[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
bug#22983: syntax-ppss returns wrong result.
From: |
Alan Mackenzie |
Subject: |
bug#22983: syntax-ppss returns wrong result. |
Date: |
Sat, 9 Sep 2017 10:20:27 +0000 |
User-agent: |
Mutt/1.7.2 (2016-11-26) |
Hello, Dmitry.
On Sat, Sep 09, 2017 at 12:44:02 +0300, Dmitry Gutov wrote:
> Hi Alan,
> On 9/7/17 11:45 PM, Alan Mackenzie wrote:
> > The solution I propose is to introduce a second cache into syntax-ppss,
> > and this cache would be used whenever (not (eq (point-min) 1)).
> > Whenever point-min changes, and isn't 1, this second cached would be
> > calculated again from scratch.
> Thanks for writing this up. I think it's a good step, and since it
> follow the current wording of the docstring, it should be highly
> compatible with the existing code.
Thanks.
> > This proposal has these advantages:
> > (i) It would make the function deliver what its unchanged doc string
> > says. This is important, given that syntax-ppss has been very widely
> > used within Emacs, and likely by external packages too; these will
> > typically have assumed the advertised behaviour of the function, without
> > having tested it in narrowed buffers.
> It will also continue to function as expected in mmm-mode, AFAICT,
> without the need for an "escape hatch" we discussed before.
> > (i) In the case which currently works, namely a non-narrowed buffer,
> > there would be only a minute slow-down (basically, there would be extra
> > code to check point-min and select the cache to use).
> > (ii) The cache for use in a narrowed buffer might well be sufficiently
> > fast in normal use. If it is not, it could be enhanced readily.
> And since the API doesn't change, and the observable behavior doesn't
> either (in the vast majority of cases; probably all except the broken
> ones), we can refine this solution easily, or even swap it for something
> else, with little cost.
Yes. I now have a provisional implementation of this new strategy,
which works on the test case for xdisp.c with which I opened the bug.
It seems to be working, generally. I need to test it more thoroughly.
In the implementation, I have left the function `syntax-ppss' untouched
except for adding a function call to set up the cache right at the
start. I have refactored syntax-ppss-flush-cache, extracting a function
which is called directly from the cache-selecting code. Other than
that, there is one new function (which switches the current cache in
use) and a few new variables to keep track of the caches.
> > I think Dmitry also proposed a method of solution some months ago,
> > though I don't remember in detail what it was. Dmitry, do you still
> > think your solution would work? If so, please elaborate on it.
> There is a simple patch at
> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=22983#47, but I after some
> consideration, I now prefer your proposed approach. We've also had some
> grander ideas about enhancing things further, but those can be added
> later, after we finally decide.
Yes, I agree.
> I do want to know what Stefan thinks of this subject now, though.
Yes.
> Caveats:
> - This solves the dependency on point-min, but does nothing about the
> dependency on the current syntax-table (which can change). I'm not
> necessarily suggesting we try to solve that now, though.
I had some ideas on this back in the spring (about having "indirect
variables") which could be used quickly to "swap out" the current
syntax-table text properties, and (more importantly) quickly swap them
back in. But that's for another day.
> - Before this change is pushed to master, or shortly after, I'd like to
> know that it actually fixed the problem Philipp experienced with
> python-mode, so we can revert 4fbd330. If it was caused by e.g.
> syntax-table changing, we've not improved much.
I am naturally interested in this, too. If my patch doesn't fix this
bug, at least it will have removed a layer of fog inhibiting its
investigation.
> All the best,
> Dmitry.
--
Alan Mackenzie (Nuremberg, Germany).
- bug#22983: syntax-ppss returns wrong result., (continued)
- bug#22983: syntax-ppss returns wrong result., Alan Mackenzie, 2017/09/02
- bug#22983: syntax-ppss returns wrong result., Eli Zaretskii, 2017/09/02
- bug#22983: syntax-ppss returns wrong result., John Wiegley, 2017/09/04
- bug#22983: syntax-ppss returns wrong result., Dmitry Gutov, 2017/09/04
- bug#22983: syntax-ppss returns wrong result., Andreas Röhler, 2017/09/05
- bug#22983: syntax-ppss returns wrong result., John Wiegley, 2017/09/05
- bug#22983: syntax-ppss returns wrong result., Alan Mackenzie, 2017/09/07
- bug#22983: syntax-ppss returns wrong result., Andreas Röhler, 2017/09/08
- bug#22983: syntax-ppss returns wrong result., Alan Mackenzie, 2017/09/10
- bug#22983: syntax-ppss returns wrong result., Dmitry Gutov, 2017/09/09
- bug#22983: syntax-ppss returns wrong result.,
Alan Mackenzie <=
- bug#22983: syntax-ppss returns wrong result., Dmitry Gutov, 2017/09/09
- bug#22983: syntax-ppss returns wrong result., Alan Mackenzie, 2017/09/10
- bug#22983: [ Patch ] Re: bug#22983: syntax-ppss returns wrong result., Alan Mackenzie, 2017/09/10
- bug#22983: [ Patch ] Re: bug#22983: syntax-ppss returns wrong result., Stefan Monnier, 2017/09/10
- bug#22983: [ Patch ] Re: bug#22983: syntax-ppss returns wrong result., Dmitry Gutov, 2017/09/10
- bug#22983: [ Patch ] Re: bug#22983: syntax-ppss returns wrong result., Stefan Monnier, 2017/09/11
- bug#22983: [ Patch ] Re: bug#22983: syntax-ppss returns wrong result., Dmitry Gutov, 2017/09/11
- bug#22983: [ Patch ] Re: bug#22983: syntax-ppss returns wrong result., Richard Stallman, 2017/09/12
- bug#22983: [ Patch ] Re: bug#22983: syntax-ppss returns wrong result., Alan Mackenzie, 2017/09/11
- bug#22983: [ Patch ] Re: bug#22983: syntax-ppss returns wrong result., Stefan Monnier, 2017/09/11