GNU bug report logs - #32504
[PATCH] syntax-is-{comment|string}-p

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Alex Branham <alex.branham <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: [PATCH] syntax-is-{comment|string}-p
Date: Wed, 22 Aug 2018 15:05:35 -0500

[Message part 1 (text/plain, inline)]

Hello -

I got tired of checking/remembering whether (nth 3 (syntax-ppss)) was a
string or a comment, so I've created two simple functions that wrap that
in a more descriptive name. I've noticed that there are a handful of
these that other modes have written, so evidently others wanted them as
well at some point.

There are two patches attached. The first creates new functions
syntax-is-comment-p and syntax-is-string-p.

The second changes most of the uses of (nth 3 (syntax-ppss)) and (nth 4
(syntax-ppss)) to use these new functions. I'm attaching it as a
separate patch since I'm not sure if yall will want it or not; it's easy
to squash if you do.

Thanks,
Alex

------------------------------------------------------------

From 393f55de705513f5514a3e0250d81053e838c447 Mon Sep 17 00:00:00 2001
From: Alex Branham <alex.branham <at> gmail.com>
Date: Wed, 22 Aug 2018 14:44:26 -0500
Subject: [PATCH 1/2] Add new functions syntax-is-{comment|string}-p

* lisp/emacs-lisp/syntax.el (syntax-is-comment-p, syntax-is-string-p):
  New functions
* doc/lispref/syntax.texi: Add documentation for new functions
---
 doc/lispref/syntax.texi   | 10 ++++++++++
 etc/NEWS                  |  4 ++++
 lisp/emacs-lisp/syntax.el | 12 ++++++++++++
 3 files changed, 26 insertions(+)

diff --git a/doc/lispref/syntax.texi b/doc/lispref/syntax.texi
index dcfade3f67..e6220e5cf9 100644
--- a/doc/lispref/syntax.texi
+++ b/doc/lispref/syntax.texi
@@ -790,6 +790,16 @@ Position Parse
 Hooks}).
 @end defun
 
+@defun syntax-is-comment-p &optional pos
+This function returns non-nil when @code{POS} (which defaults to
+point) is in a comment accord to @code{syntax-ppss}
+@end defun
+
+@defun syntax-is-string-p &optional pos
+This function returns non-nil when @code{POS} (which defaults to
+point) is in a string accord to @code{syntax-ppss}
+@end defun
+
 @node Parser State
 @subsection Parser State
 @cindex parser state
diff --git a/etc/NEWS b/etc/NEWS
index d757f52466..e138105e72 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -963,6 +963,10 @@ versions.
 The new variable 'comment-use-syntax-ppss' can be set to nil to recover the old
 behavior if needed.
 
+** New functions 'syntax-is-comment-p' and 'syntax-is-string-p'.
+These can be used as a shorthand instead of checking, for example,
+(nth 3 (syntax-ppss)).
+
 ** The 'server-name' and 'server-socket-dir' variables are set when a
 socket has been passed to Emacs.
 
diff --git a/lisp/emacs-lisp/syntax.el b/lisp/emacs-lisp/syntax.el
index ad1a9665ff..2a262c6036 100644
--- a/lisp/emacs-lisp/syntax.el
+++ b/lisp/emacs-lisp/syntax.el
@@ -616,6 +616,18 @@ syntax-ppss
        ;; a nil state.
        (parse-partial-sexp (point-min) pos))))))
 
+(defun syntax-is-comment-p (&optional pos)
+  "Return non-nil if POS is inside a comment.
+POS defaults to `point'."
+  (let ((pos (or pos (point))))
+    (nth 4 (syntax-ppss pos))))
+
+(defun syntax-is-string-p (&optional pos)
+  "Return non-nil if POS is inside a string.
+POS defaults to `point'."
+  (let ((pos (or pos (point))))
+    (nth 3 (syntax-ppss pos))))
+
 ;; Debugging functions
 
 (defun syntax-ppss-debug ()
-- 
2.18.0

[0001-Add-new-functions-syntax-is-comment-string-p.patch (text/x-patch, attachment)]

[0002-Prefer-using-new-syntax-is-comment-string-p-function.patch (text/x-patch, attachment)]

Message #8 received at 32504 <at> debbugs.gnu.org (full text, mbox):

From: Noam Postavsky <npostavs <at> gmail.com>
To: Alex Branham <alex.branham <at> gmail.com>
Cc: 32504 <at> debbugs.gnu.org
Subject: Re: bug#32504: [PATCH] syntax-is-{comment|string}-p
Date: Wed, 22 Aug 2018 23:12:42 -0400

Alex Branham <alex.branham <at> gmail.com> writes:

> I got tired of checking/remembering whether (nth 3 (syntax-ppss)) was a
> string or a comment, so I've created two simple functions that wrap that
> in a more descriptive name. I've noticed that there are a handful of
> these that other modes have written, so evidently others wanted them as
> well at some point.

