Imported Upstream version 1.61.0

Change-Id: I96a1f878d1e6164f01e9aadd5147f38fca448d90
Signed-off-by: DongHun Kwak <dh0128.kwak@samsung.com>

1 files changed, 110 insertions, 0 deletions

diff --git a/boost/hana/fwd/sort.hpp b/boost/hana/fwd/sort.hpp
new file mode 100644
index 0000000000..785b28a568
--- /dev/null
+++ b/boost/hana/fwd/sort.hpp
@@ -0,0 +1,110 @@
+/*!
+@file
+Forward declares `boost::hana::sort`.
+
+@copyright Louis Dionne 2013-2016
+Distributed under the Boost Software License, Version 1.0.
+(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
+ */
+
+#ifndef BOOST_HANA_FWD_SORT_HPP
+#define BOOST_HANA_FWD_SORT_HPP
+
+#include <boost/hana/config.hpp>
+#include <boost/hana/core/when.hpp>
+#include <boost/hana/detail/nested_by_fwd.hpp>
+
+
+BOOST_HANA_NAMESPACE_BEGIN
+    //! Sort a sequence, optionally based on a custom `predicate`.
+    //! @ingroup group-Sequence
+    //!
+    //! Given a Sequence and an optional predicate (by default `less`), `sort`
+    //! returns a new sequence containing the same elements as the original,
+    //! except they are ordered in such a way that if `x` comes before `y` in
+    //! the sequence, then either `predicate(x, y)` is true, or both
+    //! `predicate(x, y)` and `predicate(y, x)` are false.
+    //!
+    //! Also note that the sort is guaranteed to be stable. Hence, if `x`
+    //! comes before `y` in the original sequence and both `predicate(x, y)`
+    //! and `predicate(y, x)` are false, then `x` will come before `y` in the
+    //! resulting sequence.
+    //!
+    //! If no predicate is provided, the elements in the sequence must all be
+    //! compile-time `Orderable`.
+    //!
+    //! Signature
+    //! ---------
+    //! Given a `Sequence` `S(T)`, a boolean `IntegralConstant` `Bool` and a
+    //! binary predicate \f$ T \times T \to Bool \f$, `sort` has the following
+    //! signatures. For the variant with a provided predicate,
+    //! \f[
+    //!     \mathtt{sort} : S(T) \times (T \times T \to Bool) \to S(T)
+    //! \f]
+    //!
+    //! for the variant without a custom predicate, `T` is required to be
+    //! `Orderable`. The signature is then
+    //! \f[
+    //!     \mathtt{sort} : S(T) \to S(T)
+    //! \f]
+    //!
+    //! @param xs
+    //! The sequence to sort.
+    //!
+    //! @param predicate
+    //! A function called as `predicate(x, y)` for two elements `x` and `y` of
+    //! the sequence, and returning a boolean `IntegralConstant` representing
+    //! whether `x` is to be considered _less_ than `y`, i.e. whether `x` should
+    //! appear _before_ `y` in the resulting sequence. More specifically,
+    //! `predicate` must define a [strict weak ordering][1] on the elements
+    //! of the sequence. When the predicate is not specified, this defaults
+    //! to `less`. In the current version of the library, the predicate has
+    //! to return an `IntegralConstant` holding a value convertible to a `bool`.
+    //!
+    //!
+    //! Syntactic sugar (`sort.by`)
+    //! ---------------------------
+    //! `sort` can be called in a third way, which provides a nice syntax
+    //! especially when working with the `ordering` combinator:
+    //! @code
+    //!     sort.by(predicate, xs) == sort(xs, predicate)
+    //!     sort.by(predicate) == sort(-, predicate)
+    //! @endcode
+    //!
+    //! where `sort(-, predicate)` denotes the partial application of
+    //! `sort` to `predicate`.
+    //!
+    //!
+    //! Example
+    //! -------
+    //! @include example/sort.cpp
+    //!
+    //! Benchmarks
+    //! ----------
+    //! <div class="benchmark-chart"
+    //!      style="min-width: 310px; height: 400px; margin: 0 auto"
+    //!      data-dataset="benchmark.sort.compile.json">
+    //! </div>
+    //!
+    //! [1]: http://en.wikipedia.org/wiki/Strict_weak_ordering
+#ifdef BOOST_HANA_DOXYGEN_INVOKED
+    constexpr auto sort = [](auto&& xs[, auto&& predicate]) {
+        return tag-dispatched;
+    };
+#else
+    template <typename S, typename = void>
+    struct sort_impl : sort_impl<S, when<true>> { };
+
+    struct sort_t : detail::nested_by<sort_t> {
+        template <typename Xs>
+        constexpr auto operator()(Xs&& xs) const;
+
+        template <typename Xs, typename Predicate>
+        constexpr auto operator()(Xs&& xs, Predicate&& pred) const;
+    };
+
+    constexpr sort_t sort{};
+#endif
+BOOST_HANA_NAMESPACE_END
+
+#endif // !BOOST_HANA_FWD_SORT_HPP