220 7173 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 13:40:18 -0700 (PDT) Lines: 361 Approved: news@gmane.org Message-ID: References: <285a478e-ce03-42b9-9196-c7d0855e11aa@isocpp.org> <82850309-b16b-44bd-b478-e2e63e43d6ca@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_551_5641249.1381264818642" X-Trace: ger.gmane.org 1381264835 3967 80.91.229.3 (8 Oct 2013 20:40:35 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 8 Oct 2013 20:40:35 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCXLLRHD7IDRBNG32GJAKGQEMKRKVSI@isocpp.org Tue Oct 08 22:40:40 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 1VTe59-0007Vb-Lc for gclcip-std-proposals@m.gmane.org; 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Tue, 08 Oct 2013 13:40:20 -0700 (PDT) X-Received: by 10.50.83.6 with SMTP id m6mr945681igy.1.1381264820285; Tue, 08 Oct 2013 13:40:20 -0700 (PDT) In-Reply-To: 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:7173 Archived-At: ------=_Part_551_5641249.1381264818642 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable As any negation of an unary predicate can be written as std::not1(=20 unary_predicate ) there is enough to propose only one algorithm namely with= =20 name count_first_if.:) =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., 0:37:13 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: > So I would propose name count_first_if instead of the both suggested=20 > algorithms count_until and count_while. > =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., 0:35:01 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: > >> Or the following definition >> =20 >> [code] >> template >> T accumulate_first_if( InputIterator first,=20 >> InputIterator last, >> T init, >> UnaryPredicate unary_predicate ) >> { >> for ( ; first !=3D last && unary_predicate( *first ) ; ++first ) >> { >> init =3D ( T )( init + *first ); >> } >> return ( init ); >> } >> [/code] >> >> =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., 0:32:31 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: >> >>> =20 >>> [code] >>> In some thread here I proposed the similar idea for algorithm=20 >>> std::accumulate. >>> template >> BinaryOperation> >>> T accumulate_first_if( InputIterator first,=20 >>> InputIterator last, >>> T init, >>> UnaryPredicate unary_predicate, >>> BinaryOperation binary_operation ) >>> { >>> for ( ; first !=3D last && unary_predicate( *first ) ; ++first ) >>> { >>> init =3D binary_operation( init, *first ); >>> } >>> return ( init ); >>> } >>> [/code] >>> =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=20 >>> =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"= =20 >>>> 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= =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_551_5641249.1381264818642 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
As any negation of an unary predicate can be written = as std::not1( unary_predicate ) there is enough to propose only one algorit= hm namely with name count_first_if.:)

=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., = 0:37:13 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:
So I would propose n= ame count_first_if instead of the both suggested algorithms count_until and= count_while.
 

=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., 0:35:01 U= TC+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:
Or the following definition
 
[code]
template <class InputIterator= , class T, class UnaryPredicate>
T accumulate_first_if( InputIterator= first,
          &nb= sp;         InputIterator last,
=         T init,
   &nb= sp;    UnaryPredicate unary_predicate )
{
 for ( = ; first !=3D last && unary_predicate( *first ) ; ++first )
 = ;{
  init =3D ( T )( init + *first );
 }
&nb= sp;return ( init );
}
[/code]

=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., 0:32:31 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:
 
[code]
In some thread here I proposed the similar idea for = algorithm std::accumulate.
template <class InputIterator, clas= s T, class UnaryPredicate, class BinaryOperation>
T accumulate_first_= if( InputIterator first,
       &nbs= p;            InputI= terator last,
        T init,
&nbs= p;       UnaryPredicate unary_predicate,
&= nbsp;       BinaryOperation binary_operation = )
{
 for ( ; first !=3D last && unary_predicate( *first = ) ; ++first )
 {
  init =3D binary_operation( init, *f= irst );
 }
 return ( init );
}
[/co= de]
=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" 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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