220 7225 article Path: news.gmane.org!not-for-mail From: =?ISO-8859-1?Q?R=E9my_Lefevre?= Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: "count_while" and "count_until" algorithms Date: Wed, 9 Oct 2013 10:58:36 +0200 Lines: 416 Approved: news@gmane.org Message-ID: References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=bcaec53f346f9aff1804e84b19da X-Trace: ger.gmane.org 1381309155 24062 80.91.229.3 (9 Oct 2013 08:59:15 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 9 Oct 2013 08:59:15 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCN7B34JVEARBZNV2SJAKGQEQH3IAIQ@isocpp.org Wed Oct 09 10:59:20 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-la0-f70.google.com ([209.85.215.70]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1VTpby-0005OT-LF for gclcip-std-proposals@m.gmane.org; Wed, 09 Oct 2013 10:59:18 +0200 Original-Received: by mail-la0-f70.google.com with SMTP id ev20sf563130lab.5 for ; Wed, 09 Oct 2013 01:59:18 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :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; bh=Rns+m0B7w88UJ3+gVG+2gt8t9nUwRU8ByLz6TJU4ILg=; b=k5AnrWJklbl3l3kS67YJA3E29p1s/lvxrBrEOorYgLPTCA8fHxbHw1W1vPiiNENT8f n62PnYgrndmECWP4t7IGjNWujLbn0H38pwXZ58tBCsyjkbSP4XaOJ/gRpfydPG9pdxDe p+9E2IHW7UI1+4PvB4KZ3Y3tSKAEfg5oMbignFu/JWxpaVaomzjyqO/PW8iB6ZNrqQD8 DjoUhEZGPJ1yTbzwDsBh6m+PD0QtPHpCDCxJ52XN4yep9Mk+31rpypJHBLtYdMx/oaZe bN8pqKqp+XzN6fh0GOJKFmPPAHu5JtiTNar28hPhnDTBjtH95VU4j9fD8+PztHYT67ST d1OA== X-Received: by 10.180.24.105 with SMTP id t9mr731803wif.5.1381309157842; Wed, 09 Oct 2013 01:59:17 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.180.8.66 with SMTP id p2ls1347197wia.27.canary; Wed, 09 Oct 2013 01:59:16 -0700 (PDT) X-Received: by 10.180.160.165 with SMTP id xl5mr1713313wib.48.1381309156904; Wed, 09 Oct 2013 01:59:16 -0700 (PDT) Original-Received: from mail-we0-x22f.google.com (mail-we0-x22f.google.com [2a00:1450:400c:c03::22f]) by mx.google.com with ESMTPS id v7si3066268wiw.73.1969.12.31.16.00.00 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 09 Oct 2013 01:59:16 -0700 (PDT) Received-SPF: pass (google.com: domain of lefevreremy@gmail.com designates 2a00:1450:400c:c03::22f as permitted sender) client-ip=2a00:1450:400c:c03::22f; Original-Received: by mail-we0-f175.google.com with SMTP id t61so529988wes.6 for ; Wed, 09 Oct 2013 01:59:16 -0700 (PDT) X-Received: by 10.180.20.77 with SMTP id l13mr1737281wie.40.1381309156619; Wed, 09 Oct 2013 01:59:16 -0700 (PDT) Original-Received: by 10.194.192.33 with HTTP; Wed, 9 Oct 2013 01:58:36 -0700 (PDT) In-Reply-To: X-Original-Sender: lefevreremy@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of lefevreremy@gmail.com designates 2a00:1450:400c:c03::22f as permitted sender) smtp.mail=lefevreremy@gmail.com; dkim=pass header.i=@gmail.com; dmarc=pass (p=NONE dis=NONE) header.from=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:7225 Archived-At: --bcaec53f346f9aff1804e84b19da Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Good point for a counting iterator ! Unfortunately, the one in boost library doesn't fit our need here and I am not aware of any counting iterator in C++14. 2013/10/9 Peter Sommerlad > +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" > wrote: > > What about creating an iterator adapter instead? One which keeps track o= f > how many times it has been incremented? > > 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(); > > Then you could apply it to other algorithms besides find/find_if. > > On Tuesday, October 8, 2013 3:04:23 PM UTC-5, R=E9my Lefevre wrote: >> >> Hi, >> >> I thought about two new algorithms, that could be named "count_while" an= d >> "count_until". Here are their behavior: >> >> template >> >> >> >> typename iterator_traits**::difference_type >> >> >> >> count_while (InputIterator first, InputIterator last, UnaryPredicate= pred) >> >> >> { >> typename iterator_traits**::difference_type ret =3D 0; >> >> >> >> while (first!=3Dlast && pred(*first)) { >> >> >> >> ++ret; >> ++first; >> >> >> >> } >> return ret; >> >> } >> >> >> template >> >> >> >> typename iterator_traits**::difference_type >> >> >> >> count_until (InputIterator first, InputIterator last, UnaryPredicate= pred) >> >> >> { >> >> typename iterator_traits**::difference_type ret =3D 0; >> >> >> >> while (first!=3Dlast && !pred(*first)) { >> >> >> >> ++ret; >> ++first; >> >> >> >> } >> return ret; >> >> >> } >> >> >> What do you think about adding these two components to the algorithms >> library ? >> > -- > > --- > 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-proposals/. > > -- > > --- > You received this message because you are subscribed to a topic in the > Google Groups "ISO C++ Standard - Future Proposals" group. > To unsubscribe from this topic, visit > https://groups.google.com/a/isocpp.org/d/topic/std-proposals/bXrQrkBw59c/= unsubscribe > . > To unsubscribe from this group and all its topics, 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-proposals/. > --=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/. --bcaec53f346f9aff1804e84b19da Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Good point for a counting iterator ! Unfortunately, the on= e in boost library doesn't fit our need here and I am not aware of any = counting iterator in C++14.


2013/10/9 Peter Sommerlad <Peter.Sommerlad@hsr.ch>
<= blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px= #ccc solid;padding-left:1ex">
+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=A0iPad

On 09.10.2013, at 07:13, "Benjamin Lin= dley" <benjameslindley@gmail.com> wrote:

What about creating an iterato= r adapter instead?=A0 One which keeps track of how many times it has been i= ncremented?

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

Then you could apply it to other algorithms b= esides find/find_if.

On Tuesday, October 8, 2013 3:04:23 PM UTC-5, R= =E9my Lefevre wrote:
Hi,

I thought about two new algorithms, that could = be named "count_while" and "count_until". Here are thei= r behavior:

template <class InputIterator, class UnaryPredicate&=
gt;




=A0 typename iterator_traits<InputIterator>::difference_type



=A0 =A0 count_while (InputIterator first, InputIterator last, UnaryP=
redicate pred)




{
=A0 typename iterator_traits<InputIterator>::difference_type ret =3D 0=
;




=A0 while (firs=
t!=3Dlast && pred(*f=
irst)) {




=A0 =A0 ++re=
t;
=A0 =
=A0 ++first<=
/span>;




=A0 }
=A0=
 return ret;

}

template <class InputIterator, class UnaryPredicate&=
gt;




=A0 typename iterator_traits<InputIterator>::difference_type



=A0 =A0 count_until (InputIterator first, InputIterator last, UnaryP=
redicate pred)




{
<=
pre>=A0 ty=
pename iterator_traits<InputIterat=
or>::difference_type ret =3D 0;




=A0 while (firs=
t!=3Dlast && !pred(*=
first)) {




=A0 =A0 ++re=
t;
=A0 =
=A0 ++first<=
/span>;




=A0 }
=A0=
 return ret;


}

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

--
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