From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Michael Heerdegen Newsgroups: gmane.emacs.devel Subject: Re: Make peg.el a built-in library? Date: Fri, 22 Oct 2021 18:33:02 +0200 Message-ID: <87a6j1dnpd.fsf@web.de> References: <875yvtbbn3.fsf@ericabrahamsen.net> <87a6jjc7c8.fsf@web.de> <87v926w3bs.fsf@ericabrahamsen.net> <87zgrhh4he.fsf@web.de> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="31944"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (gnu/linux) Cc: emacs-devel@gnu.org To: Helmut Eller Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Fri Oct 22 18:35:18 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 1mdxVm-00088q-7h for ged-emacs-devel@m.gmane-mx.org; Fri, 22 Oct 2021 18:35:18 +0200 Original-Received: from localhost ([::1]:58042 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mdxVk-0000LF-8C for ged-emacs-devel@m.gmane-mx.org; Fri, 22 Oct 2021 12:35:16 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:44740) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mdxTi-0007yd-3B for emacs-devel@gnu.org; Fri, 22 Oct 2021 12:33:10 -0400 Original-Received: from mout.web.de ([212.227.17.12]:38977) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mdxTg-0000qM-4o for emacs-devel@gnu.org; Fri, 22 Oct 2021 12:33:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=web.de; s=dbaedf251592; t=1634920383; bh=Sp7X0sVedhAJBMsM217V7mj4z9nrtf0pUTqaC+KyFZA=; h=X-UI-Sender-Class:From:To:Cc:Subject:References:Date:In-Reply-To; b=B8vK6VbcIfgpLKh7d8AMMXmSrGvemEvFMGljvdQsJLCsiUhGT9Vk0vKmngQrEgOBq U8l5dCYU1VsZomyoDACRxak86fMzRshskMKKyndriBYoG/CsN1I47At8ux3MZHt9du VTuVQhNJxK0gY2P5xZDnuxCWbpqqaedkvKeLxMr8= X-UI-Sender-Class: c548c8c5-30a9-4db5-a2e7-cb6cb037b8f9 Original-Received: from drachen.dragon ([92.208.225.87]) by smtp.web.de (mrweb106 [213.165.67.124]) with ESMTPSA (Nemesis) id 1MhWkj-1n8MCy28AN-00eKga; Fri, 22 Oct 2021 18:33:03 +0200 In-Reply-To: (Helmut Eller's message of "Sun, 10 Oct 2021 07:58:13 +0200") X-Provags-ID: V03:K1:i0quGjgkfaWvUIxnvaoqclja4AbC+n/tbF/iLYfH9kApatrntQY xGJyc7lev+VqJG9OH99gJkN2qZ3F42pgfFYBfkhUWtg8pyYsnfWRtY4NYWmxrCdtb75Mhjn cFIcdOQJTgalWdqIm6yZVVE0oN+jm0E8O1INl7lVVn0WBTFMpMhT1SzRx/wzN5DRCgVipJ2 cmljLwi/m+neZ13QDWzvA== X-UI-Out-Filterresults: notjunk:1;V03:K0:bZpUib27RvA=:xywBh9DXWGM6xugQQfkw64 EdWqwDp+Jr/OBcWCGDi1beYUoBKmfJSprLMf0vU76f1LmNbAzKmePpWJgnCUSfYDVtDHmYnZm 458x+DKRv23A/aI0PYIrrn01HyokU5iC8cXR2r8tLd2r663nYe80RwHOY1Trph5dvzwK+e042 uVp38+Jr3/C+8Ug583Cab7xSXy4VDBYwwickW+dZlMYB5vkcYQWC3+AEL9x9HWR3UTyf/jHbG q+2tK4KO5Xl3OSBeav0w2aC9PH48yb781C7c9Mwnxa/ZoPWVXynPC70kuYgcSfMiwk9UIi9N5 p9Vk9WL3XhOzeIKzoFndY2rPnv4lCcplOjfBMqrQKFiG0TZovAy9XMVfpOhizJ91HTcR56NQ2 ZhSb1WV+62PbJOAzjHy443q3WM4ZRFToMscZLhZ4ZCmM97Eq7PWjM1envm1MoLh3tRQcCnnyZ nzF0Uku3zk5yPzfmdMAmh9O6uoKJs4hKgzxzhXyd4oasGncmyzzrfrJQBQi1kcqXRiw/ZF5rz BqNj5t4UyptkjAVPbGkt2Dm+bDxj3gUUjBbmPGflE7BvOru67tAgdzoPLczo7j+lXK9Qpg9Vb t0XBVv8Wq7Hof5rkIBPuNHdfnTYdl7qAAMzZF3i4dbRZI5VGpeStq24feD3lyXUc6AOMA1i91 gwBfEMd1wx7HUGTV/YQuK4UC5mzx1Kn+69M2ngAhBWlxwdsStKFmHsyMdRfzhuAaVfCWP7PT5 41M1CaVik9uJ82c8VgSc6n7mP/1PsTy7USQdtL9AByLCd9LaxwVErQKTghfhpjCXh0uQOlkq Received-SPF: pass client-ip=212.227.17.12; envelope-from=michael_heerdegen@web.de; helo=mout.web.de X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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:277571 Archived-At: Helmut Eller writes: > On Sun, Oct 10 2021, Michael Heerdegen wrote: > > > Is it practically possible to transform a regexp into a really > > equivalent PEG, or is it too difficult, or would the resulting PEG just > > be too large or inefficient? > > The LPEG people wrote a paper[*] about this problem. IIUC their answer to the ordered `or' operator problem is simply, at the end, to apply the distributive law when performing the transcription. So e.g. (and (or "a" "aa") "b") doesn't match "aab" as a peg, but (or (and "a" "b") (and "aa" "b")) does. Michael.