What about syntax-ppss-context in syntax.el?

Message #11 received at 32504 <at> debbugs.gnu.org (full text, mbox):

From: Alex Branham <alex.branham <at> gmail.com>
To: Noam Postavsky <npostavs <at> gmail.com>
Cc: 32504 <at> debbugs.gnu.org
Subject: Re: bug#32504: [PATCH] syntax-is-{comment|string}-p
Date: Thu, 23 Aug 2018 08:01:36 -0500

On Wed 22 Aug 2018 at 22:12, Noam Postavsky <npostavs <at> gmail.com> wrote:

> Alex Branham <alex.branham <at> gmail.com> writes:
>
>> I got tired of checking/remembering whether (nth 3 (syntax-ppss)) was a
>> string or a comment, so I've created two simple functions that wrap that
>> in a more descriptive name. I've noticed that there are a handful of
>> these that other modes have written, so evidently others wanted them as
>> well at some point.
>
> What about syntax-ppss-context in syntax.el?

Thanks, I didn't know about syntax-ppss-context. It doesn't seem to be
documented anywhere.

I think I still slightly prefer having these two functions since when
searching for something like "syntax string" syntax-is-string-p will pop
up but syntax-ppss-context won't.

Thanks again,
Alex

Message #14 received at 32504 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Alex Branham <alex.branham <at> gmail.com>
Cc: npostavs <at> gmail.com, 32504 <at> debbugs.gnu.org
Subject: Re: bug#32504: [PATCH] syntax-is-{comment|string}-p
Date: Thu, 23 Aug 2018 16:58:15 +0300

> From: Alex Branham <alex.branham <at> gmail.com>
> Date: Thu, 23 Aug 2018 08:01:36 -0500
> Cc: 32504 <at> debbugs.gnu.org
> 
> > What about syntax-ppss-context in syntax.el?
> 
> Thanks, I didn't know about syntax-ppss-context. It doesn't seem to be
> documented anywhere.

If it's useful, we could document it.

Message #17 received at 32504 <at> debbugs.gnu.org (full text, mbox):

From: Phil Sainty <psainty <at> orcon.net.nz>
To: Alex Branham <alex.branham <at> gmail.com>
Cc: bug-gnu-emacs <bug-gnu-emacs-bounces+psainty=orcon.net.nz <at> gnu.org>,
 Noam Postavsky <npostavs <at> gmail.com>, 32504 <at> debbugs.gnu.org
Subject: Re: bug#32504: [PATCH] syntax-is-{comment|string}-p
Date: Fri, 24 Aug 2018 11:18:49 +1200

Note also the "Todo" item in syntax.el:

;; - new functions `syntax-state', ... to replace uses of 
parse-partial-state
;;   with something higher-level (similar to syntax-ppss-context).

Presumably that comment should be removed in any patch for this bug.

Message #20 received at 32504 <at> debbugs.gnu.org (full text, mbox):

From: Alex Branham <alex.branham <at> gmail.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: npostavs <at> gmail.com, 32504 <at> debbugs.gnu.org
Subject: Re: bug#32504: [PATCH] syntax-is-{comment|string}-p
Date: Fri, 24 Aug 2018 11:11:47 -0500

On Thu 23 Aug 2018 at 08:58, Eli Zaretskii <eliz <at> gnu.org> wrote:

>> From: Alex Branham <alex.branham <at> gmail.com>
>> Date: Thu, 23 Aug 2018 08:01:36 -0500
>> Cc: 32504 <at> debbugs.gnu.org
>>
>> > What about syntax-ppss-context in syntax.el?
>>
>> Thanks, I didn't know about syntax-ppss-context. It doesn't seem to be
>> documented anywhere.
>
> If it's useful, we could document it.

I'm ambivalent about its usefulness - I don't see it used anywhere in
Emacs's code and only once in the packages I have installed.

