220 33845 article Path: news.gmane.org!.POSTED!not-for-mail From: Nicol Bolas Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: string_view for fstream::open() Date: Fri, 11 Aug 2017 13:54:59 -0700 (PDT) Lines: 74 Approved: news@gmane.org Message-ID: References: <3456831.gsseCm4DuK@tjmaciei-mobl1> <6240d6af-a518-4788-a56f-b7d0c8976dc4@isocpp.org> <23479188.ocqGNj8Gyb@tjmaciei-mobl1> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_2469_876993217.1502484899621" X-Trace: blaine.gmane.org 1502484902 20813 195.159.176.226 (11 Aug 2017 20:55:02 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 11 Aug 2017 20:55:02 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCEKFTV6ZUMBBJFTXDGAKGQEUBOP6PY@isocpp.org Fri Aug 11 22:54:58 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pf0-f197.google.com ([209.85.192.197]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dgGxL-000521-Ig for gclcip-std-proposals@m.gmane.org; Fri, 11 Aug 2017 22:54:55 +0200 Original-Received: by mail-pf0-f197.google.com with SMTP id p20sf48955347pfj.2 for ; Fri, 11 Aug 2017 13:55:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=Z+cKIevy7yphXRoUHxcnd1LUiJgdTjOnDJeXKwe6tfA=; b=hOlqr0FGY3UwsMHc0JR5t62Kp9uTj2fYMueh3LFwrAlYFCGqx+4XQ/JIzwgcgoDW0j KK3htJVyn5GLnJpTyd9NebJdzr22WUNIUts3UDxnCul6UZRT4v/3LB6C9Nw5m8WHpEYJ vFtMxEyYy77xZU8bOlmV/keD11Zr229bql4LO6gGDXHCGfdTdVf0Fm9yMEvJOYMalLbf wQgH5z5UVnasKGS3Z90mxTOudcrN4EjVmll/w71ewiF/OWeUOjAvPvtfMSRvKltB3n1i uf5A8xZVp3n2y55LH9weylwzT9img+MCLgekc3D9YYT7wpqPVCb/OXEnMp83Q2RaYhUD TUcg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=Z+cKIevy7yphXRoUHxcnd1LUiJgdTjOnDJeXKwe6tfA=; b=TfBltz6bKeRQMnkM8g81a0+5W+bYgLIdfBwph1WVluP6UPoUGl+CLpGZCIh14WiPPU PrxBMWKU+tde7VOJPld2rit1DOiAoedB9NI6tUDzFy6rJV/My37X60gGdkAf6ocKJa9M XXgQhLOQCLYPQ/mYNW5h46Jl9x6zE6H8w7NtNBvAaBQlXETPziEXV8RQtliNNa7TYQPc kc4sMBNLMTgdUsdOQwH7lwnaGlAb3A+4Hx2yUucn3quakTZPnQrPzLsv1X22GaZb8IdQ wea41cstMeLVoz5DlezHuZmnPs2b83QZiPkyxT8QNqxHX0x2l0bxbN2iglCdDtEIz3n4 8vKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:message-id:in-reply-to:references :subject:mime-version:x-original-sender:reply-to:precedence :mailing-list:list-id:x-spam-checked-in-group:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=Z+cKIevy7yphXRoUHxcnd1LUiJgdTjOnDJeXKwe6tfA=; b=n9PQ44J2kmKolao37uynU7lrIDEeqO+ikZTYAUNxRfkgD7cARZ1tIE5HPrENVjoDuB Zo6aVLkp2H+P69yxMNcZKp1S+UZUowx05zm8bxOOyQ8mx8bDvtAA26tPxRAN4qTb5/X9 QVUnSkmm8xU1m2Ea/AoT27hoA7kkZtCw0ZV9pXGm4tCjwmkZHK0OY3qcsA2n6z74SZ+S BeycFNci9f2kI+IAUqzSBJKhNzMAyUS0son8aV+zsZ7k0cs5K3ywRqmc7yBFvkYnaGLH PN6fWE37Sq83uo6TzMWq2Gqfuh2yVFJWWzm9CNuAiCk+Il8VvRDlAJLFk78epPgTb3Me jYYA== X-Gm-Message-State: AHYfb5hocfTrJWzFa1S9keyxXQ8RVq/hfQUFnLO3gGzkKD2XT2ajrlA3 Izezru+TEqN6EWBg X-Received: by 10.101.69.138 with SMTP id o10mr11238499pgq.63.1502484901584; Fri, 11 Aug 2017 13:55:01 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.36.184.70 with SMTP id m67ls323140ite.18.gmail; Fri, 11 Aug 2017 13:55:00 -0700 (PDT) X-Received: by 10.31.99.198 with SMTP id x189mr93042vkb.24.1502484900263; Fri, 11 Aug 2017 13:55:00 -0700 (PDT) In-Reply-To: <23479188.ocqGNj8Gyb@tjmaciei-mobl1> X-Original-Sender: jmckesson@gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:33845 Archived-At: ------=_Part_2469_876993217.1502484899621 Content-Type: multipart/alternative; boundary="----=_Part_2470_501504542.1502484899621" ------=_Part_2470_501504542.1502484899621 Content-Type: text/plain; charset="UTF-8" On Friday, August 11, 2017 at 4:36:36 PM UTC-4, Thiago Macieira wrote: > > On sexta-feira, 11 de agosto de 2017 10:01:28 PDT Nicol Bolas wrote: > > `cstring_view` is just a `const char*` with a nice wrapper. It is just a > > pointer, which means `size()` is always O(n). But this also means that > > sticking a literal in it costs nothing. But if you try to use it with > > begin/end iterator pairs, you provoke an O(n) operation. > > Actually, no. The end iterator can be a sentinel, such that the call to > cstring_view::end() is O(1). > A fact I mentioned later in that post, but one that relies on Ranges TS and its range algorithms. In a pre-Ranges TS world, that's not an acceptable implementation, since all of our current algorithms are based on iterator pairs, not iterator/sentinels. -- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an email to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/ef0ef4f3-b2bc-4867-9cde-4d3b15c97d1e%40isocpp.org. ------=_Part_2470_501504542.1502484899621 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On Friday, August 11, 2017 at 4:36:36 PM UTC-4, Thiago Mac= ieira wrote:
On sexta-feira, 11= de agosto de 2017 10:01:28 PDT Nicol Bolas wrote:
> `cstring_view` is just a `const char*` with a nice wrapper. It is = just a
> pointer, which means `size()` is always O(n). But this also means = that
> sticking a literal in it costs nothing. But if you try to use it w= ith
> begin/end iterator pairs, you provoke an O(n) operation.

Actually, no. The end iterator can be a sentinel, such that the call to= =20
cstring_view::end() is O(1).

A fact I mentioned later in that post, but one th= at relies on Ranges TS and its range algorithms. In a pre-Ranges TS world, = that's not an acceptable implementation, since all of our current algor= ithms are based on iterator pairs, not iterator/sentinels.

--
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To view this discussion on the web visit https://groups.google.= com/a/isocpp.org/d/msgid/std-proposals/ef0ef4f3-b2bc-4867-9cde-4d3b15c97d1e= %40isocpp.org.
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