From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Eric Abrahamsen <eric@ericabrahamsen.net>
Cc: Eli Zaretskii <eliz@gnu.org>, emacs-devel@gnu.org
Subject: Re: Make peg.el a built-in library?
Date: Thu, 30 Sep 2021 15:44:28 -0400 [thread overview]
Message-ID: <jwvilyheuaz.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <875yvafjr9.fsf@ericabrahamsen.net> (Eric Abrahamsen's message of "Wed, 08 Sep 2021 21:36:10 -0700")
> Whether or not PEG gets added to core I'd like to propose some patches.
> The "peg-doc-patches.diff" attachment adds some documentation to the
> Commentary section, including an example grammar based on a
> much-simplified version of what gnus-search does.
Looks great, thanks.
> The peg-allow-symbols patch is more tentative. The issue is that _all_
> of the entry-points to peg code are macros, meaning you can't build your
> grammar up in a variable, and then pass that variable to any of
> `peg-run', `peg-parse', `with-peg-rules', etc. Nobody will evaluate the
> variable; you have to literally write the rules inside the
> `with-peg-rules' form. It seems like a fairly plausible use-case to
> store the rules in a variable or an option, even if you're not doing
> run-time manipulation of them. The only solution, as Adam found with
> org-ql, is to `eval' one of the macros.
>
> This doesn't seem necessary! The patch has `with-peg-rules' check if the
> rules are a symbol, and take the `symbol-value' if so. But I wonder if
> it wouldn't be nicer to break some of the code out: `peg-normalize'
> seems to be the entry-point for "compile this grammar", and that could
> be modified to work the way that some languages provide for pre-compiled
> regexps: a way to let the developer build and compile the grammar at
> load-time or launch-time, then feed the stored compiled version to
> parsing routines.
`peg` is the macro that's supposed to be this compilation step: you pass
it a PEX and you receive a value in return. It's a bit like `lambda`.
You can then use this value (a "peg matcher") to parse something by
passing it to `peg-run`.
So you can do
(let ((parser (peg PEX)))
...
(peg-run parser ...)
...)
What might still be missing, tho is a way to invoke this `parser` from
within a PEX. So we might want to add a new PEX form that would be akin
to `funcall`. We could name it `call`:
(let* ((parser (peg PEX))
...
(with-peg-rules
((foo ...)
(bar ... (call parser) ...)
(baz ...))
...))
so (peg-parse (call FORM)) would end up equivalent to (peg-run FORM ...).
WDYT?
Stefan
next prev parent reply other threads:[~2021-09-30 19:44 UTC|newest]
Thread overview: 100+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-25 18:52 Make peg.el a built-in library? Eric Abrahamsen
2021-08-26 6:17 ` Eli Zaretskii
2021-08-26 15:34 ` Eric Abrahamsen
2021-09-09 4:36 ` Eric Abrahamsen
2021-09-19 15:25 ` Eric Abrahamsen
2021-09-30 19:44 ` Stefan Monnier [this message]
2021-09-30 20:34 ` Adam Porter
2021-10-01 8:14 ` Augusto Stoffel
2021-10-01 18:05 ` Stefan Monnier
2021-10-01 18:40 ` Eric Abrahamsen
