This page is a snapshot from the LWG issues list, see the Library Active Issues List for more information and the meaning of CD1 status.

576. find_first_of is overconstrained

Section: 26.6.9 [alg.find.first.of] Status: CD1 Submitter: Doug Gregor Opened: 2006-04-25 Last modified: 2016-01-28

Priority: Not Prioritized

View all other issues in [alg.find.first.of].

View all issues with CD1 status.

Discussion:

In 25.1.4 Find First [lib.alg.find.first], the two iterator type parameters to find_first_of are specified to require Forward Iterators, as follows:

template<class ForwardIterator1, class ForwardIterator2>
  ForwardIterator1
  find_first_of(ForwardIterator1 first1, ForwardIterator1 last1,
                        ForwardIterator2 first2, ForwardIterator2 last2);
template<class ForwardIterator1, class ForwardIterator2,
                  class BinaryPredicate>
ForwardIterator1
  find_first_of(ForwardIterator1 first1, ForwardIterator1 last1,
                         ForwardIterator2 first2, ForwardIterator2 last2,
                        BinaryPredicate pred);

However, ForwardIterator1 need not actually be a Forward Iterator; an Input Iterator suffices, because we do not need the multi-pass property of the Forward Iterator or a true reference.

Proposed resolution:

Change the declarations of find_first_of to:

template<class ForwardIterator1InputIterator1, class ForwardIterator2>
  ForwardIterator1InputIterator1
  find_first_of(ForwardIterator1InputIterator1 first1, ForwardIterator1InputIterator1 last1,
                        ForwardIterator2 first2, ForwardIterator2 last2);
template<class ForwardIterator1InputIterator1, class ForwardIterator2,
                  class BinaryPredicate>
ForwardIterator1InputIterator1
  find_first_of(ForwardIterator1InputIterator1 first1, ForwardIterator1InputIterator1 last1,
                         ForwardIterator2 first2, ForwardIterator2 last2,
                        BinaryPredicate pred);

pFad - Phonifier reborn

Note: This service is not intended for secure transactions such as banking, social media, email, or purchasing. Use at your own risk. We assume no liability whatsoever for broken pages.

Alternative Proxies:

576. find_first_of is overconstrained

Pfad - The Proxy pFad of © 2024 Garber Painting. All rights reserved.