public decimal Parse(string input)
{
Lexer lexer = new Lexer(this, input);
lexer.Run();
flushWordNumBuf();
while (stack.Count != 0)
{
postfix.Add(stack.Pop());
}
return evaluate();
}
static State lexWhitespace(Lexer l)
{
switch (getType(l.read()))
{
case CharType.Whitespace:
l.discard();
return lexWhitespace;
case CharType.OpenParanthesis:
l.next();
l.emit(Token.OpenParanthesis);
l.reset();
return lexWhitespace;
case CharType.CloseParanthesis:
l.next();
l.emit(Token.CloseParanthesis);
l.reset();
return lexWhitespace;
case CharType.Number:
l.reset();
return lexNumber;
case CharType.Operator:
l.reset();
return lexOperator;
case CharType.Letter:
l.reset();
return lexWord;
case CharType.EOF:
return null;
default:
throw new Exception("Invalid input.");
}
}
static State lexWord(Lexer l)
{
switch (getType(l.read()))
{
case CharType.Letter:
l.next();
return lexWord;
case CharType.EOF:
l.emit(Token.Word);
return null;
default:
l.emit(Token.Word);
l.reset();
return lexWhitespace;
}
}
static State lexOperator(Lexer l)
{
switch (getType(l.read()))
{
case CharType.Operator:
l.next();
return lexOperator;
case CharType.EOF:
l.emit(Token.Operator);
return null;
default:
l.emit(Token.Operator);
l.reset();
return lexWhitespace;
}
}