220 7219 article Path: news.gmane.org!not-for-mail From: Peter Sommerlad Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: "count_while" and "count_until" algorithms Date: Wed, 9 Oct 2013 07:58:28 +0200 Lines: 352 Approved: news@gmane.org Message-ID: References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 (1.0) Content-Type: multipart/alternative; boundary="Apple-Mail-B36A059F-E1FB-4422-B3F9-1AC3C3F9687A" Content-Transfer-Encoding: 7bit X-Trace: ger.gmane.org 1381298310 6610 80.91.229.3 (9 Oct 2013 05:58:30 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 9 Oct 2013 05:58:30 +0000 (UTC) To: "" Original-X-From: std-proposals+bncBD3OHQEN4AJBBB7B2OJAKGQEJ3VOKJQ@isocpp.org Wed Oct 09 07:58:33 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-wi0-f197.google.com ([209.85.212.197]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1VTmn2-0005Ng-OK for gclcip-std-proposals@m.gmane.org; Wed, 09 Oct 2013 07:58:32 +0200 Original-Received: by mail-wi0-f197.google.com with SMTP id hm2sf369867wib.0 for ; Tue, 08 Oct 2013 22:58:32 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=subject:references:from:in-reply-to:message-id:date:to:mime-version :x-original-sender:x-original-authentication-results:reply-to :precedence:mailing-list:list-id:list-post:list-help:list-archive :list-subscribe:list-unsubscribe:content-type :content-transfer-encoding; bh=/wl/WbQa6l8AHe2n8LZsCiKY9wz4UaGlpYCkDJvmJt4=; b=MnqRRCC8j4S5C0cZvapbZFYIbs9kvAJWYaMI7ZyL55m6W02DCvntNn/LFwZb/JWnXq NpcQZr/7qyiIVi9djQTNO9PRImnLl+1O+XaTXel04R/8eYzRjlELVab5fnBHLdT1V3FA 6Xhcd1IMEubkWikPtLIQEuzIoa8cvo9baZz03wD7tRcuhPHemH1MEonLXfpmB0wlZneg nSHS/aJVAknVyBOrqo48P5L0DjgBOASnCnmCt7DkU8n8b3A2ZTmYG4X4zlh48MQY/bdE N9dYv9CUEFFl4BgF/OGHdJAVa85KUk8cAvDzJBIw+Y6D3JSwGnPqIVItecZVxvz1ManC Nc5Q== X-Received: by 10.180.24.105 with SMTP id t9mr457290wif.5.1381298312095; Tue, 08 Oct 2013 22:58:32 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.180.94.198 with SMTP id de6ls1394950wib.12.canary; Tue, 08 Oct 2013 22:58:31 -0700 (PDT) X-Received: by 10.15.94.201 with SMTP id bb49mr8858916eeb.23.1381298311091; Tue, 08 Oct 2013 22:58:31 -0700 (PDT) Original-Received: from mx2.hsr.ch (mx2.hsr.ch. [2001:620:130:a036::51]) by mx.google.com with ESMTP id x42si30567103eea.284.1969.12.31.16.00.00; Tue, 08 Oct 2013 22:58:31 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of psommerl@hsr.ch designates 2001:620:130:a036::51 as permitted sender) client-ip=2001:620:130:a036::51; Original-Received: from localhost (localhost [127.0.0.1]) by mx2.hsr.ch (Postfix) with ESMTP id 0BAC1DA6 for ; Wed, 9 Oct 2013 07:58:31 +0200 (CEST) Original-Received: from mx2.hsr.ch ([127.0.0.1]) by localhost (mx2.hsr.ch [127.0.0.1]) (amavisd-new, port 10024) with LMTP id IIjdbHd5lw9o for ; Wed, 9 Oct 2013 07:58:28 +0200 (CEST) Original-Received: from webmail.hsr.ch (sid00201.hsr.ch [152.96.21.201]) by mx2.hsr.ch (Postfix) with ESMTP id 50159CDF for ; Wed, 9 Oct 2013 07:58:28 +0200 (CEST) Original-Received: from [192.168.1.8] (152.96.21.55) by smtp.hsr.ch (152.96.21.201) with Microsoft SMTP Server (TLS) id 14.3.158.1; Wed, 9 Oct 2013 07:58:27 +0200 X-Mailer: iPad Mail (10B329) In-Reply-To: X-Originating-IP: [152.96.21.55] X-Original-Sender: peter.sommerlad@hsr.ch X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of psommerl@hsr.ch designates 2001:620:130:a036::51 as permitted sender) smtp.mail=psommerl@hsr.ch 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:7219 Archived-At: --Apple-Mail-B36A059F-E1FB-4422-B3F9-1AC3C3F9687A Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable +1 for composability instead of proliferation... Do we have boost's counting iterator adapter in c++14 or library TS? Sent from Peter Sommerlad's iPad On 09.10.2013, at 07:13, "Benjamin Lindley" wro= te: > What about creating an iterator adapter instead? One which keeps track o= f how many times it has been incremented? >=20 > typedef std::istream_iterator base_t; > base_t ib(std::cin), ie; > std::counting_iterator b(ib), e(ie); > auto p =3D std::find_if(b, e, pred); > std::cout << p.count(); >=20 > Then you could apply it to other algorithms besides find/find_if. >=20 > On Tuesday, October 8, 2013 3:04:23 PM UTC-5, R=E9my Lefevre wrote: >>=20 >> Hi, >>=20 >> I thought about two new algorithms, that could be named "count_while" an= d "count_until". Here are their behavior: >>=20 >> template >>=20 >>=20 >> typename iterator_traits::difference_type >>=20 >>=20 >> count_while (InputIterator first, InputIterator last, UnaryPredicate= pred) >>=20 >>=20 >> { >> typename iterator_traits::difference_type ret =3D 0; >>=20 >>=20 >> while (first!=3Dlast && pred(*first)) { >>=20 >>=20 >> ++ret; >> ++first; >>=20 >>=20 >> } >> return ret; >>=20 >>=20 >> } >>=20 >> template >>=20 >>=20 >> typename iterator_traits::difference_type >>=20 >>=20 >> count_until (InputIterator first, InputIterator last, UnaryPredicate= pred) >>=20 >>=20 >> { >> typename iterator_traits::difference_type ret =3D 0; >>=20 >>=20 >> while (first!=3Dlast && !pred(*first)) { >>=20 >>=20 >> ++ret; >> ++first; >>=20 >>=20 >> } >> return ret; >>=20 >>=20 >> } >>=20 >> What do you think about adding these two components to the algorithms li= brary ? >=20 > --=20 > =20 > ---=20 > 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. > Visit this group at http://groups.google.com/a/isocpp.org/group/std-propo= sals/. --=20 ---=20 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 e= mail to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposa= ls/. --Apple-Mail-B36A059F-E1FB-4422-B3F9-1AC3C3F9687A Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
+1 for composability instead of pr= oliferation...

