Re: Languages with optional spaces

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From	"Ev. Drikos" <drikosev@gmail.com>
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Subject	Re: Languages with optional spaces
Date	Fri, 28 Feb 2020 13:34:40 +0200
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On 25/02/2020 19:00, Martin Ward wrote:
> ...So any statement either starts
> with a keyword (a control character), which determines
> the statement type, or it is an assignment with the LET
> keyword omitted...

A scanner generator that supports ie "difference" operators can build a
DFA that splits ie the text FORI to FOR & I without space overhead, if
the reserved keywords are also tokens of the lexer.

The lexical rules below result ie to a DFA with 10 states. Even if I
erase the difference operator "-=" till the end of the document, the
DFA built still has 10 states but the text FORI is returned as an "id".

So, the rules below ensure that an "id" doesn't start with FOR or PRINT,
not sure though if this is what the OP really wanted once he said that
in theory FORI could be a variable (perhaps it can't be just an LHS?).

Ev. Drikos

-----------------------------------------------------------------------
token ::=
            FOR
      |     PRINT
      |     id

FOR ::=
            F O R

PRINT ::=
            P R I N T

id ::=
            {A..Z [{$|A .. Z|0 .. 9}...]} -= {key[{$|A .. Z|0..9}...]}

key ::=
            FOR
      |     PRINT

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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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