From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Overlays as an AA-tree Date: Sun, 19 Feb 2017 18:10:29 -0500 Message-ID: References: <87d1jylv43.fsf@fastmail.com> <87fujv64mn.fsf@hochschule-trier.de> <87fujvpkzc.fsf@fastmail.com> <87vasr5tqd.fsf@hochschule-trier.de> <87d1ex4kon.fsf@hochschule-trier.de> <87d1evod6x.fsf@fastmail.com> <877f53ftab.fsf@hochschule-trier.de> <878tpiqiuc.fsf@hochschule-trier.de> <87shnppspb.fsf@hochschule-trier.de> <87o9yc9v30.fsf@hochschule-trier.de> <87a89vaes3.fsf@hochschule-trier.de> <87efz7n0g5.fsf@fastmail.com> <877f4uah6i.fsf@hochschule-trier.de> <83k28u1uyz.fsf@gnu.org> <871suxs9ad.fsf@hochschule-trier.de> <837f4pxpdc.fsf@gnu.org> <877f4lls9e.fsf@hochschule-trier.de> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: blaine.gmane.org 1487545883 2934 195.159.176.226 (19 Feb 2017 23:11:23 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 19 Feb 2017 23:11:23 +0000 (UTC) User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.0.50 (gnu/linux) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Mon Feb 20 00:11:19 2017 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cfadT-0008Py-5N for ged-emacs-devel@m.gmane.org; Mon, 20 Feb 2017 00:11:19 +0100 Original-Received: from localhost ([::1]:35354 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cfadV-0006xc-KY for ged-emacs-devel@m.gmane.org; Sun, 19 Feb 2017 18:11:21 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:59664) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cfacw-0006xX-5m for emacs-devel@gnu.org; Sun, 19 Feb 2017 18:10:46 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cfacq-0002DK-W0 for emacs-devel@gnu.org; Sun, 19 Feb 2017 18:10:46 -0500 Original-Received: from [195.159.176.226] (port=51923 helo=blaine.gmane.org) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1cfacq-0002Cq-In for emacs-devel@gnu.org; Sun, 19 Feb 2017 18:10:40 -0500 Original-Received: from list by blaine.gmane.org with local (Exim 4.84_2) (envelope-from ) id 1cfacf-0004Vo-Ii for emacs-devel@gnu.org; Mon, 20 Feb 2017 00:10:29 +0100 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 29 Original-X-Complaints-To: usenet@blaine.gmane.org Cancel-Lock: sha1:y1No3bIaBa9pNjusXhSGwjisWo8= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 195.159.176.226 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 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.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:212481 Archived-At: > Here is one such case were the tree is forced to search through all > overlays in order to find the next change: > |--------------------------| > |-------------------| > |-------------| > B ^ E > P > We are looking for the next change after P, which is E. But E is the > end of some overlay, and the tree knows nothing about the order of > these, so it needs to consider all overlays. Maybe I don't understand your example, but AFAICT it doesn't need to consider all overlays: only those that cover P. > A stateful folding mode using overlays to keep data about, possibly > closed, folds. Even if that results in thousands of overlays in the buffer, any particular location in the buffer shouldn't have a "folding nesting" so terribly high that it is covered by hundreds of overlays. The complexity of overlays-in and overlays-at is necessarily of O(N) where N is the number of overlays covering the area. Even O(N log M) (where M is the total number of overlays) should be fine. Stefan