex digits => too large number
if (text.All(char.IsDigit) ||
(text.StartsWith("0x", StringComparison.Ordinal) && text.Skip(2).All(c => char.IsDigit(c) || (c >= 'a' && c <= 'f'))))
{
error = $"number number {text} is too large for integral literal, try to append 'd' to real number literal";
}
else
{
error = $"could not parse {text} as numeric literal";
}
return(null);
}
