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bug#50538: [PATCH] 28.0.50; electric-pair-mode fails to pair double quot
From: |
Alan Mackenzie |
Subject: |
bug#50538: [PATCH] 28.0.50; electric-pair-mode fails to pair double quotes in some cases in CC mode |
Date: |
Fri, 17 Sep 2021 17:08:33 +0000 |
Hello, Jim.
On Thu, Sep 16, 2021 at 14:36:06 -0700, Jim Porter wrote:
> On 9/16/2021 1:49 PM, Alan Mackenzie wrote:
> > There were two or three minor problems with the patch:
> > 1-/. CC Mode doesn't use syntax-ppss at all. This was because way back
> > when, syntax-ppss was buggy, and even now doesn't do the right thing for
> > CC Mode in some edge cases (e.g. with the buffer narrowed and point-min
> > inside a string or comment). Instead it uses its own internal syntactic
> > cacheing, largely centred around the function c-semi-pp-to-literal.
> > 2/- Rather than using get-text-property and friends directly, CC Mode
> > uses the macros c-get-char-property, etc. This is (?was) to maintain
> > compatibility with XEmacs.
> > 3/- (A bit more serious) The patch looks for the last " in the current
> > line without taking account of any escaped new lines. There is already
> > a CC Mode macro which does all the work here, c-point, which can be given
> > the argument 'eoll for "end of logical line".
> Thanks, I've incorporated all these changes into the attached patch. The
> only difference between my patch and the version you provided was to
> keep the `(search-backward "\"")' portion from my patch, since the code
> needs to find the last double-quote, not the end of line.
Duh! Sorry about that, I clean forgot about it. I did say that I
hadn't tested it, though. ;-)
> As an aside, it's probably worth explaining why my patch searches for
> the last double-quote in the first place. As far as I understand CC
> Mode, when there's an unterminated double-quote on a line, both the
> quote and the newline have a string fence property applied to them.
Yes.
> This means we could check the newline for that property, *but* there's
> no guarantee a newline actually exists: `(c-point 'eoll)' could
> actually point to the end of the buffer. To get around that, we search
> backwards for the last double-quote of the (logical) line, since
> that's guaranteed to exist.
Yes. This is a very important case, the one that occurs when somebody's
typing a new file, or at the end of an existing one.
> If we wanted to, we could avoid searching backwards for the last
> double-quote when a newline exists, but I'm not sure the gain in
> performance (likely very small) is worth the extra code complexity.
I'm fairly sure it wouldn't be.
[ Patch snipped but read. ]
--
Alan Mackenzie (Nuremberg, Germany).
- bug#50538: [PATCH] 28.0.50; electric-pair-mode fails to pair double quotes in some cases in CC mode, (continued)
- bug#50538: [PATCH] 28.0.50; electric-pair-mode fails to pair double quotes in some cases in CC mode, Jim Porter, 2021/09/16
- bug#50538: [PATCH] 28.0.50; electric-pair-mode fails to pair double quotes in some cases in CC mode, Alan Mackenzie, 2021/09/16
- bug#50538: [PATCH] 28.0.50; electric-pair-mode fails to pair double quotes in some cases in CC mode, João Távora, 2021/09/16
- bug#50538: [PATCH] 28.0.50; electric-pair-mode fails to pair double quotes in some cases in CC mode, Alan Mackenzie, 2021/09/17
- bug#50538: [PATCH] 28.0.50; electric-pair-mode fails to pair double quotes in some cases in CC mode, Alan Mackenzie, 2021/09/16
- bug#50538: [PATCH] 28.0.50; electric-pair-mode fails to pair double quotes in some cases in CC mode, Alan Mackenzie, 2021/09/16
- bug#50538: [PATCH] 28.0.50; electric-pair-mode fails to pair double quotes in some cases in CC mode, Jim Porter, 2021/09/16
- bug#50538: [PATCH] 28.0.50; electric-pair-mode fails to pair double quotes in some cases in CC mode,
Alan Mackenzie <=
- bug#50538: [PATCH v3] 28.0.50; electric-pair-mode fails to pair double quotes in some cases in CC mode, Jim Porter, 2021/09/22
- bug#50538: [PATCH v3] 28.0.50; electric-pair-mode fails to pair double quotes in some cases in CC mode, Alan Mackenzie, 2021/09/26
- bug#50538: [PATCH v4] 28.0.50; electric-pair-mode fails to pair double quotes in some cases in CC mode, Jim Porter, 2021/09/28