From: Alan Mackenzie <acm@muc.de>
To: Ergus <spacibba@aol.com>
Cc: 36678@debbugs.gnu.org
Subject: bug#36678: 27.0.50; imenu not working in C++ (maybe because of namespace)
Date: Fri, 2 Aug 2019 19:33:15 +0000 [thread overview]
Message-ID: <20190802193315.GC11966__19257.0704895601$1564774523$gmane$org@ACM> (raw)
In-Reply-To: <20190731155610.x33urisumbblyryu@Ergus>
Hello, Ergus.
On Wed, Jul 31, 2019 at 17:56:13 +0200, Ergus wrote:
> Hi Alan:
> Sorry for the long delay replying this.
No problem!
> I have been thinking on this for a while because this issue affects me
> constantly as I use most of the time C++ now.
I've actually spent some time on this. What I now have is the ability of
imenu to find functions, even when they are not at column zero, and to
record the enclosing namespace/class/etc. of these functions. On M-x
imenu <tab>, which lists all found functions (more or less), the
namespace/class bit only gets displayed as needed to distinguish from
other functions of the same name.
The above is a bit of an exaggeration: it is not yet clean or robust
code, and hasn't been tested much, but does sort of work on the files
I've tried it on.
What is still missing is a scanning of a function's parameters, needed to
distinguish, say, a constructor with two parameters from the same with
none. This is still looking a bit tricky.
> Maybe this is a stupid suggestion, but I was thinking that if the issue
> is performance (for ii) we could add a special function to implement the
> expensive part for the functional search in C and use the C regexps.
At the moment, the scanning of these C++ files is taking a small number
of seconds on my (pretty fast) Ryzen machine. This is slow for imenu.
I can't honestly see how we might use a C function to speed all this up.
Currently, my new code is just using (c-beginning-of-defun -1) to find
the next function, thus avoiding the need to write reams of syntactical
analysis code, but not being fast.
> Maybe it could be restrictive somehow, but if this solves a problem,
> could be good enough and important for C++-mode. Because namespace use
> is becoming more and more extended in C++ with the new standards. And
> the most common indentations are the
> Probably:
> 1) For example it could do a first filtration for the buffer in a C
> function using C regexp (with fake positives) and then filter again in
> the Lisp side?
> 2) Or, we could just iterate the file by lines in C and then modify the
> regex for the next line conditionally (which is cheaper than in
> Lisp). This could create a list in C that we can then use in the Lisp
> side more efficiently.
All this might be workable, I just don't know. But it would probably
make sense to write it in Lisp first, and only then optimise it with C if
it really is too slow.
> In case we figure out a nice method for that. Does it makes sense?
[ .... ]
--
Alan Mackenzie (Nuremberg, Germany).
next prev parent reply other threads:[~2019-08-02 19:33 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-15 20:33 bug#36678: 27.0.50; imenu not working in C++ (maybe because of namespace) Ergus
[not found] ` <mailman.1463.1563222851.2688.bug-gnu-emacs@gnu.org>
2019-07-17 14:39 ` Alan Mackenzie
2019-07-17 16:34 ` Alan Mackenzie
2019-07-31 15:56 ` Ergus
2019-08-02 19:33 ` Alan Mackenzie [this message]
[not found] ` <20190802193315.GC11966@ACM>
2019-08-02 19:56 ` Paul Smith
2019-08-03 2:25 ` Richard Stallman
[not found] ` <E1htjjb-0002eO-Fo@fencepost.gnu.org>
2019-08-03 7:20 ` Eli Zaretskii
2019-08-03 14:43 ` Paul Smith
2019-08-05 2:24 ` Richard Stallman
2019-08-03 11:27 ` Alan Mackenzie
2019-08-03 15:09 ` Paul Smith
2019-08-04 3:01 ` Richard Stallman
2019-08-04 13:56 ` Paul Smith
2019-08-05 2:25 ` Richard Stallman
2019-08-04 2:56 ` Richard Stallman
2019-08-04 8:51 ` Alan Mackenzie
2019-08-05 2:26 ` Richard Stallman
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