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Gather does not (in general) work with forward iterators, even though it does on some systems

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[SVN r83158]
This commit is contained in:
Marshall Clow
2013-02-25 22:31:52 +00:00
parent 5f45246c6c
commit ef16153353
3 changed files with 18 additions and 19 deletions
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16
doc/gather.qbk
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@ -22,13 +22,13 @@ There are two versions; one takes two iterators, and the other takes a range.
``
namespace boost { namespace algorithm {
template <typename ForwardIterator, typename Pred>
std::pair<ForwardIterator,ForwardIterator>
gather ( ForwardIterator first, ForwardIterator last, ForwardIterator pivot, Pred pred );
template <typename BidirectionalIterator, typename Pred>
std::pair<BidirectionalIterator,BidirectionalIterator>
gather ( BidirectionalIterator first, BidirectionalIterator last, BidirectionalIterator pivot, Pred pred );
template <typename ForwardRange, typename Pred>
std::pair<typename boost::range_iterator<ForwardRange>::type, typename boost::range_iterator<ForwardRange>::type>
gather ( ForwardRange &range, typename boost::range_iterator<ForwardRange>::type pivot, Pred pred );
template <typename BidirectionalRange, typename Pred>
std::pair<typename boost::range_iterator<const BidirectionalRange>::type, typename boost::range_iterator<const BidirectionalRange>::type>
gather ( const BidirectionalRange &range, typename boost::range_iterator<const BidirectionalRange>::type pivot, Pred pred );
}}
``
@ -53,11 +53,11 @@ where `first` and `second` are the fields of the pair that is returned by the ca
[heading Iterator Requirements]
`gather` work on all iterators except input or output iterators.
`gather` work on bidirectional iterators or better. This requirement comes from the usage of `stable_partition`, which requires bidirectional iterators. Some standard libraries (libstdc++ and libc++, for example) have implementations of `stable_partition` that work with forward iterators. If that is the case, then `gather` will work with forward iterators as well.
[heading Storage Requirements]
`gather` uses stable_partition, which will attempt to allocate temporary memory, but will work in-situ if there is none available.
`gather` uses `stable_partition`, which will attempt to allocate temporary memory, but will work in-situ if there is none available.
[heading Complexity]