Re: Applesoft tokenization phases?

From	awanderin <awanderin@gmail.com>
Newsgroups	comp.compilers
Subject	Re: Applesoft tokenization phases?
Date	2020-03-16 00:07 -0600
Organization	A noiseless patient Spider
Message-ID	<20-03-016@comp.compilers> (permalink)
References	<20-03-013@comp.compilers>

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"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

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