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1180. Missing string_type member typedef in class sub_match

Section: 28.6.8.2 [re.submatch.members] Status: C++11 Submitter: Daniel Krügler Opened: 2009-07-25 Last modified: 2016-01-28

Priority: Not Prioritized

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Discussion:

The definition of class template sub_match is strongly dependent on the type basic_string<value_type>, both in interface and effects, but does not provide a corresponding typedef string_type, as e.g. class match_results does, which looks like an oversight to me that should be fixed.

[ 2009-11-15 Moved to Tentatively Ready after 5 positive votes on c++std-lib. ]

Proposed resolution:

  1. In the class template sub_match synopsis 28.6.8 [re.submatch]/1 change as indicated: 

    template <class BidirectionalIterator>
class sub_match : public std::pair<BidirectionalIterator, BidirectionalIterator> {
public:
  typedef typename iterator_traits<BidirectionalIterator>::value_type value_type;
  typedef typename iterator_traits<BidirectionalIterator>::difference_type difference_type;
  typedef BidirectionalIterator iterator;
  typedef basic_string<value_type> string_type;

  bool matched;

  difference_type length() const;
  operator basic_string<value_type>string_type() const;
  basic_string<value_type>string_type str() const;
  int compare(const sub_match& s) const;
  int compare(const basic_string<value_type>string_type& s) const;
  int compare(const value_type* s) const;
};

  2. In 28.6.8.2 [re.submatch.members]/2 change as indicated: 

    operator basic_string<value_type>string_type() const;

    Returns: matched ? basic_string<value_type> string_type(first, second) : basic_string<value_type> string_type().

  3. In 28.6.8.2 [re.submatch.members]/3 change as indicated: 

    basic_string<value_type>string_type str() const;

    Returns: matched ? basic_string<value_type> string_type(first, second) : basic_string<value_type> string_type().

  4. In 28.6.8.2 [re.submatch.members]/5 change as indicated: 

    int compare(const basic_string<value_type>string_type& s) const;