Alex

Message #23 received at 32504 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Alex Branham <alex.branham <at> gmail.com>
Cc: npostavs <at> gmail.com, 32504 <at> debbugs.gnu.org
Subject: Re: bug#32504: [PATCH] syntax-is-{comment|string}-p
Date: Fri, 24 Aug 2018 22:28:07 +0300

> From: Alex Branham <alex.branham <at> gmail.com>
> Cc: npostavs <at> gmail.com, 32504 <at> debbugs.gnu.org
> Date: Fri, 24 Aug 2018 11:11:47 -0500
> 
> >> > What about syntax-ppss-context in syntax.el?
> >>
> >> Thanks, I didn't know about syntax-ppss-context. It doesn't seem to be
> >> documented anywhere.
> >
> > If it's useful, we could document it.
> 
> I'm ambivalent about its usefulness - I don't see it used anywhere in
> Emacs's code and only once in the packages I have installed.

That could be because it isn't documented.  After all, that was your
reason for not knowing about it, right?

Message #26 received at 32504 <at> debbugs.gnu.org (full text, mbox):

From: Alex Branham <alex.branham <at> gmail.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: npostavs <at> gmail.com, 32504 <at> debbugs.gnu.org
Subject: Re: bug#32504: [PATCH] syntax-is-{comment|string}-p
Date: Fri, 24 Aug 2018 14:49:21 -0500

On Fri 24 Aug 2018 at 14:28, Eli Zaretskii <eliz <at> gnu.org> wrote:

> That could be because it isn't documented.  After all, that was your
> reason for not knowing about it, right?

Yes, absolutely. I meant I'm ambivalent about its usefulness versus
syntax-is-comment/string-p, which seem more descriptive to me.

Message #29 received at 32504 <at> debbugs.gnu.org (full text, mbox):

From: Noam Postavsky <npostavs <at> gmail.com>
To: Alex Branham <alex.branham <at> gmail.com>
Cc: Eli Zaretskii <eliz <at> gnu.org>, 32504 <at> debbugs.gnu.org
Subject: Re: bug#32504: [PATCH] syntax-is-{comment|string}-p
Date: Fri, 24 Aug 2018 22:26:51 -0400

Alex Branham <alex.branham <at> gmail.com> writes:

>>> Thanks, I didn't know about syntax-ppss-context. It doesn't seem to be
>>> documented anywhere.
>>
>> If it's useful, we could document it.
>
> I'm ambivalent about its usefulness - I don't see it used anywhere in
> Emacs's code and only once in the packages I have installed.

For a bit of prior art, there are some similar functions in python.el:
python-syntax-context, python-syntax-context-type,
python-syntax-comment-or-string-p, python-syntax-closing-paren-p.

Also, syntax.el has a couple of commented out "XEmacs compatibility
functions": buffer-syntactic-context, buffer-syntactic-context-depth.

I think it would make sense to provide symbolic names for all the
elements returned by syntax-ppss, maybe like this:

    (cl-defstruct (syntax-state (:constructor nil)
                                (:type list))
      depth list-start sexp-end
      string-start comment quoted
      min-depth comment-style comment-or-string-start
      open-parens syntax-sequence)

Message #32 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Andreas Röhler <andreas.roehler <at> easy-emacs.de>
To: bug-gnu-emacs <at> gnu.org
Subject: Re: bug#32504: [PATCH] syntax-is-{comment|string}-p
Date: Sun, 26 Aug 2018 08:33:38 +0200

On 24.08.2018 21:49, Alex Branham wrote:
> 
> On Fri 24 Aug 2018 at 14:28, Eli Zaretskii <eliz <at> gnu.org> wrote:
> 
>> That could be because it isn't documented.  After all, that was your
>> reason for not knowing about it, right?
> 
> Yes, absolutely. I meant I'm ambivalent about its usefulness versus
> syntax-is-comment/string-p, which seem more descriptive to me.
> 
> 
> 

+1

Using here my home-made ar-in-comment-p, ar-in-string-p

But there is another thing, syntax-ppss-context isn't that convenient: 
it requires still a check for eq instead of simply delivering a boolean.

