From: Alan Mackenzie <acm@muc.de>
To: Daniel Colascione <dancol@dancol.org>
Cc: Emacs developers <emacs-devel@gnu.org>
Subject: Re: POC: customizable cc-mode keywords
Date: Sun, 11 May 2014 21:13:51 +0000 [thread overview]
Message-ID: <20140511211351.GC2759@acm.acm> (raw)
In-Reply-To: <53632C6F.5070903@dancol.org>
Hi, Daniel.
On Thu, May 01, 2014 at 10:26:07PM -0700, Daniel Colascione wrote:
> cc-mode has trouble with parsing dialects of C that use the preprocessor
> heavily.
This has been true since 4004 BC, since C hackers are able to write
monstrosities using macros. But we do our best to cope with the less
outlandish variants.
> Consider this example from the Linux kernel:
> static int perf_event_period(struct perf_event *event, u64 __user *arg)
> __user is defined to some GCC static analysis nonsense, but since
> cc-mode doesn't know that, we see __user fontified in
> font-lock-variable-name-face and *arg untouched. This example is fairly
> benign (if ugly), but there are other cases where variations in
> pre-processor C dialect confuse cc-mode in larger regions, leading to
> odd fontification and indentation.
> The patch below adds customizable options for additional C-family
> language "keywords".
> To add this feature, we have to change how cc-mode evaluates its
> language variables.
:-)
> Today, we use clever macros to hard-code the values of all cc-mode
> language variables into the mode functions of each cc-mode major mode
> function or into c-init-language-vars-for, but in order to allow users
> to customize cc-mode syntax, we have to be able to recompute language
> constants and variables at runtime.
Do we, now? You can imagine I've one or two reservations about this
idea. It's far from clear that this level of customisation is a good
thing. The current idea is that the language variables are for creating
new CC Mode languages, not as a means of customisation.
> The new code simply evaluates cc-mode language setter forms at mode
> initialization instead. This approach is slower, but not by much: it
> takes 0.9ms to set up cc-mode's ~130 language variables using the
> precompiled function approach, while it takes 1.6ms to do the same work
> using dynamic evaluation. I can live with this performance regression.
Have you considered turning the pertinent language variables into
customisable variables in cc-vars.el, along the lines of
*-font-lock-extra-types?
> As implemented, the keyword list can only be customized globally, but
> it'd be nice to be able to do something buffer-local too.
[ snipped patch for now. ]
--
Alan Mackenzie (Nuremberg, Germany).
next prev parent reply other threads:[~2014-05-11 21:13 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-02 5:26 POC: customizable cc-mode keywords Daniel Colascione
2014-05-10 23:13 ` Daniel Colascione
2014-05-11 21:13 ` Alan Mackenzie [this message]
2014-05-11 21:23 ` Daniel Colascione
2014-05-16 17:52 ` Alan Mackenzie
2014-05-16 18:06 ` Daniel Colascione
2014-05-18 21:33 ` Alan Mackenzie
2014-05-18 22:28 ` Daniel Colascione
2014-05-19 2:25 ` Stefan Monnier
2014-05-25 18:08 ` Alan Mackenzie
2014-09-08 17:28 ` Stefan Monnier
2014-09-11 13:55 ` Further CC-mode changes Stefan Monnier
2014-09-12 23:59 ` Alan Mackenzie
2014-09-13 1:09 ` Ivan Andrus
2014-09-13 10:04 ` Alan Mackenzie
2014-09-13 3:04 ` Stefan Monnier
2014-09-13 15:10 ` Alan Mackenzie
2014-09-13 19:24 ` Stefan Monnier
2014-09-13 23:08 ` Syntax-propertize and CC-mode [Was: Further CC-mode changes] Alan Mackenzie
2014-09-14 4:04 ` Stefan Monnier
2014-09-16 17:30 ` Sync'ing cc-mode Stefan Monnier
2014-09-26 19:19 ` Stefan Monnier
2014-09-15 20:24 ` Further CC-mode changes Glenn Morris
2014-09-16 3:07 ` Stephen J. Turnbull
2014-09-16 13:39 ` Stefan Monnier
2014-09-16 14:22 ` David Kastrup
2014-09-16 23:40 ` Stephen J. Turnbull
2014-09-17 1:02 ` Stefan Monnier
2014-09-17 1:48 ` Stephen J. Turnbull
2014-09-17 5:22 ` David Kastrup
2014-09-17 13:00 ` Stefan Monnier
2014-09-17 18:31 ` Glenn Morris
2014-09-17 19:12 ` David Kastrup
2014-09-17 5:24 ` Eli Zaretskii
2014-09-17 6:54 ` Stephen J. Turnbull
2014-09-17 7:20 ` Eli Zaretskii
2014-09-17 7:30 ` David Kastrup
2014-09-17 13:04 ` Stefan Monnier
2014-09-17 18:25 ` Glenn Morris
2014-09-18 5:20 ` Stephen J. Turnbull
2014-09-18 9:44 ` Emilio Lopes
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