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From: Anna Glasgall <anna@crossproduct.net>
To: emacs-devel@gnu.org
Subject: Re: "Raw" string literals for elisp
Date: Wed, 08 Sep 2021 16:40:09 -0400	[thread overview]
Message-ID: <c539acf4a29f85e82c138706e7146dd537eb8534.camel@crossproduct.net> (raw)
In-Reply-To: <4209edd83cfee7c84b2d75ebfcd38784fa21b23c.camel@crossproduct.net>

On Tue, 2021-09-07 at 21:49 -0400, Anna Glasgall wrote:
> 
[snip]
> I've successfully taught the elisp reader (read1 in lread.c) how to
> read r-strings. I thought I had managed to make lisp-mode/elisp-mode
> happy by allowing "r" to be a prefix character (C-x C-e and the
> underlying forward-sexp/backward-sexp seemed to work fine at first),
> but realized that I ran into trouble with strings containing the
> sequence of characters '\\"'.
> 
> The reader correctly reads r"a\\"" as a string containing the
> sequence
> of characters 'a', '\', '"', and M-: works. Unfortunately, if I try
> sexp-based navigation or e.g. C-x C-e, it falls apart. The parser in
> syntax.c, which afaict is what lisp-mode is using to try and find
> sexps
> in buffer text, doesn't seem to know what to do with this expression.
> I've spent some time staring at syntax.c, but I must confess that I'm
> entirely defeated in terms of what changes need to be made here to
> teach this other parser about prefixed strings in where the prefix
> has
> meaning that affects the interpretation of the characters between
> string fences.
> 

I've taken the suggestion Lars Ingebrigtsen made further up-thread and
implemented another draft of this using #r"" instead of r""; not only
does this not break existing elisp syntax (as noted by Po Lu earlier),
forward-sexp and backwards-sexp understand the new syntax without
having to be taught about it, to my considerable surprise. Or at least
they understand it to the same extent that they understand #s() or
#^[], anyway.

Alan (Dr. Mackenzie? Forgive me, not sure what standards are here),
your point about strings ending in \ is very well taken and I'm frankly
not sure what the easiest path forward here is. Having "raw literals
cannot end in a \" is a weird and unpleasant restriction, although the
fact that it is one that Python places on r-strings (to my considerable
surprise; I've been using Python since the mid-00s and have never run
across this particular syntax oddity before) may mean that it is
perhaps not so bad. The C++ concept of allowing r-strings to specify
their own delimiters is perhaps maximally flexible, but is definitely
going to be a heavier lift to implement than any of the above. I'd love
to hear people's opinions on the merits of the various possible
approaches here.

You've all given me a great deal of food for thought, which I will
attempt to digest before spinning a new revision of this patch.

thanks,

Anna

> I've attached a copy of my WIP patch; it's definitely not near final
> code quality and doesn't have documentation yet, all of which I would
> take care of before submitting for inclusion. I also haven't filled
> out
> the copyright assignment paperwork yet, but should this work reach a
> point where it was likely to be accepted, I'd be happy to do that.
> 
> 
> I'd very much appreciate some pointers on what to try next here, or
> some explanation of how syntax.c/syntax.el works beyond what's in the
> reference manual. If this is a fool's errand I'm tilting at here, I'd
> also appreciate being told that before I sink more time into it :)
> 
> thanks,
> 
> Anna Glasgall
> 
> 





  parent reply	other threads:[~2021-09-08 20:40 UTC|newest]

