/// <summary>Parses a token that starts with a digit.</summary>
/// <returns>The kind of token recognized.</returns>
private ExpressionTokenKind ParseFromDigit()
{
Debug.Assert(this.IsValidDigit || ('-' == this.ch), "this.IsValidDigit || ('-' == this.ch)");
ExpressionTokenKind result;
int tokenPos = this.textPos;
char?startChar = this.ch;
this.NextChar();
if (startChar == '0' && (this.ch == 'x' || this.ch == 'X'))
{
result = ExpressionTokenKind.BinaryLiteral;
do
{
this.NextChar();
}while (this.ch.HasValue && WebConvert.IsCharHexDigit(this.ch.Value));
}
else
{
result = ExpressionTokenKind.IntegerLiteral;
while (this.IsValidDigit)
{
this.NextChar();
}
// DateTimeOffset and Guids will have '-' in them
if (this.ch == '-')
{
if (this.TryParseDateTimeoffset(tokenPos))
{
return(ExpressionTokenKind.DateTimeOffsetLiteral);
}
else if (this.TryParseGuid(tokenPos))
{
return(ExpressionTokenKind.GuidLiteral);
}
}
// Guids will have alpha-numeric characters along with '-', so if a letter is encountered
// try to see if this is Guid or not.
if (this.ch.HasValue && Char.IsLetter(this.ch.Value))
{
if (this.TryParseGuid(tokenPos))
{
return(ExpressionTokenKind.GuidLiteral);
}
}
if (this.ch == '.')
{
result = ExpressionTokenKind.DoubleLiteral;
this.NextChar();
this.ValidateDigit();
do
{
this.NextChar();
}while (this.IsValidDigit);
}
if (this.ch == 'E' || this.ch == 'e')
{
result = ExpressionTokenKind.DoubleLiteral;
this.NextChar();
if (this.ch == '+' || this.ch == '-')
{
this.NextChar();
}
this.ValidateDigit();
do
{
this.NextChar();
}while (this.IsValidDigit);
}
if (this.ch == 'M' || this.ch == 'm')
{
result = ExpressionTokenKind.DecimalLiteral;
this.NextChar();
}
else if (this.ch == 'd' || this.ch == 'D')
{
result = ExpressionTokenKind.DoubleLiteral;
this.NextChar();
}
else if (this.ch == 'L' || this.ch == 'l')
{
result = ExpressionTokenKind.Int64Literal;
this.NextChar();
}
else if (this.ch == 'f' || this.ch == 'F')
{
result = ExpressionTokenKind.SingleLiteral;
this.NextChar();
}
else
{
string valueStr = this.text.Substring(tokenPos, this.textPos - tokenPos);
result = MakeBestGuessOnNoSuffixStr(valueStr, result);
}
}
return(result);
}
