220 7165 <15c8d7a7-0547-466a-846a-e5f4656b62cd@isocpp.org> article Path: news.gmane.org!not-for-mail From: Vlad from Moscow Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: "count_while" and "count_until" algorithms Date: Tue, 8 Oct 2013 13:28:49 -0700 (PDT) Lines: 291 Approved: news@gmane.org Message-ID: <15c8d7a7-0547-466a-846a-e5f4656b62cd@isocpp.org> References: <3c5637a3-5760-4825-83e1-c4bfc062e652@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_74_30897740.1381264129783" X-Trace: ger.gmane.org 1381264129 28399 80.91.229.3 (8 Oct 2013 20:28:49 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 8 Oct 2013 20:28:49 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCXLLRHD7IDRBA6W2GJAKGQE7ANICXA@isocpp.org Tue Oct 08 22:28:53 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ob0-f200.google.com ([209.85.214.200]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1VTdtk-0000lh-Sq for gclcip-std-proposals@m.gmane.org; Tue, 08 Oct 2013 22:28:53 +0200 Original-Received: by mail-ob0-f200.google.com with SMTP id wo20sf4435810obc.7 for ; Tue, 08 Oct 2013 13:28:52 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; 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 :content-type; bh=ehWy/MU1cscNNhMA9fpmVP6KE2oLOqCpIitozBhlpHU=; b=eJCBTc6PoTuGvvkiD+cGIleWKpXXe3XcZu2tJPvLhGLdabKM+IReQAp3V52cdv7Hkh 2NdQuZr4t6jVAbWVQJS6hDNfzh798ucXkmC5t0dlY4jgo8rNvjUjuV5cSosZSxZGPj0W oPv7nOOHBMkR6PMoUNwf4HsRyjWSW5qpw8p4GRJ3gMWtk7ZzJILNFMJPtwerOfcIQ/tc kGZZ5k/HO3b4NLcnHSWaSqiSIkSewwIbR/evt+c4BDnFlEyROCni5QcI1HDjMVLsAEL9 /6KGuvdt7lPStdk5bKzgJFfz1sJbi/o9fZnll46t8h4+KZOgvZMO+Z2RIdrNK323EFLX Wqhw== X-Received: by 10.43.14.4 with SMTP id po4mr1998729icb.18.1381264131930; Tue, 08 Oct 2013 13:28:51 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.92.69 with SMTP id ck5ls3716340igb.20.canary; Tue, 08 Oct 2013 13:28:51 -0700 (PDT) X-Received: by 10.50.87.71 with SMTP id v7mr168296igz.11.1381264131380; Tue, 08 Oct 2013 13:28:51 -0700 (PDT) In-Reply-To: <3c5637a3-5760-4825-83e1-c4bfc062e652@isocpp.org> X-Original-Sender: vlad.moscow@mail.ru 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:7165 Archived-At: ------=_Part_74_30897740.1381264129783 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Though maybe I am mistaken because the equivalent code does not work for=20 iterators that have std::input_iterator_tag. =D1=81=D1=80=D0=B5=D0=B4=D0=B0, 9 =D0=BE=D0=BA=D1=82=D1=8F=D0=B1=D1=80=D1= =8F 2013 =D0=B3., 0:26:47 UTC+4 =D0=BF=D0=BE=D0=BB=D1=8C=D0=B7=D0=BE=D0=B2= =D0=B0=D1=82=D0=B5=D0=BB=D1=8C Vlad from Moscow=20 =D0=BD=D0=B0=D0=BF=D0=B8=D1=81=D0=B0=D0=BB: > Till now I do not see any great sense in introducing these algorithms. Th= e=20 > first algorithm is in fact equivalent to > =20 > std::distance( first, std::find_if( first, last, std::not_equal_to() )= =20 > ); > =20 > The second algorithm is equivalent to > =20 > std::distance( first, std::find_if( first, last, std::equal_to() ) ); > =20 > > =D1=81=D1=80=D0=B5=D0=B4=D0=B0, 9 =D0=BE=D0=BA=D1=82=D1=8F=D0=B1=D1=80=D1= =8F 2013 =D0=B3., 0:04:23 UTC+4 =D0=BF=D0=BE=D0=BB=D1=8C=D0=B7=D0=BE=D0=B2= =D0=B0=D1=82=D0=B5=D0=BB=D1=8C R=C3=A9my Lefevre =D0=BD=D0=B0=D0=BF=D0=B8= =D1=81=D0=B0=D0=BB: > >> Hi, >> >> I thought about two new algorithms, that could be named "count_while" an= d=20 >> "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=20 >> library ? >> > --=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/. ------=_Part_74_30897740.1381264129783 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Though maybe I am mistaken because the equivalent cod= e does not work for iterators that have std::input_iterator_tag.
=
=D1=81=D1=80=D0=B5=D0=B4=D0=B0, 9 =D0=BE=D0=BA=D1=82=D1=8F=D0=B1=D1=80= =D1=8F 2013 =D0=B3., 0:26:47 UTC+4 =D0=BF=D0=BE=D0=BB=D1=8C=D0=B7=D0= =BE=D0=B2=D0=B0=D1=82=D0=B5=D0=BB=D1=8C Vlad from Moscow =D0=BD=D0=B0=D0=BF= =D0=B8=D1=81=D0=B0=D0=BB:
Till now I do not see any great sense in introducing these algo= rithms. The first algorithm is in fact equivalent to
 
=
std::distance( first, std::find_if( first, last, std::not_equal_to<= T>() ) );
 
The second algorithm is equivalent = to
 
std::distance( first, std::find_if( first, la= st, std::equal_to<T>() ) );
 

=D1=81=D1= =80=D0=B5=D0=B4=D0=B0, 9 =D0=BE=D0=BA=D1=82=D1=8F=D0=B1=D1=80=D1=8F 2013&nb= sp;=D0=B3., 0:04:23 UTC+4 =D0=BF=D0=BE=D0=BB=D1=8C=D0=B7=D0=BE=D0=B2=D0=B0= =D1=82=D0=B5=D0=BB=D1=8C R=C3=A9my Lefevre =D0=BD=D0=B0=D0=BF=D0=B8=D1=81= =D0=B0=D0=BB:
Hi,
I thought about two new algorithms, that could be named "count_while" and = "count_until". Here are their behavior:

template<=
/span> <class InputIterator, class UnaryP=
redicate>


  typename iterator_traits<InputIterator>::difference_type


    count_while (=
InputIterator first, InputIterator last, UnaryPredicate pred)


{
  typename iterator_tr=
aits<InputIterator>::diff=
erence_type ret =3D<=
span style=3D"color: rgb(0, 0, 0);"> 0;


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


    ++ret;
    ++first;


  }
  return ret;


}
= 

template<=
/span> <class InputIterator, class UnaryP=
redicate>


  typename iterator_traits<InputIterator>::difference_type


    count_until (=
InputIterator first, InputIterator last, UnaryPredicate pred)


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


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


    ++ret;
    ++first;


  }
  return ret;<=
br>

}

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

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