Thread overview: 120+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-08  1:49 "Raw" string literals for elisp Anna Glasgall
2021-09-08  7:10 ` Po Lu
2021-09-08 14:19   ` Anna Glasgall
2021-09-08  7:12 ` Lars Ingebrigtsen
2021-09-08 14:20   ` Anna Glasgall
2021-09-08 11:30 ` Alan Mackenzie
2021-09-08 14:27   ` Anna Glasgall
2021-09-08 11:34 ` Adam Porter
2021-09-08 13:59   ` Clément Pit-Claudel
2021-09-08 14:12     ` Adam Porter
2021-09-09  3:09   ` Richard Stallman
2021-09-08 13:10 ` Stefan Monnier
2021-09-08 14:31   ` Anna Glasgall
2021-09-08 15:27     ` Mattias Engdegård
2021-09-08 15:41       ` Stefan Kangas
2021-09-08 16:45         ` Mattias Engdegård
2021-09-08 16:01       ` Alan Mackenzie
2021-09-08 18:24         ` Mattias Engdegård
2021-09-08 19:00           ` Alan Mackenzie
2021-09-08 19:22         ` Philip Kaludercic
2021-09-08 19:36           ` Alan Mackenzie
2021-09-08 21:11           ` Stefan Kangas
2021-09-08 21:24             ` Philip Kaludercic
2021-09-09  6:52             ` tomas
2021-09-08 15:54     ` Stefan Kangas
2021-09-08 16:05     ` tomas
2021-09-08 16:42       ` Lars Ingebrigtsen
2021-09-08 20:08         ` Stefan Monnier
2021-09-08 20:18       ` Stefan Monnier
2021-09-09  7:04         ` tomas
2021-09-09 10:30         ` Mattias Engdegård
2021-09-09 11:36           ` Stefan Kangas
2021-09-09 13:33             ` Mattias Engdegård
2021-09-09 14:32               ` tomas
2021-09-14 10:43               ` Augusto Stoffel
2021-09-14 11:42                 ` Ihor Radchenko
2021-09-14 13:18                   ` Stefan Monnier
2021-09-14 13:22                     ` Stefan Kangas
2021-09-14 14:01                       ` Ihor Radchenko
2021-09-14 14:39                       ` Clément Pit-Claudel
2021-09-14 15:33                         ` Amin Bandali
2021-09-14 16:05                         ` Eli Zaretskii
2021-09-14 17:49                   ` Jose E. Marchesi
2021-09-08 20:40 ` Anna Glasgall [this message]
2021-09-08 21:28   ` Alan Mackenzie
2021-10-02 21:03   ` Daniel Brooks
2021-10-04  0:13     ` Richard Stallman
2021-10-04  0:36       ` Daniel Brooks
2021-10-04 12:00         ` Eli Zaretskii
2021-10-04 15:36           ` character sets as they relate to “Raw” " Daniel Brooks
2021-10-04 16:34             ` Stefan Monnier
2021-10-04 20:49               ` Daniel Brooks
2021-10-04 21:19                 ` Alan Mackenzie
2021-10-04 22:19                   ` Daniel Brooks
2021-10-05 11:20                     ` Alan Mackenzie
2021-10-05 17:08                       ` Daniel Brooks
2021-10-06 20:54                         ` Richard Stallman
2021-10-07  7:01                           ` Eli Zaretskii
2021-10-05  8:55                 ` Yuri Khan
2021-10-05 16:25                   ` Juri Linkov
2021-10-05 17:15                     ` Eli Zaretskii
2021-10-05 18:40                       ` [External] : " Drew Adams
2021-10-06 20:54                       ` Richard Stallman
2021-10-07  6:54                         ` Eli Zaretskii
2021-10-07 13:14                           ` Stefan Kangas
2021-10-07 13:34                             ` Eli Zaretskii
2021-10-07 14:48                               ` Stefan Kangas
2021-10-07 16:00                                 ` Eli Zaretskii
2021-10-08  0:37                                   ` Stefan Kangas
2021-10-08  6:53                                     ` Eli Zaretskii
2021-10-08 15:09                                       ` Display of em dashes in our documentation Stefan Kangas
2021-10-08 16:12                                         ` Eli Zaretskii
2021-10-08 17:17                                           ` Stefan Kangas
2021-10-10  8:00                                             ` Juri Linkov
2021-10-08 17:27                                           ` Daniel Brooks
2021-10-08 18:26                                           ` [External] : " Drew Adams
2021-10-08 17:17                                       ` character sets as they relate to “Raw” string literals for elisp Alan Mackenzie
2021-10-08 17:42                                         ` Eli Zaretskii
2021-10-08 18:47                                           ` Eli Zaretskii
2021-10-08 20:01                                             ` Alan Mackenzie
2021-10-09  6:18                                               ` Eli Zaretskii
2021-10-09 10:57                                                 ` Alan Mackenzie
2021-10-09 11:49                                                   ` Eli Zaretskii
2021-10-09 13:08                                                     ` Alan Mackenzie
2021-10-09 13:15                                                       ` Eli Zaretskii
2021-10-09 15:07                                                         ` Alan Mackenzie
2021-10-11  0:45                                                           ` linux console limitations Daniel Brooks
2021-10-12 10:18                                                             ` Alan Mackenzie
2021-10-14  4:05                                                               ` Daniel Brooks
2021-10-10  8:03                                                   ` character sets as they relate to “Raw” string literals for elisp Juri Linkov
2021-10-05 18:23                     ` [External] : " Drew Adams
2021-10-05 19:13                       ` Stefan Kangas
2021-10-05 19:20                         ` Drew Adams
2021-10-05 17:13                   ` Daniel Brooks
2021-10-05 12:04                 ` Eli Zaretskii
2021-10-05 21:20                 ` Richard Stallman
2021-10-05 22:13                   ` Daniel Brooks
2021-10-06 12:13                     ` Eli Zaretskii
2021-10-06 18:57                       ` Daniel Brooks
2021-10-07  4:23                         ` Eli Zaretskii
2021-10-07 22:27                         ` Richard Stallman
2021-10-08 10:37                         ` Po Lu
2021-10-08 10:53                           ` Basil L. Contovounesios
2021-10-08 11:27                             ` tomas
2021-10-05 22:25                   ` character sets as they relate to “Raw†" Stefan Kangas
2021-10-06  6:21                     ` Daniel Brooks
2021-10-07 22:20                       ` Richard Stallman
2021-10-06 12:29                     ` Eli Zaretskii
2021-10-06 12:52                       ` Stefan Kangas
2021-10-06 13:10                         ` Jean-Christophe Helary
2021-10-06 11:53                   ` character sets as they relate to “Raw” " Eli Zaretskii
2021-10-04 18:57             ` Eli Zaretskii
2021-10-04 19:14               ` Yuri Khan
2021-10-05 21:20                 ` Richard Stallman
2021-10-06  3:48                   ` character sets as they relate to “Raw†" Matthew Carter
2021-10-04 22:29         ` "Raw" " Richard Stallman
2021-10-05  5:39           ` Daniel Brooks
2021-10-05  5:43             ` Jean-Christophe Helary
2021-10-05  8:24               ` Richard Stallman
2021-10-05 12:23               ` Eli Zaretskii

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