From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: cc-mode fontification feels random Date: Fri, 04 Jun 2021 22:11:25 +0300 Message-ID: <83o8clla1u.fsf@gnu.org> References: <831r9iw473.fsf@gnu.org> <2d6d1cb0-2e8f-ceea-cb83-3bb840b65115@dancol.org> <83zgw6udxt.fsf@gnu.org> <87czt1zzns.fsf@gmail.com> <371647e9-9508-ae98-26f0-3649d7ba114e@dancol.org> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="38410"; mail-complaints-to="usenet@ciao.gmane.io" Cc: emacs-devel@gnu.org, monnier@iro.umontreal.ca, joaotavora@gmail.com To: Daniel Colascione Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Fri Jun 04 21:12:07 2021 Return-path: Envelope-to: ged-emacs-devel@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lpFEk-0009hB-MJ for ged-emacs-devel@m.gmane-mx.org; Fri, 04 Jun 2021 21:12:06 +0200 Original-Received: from localhost ([::1]:33280 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lpFEi-0007pd-QH for ged-emacs-devel@m.gmane-mx.org; Fri, 04 Jun 2021 15:12:04 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:53370) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lpFEE-00075z-4c for emacs-devel@gnu.org; Fri, 04 Jun 2021 15:11:35 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]:47786) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lpFED-0008T2-A1; Fri, 04 Jun 2021 15:11:33 -0400 Original-Received: from 84.94.185.95.cable.012.net.il ([84.94.185.95]:1892 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lpFEC-0005Kt-Os; Fri, 04 Jun 2021 15:11:33 -0400 In-Reply-To: <371647e9-9508-ae98-26f0-3649d7ba114e@dancol.org> (message from Daniel Colascione on Fri, 4 Jun 2021 11:36:05 -0700) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.io gmane.emacs.devel:270399 Archived-At: > Cc: Eli Zaretskii , emacs-devel@gnu.org > From: Daniel Colascione > Date: Fri, 4 Jun 2021 11:36:05 -0700 > > On 6/4/21 11:25 AM, Stefan Monnier wrote: > >> But I don't understand what's stopping these tree-sitter C modules (like > >> [1] and [2]) to have access to the buffer's contents directly and have > >> the best of both worlds. > > I think it's a direct result of them being "modules": the API doesn't > > let modules access a buffer's content directly, so it's more efficient > > copy the content via `buffer-substring` and toss it on the other side > > than having to use something like `char-after`. > > The problem is more fundamental than that. Internally, each buffer has a > gap. External tools that operate on char arrays don't expect a gap. > (They also don't expect to operate on Emacs internal coding, but that's > another issue.) If we *did* grant direct buffer access via modules, we'd > at least have to memcpy half (on average) the buffer to close the gap, > then memcpy half the buffer (on average) to open the gap again when we > began editing. I see no reason for copying, nor for making these tools aware of the gap. At least tree-sitter allows the application to provide a function through which tree-sitter will access the edited text. It should be simple to write such a function, because on the C level we always know where the gap is. > Besides, memory copies are really, really, ridiculously fast. My system > can cat from /dev/zero to /dev/null at ~18GB/sec. Copying a buffer's > contents so we can give it to tree-sitter should be no issue at all. Why copy at all? all these libraries need is access to buffer text. We can just give it to them.