[boost] New algorithm in Boost.Algorithm: "gather" -- looking for comments

Subject: [boost] New algorithm in Boost.Algorithm: "gather" -- looking for comments
From: Marshall Clow (mclow.lists_at_[hidden])
Date: 2013-01-21 19:49:54

I have committed a new algorithm named "gather" into Boost.Algorithm.

Actually, it's one I wrote for Sean Parent as part of ASL about five years ago, and it's the first (of hopefully many) of the bits oF ASL to be moved into boost.

Here's a summary:

gather() takes a collection of elements defined by a pair of iterators and moves the ones satisfying a predicate to them to a position (called the pivot) within the sequence. The algorithm is stable. The result is a pair of iterators that contains the items that satisfy the predicate.

template <typename ForwardIterator, typename Pred>
std::pair<ForwardIterator,ForwardIterator> 
gather ( ForwardIterator first, ForwardIterator last, ForwardIterator pivot, Pred pred );

Given an sequence containing:
    int [] arr = { 0 1 2 3 4 5 6 7 8 9 };

A call to gather ( arr, arr + 10, arr + 4, IsEven) will result in:

    1 3 0 2 4 6 8 5 7 9
        |---|-----|
      first |  second
          pivot

where first and second are the fields of the pair returned by the call.

-- Marshall

Marshall Clow     Idio Software   <mailto:mclow.lists_at_[hidden]>

A.D. 1517: Martin Luther nails his 95 Theses to the church door and is promptly moderated down to (-1, Flamebait).
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