220 7229 article Path: news.gmane.org!not-for-mail From: "Billy O'Neal" Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: "count_while" and "count_until" algorithms Date: Wed, 9 Oct 2013 07:07:25 -0700 Lines: 601 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=047d7bd76d1e24bcec04e84f6afc X-Trace: ger.gmane.org 1381327690 16669 80.91.229.3 (9 Oct 2013 14:08:10 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 9 Oct 2013 14:08:10 +0000 (UTC) To: std-proposals Original-X-From: std-proposals+bncBDKLBLVE6ADBBSOG2WJAKGQEOVFFF7I@isocpp.org Wed Oct 09 16:08:16 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ie0-f200.google.com ([209.85.223.200]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1VTuQw-0000kn-KB for gclcip-std-proposals@m.gmane.org; Wed, 09 Oct 2013 16:08:15 +0200 Original-Received: by mail-ie0-f200.google.com with SMTP id tp5sf3537945ieb.7 for ; Wed, 09 Oct 2013 07:08:10 -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=/xfKgGyuAHogFlOOiD6CSfANvBxpqXk/br9t6HmDA6E=; b=FjG/NoVZEs6X398g8kypJsAQfehJjX+KtP4dUdGQXOB6gito1Ua9bmut64VQpIFCKE tJkP8EapcxYEqj2+Q3zAdiTet4QmKpwL3k1nmI8m5+WiSa6ZxYkXXOC9ot8TYyhp9jbu ziJa7I2/T10NK51g5NOf60MjTr2MDrh7zpWDwjlTEzvbxbmZ6jcWoufDcaavXJA6rTys C/SoMn7msXur/1o46656B8lIEir5eVV+6z3btqCp4Bb9ujKXX5uw/o95Coq0iB4pz0A4 i/VsmzRaExK3DuHrAPyortAKxZ4y/sCaNKboWUBi60FSvBi6Kmr97hdBVYGvw2xNKq8K 5iyw== X-Received: by 10.182.19.133 with SMTP id f5mr1565748obe.36.1381327690020; Wed, 09 Oct 2013 07:08:10 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.182.42.195 with SMTP id q3ls140887obl.71.gmail; Wed, 09 Oct 2013 07:08:09 -0700 (PDT) X-Received: by 10.182.114.231 with SMTP id jj7mr5992674obb.33.1381327689388; Wed, 09 Oct 2013 07:08:09 -0700 (PDT) Original-Received: from mail-ie0-x22f.google.com (mail-ie0-x22f.google.com [2607:f8b0:4001:c03::22f]) by mx.google.com with ESMTPS id pu10si4295187obb.152.1969.12.31.16.00.00 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 09 Oct 2013 07:08:09 -0700 (PDT) Received-SPF: pass (google.com: domain of billy.oneal@gmail.com designates 2607:f8b0:4001:c03::22f as permitted sender) client-ip=2607:f8b0:4001:c03::22f; Original-Received: by mail-ie0-f175.google.com with SMTP id aq17so1493270iec.20 for ; Wed, 09 Oct 2013 07:08:07 -0700 (PDT) X-Received: by 10.50.154.66 with SMTP id vm2mr2061507igb.57.1381327687691; Wed, 09 Oct 2013 07:08:07 -0700 (PDT) Original-Received: by 10.43.166.67 with HTTP; Wed, 9 Oct 2013 07:07:25 -0700 (PDT) In-Reply-To: X-Original-Sender: billy.oneal@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of billy.oneal@gmail.com designates 2607:f8b0:4001:c03::22f as permitted sender) smtp.mail=billy.oneal@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:7229 Archived-At: --047d7bd76d1e24bcec04e84f6afc Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On the other hand, it is typically trivial to initialize "last" with the count of the container to which it points. (Depending on the container) Billy O'Neal https://github.com/BillyONeal/ http://stackoverflow.com/users/82320/billy-oneal Malware Response Instructor - BleepingComputer.com On Wed, Oct 9, 2013 at 4:13 AM, R=E9my Lefevre wrot= e: > Furthermore, the counting_iterator doesn't always work. For example, if > find/find_if reaches the end of the range, the behavior is to return the > iterator named "last" passed in argument. But this iterator has not been > incremented by the algorithm and its counter is set to 0 instead of the > distance between first and last, leading to a wrong result. > > > 2013/10/9 R=E9my Lefevre > >> 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 >>> of 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" >>>> and "count_until". Here are their behavior: >>>> >>>> template >>>> >>>> >>>> >>>> >>>> >>>> >>>> typename iterator_traits**::difference_type >>>> >>>> >>>> >>>> >>>> >>>> >>>> count_while (InputIterator first, InputIterator last, UnaryPredica= te 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, UnaryPredica= te 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/bXrQrkBw59= c/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/. >>> >> >> > -- > > --- > 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/. > --=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/. --047d7bd76d1e24bcec04e84f6afc Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
On the other hand, it is typically trivial to initialize &= quot;last" with the count of the container to which it points. (Depend= ing on the container)

Billy O'Neal
Malware Response Instructor - BleepingComputer.com


On Wed, Oct 9, 2013 at 4:13 AM, R=E9my L= efevre <lefevreremy@gmail.com> wrote:
Furthermore, the counting_iterator doesn't always work= .. For example, if find/find_if reaches the end of the range, the behavior i= s to return the iterator named "last" passed in argument. But thi= s iterator has not been incremented by the algorithm and its counter is set= to 0 instead of the distance between first and last, leading to a wrong re= sult.

2013/10/9 R=E9my Lefevre <lefevreremy= @gmail.com>
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:0px 0px 0px 0.8ex;padding-= left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-le= ft-style:solid">
+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 Lindley" &l= t;benjamesli= ndley@gmail.com> wrote:

What about creating an iterator adapter ins= tead?=A0 One which keeps track of how many times it has been incremented?
typedef std::istream_iterator<int> base_t= ;
base_t ib(std::cin), ie;
std::counting_iter= ator<base_t> b= (ib), e(ie= );
auto p =3D std::find_if(b, e, pred<= /span>);
std::cout <= span style=3D"color:rgb(102,102,0)"><< 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, cl=
ass UnaryPre=
dicate>







=A0 typename iterator_traits<<=
span style=3D"color:rgb(102,0,102)">InputIterator>::difference_type







=A0 =A0 count_while (InputIterator first, InputIterator last,=
 UnaryPredicate pr=
ed)







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







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







=A0 =A0 ++ret;
=A0 =A0 ++first;







=A0 }
=A0 return ret;


}

template <=
class InputIterator, cl=
ass UnaryPre=
dicate>







=A0 typename iterator_traits<<=
span style=3D"color:rgb(102,0,102)">InputIterator>::difference_type







=A0 =A0 count_until (InputIterator first, InputIterator last,=
 UnaryPredicate pr=
ed)







{
=A0 typename iterator_traits&l=
t;InputIterator>::difference_type ret <=
/span>=3D 0;=








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







=A0 =A0 ++ret;
=A0 =A0 ++first;







=A0 }
=A0 return ret;

}
<=
/code>

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

--
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--
 
---
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