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Re: Parsing a language with optional spaces
From: |
uxio prego |
Subject: |
Re: Parsing a language with optional spaces |
Date: |
Tue, 7 Jul 2020 13:48:19 +0200 |
Hi,
> On 7 Jul 2020, at 10:55, John P. Hartmann <jphartmann@gmail.com> wrote:
>
> On 7/7/20 05:35, Akim Demaille wrote:
>> I believe you need to read again the documentation of /
>> 'r/s'
>
> It is not as simple as that. As I don't speak BASIC, let me rephrase this
> problem in FORTRAN IV which is also "blank agnostic":
>
> DO <number> <variable> = <expression> , <expression> [, <expression>]
>
> It is not until you reach the comma after the first expression that you know
> whether the statement is the beginning of a loop or it is an assignment. And
> the expression can contain commas in function calls, which defeats any
> trivial lookahead scanning. E.g.,
>
> D O 17 6PQ R=FUN X(1 4, V 8)
>
> is an assignment to variable DO176PQR. The function arguments can also be
> expressions that contain function calls.
>
> As you can see, this more or less defeats any attempt to write a lex scanner.
> And you cannot just squeeze out all blanks in a front end because "Hollerith
> fields" can contain blanks that are significant (must remain).
Then you couple the squeeze out all blanks approach with BEGIN/END %x regions?
https://lists.gnu.org/archive/html/help-bison/2020-07/msg00012.html
FBCC uses regions, sorry can't find proper documentation but
https://bellard.org//fbcc/
I'd rather shoot myself on a foot than use regions. IDK if that closes a loop
on the elegance question. But the tool's been there since forever.
- Re: Which lexer do people use?, (continued)
- Re: Which lexer do people use?, Christian Schoenebeck, 2020/07/06
- Parsing a language with optional spaces, Maury Markowitz, 2020/07/06
- Re: Parsing a language with optional spaces, Christian Schoenebeck, 2020/07/06
- Re: Parsing a language with optional spaces, Maury Markowitz, 2020/07/06
- Re: Parsing a language with optional spaces, Christian Schoenebeck, 2020/07/06
- Re: Parsing a language with optional spaces, Akim Demaille, 2020/07/08
- Re: Parsing a language with optional spaces, Akim Demaille, 2020/07/06
- Re: Parsing a language with optional spaces, Maury Markowitz, 2020/07/06
- Re: Parsing a language with optional spaces, Akim Demaille, 2020/07/06
- Re: Parsing a language with optional spaces, John P. Hartmann, 2020/07/07
- Re: Parsing a language with optional spaces,
uxio prego <=
- Re: Parsing a language with optional spaces, Akim Demaille, 2020/07/08
- Re: Parsing a language with optional spaces, Christian Schoenebeck, 2020/07/08
- Re: Parsing a language with optional spaces, Akim Demaille, 2020/07/08
- Re: Parsing a language with optional spaces, Christian Schoenebeck, 2020/07/08
- Re: Parsing a language with optional spaces, Daniele Nicolodi, 2020/07/08
- Re: Parsing a language with optional spaces, Akim Demaille, 2020/07/09
- Re: Parsing a language with optional spaces, Akim Demaille, 2020/07/09
- Re: Parsing a language with optional spaces, uxio prego, 2020/07/11
- Re: Parsing a language with optional spaces, Christian Schoenebeck, 2020/07/12
- Re: Parsing a language with optional spaces, Akim Demaille, 2020/07/13