range/doc/reference/algorithm/partition.qbk

[/
    Copyright 2010 Neil Groves
    Distributed under the Boost Software License, Version 1.0.
    (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
/]
[section:partition partition]

[heading Prototype]

``
template<
    class ForwardRange,
    class UnaryPredicate
    >
typename range_iterator<ForwardRange>::type
partition(ForwardRange& rng, UnaryPredicate pred);

template<
    class ForwardRange,
    class UnaryPredicate
    >
typename range_iterator<const ForwardRange>::type
partition(const ForwardRange& rng, UnaryPredicate pred);

template<
    range_return_value re,
    class ForwardRange,
    class UnaryPredicate
    >
typename range_return<ForwardRange, re>::type
partition(ForwardRange& rng, UnaryPredicate pred);

template<
    range_return_value re,
    class ForwardRange,
    class UnaryPredicate
    >
typename range_return<const ForwardRange, re>::type
partition(const ForwardRange& rng, UnaryPredicate pred);
``

[heading Description]

`partition` orders the elements in `rng` based on `pred`, such that the elements that satisfy `pred` precede the elements that do not. In the versions that return a single iterator, the return value is the middle iterator. In the versions that have a configurable range_return, `found` corresponds to the middle iterator.


[heading Definition]

Defined in the header file `boost/range/algorithm/partition.hpp`

[heading Requirements]

* `ForwardRange` is a model of the __forward_range__ Concept. For C++ versions prior to C++11 the underlying std::partition requires Bidirectional Iterators, hence the requirement for older library versions is for a __bidirectional_range__.
* `UnaryPredicate` is a model of the `PredicateConcept`.
* `ForwardRange`'s value type is convertible to `UnaryPredicate`'s argument type.

[heading Complexity]

Linear. Exactly `distance(rng)` applications of `pred`, and at most `distance(rng) / 2` swaps.

[endsect]