Andreas

Message #35 received at 32504 <at> debbugs.gnu.org (full text, mbox):

From: Alex Branham <alex.branham <at> gmail.com>
To: Noam Postavsky <npostavs <at> gmail.com>
Cc: Eli Zaretskii <eliz <at> gnu.org>, 32504 <at> debbugs.gnu.org
Subject: Re: bug#32504: [PATCH] syntax-is-{comment|string}-p
Date: Thu, 30 Aug 2018 09:39:52 -0500

> I think it would make sense to provide symbolic names for all the
> elements returned by syntax-ppss, maybe like this:

That makes sense to me.

>     (cl-defstruct (syntax-state (:constructor nil)
>                                 (:type list))
>       depth list-start sexp-end
>       string-start comment quoted
>       min-depth comment-style comment-or-string-start
>       open-parens syntax-sequence)

I'm not a big fan of the docstrings generated by this, is there a way to
change them to be more helpful? For example, syntax-state-comment looks
like this:

syntax-state-comment is a Lisp function.

(syntax-state-comment CL-X)

This function has a compiler macro ‘syntax-state-comment--cmacro’.

Access slot "comment" of ‘(syntax-state (:constructor nil) (:type list))’ struct CL-X.


But it would be a lot better (in my eyes, anyway) if it looked something
like this, had the -p suffix, and made CL-X default to point:

syntax-state-comment-p is a Lisp function.

(syntax-state-comment-p &optional CL-X)

This function has a compiler macro ‘syntax-state-comment-p--cmacro’.

Return non-nil if the syntax of CL-X is a comment. CL-X defaults to point.

Message #38 received at 32504 <at> debbugs.gnu.org (full text, mbox):

From: Noam Postavsky <npostavs <at> gmail.com>
To: Alex Branham <alex.branham <at> gmail.com>
Cc: Eli Zaretskii <eliz <at> gnu.org>, 32504 <at> debbugs.gnu.org
Subject: Re: bug#32504: [PATCH] syntax-is-{comment|string}-p
Date: Thu, 30 Aug 2018 21:21:54 -0400

Alex Branham <alex.branham <at> gmail.com> writes:

>>     (cl-defstruct (syntax-state (:constructor nil)
>>                                 (:type list))
>>       depth list-start sexp-end
>>       string-start comment quoted
         ^^^^^^^^^^^^
That should be string-terminator

>>       min-depth comment-style comment-or-string-start
>>       open-parens syntax-sequence)
>
> I'm not a big fan of the docstrings generated by this, is there a way to
> change them to be more helpful?

Hmm, doesn't look like it.  Well, that's just a convenient way of
defining them all quickly for discussion, it wouldn't be that much
harder to write out defuns I guess.

> But it would be a lot better (in my eyes, anyway) if it looked something
> like this, had the -p suffix, and made CL-X default to point:

> Return non-nil if the syntax of CL-X is a comment.

I don't think it should be a -p predicate, because there is meaningful
distinction between non-nil values:

     4. nil if outside a comment, t if inside a non-nestable comment,
        else an integer (the current comment nesting).

> CL-X defaults to point.

And, my intention is to operate on the return value of syntax-ppss, not
give a point to call it with.  So it could be used as:

    (syntax-state-comment (syntax-ppss))

or

    (let ((ppss (syntax-ppss)))
      (and (syntax-state-comment ppss)
           (syntax-state-comment-or-string-start ppss)))

or

    (syntax-state-comment (parse-partial-sexp ...))

Message #41 received at 32504 <at> debbugs.gnu.org (full text, mbox):

From: Alex Branham <alex.branham <at> gmail.com>
To: Noam Postavsky <npostavs <at> gmail.com>
Cc: Eli Zaretskii <eliz <at> gnu.org>, 32504 <at> debbugs.gnu.org
Subject: Re: bug#32504: [PATCH] syntax-is-{comment|string}-p
Date: Thu, 30 Aug 2018 21:50:37 -0500

On Thu 30 Aug 2018 at 20:21, Noam Postavsky <npostavs <at> gmail.com> wrote:

>> I'm not a big fan of the docstrings generated by this, is there a way to
>> change them to be more helpful?
>
> Hmm, doesn't look like it.  Well, that's just a convenient way of
> defining them all quickly for discussion, it wouldn't be that much
> harder to write out defuns I guess.

Fair enough.

> I don't think it should be a -p predicate, because there is meaningful
> distinction between non-nil values:
>
>      4. nil if outside a comment, t if inside a non-nestable comment,
>         else an integer (the current comment nesting).

That makes sense, but the -p predicate seems more discoverable to me. We
can always note in the docstring that the actual return value is usable.
I don't have a super strong opinion though.

