Section: 28.6.9 [re.results] Status: NAD Editorial Submitter: Daniel Krügler Opened: 2007-02-26 Last modified: 2016-01-28
Priority: Not Prioritized
View all other issues in [re.results].
View all issues with NAD Editorial status.
Discussion:
According to the description given in 28.6.9 [re.results]/2 the class template match_results "shall satisfy the requirements of a Sequence, [..], except that only operations defined for const-qualified Sequences are supported". Comparing the provided operations from 28.6.9 [re.results]/3 with the sequence/container tables 80 and 81 one recognizes the following missing operations:
1) The members
const_iterator rbegin() const; const_iterator rend() const;
should exists because 23.1/10 demands these for containers (all sequences are containers) which support bidirectional iterators. Aren't these supported by match_result? This is not explicitely expressed, but it's somewhat implied by two arguments:
(a) Several typedefs delegate to
iterator_traits<BidirectionalIterator>.
(b) The existence of const_reference operator[](size_type n) const
implies even random-access iteration.
I also suggest, that match_result should explicitly mention,
which minimum iterator category is supported and if this does
not include random-access the existence of operator[] is
somewhat questionable.
2) The new "convenience" members
const_iterator cbegin() const; const_iterator cend() const; const_iterator crbegin() const; const_iterator crend() const;
should be added according to tables 80/81.
Proposed resolution:
Add the following members to the match_results synopsis after end() in 28.6.9 [re.results]
para 3:
const_iterator cbegin() const; const_iterator cend() const;
In section 28.6.9.5 [re.results.acc] change:
const_iterator begin() const; const_iterator cbegin() const;-7- Returns: A starting iterator that enumerates over all the sub-expressions stored in
*this.const_iterator end() const; const_iterator cend() const;-8- Returns: A terminating iterator that enumerates over all the sub-expressions stored in
*this.
[ Kona (2007): Voted to adopt proposed wording in N2409 except removing the entry in the table container requirements. Moved to Review. ]
[ Bellevue: Proposed wording now in the WP. ]