2021-10-02 3:57 ` Stefan Monnier
2021-10-02 7:32 ` Adam Porter
2021-10-02 14:45 ` Stefan Monnier
2021-10-02 15:13 ` Adam Porter
2021-08-26 17:02 ` Adam Porter
2021-08-26 17:25 ` Eric Abrahamsen
2021-08-27 3:17 ` Eric Abrahamsen
2021-08-27 6:41 ` Helmut Eller
2021-08-27 16:57 ` Eric Abrahamsen
2021-09-26 10:59 ` Augusto Stoffel
2021-09-26 15:06 ` Eric Abrahamsen
2021-09-26 18:36 ` Augusto Stoffel
2021-09-27 16:18 ` Eric Abrahamsen
2021-09-27 22:34 ` Richard Stallman
2021-09-28 3:52 ` Eric Abrahamsen
2021-09-28 8:09 ` tomas
2021-09-28 9:32 ` Helmut Eller
2021-09-28 10:45 ` tomas
2021-09-28 15:24 ` Augusto Stoffel
2021-09-30 6:04 ` Richard Stallman
2021-10-01 3:27 ` Eric Abrahamsen
2021-10-09 1:31 ` Michael Heerdegen
2021-10-09 5:28 ` Michael Heerdegen
2021-10-09 8:12 ` Helmut Eller
2021-10-09 12:52 ` Stefan Monnier
2021-10-10 5:49 ` Helmut Eller
2021-10-14 10:25 ` Michael Heerdegen
2021-10-09 12:54 ` Stefan Monnier
2021-10-09 16:47 ` Eric Abrahamsen
2021-10-10 4:20 ` Michael Heerdegen
2021-10-10 21:40 ` Eric Abrahamsen
2021-10-13 2:58 ` Michael Heerdegen
2021-10-09 16:49 ` Eric Abrahamsen
2021-10-10 3:43 ` Stefan Monnier
2021-10-10 4:46 ` Michael Heerdegen
2021-10-10 5:58 ` Helmut Eller
2021-10-10 13:56 ` Stefan Monnier
2021-10-22 16:33 ` Michael Heerdegen
2021-10-31 23:43 ` Michael Heerdegen
2021-11-15 23:16 ` Michael Heerdegen
2022-11-07 3:33 ` Ihor Radchenko
2022-11-07 19:46 ` Eric Abrahamsen
2022-11-08 6:57 ` Helmut Eller
2022-11-08 8:51 ` Ihor Radchenko
2022-11-10 4:04 ` Richard Stallman
2022-11-10 5:25 ` tomas
2022-11-10 8:15 ` Eli Zaretskii
2022-11-10 8:29 ` tomas
2022-11-11 4:36 ` Richard Stallman
2022-11-08 8:47 ` Ihor Radchenko
2022-11-08 16:18 ` Eric Abrahamsen
2022-11-08 19:08 ` tomas
2022-11-08 19:42 ` Eric Abrahamsen
2022-11-16 4:27 ` [PATCH] " Eric Abrahamsen
2022-11-16 5:07 ` tomas
2022-11-16 5:39 ` Eric Abrahamsen
2022-11-16 15:53 ` tomas
2022-11-16 6:24 ` Ihor Radchenko
2022-11-16 18:15 ` Eric Abrahamsen
2022-11-17 12:21 ` Ihor Radchenko
2022-11-27 1:46 ` Eric Abrahamsen
2022-11-27 8:57 ` Eli Zaretskii
2022-11-28 1:09 ` Eric Abrahamsen
2022-11-28 12:16 ` Eli Zaretskii
2023-09-25 1:30 ` Eric Abrahamsen
2023-09-25 2:27 ` Adam Porter
2023-09-25 13:00 ` Alexander Adolf
2024-03-24 14:19 ` Ihor Radchenko
2024-03-24 15:32 ` Eli Zaretskii
2024-03-25 1:45 ` Eric Abrahamsen
2023-01-11 7:39 ` Michael Heerdegen
2023-01-11 8:04 ` Ihor Radchenko
2023-01-11 11:01 ` Michael Heerdegen
2023-01-11 11:32 ` tomas
2023-02-05 12:10 ` Ihor Radchenko
2023-02-05 15:41 ` Eduardo Ochs
2023-02-05 15:45 ` Ihor Radchenko
2023-02-05 16:19 ` Eduardo Ochs
2023-02-05 16:50 ` Ihor Radchenko
2023-02-09 5:44 ` Jean Louis
2023-02-06 0:33 ` Michael Heerdegen
2022-11-08 14:01 ` Stefan Monnier
2022-11-08 14:42 ` tomas
2022-11-08 15:08 ` Visuwesh
2022-11-08 16:29 ` Juanma Barranquero
2022-12-02 20:20 ` Augusto Stoffel
2022-11-08 16:10 ` Eric Abrahamsen
2022-11-08 18:59 ` tomas
2022-11-08 19:42 ` Eric Abrahamsen
2022-11-08 22:03 ` Tim Cross
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