// Reads a decimal number with optional exponentiation
private Token ReadToComma(char ch)
{
StringBuilder sb = new StringBuilder();
sb.Append(ch);
while (!reader.EndOfInput())
{
char cPeek = reader.Peek();
if (cPeek == ',')
{
break;
}
cPeek = reader.GetNext();
sb.Append(cPeek);
}
return(new Token(sb.ToString(), TokenTypes.QUOTE));
}
private Token GetNextToken()
{
while (!reader.EndOfInput())
{
char ch = reader.GetNext();
// skipping whitespaces
if (Char.IsWhiteSpace(ch))
{
continue;
}
switch (ch)
{
case '=':
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.EQUAL));
case '+':
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.PLUS));
case '-':
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.MINUS));
case '(':
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.LPAREN));
case ')':
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.RPAREN));
case ',':
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.COMMA));
case '^':
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.EXP));
case '%':
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.MODULUS));
case '!':
if (reader.Peek() == '=')
{
reader.GetNext(); // go past the equal
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.NOTEQUAL));
}
else
{
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.NOT));
}
case '&':
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.PLUSSTRING));
case '|':
if (reader.Peek() == '|')
{
reader.GetNext(); // go past the '|'
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.OR));
}
break;
case '>':
if (reader.Peek() == '=')
{
reader.GetNext(); // go past the equal
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.GREATERTHANOREQUAL));
}
else
{
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.GREATERTHAN));
}
case '/':
if (reader.Peek() == '*')
{ // beginning of a comment of form /* a comment */
reader.GetNext(); // go past the '*'
ReadComment();
continue;
}
else
{
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.FORWARDSLASH));
}
case '<':
if (reader.Peek() == '=')
{
reader.GetNext(); // go past the equal
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.LESSTHANOREQUAL));
}
else if (reader.Peek() == '>')
{
reader.GetNext(); // go past the >
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.NOTEQUAL));
}
else
{
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.LESSTHAN));
}
case '*':
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.STAR));
case '"':
case '\'':
return(ReadQuoted(ch));
case '{':
return(ReadIdentifier(ch, 4));
default:
break;
} // end of swith
if (Char.IsDigit(ch))
{
return(ReadNumber(ch));
}
else if (ch == '.')
{
char tc = reader.Peek();
if (Char.IsDigit(tc))
{
return(ReadNumber(ch));
}
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.DOT));
}
else if (Char.IsLetter(ch) || ch == '_')
{
return(ReadIdentifier(ch));
}
else
{
return(new Token(ch.ToString(), reader.Line, reader.Column, reader.Line, reader.Column, TokenTypes.OTHER));
}
}
return(null);
}