>> CL-X defaults to point.
>
> And, my intention is to operate on the return value of syntax-ppss, not
> give a point to call it with.  So it could be used as:
>
>     (syntax-state-comment (syntax-ppss))
>
> or
>
>     (let ((ppss (syntax-ppss)))
>       (and (syntax-state-comment ppss)
>            (syntax-state-comment-or-string-start ppss)))
>
> or
>
>     (syntax-state-comment (parse-partial-sexp ...))

Right, but whenever I want to call on these functions, 90% of the time
the question I'm trying to answer is "Is point in a comment/string?" And
the 3rd party ***-is-comment/string-p functions I've looked at usually
(always?) look at positions.

Thanks,
Alex

Message #44 received at 32504 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Noam Postavsky <npostavs <at> gmail.com>
Cc: Alex Branham <alex.branham <at> gmail.com>, 32504 <at> debbugs.gnu.org
Subject: Re: bug#32504: [PATCH] syntax-is-{comment|string}-p
Date: Mon, 24 Jun 2019 00:05:11 +0200

Noam Postavsky <npostavs <at> gmail.com> writes:

> Alex Branham <alex.branham <at> gmail.com> writes:
>
>> I got tired of checking/remembering whether (nth 3 (syntax-ppss)) was a
>> string or a comment, so I've created two simple functions that wrap that
>> in a more descriptive name. I've noticed that there are a handful of
>> these that other modes have written, so evidently others wanted them as
>> well at some point.
>
> What about syntax-ppss-context in syntax.el?

I went ahead and documented it; if I read this thread right, it's
sufficient for the use case presented.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Message #51 received at 32504 <at> debbugs.gnu.org (full text, mbox):

From: Noam Postavsky <npostavs <at> gmail.com>
To: Alex Branham <alex.branham <at> gmail.com>
Cc: Eli Zaretskii <eliz <at> gnu.org>, 32504 <at> debbugs.gnu.org
Subject: Re: bug#32504: [PATCH] syntax-is-{comment|string}-p
Date: Mon, 08 Jul 2019 20:05:15 -0400

[Message part 1 (text/plain, inline)]

Alex Branham <alex.branham <at> gmail.com> writes:

> On Thu 30 Aug 2018 at 20:21, Noam Postavsky <npostavs <at> gmail.com> wrote:
>
>>> I'm not a big fan of the docstrings generated by this, is there a way to
>>> change them to be more helpful?
>>
>> Hmm, doesn't look like it.  Well, that's just a convenient way of
>> defining them all quickly for discussion, it wouldn't be that much
>> harder to write out defuns I guess.
>
> Fair enough.

The recent talk about accessors for decoded time reminded me of this.
Here's an initial patch.

[0001-Add-named-accessors-for-syntax-ppss-state-Bug-32504.patch (text/plain, attachment)]

[Message part 3 (text/plain, inline)]

>>> CL-X defaults to point.
>>
>> And, my intention is to operate on the return value of syntax-ppss, not
>> give a point to call it with.
>
> Right, but whenever I want to call on these functions, 90% of the time
> the question I'm trying to answer is "Is point in a comment/string?" And
> the 3rd party ***-is-comment/string-p functions I've looked at usually
> (always?) look at positions.

Well, for me I just want to stop having to look up the docstring of
parse-partial-sexp every damn time I see (nth X PPSS).  But I wouldn't
be against having syntax-is-comment/string-p which take a position as
well.

Message #54 received at 32504 <at> debbugs.gnu.org (full text, mbox):

From: Leo Liu <sdl.web <at> gmail.com>
To: Noam Postavsky <npostavs <at> gmail.com>
Cc: Alex Branham <alex.branham <at> gmail.com>, 32504 <at> debbugs.gnu.org
Subject: Re: bug#32504: [PATCH] syntax-is-{comment|string}-p
Date: Thu, 11 Jul 2019 13:11:33 +0800

On 2019-07-08 20:05 -0400, Noam Postavsky wrote:
> Well, for me I just want to stop having to look up the docstring of
> parse-partial-sexp every damn time I see (nth X PPSS).  But I wouldn't
> be against having syntax-is-comment/string-p which take a position as
> well.

syntax-ppss-context looks better. It is there for a long time and I have
personally used it many times (13 times in one of my projects).
Introduce a new set seems overkill at this point.

BTW, please don't name functions combining -is- and -p. They sound odd.

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