Re: Languages with optional spaces

From	gah4@u.washington.edu
Newsgroups	comp.compilers
Subject	Re: Languages with optional spaces
Date	2020-03-02 21:12 -0800
Organization	Compilers Central
Message-ID	<20-03-007@comp.compilers> (permalink)
References	<20-02-015@comp.compilers>

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On Wednesday, February 19, 2020 at 8:24:02 AM UTC-8, Maury Markowitz wrote:
> I'm trying to write a lex/yacc (flex/bison) interpreter for classic BASICs
> like the original DEC/MS, HP/DG etc.

> I have it mostly working for a good chunk
> of 101 BASIC Games (DEF FN is the last feature to add).

> Then I got to Super Star Trek. To save memory, SST removes most spaces, so
> lines look like this:

> 100FORI=1TO10

The first BASIC systems I ever used were the HP TSB2000 systems
that were very popular in the 1970's.  These systems tokenize each
line on entry, and also syntax check it.  If a line fails, it isn't
even stored. Extra spaces or none, the line is stored the same way.
(And this is the system that many of the original Star Trek games
were written on.) Also, numeric constants are converted to their
internal representation.  The LIST command converts the tokenized form
back to text form, and adds appropriate blank space.

Note also that the TSB2000 systems only allow the traditional
single letter, or number-digit, form for variable names.

The microcomputer BASIC systems that I remember tokenize lines, but
don't do any more checking on them. As noted, blanks are stored and
used when the LIST command displays the program.

Looking at the GW-BASIC manual:

http://www.divonasperi.it/divona/tam/tecnologia/dow-all/GW%20Basic%20(inglese).pdf

and the PC-BASIC manual:

https://robhagemans.github.io/pcbasic/doc/1.2/#memory

(the latter intended to be bug-for-bug compatible with the MS version.)

I don't see in either manual mention of the effects, or lack thereof,
of blanks in statements.  There is explanation of reserved words,
and their possible use in variable names. It seems to me that
the treatment of missing blanks is an accident of the parser design.

Bug-for-bug emulation, then, needs to find all those accidents
and implement them.

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Thread

Languages with optional spaces Maury Markowitz <maury.markowitz@gmail.com> - 2020-02-19 07:35 -0800
  Re: Languages with optional spaces Jerry <awanderin@gmail.com> - 2020-02-20 23:38 -0700
    Re: Languages with optional spaces Maury Markowitz <maury.markowitz@gmail.com> - 2020-02-25 06:13 -0800
      Re: Languages with optional spaces awanderin <awanderin@gmail.com> - 2020-02-26 10:03 -0700
    Re: Languages with optional spaces "Ev. Drikos" <drikosev@gmail.com> - 2020-03-12 17:45 +0200
  Re: Languages with optional spaces "Ev. Drikos" <drikosev@gmail.com> - 2020-02-23 12:33 +0200
    Re: Languages with optional spaces Martin Ward <martin@gkc.org.uk> - 2020-02-25 17:00 +0000
      Re: Languages with optional spaces "Ev. Drikos" <drikosev@gmail.com> - 2020-02-28 13:34 +0200
    Re: Languages with optional spaces Christopher F Clark <christopher.f.clark@compiler-resources.com> - 2020-02-29 11:48 +0200
      Re: Languages with optional spaces "Ev. Drikos" <drikosev@gmail.com> - 2020-02-29 21:38 +0200
        Re: Languages with optional spaces Christopher F Clark <christopher.f.clark@compiler-resources.com> - 2020-03-01 10:07 +0200
        Re: Languages with optional spaces "Ev. Drikos" <drikosev@gmail.com> - 2020-03-01 19:41 +0200
          Re: Languages with optional spaces Christopher F Clark <christopher.f.clark@compiler-resources.com> - 2020-03-02 08:33 +0200
            Re: Languages with optional spaces "Ev. Drikos" <drikosev@gmail.com> - 2020-03-02 20:04 +0200
      Re: Languages with optional spaces Hans-Peter Diettrich <DrDiettrich1@netscape.net> - 2020-03-01 00:28 +0100
  Re: Languages with optional spaces Maury Markowitz <maury.markowitz@gmail.com> - 2020-02-25 06:11 -0800
  Re: Languages with optional spaces Kaz Kylheku <493-878-3164@kylheku.com> - 2020-02-26 08:06 +0000
  Re: Languages with optional spaces and tools Hans-Peter Diettrich <DrDiettrich1@netscape.net> - 2020-02-28 20:16 +0100
  Re: Languages with optional spaces gah4@u.washington.edu - 2020-03-02 21:12 -0800
  Re: Languages with optional spaces Gene <gene.ressler@gmail.com> - 2020-04-14 10:08 -0700
  Re: Languages with optional spaces mertesthomas@gmail.com - 2020-04-19 04:04 -0700
  Re: Languages with optional spaces aston.goldsmith@gmail.com - 2020-05-05 13:05 -0700

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