[section:stable_sort stable_sort]

[heading Prototype]

``
template<class RandomAccessRange>
RandomAccessRange& stable_sort(RandomAccessRange& rng);

template<class RandomAccessRange>
const RandomAccessRange& stable_sort(const RandomAccessRange& rng);

template<class RandomAccessRange, class BinaryPredicate>
RandomAccessRange& stable_sort(RandomAccessRange& rng, BinaryPredicate pred);

template<class RandomAccessRange, class BinaryPredicate>
const RandomAccessRange& stable_sort(const RandomAccessRange& rng, BinaryPredicate pred);
``

[heading Description]

`stable_sort` sorts the elements in `rng` into ascending order. `stable_sort` is guaranteed to be stable. The order is preserved for equivalent elements.

For versions of the `stable_sort` function without a predicate ascending order is defined by `operator<()` such that for all adjacent elements `[x,y]`, `y < x == false`.

For versions of the `stable_sort` function with a predicate, ascending order is designed by `pred` such that for all adjacent elements `[x,y]`, `pred(y,x) == false`.

[heading Definition]

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

[heading Requirements]

[*For versions of stable_sort without a predicate]

* `RandomAccessRange` is a model of the __random_access_range__ Concept.
* `RandomAccessRange` is mutable.
* `RandomAccessRange`'s value type is a model of the `LessThanComparableConcept`.
* The ordering relation on `RandomAccessRange`'s value type is a [*strict weak ordering], as defined in the `LessThanComparableConcept` requirements.

[*For versions of stable_sort with a predicate:]

* `RandomAccessRange` is a model of the __random_access_range__ Concept.
* `RandomAccessRange` is mutable.
* `BinaryPredicate` is a model of the `StrictWeakOrderingConcept`.
* `RandomAccessRange`'s value type is convertible to both of `BinaryPredicate`'s argument types.

[heading Complexity]

Best case: `O(N)` where `N` is `distance(rng)`.
Worst case: `O(N log(N)^2)` comparisons, where `N` is `distance(rng)`.

[endsect]