Imported Upstream version 1.61.0

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

1 files changed, 105 insertions, 0 deletions

diff --git a/boost/hana/fwd/slice.hpp b/boost/hana/fwd/slice.hpp
new file mode 100644
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+++ b/boost/hana/fwd/slice.hpp
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+/*!
+@file
+Forward declares `boost::hana::slice` and `boost::hana::slice_c`.
+
+@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_SLICE_HPP
+#define BOOST_HANA_FWD_SLICE_HPP
+
+#include <boost/hana/config.hpp>
+#include <boost/hana/core/when.hpp>
+
+#include <cstddef>
+
+
+BOOST_HANA_NAMESPACE_BEGIN
+    //! Extract the elements of a `Sequence` at the given indices.
+    //! @ingroup group-Sequence
+    //!
+    //! Given an arbitrary sequence of `indices`, `slice` returns a new
+    //! sequence of the elements of the original sequence that appear at
+    //! those indices. In other words,
+    //! @code
+    //!     slice([x1, ..., xn], [i1, ..., ik]) == [x_i1, ..., x_ik]
+    //! @endcode
+    //!
+    //! The indices do not have to be ordered or contiguous in any particular
+    //! way, but they must not be out of the bounds of the sequence. It is
+    //! also possible to specify the same index multiple times, in which case
+    //! the element at this index will be repeatedly included in the resulting
+    //! sequence.
+    //!
+    //!
+    //! @param xs
+    //! The sequence from which a subsequence is extracted.
+    //!
+    //! @param indices
+    //! A compile-time `Foldable` containing non-negative `IntegralConstant`s
+    //! representing the indices. The indices are 0-based, and they must all
+    //! be in bounds of the `xs` sequence. Note that any `Foldable` will
+    //! really do (no need for an `Iterable`, for example); the linearization
+    //! of the `indices` is used to determine the order of the elements
+    //! included in the slice.
+    //!
+    //!
+    //! Example
+    //! -------
+    //! @include example/slice.cpp
+#ifdef BOOST_HANA_DOXYGEN_INVOKED
+    constexpr auto slice = [](auto&& xs, auto&& indices) {
+        return tag-dispatched;
+    };
+#else
+    template <typename S, typename = void>
+    struct slice_impl : slice_impl<S, when<true>> { };
+
+    struct slice_t {
+        template <typename Xs, typename Indices>
+        constexpr auto operator()(Xs&& xs, Indices&& indices) const;
+    };
+
+    constexpr slice_t slice{};
+#endif
+
+    //! Shorthand to `slice` a contiguous range of elements.
+    //! @ingroup group-Sequence
+    //!
+    //! `slice_c` is simply a shorthand to slice a contiguous range of
+    //! elements. In particular, `slice_c<from, to>(xs)` is equivalent to
+    //! `slice(xs, range_c<std::size_t, from, to>)`, which simply slices
+    //! all the elements of `xs` contained in the half-open interval
+    //! delimited by `[from, to)`. Like for `slice`, the indices used with
+    //! `slice_c` are 0-based and they must be in the bounds of the sequence
+    //! being sliced.
+    //!
+    //!
+    //! @tparam from
+    //! The index of the first element in the slice.
+    //!
+    //! @tparam to
+    //! One-past the index of the last element in the slice. It must hold
+    //! that `from <= to`.
+    //!
+    //!
+    //! Example
+    //! -------
+    //! @include example/slice_c.cpp
+#ifdef BOOST_HANA_DOXYGEN_INVOKED
+    template <std::size_t from, std::size_t to>
+    constexpr auto slice_c = [](auto&& xs) {
+        return hana::slice(forwarded(xs), hana::range_c<std::size_t, from, to>);
+    };
+#else
+    template <std::size_t from, std::size_t to>
+    struct slice_c_t;
+
+    template <std::size_t from, std::size_t to>
+    constexpr slice_c_t<from, to> slice_c{};
+#endif
+BOOST_HANA_NAMESPACE_END
+
+#endif // !BOOST_HANA_FWD_SLICE_HPP