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2272. quoted should use char_traits::eq for character comparison

Section: 31.7.9 [quoted.manip] Status: C++14 Submitter: Marshall Clow Opened: 2013-07-12 Last modified: 2016-01-28

Priority: Not Prioritized

View all other issues in [quoted.manip].

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Discussion:

In 31.7.9 [quoted.manip] p2 b2:

— Each character in s. If the character to be output is equal to escape or delim, as determined by operator==, first output escape.

In 31.7.9 [quoted.manip] p3 b1 sb1:

— If the first character extracted is equal to delim, as determined by operator==, […]

these should both use traits::eq.

Also, I believe that 31.7.9 [quoted.manip] p3 implies that: 

std::ostream _stream;
std::string _string;
_stream << _string;
_stream << quoted(_string);

should both compile, or both fail to compile, based on whether or not their char_traits match. But I believe that the standard should say that explicitly.

[ 2013-09 Chicago ]

Marshall Clow improved the wording with support from Stefanus.

[ 2013-09 Chicago (late night issues) ]

Moved to Ready, after confirming wording correctly reflects discussion earlier in the day.

Proposed resolution:

This wording is relative to N3691.

  1. Change 31.7.9 [quoted.manip] p2+3 as indicated:

    template <class charT>
  unspecified quoted(const charT* s, charT delim=charT('"'), charT escape=charT('\\'));
template <class charT, class traits, class Allocator>
  unspecified quoted(const basic_string<charT, traits, Allocator>& s,
                     charT delim=charT('"'), charT escape=charT('\\'));

    -2- Returns: An object of unspecified type such that if out is an instance of basic_ostream with member type char_type the same as charT and with member type traits_type, which in the second form is the same as traits, then the expression out << quoted(s, delim, escape) behaves as if it inserts the following characters into out using character inserter function templates (27.7.3.6.4), which may throw ios_base::failure (27.5.3.1.1):

    • delim

    • Each character in s. If the character to be output is equal to escape or delim, as determined by operator==traits_type::eq, first output escape.

    • delim

    template <class charT, class traits, class Allocator>
  unspecified quoted(basic_string<charT, traits, Allocator>& s,
                     charT delim=charT('"'), charT escape=charT('\\'));

    -3- Returns: An object of unspecified type such that:

    • If in is an instance of basic_istream with member types char_type and traits_type the same as charT and traits, respectively, then the expression in >> quoted(s, delim, escape) behaves as if it extracts the following characters from in using basic_istream::operator>> (27.7.2.2.3) which may throw ios_base::failure (27.5.3.1.1):

      • If the first character extracted is equal to delim, as determined by operator==traits_type::eq, then: […]

    • If out is an instance of basic_ostream with member types char_type and traits_type the same as charT and traits, respectively, then the expression out << quoted(s, delim, escape) behaves as specified for the const basic_string<charT, traits, Allocator>& overload of the quoted function.