Re: Applesoft tokenization phases?

Jerry Awanderin wrote:
> > Also, an online AppleSoft simulator at calormen.com [3] accepts ie both
> > DIFF and FEND as valid variable names.
>
> It is doing things differently than actual Applesoft.
>
> > As it seems, this issue can affect a design choice for the tokenization
> > phases of an Applesoft front-end. Is the manual just informative or the
> > online simulator does not accept (precisely) the particular dialect?
>
> The latter; the simulator accepts a different dialect.


For situations like this, we added classes (and inheritance) to Yacc++
lexers and parsers, so that one could define a common subset and then
extend it to cover the cases that are unique or different dialects.
However, one can do similar things with lexer states, flag/switch
variables, or a host of other techniques. You just have to decide how
much mess you are willing to handle and how important supporting the
variations are.


There is a reason, BASIC compilers that remove spaces often restrict
variables (like the original Basic version did) to a letter optionally
followed by a digit (and a dollar sign to indicate strings). It makes
the lexing much simpler, even without spaces.


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