Re: Supporting multiple input syntaxes

From	Rock Brentwood <rockbrentwood@gmail.com>
Newsgroups	comp.compilers
Subject	Re: Supporting multiple input syntaxes
Date	2021-03-14 17:36 -0700
Organization	Compilers Central
Message-ID	<21-03-003@comp.compilers> (permalink)
References	<20-08-002@comp.compilers>

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On Wednesday, August 12, 2020 at 5:32:56 PM UTC-5, luser droog wrote:
> I've got my project successfully parsing the circa-1975 C syntax
> from that old manual. I'd like to add parsers for K&R1 and c90
> syntaxes.
>
> How separate should these be? Should they be complete
> separate grammars, or more piecewise selection?

I'm in a similar situation with a utility that I want to grandfather in the
old syntax for, but write with a new and better syntax. My recommendation is
this: stick to C99, since that's already in POSIX. Write a separate utility to
convert legacy syntax to C99 (and to call out any
irregularities/inconsistencies in the program being converted). That's, like,
"lint" on steroids.

The other syntaxes would be used in the other utilities, only - one per
utility. It can also be hybridized with "indent" and a driver routine can
control the conversion, so that all the conversion utilities can be combined
to one. So, on input, the source syntax is selected, and on output the format
is driven in much the same way that it is with indent. It's an excellent
exercise in Text-To-AST-To-Text programming.

Each program, upon upward conversion to C99, would replace the original, once
it passes the consistency checks provided by the utility; so there isn't a
question of cueing error messages to the format of the older program, because
the older program would be replaced. Doing all of this is an example of
"refactoring" used to pay off "code debt". And there's a lot of code debt out
there that needs to be paid up.

Technical Debt (Wikipedia): https://en.wikipedia.org/wiki/Technical_debt
Code Refactoring (Wikipedia): https://en.wikipedia.org/wiki/Code_refactoring

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Thread

Supporting multiple input syntaxes luser droog <mijoryx@yahoo.com.dmarc.email> - 2020-08-12 15:20 -0700
  Re: Supporting multiple input syntaxes Kaz Kylheku <793-849-0957@kylheku.com> - 2020-08-13 00:43 +0000
  Re: Supporting multiple input syntaxes Hans-Peter Diettrich <DrDiettrich1@netscape.net> - 2020-08-13 10:27 +0200
    Re: Supporting multiple input syntaxes luser droog <mijoryx@yahoo.com.dmarc.email> - 2020-08-13 21:36 -0700
    Re: Supporting multiple input syntaxes luser droog <mijoryx@yahoo.com.dmarc.email> - 2020-08-23 22:16 -0700
  Re: Supporting multiple input syntaxes minforth@arcor.de - 2020-08-13 14:15 -0700
    Re: Supporting multiple input syntaxes luser droog <mijoryx@yahoo.com.dmarc.email> - 2020-08-13 21:37 -0700
    RE: Supporting mulitple input syntaxes Christopher F Clark <christopher.f.clark@compiler-resources.com> - 2020-08-14 12:44 +0300
  Supporting multiple input syntaxes David Lovemore <davidlovemore@gmail.com> - 2020-08-15 06:42 -0700
    Re: Supporting multiple input syntaxes luser droog <mijoryx@yahoo.com.dmarc.email> - 2020-08-15 15:20 -0700
      Re: Supporting multiple input syntaxes David Lovemore <davidlovemore@gmail.com> - 2020-08-16 02:21 -0700
        Re: Supporting multiple input syntaxes luser droog <mijoryx@yahoo.com.dmarc.email> - 2020-08-20 14:45 -0700
          Re: Supporting multiple input syntaxes luser droog <mijoryx@yahoo.com.dmarc.email> - 2020-08-23 19:35 -0700
            Re: implementation languages, was Supporting multiple input syntaxes luser droog <mijoryx@yahoo.com.dmarc.email> - 2020-08-23 20:39 -0700
              Re: implementation languages, was Supporting multiple input syntaxes Thomas Koenig <tkoenig@netcologne.de> - 2020-08-24 17:01 +0000
                Re: implementation languages, was Supporting multiple input syntaxes luser droog <mijoryx@yahoo.com.dmarc.email> - 2020-08-28 10:56 -0700
              Re: stack languages, was Supporting multiple input syntaxes luser droog <mijoryx@yahoo.com.dmarc.email> - 2020-08-24 12:14 -0700
  Re: Supporting multiple input syntaxes gah4 <gah4@u.washington.edu> - 2020-08-23 14:26 -0700
  Re: Supporting multiple input syntaxes antispam@math.uni.wroc.pl - 2021-02-11 23:27 +0000
    Re: Supporting multiple input syntaxes Elijah Stone <elronnd@elronnd.net> - 2021-02-17 01:44 -0800
      Re: Supporting multiple input syntaxes antispam@math.uni.wroc.pl - 2021-02-23 23:28 +0000
        Re: Supporting multiple input syntaxes "ltc...@gmail.com" <ltcmelo@gmail.com> - 2021-03-14 21:08 -0400
  Re: Supporting multiple input syntaxes Rock Brentwood <rockbrentwood@gmail.com> - 2021-03-14 17:36 -0700

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