private IToken TryGetNumericLiteral()
{
bool dotoccurred = false;
bool expoccurred = false;
bool negoccurred = false;
if (Length == 1)
{
dotoccurred = true;
}
char next = Peek();
while (Char.IsDigit(next) || next == '-' || next == '+' || next == 'e' || (next == '.' && !dotoccurred))
{
// Consume the Character
ConsumeCharacter();
if (next == '+')
{
// Can only be first character in the numeric literal or come immediately after the 'e'
if (Length > 1 && !Value.EndsWith("e+"))
{
throw Error("Unexpected Character (Code " + (int)next + ") +\nThe plus sign can only occur once at the Start of a Numeric Literal and once immediately after the 'e' exponent specifier, if this was intended as an additive operator please insert space to disambiguate this");
}
}
if (next == '-')
{
if (negoccurred && !Value.EndsWith("e-"))
{
// Negative sign already seen
throw Error("Unexpected Character (Code " + (int)next + ") -\nThe minus sign can only occur once at the Start of a Numeric Literal, if this was intended as a subtractive operator please insert space to disambiguate this");
}
else
{
negoccurred = true;
// Check this is at the start of the string or immediately after the 'e'
if (Length > 1 && !Value.EndsWith("e-"))
{
throw Error("Unexpected Character (Code " + (int)next + ") -\nThe minus sign can only occur at the Start of a Numeric Literal and once immediately after the 'e' exponent specifier, if this was intended as a subtractive operator please insert space to disambiguate this");
}
}
}
else if (next == 'e')
{
if (expoccurred)
{
// Exponent already seen
throw Error("Unexpected Character (Code " + (int)next + " e\nThe Exponent specifier can only occur once in a Numeric Literal");
}
else
{
expoccurred = true;
// Check that it isn't the start of the string
if (Length == 1)
{
throw Error("Unexpected Character (Code " + (int)next + " e\nThe Exponent specifier cannot occur at the start of a Numeric Literal");
}
}
}
else if (next == '.')
{
dotoccurred = true;
}
next = Peek();
}
// Decimals can't end with a . so backtrack
if (Value.EndsWith("."))
{
Backtrack();
}
String value = Value;
if (!SparqlSpecsHelper.IsValidNumericLiteral(value))
{
// Invalid Numeric Literal
throw Error("The format of the Numeric Literal '" + Value + "' is not valid!");
}
// Return the Token
LastTokenType = Token.PLAINLITERAL;
return(new PlainLiteralToken(Value, CurrentLine, StartPosition, EndPosition));
}