Re: Applesoft tokenization phases?

"Ev. Drikos" <drikosev@gmail.com> writes:
> This question relates to thread "Languages with Optional Spaces".
>
> In an Applesoft II manual I've found at "classiccmp.org" [1], page 7,
> we read that in a variable name any alphanumeric characters after the
> first two are ignored, unless they contain a reserved world. FEND ie
> would be illegal as it contains END.
>
> To implement such a rule one could first recognize keywords and then
> recognize any names. We see in p123 that stmt I is tokenized as II:
> I. stmt: 100 FOR A = LOFT OR CAT To 15
> II. tokens: 100 FOR A = LOF TO RC AT To 15
>
> Yet, I've found ie a program at "hoist-point.com" [2] that contains:
> 110 DIFF = ABS(A(I)-N)


If you type that into Applesoft BASIC, it parses it as:


      110 D IF F = ABS (A(I) - N)


The spaces are how Applesoft lists it (it puts spaces around each token;
variables are not parsed as tokens at entry time, they are only parsed
at run-time).




> 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.


--
Jerry awanderin at gmail dot com

Return to the comp.compilers page.
Search the comp.compilers archives again.