Do we have boost's counting iterato= r adapter in c++14 or library TS?

Sent from Peter Sommerlad's = ;iPad

On 09.10.2013, at 07:13, "Benjamin Lindley" <= benjameslindley@gmail.com&= gt; wrote:

= What about creating an iterator adapter instead?  One which keeps trac= k of how many times it has been incremented?

<= code class=3D"prettyprint">
typedef std::istream_iterator<int> base_t;
base_t ib(std::= cin), ie;
std::counting_iterator<base_t> b(ib), e(ie);
auto p =3D std::find_if(b,= e, pred);
std::cout << p.count();

Then you could apply it to other algorithms besides find/fin= d_if.

On Tuesday, October 8, 2013 3:04:23 PM UTC-5, R=E9my Lefevre w= rote:
Hi,
<= br>I thought about two new algorithms, that could be named "count_while" an= d "count_until". Here are their behavior:

template <class<=
/var> InputIterator, class UnaryPredicate>


  typename=
 iterator_traits<InputIter=
ator>::difference_type


    count_while (InputIterator first, InputIterator last,<=
/span> UnaryPredicate pred=
)


{
  typenam=
e iterator_traits<InputIterator>::difference_type ret =3D 0;


  while =
(first!=3Dlast && <=
/var>pred(*first)) {


    ++ret;
    ++first;


  }
  =
return ret;


}

template <class<=
/var> InputIterator, class UnaryPredicate>


  typename=
 iterator_traits<InputIter=
ator>::difference_type


    count_until (InputIterator first, InputIterator last,<=
/span> UnaryPredicate pred=
)


{
  typename iterator_traits<InputIterator=
>::difference_type ret =3D 0;


  while =
(first!=3Dlast && <=
/var>!pred(*first)) {


    ++ret;
    ++first;


  }
  =
return ret;


}

What do you think about adding these two components to the algorithms l= ibrary ?

--
 
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To post to this group, send email to std-proposals@isocpp.org.
Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/<= /a>.

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