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: Help with recursive destructive function Date: Mon, 07 May 2018 12:26:45 -0400 Message-ID: References: <87efiqzzd2.fsf@ericabrahamsen.net> <87bmdu3mtf.fsf@web.de> <87zi1e9kju.fsf@web.de> <87o9hs3aht.fsf@ericabrahamsen.net> <87bmds9qcg.fsf@web.de> <87k1sg185t.fsf@ericabrahamsen.net> <044bdbf1-39a2-0e71-ec79-3d375d9109c8@gmail.com> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: blaine.gmane.org 1525710306 11059 195.159.176.226 (7 May 2018 16:25:06 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 7 May 2018 16:25:06 +0000 (UTC) User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Mon May 07 18:25:02 2018 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 1fFiwg-0002h7-88 for ged-emacs-devel@m.gmane.org; Mon, 07 May 2018 18:25:02 +0200 Original-Received: from localhost ([::1]:47107 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fFiyl-0004Qi-6x for ged-emacs-devel@m.gmane.org; Mon, 07 May 2018 12:27:11 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:56706) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fFiyf-0004Qd-4F for emacs-devel@gnu.org; Mon, 07 May 2018 12:27:06 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fFiyb-0003Lq-U9 for emacs-devel@gnu.org; Mon, 07 May 2018 12:27:05 -0400 Original-Received: from [195.159.176.226] (port=40510 helo=blaine.gmane.org) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1fFiyb-0003L6-NQ for emacs-devel@gnu.org; Mon, 07 May 2018 12:27:01 -0400 Original-Received: from list by blaine.gmane.org with local (Exim 4.84_2) (envelope-from ) id 1fFiwM-0002Nv-GO for emacs-devel@gnu.org; Mon, 07 May 2018 18:24:42 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 34 Original-X-Complaints-To: usenet@blaine.gmane.org Cancel-Lock: sha1:4AiJS9Lef8uErNLLMJ6HaVV6tDE= 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:225121 Archived-At: > (defun deep-edit (f data) > (let ((cur (list #'car #'setcar data)) > (stack (list (list #'cdr #'setcdr data)))) > (while cur > (let* ((getter (car cur)) > (setter (cadr cur)) > (tree (caddr cur)) > (subtree (funcall getter tree))) > (funcall setter tree (funcall f subtree)) > (cond > ((consp subtree) > (push (list #'cdr #'setcdr subtree) stack) > (setq cur (list #'car #'setcar subtree))) > (t (setq cur (pop stack)))))))) BTW, a "cleaner" (tho less efficient) way uses gv-ref: (defun deep-edit (f data) (let ((cur (gv-ref (car data))) (stack (list (gv-ref (cdr data))))) (while (or cur stack) ;; Probably should use (cl-callf f (gv-deref cell)). (pcase (setf (gv-deref cur) (funcall f (gv-deref cell))) ((and (pred consp) subtree) (push (gv-ref (cdr subtree)) stack) (setq cur (gv-ref (car subtree)))) (t (setq cur (pop stack))))))) tho the above has a bug when cur is nil, so it won't work as is. Stefan "it'd be great to be able to represent a gv-ref as a 3-element tuple so as to make it as efficient as your code, tho"